[Federal Register Volume 81, Number 251 (Friday, December 30, 2016)]
[Rules and Regulations]
[Pages 96572-96701]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-30246]
[[Page 96571]]
Vol. 81
Friday,
No. 251
December 30, 2016
Part II
Department of Transportation
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Federal Aviation Administration
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14 CFR Parts 21, 23, 35, et al.
Revision of Airworthiness Standards for Normal, Utility, Acrobatic, and
Commuter Category Airplanes; Final Rule
Federal Register / Vol. 81 , No. 251 / Friday, December 30, 2016 /
Rules and Regulations
[[Page 96572]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Parts 21, 23, 35, 43, 91, 121, and 135
[Docket No.: FAA-2015-1621; Amdt. Nos. 21-100, 23-64, 35-10, 43-49, 91-
346, 121-378, and 135-136]
RIN 2120-AK65
Revision of Airworthiness Standards for Normal, Utility,
Acrobatic, and Commuter Category Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA amends its airworthiness standards for normal,
utility, acrobatic, and commuter category airplanes by replacing
current prescriptive design requirements with performance-based
airworthiness standards. These standards also replace the current
weight and propulsion divisions in small airplane regulations with
performance- and risk-based divisions for airplanes with a maximum
seating capacity of 19 passengers or less and a maximum takeoff weight
of 19,000 pounds or less. These airworthiness standards are based on,
and will maintain, the level of safety of the current small airplane
regulations, except for areas addressing loss of control and icing, for
which the safety level has been increased. The FAA adopts additional
airworthiness standards to address certification for flight in icing
conditions, enhanced stall characteristics, and minimum control speed
to prevent departure from controlled flight for multiengine airplanes.
This rulemaking is in response to the Congressional mandate set forth
in the Small Airplane Revitalization Act of 2013.
DATES: Effective August 30, 2017.
ADDRESSES: For information on where to obtain copies of rulemaking
documents and other information related to this final rule, see ``How
To Obtain Additional Information'' in the SUPPLEMENTARY INFORMATION
section of this document.
FOR FURTHER INFORMATION CONTACT: For technical questions concerning
this action, contact Lowell Foster, Regulations and Policy, ACE-111,
Federal Aviation Administration, 901 Locust St., Kansas City, MO 64106;
telephone (816) 329-4125; email [email protected].
SUPPLEMENTARY INFORMATION: All sections of part 23 contain revisions,
except the FAA did not make any changes to the following sections:
23.1457, Cockpit Voice Recorders, 23.1459, Flight Data Recorders, and
23.1529, Instructions for Continued Airworthiness. Sections 23.1459 and
23.1529 were changed to align the cross references with the rest of
part 23. The three sections otherwise remain unchanged relative to the
former regulations.
Authority for This Rulemaking
The FAA's authority to issue rules on aviation safety is found in
Title 49 of the United States Code. Subtitle I, Section 106 describes
the authority of the FAA Administrator. Subtitle VII, Aviation
Programs, describes in more detail the scope of the agency's authority.
This rulemaking is promulgated under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701. Under that section,
the FAA is charged with promoting safe flight of civil airplanes in air
commerce by prescribing minimum standards required in the interest of
safety for the design and performance of airplanes. This regulation is
within the scope of that authority because it prescribes new
performance-based safety standards for the design of normal, utility,
acrobatic, and commuter category airplanes.
Additionally, this rulemaking addresses the Congressional mandate
set forth in the Small Airplane Revitalization Act of 2013 (Pub. L.
113-53; 49 U.S.C. 44704 note) (SARA). Section 3 of SARA requires the
Administrator to issue a final rule to advance the safety and continued
development of small airplanes by reorganizing the certification
requirements for such airplanes under part 23 to streamline the
approval of safety advancements. SARA directs that the rule address
specific recommendations of the 2013 Part 23 Reorganization Aviation
Rulemaking Committee (Part 23 ARC).
Table of Contents
I. Overview of Final Rule
II. Background
A. Statement of the Problem
B. History
C. Summary of the NPRM
III. Discussion of the Public Comments and Final Rule
A. Delayed Effective Date
B. Overview of Comments
C. General Public Comments
D. Part 23, Airworthiness Standards
1. Legacy Rules
a. Cockpit Voice Recorders (Sec. 23.1457)/Flight Data Recorders
(Sec. 23.1459)
b. Instructions for Continued Airworthiness (Sec. 23.1529)
2. Subpart A--General
3. Subpart B--Flight
4. Subpart C--Structures
5. Subpart D--Design and Construction
6. Subpart E--Powerplant
7. Subpart F--Equipment
8. Subpart G--Flightcrew Interface and Other Information
E. Miscellaneous Amendments (Sec. Sec. 21.9, 21.17, 21.24,
21.35, 21.50, 21.101, Appendix E to Part 43, and 91.323)
1. Production of Replacement and Modification Articles (Sec.
21.9)
2. Designation of Applicable Regulations (Sec. 21.17)
3. Issuance of Type Certificate: Primary Category Aircraft
(Sec. 21.24)
4. Flight Tests (Sec. 21.35)
5. Instructions for Continued Airworthiness and Manufacturer's
Maintenance Manuals Having Airworthiness Limitations Sections (Sec.
21.50)
6. Designation of Applicable Regulations (Sec. 21.101)
7. Special Federal Regulations 23 (SFAR No. 23)
8. Altimeter System Test and Inspection (Appendix E to Part 43)
9. Increased Maximum Certification Weights for Certain Airplanes
Operated in Alaska (Sec. 91.323)
10. Additional Emergency Equipment (Sec. 121.310)
11. Additional Airworthiness Requirements (Sec. 135.169)
IV. Regulatory Notices and Analyses
A. Regulatory Evaluation Summary
B. Initial Regulatory Flexibility Determination
C. International Trade Impact Assessment
D. Unfunded Mandates Assessment
E. Paperwork Reduction Act
F. International Compatibility and Cooperation
G. Environmental Analysis
H. Regulations Affecting Intrastate Aviation in Alaska
V. Executive Order Determination
A. Executive Order 13132, Federalism
B. Executive Order 13211, Regulations That Significantly Affect
Energy Supply, Distribution, or Use
VI. How To Obtain Additional Information
A. Rulemaking Documents
B. Comments Submitted to the Docket
C. Small Business Regulatory Enforcement Fairness Act
Appendix 1 to the Preamble--Current to Proposed Regulations Cross-
Reference Table
Appendix 2 to the Preamble--Abbreviations and Acronyms Frequently
Used in This Document
I. Overview of Final Rule
This rule amends Title 14, Code of Federal Regulations (14 CFR)
part 23 by replacing current prescriptive design requirements with
performance-based airworthiness standards. It maintains the level of
safety associated with current part 23 except for areas addressing loss
of control and icing where a higher level of safety is established,
provides greater flexibility to applicants seeking certification of
their airplane designs, and facilitates
[[Page 96573]]
faster adoption of safety enhancing technology in type-certificated
products while reducing regulatory time and cost burdens for the
aviation industry and FAA. This final rule also reflects the FAA's
safety continuum philosophy,\1\ which balances an acceptable level of
safety with the societal burden of achieving that level of safety,
across the broad range of airplane types certificated under part 23.
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\1\ The FAA's safety continuum philosophy is that one level of
safety is not appropriate for all aviation.
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This final rule allows the use of consensus standards accepted by
the Administrator as a means of compliance to part 23's performance-
based regulations. The use of these FAA-accepted consensus standards as
a means of compliance will streamline the certification process.
However, consensus standards are one means, but not the only means, of
showing compliance to the performance-based standards of part 23.
Applicants, individuals, or organizations also have the option to
propose their own means of compliance as they do today.
In this final rule, the FAA adopts additional airworthiness
standards to address certification for flight in icing conditions and
enhanced stall characteristics to prevent inadvertent departure from
controlled flight. Manufacturers that choose to certify an airplane for
flight in Supercooled Large Drops (SLD) \2\ must demonstrate safe
operations in SLD conditions. For those manufacturers who choose
instead to certify an airplane with a prohibition against flight in SLD
conditions, this final rule will require a means for detecting SLD
conditions and showing the airplane can safely avoid or exit such
conditions.
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\2\ SLD conditions include freezing drizzle and freezing rain,
which contain drops larger than those specified in appendix C to
part 25, and can accrete aft of leading edge ice protection systems.
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This final rule adopts additional airworthiness standards to
address enhanced stall characteristics to prevent loss of control
(LOC). This final rule requires applicants to use new design approaches
and technologies to improve airplane stall characteristics and pilot
situational awareness to prevent LOC accidents.
Additionally, this final rule also streamlines the process for
design approval holders applying for a type design change, or for a
third party modifier applying for a supplemental type certificate
(STC), to incorporate new and improved equipment in part 23 airplanes.
The revised part 23 standards are much less prescriptive; therefore,
the certification process for modifications is simplified.
Certification of an amended type certificate (TC) or STC under this
final rule requires fewer special conditions or exemptions, lowering
costs and causing fewer project delays.
This final rule also revises 14 CFR part 21, ``Certification
Procedures for Products and Articles,'' to simplify the approval
process for low-risk articles. Specifically, it amends Sec. 21.9 to
allow FAA-approved production of replacement and modification articles
for airplanes certificated under part 23, using methods not listed in
Sec. 21.9(a). This will reduce constraints on the use of non-required,
low-risk articles, such as carbon monoxide detectors and weather
display systems.
Lastly, this final rule removes Special Federal Regulation No. 23
(SFAR No. 23) and contains conforming amendments to 14 CFR parts 21,
35, 43, 91, and 135. These conforming amendments align part 23
references to the part 23 rules contained in this final rule.
The FAA has analyzed the benefits and costs associated with this
rule. This rule responds to the Small Airplane Revitalization Act of
2013 (SARA) and to industry recommendations for performance-based
standards. This rule reduces new certification processing by
streamlining new certification processing. In addition, this rule
improves safety by adding stall characteristic, stall warnings, and
icing requirements. The following table summarizes the benefit and cost
analysis, showing the estimated cost is substantially less than the
benefits resulting from the combined value of the safety benefits and
the cost savings. The following table shows these results.
Estimated Benefits and Costs
[2015 $ Millions]
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Safety benefits +
Stall & spin + cost savings =
other costs total benefits
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Total........................... $0.8 + $3.1 = $3.9 $17.9 + $9.9 =
$27.8.
Present value at 7%............. $0.8 + $3.1 = $3.9 $6.1 + $4.9 =
$11.0.
Present value at 3%............. $0.8 + $3.1 = $3.9 $11.1 + $7.1 =
$18.3.
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* These numbers are subject to rounding error.
Accordingly, the FAA has determined that the rule will be cost
beneficial.
II. Background
A. Statement of the Problem
The range of airplanes certificated under part 23 is diverse in
terms of performance capability, number of passengers, design
complexity, technology, and intended use. Currently, certification
requirements of part 23 airplanes are determined by reference to a
combination of factors, including weight, number of passengers, and
propulsion type. The resulting divisions (i.e., normal, utility,
acrobatic, and commuter categories) historically were appropriate
because there was a clear relationship between the propulsion and
weight of the airplane and its associated performance and complexity.
Technological developments have altered the dynamics of that
relationship. For example, high-performance and complex airplanes now
exist within the weight range that historically was occupied only by
light and simple airplanes. The introduction of high-performance,
lightweight airplanes required subsequent amendments of part 23 to
include more stringent and demanding standards--often based on the part
25 requirements for larger transport category airplanes--to ensure an
adequate level of safety for airplanes under part 23. The unintended
result is that some of the more stringent and demanding standards for
high-performance airplanes now apply to the certification of simple and
low-performance airplanes. Because of this increased complexity, it
takes excessive time and resources to certify new part 23 airplanes.
B. History
In 2008, the FAA initiated the Part 23 Certification Process Study
(CPS) \3\ to review part 23. Collaborating with industry, the CPS
team's challenge was
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to determine the future of part 23, given products at the time and
anticipated future products. The team identified opportunities for
improvements by examining the entire life cycle of a part 23 airplane,
including operations and maintenance. The CPS recommended reorganizing
part 23 using criteria focused on performance and design complexity.
The CPS also recommended the FAA implement general airworthiness
requirements, with the means of compliance defined in industry
consensus standards.
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\3\ See docket number FAA-2015-1621.
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In 2010, following the publication of the CPS, the FAA held a
series of public meetings to seek feedback concerning the findings and
recommendations. Overall, the feedback was supportive of, and in some
cases augmented, the CPS recommendations.
One notable difference between the CPS findings and the public
feedback was the public's request that the FAA revise part 23
certification requirements for simple, entry-level airplanes. Over the
past two decades, part 23 standards have become more complex as
industry has generally shifted towards correspondingly complex, high-
performance airplanes. This transition has placed an increased burden
on applicants seeking to certificate smaller, simpler airplanes. Public
comments requested that the FAA focus on reducing the costs and time
burden associated with certificating small airplanes by restructuring
the requirements based on risk. The risk exposure for most simple
airplane designs is typically low, because of the small number of
occupants.
On August 15, 2011, the Administrator chartered the Part 23 ARC to
consider the following CPS recommendations:
Recommendation 1.1.1--Reorganize part 23 based on airplane
performance and complexity, rather than the existing weight and
propulsion divisions.
Recommendation 1.1.2--Certification requirements for part
23 airplanes should be written on a broad, general, and progressive
level, segmented into tiers based on complexity and performance.
The ARC's recommendations took into account the Federal Aviation
Modernization and Reform Act of 2012 (Pub. L. 112-95) (FAMRA), which
requires the Administrator, in consultation with the aviation industry,
to assess the airplane certification and approval process. The purpose
of the ARC's assessment was to develop recommendations for streamlining
and reengineering the certification process to improve efficiency,
reduce costs, and ensure the Administrator can conduct certifications
and approvals in a manner that supports and enables the development of
new products and technologies and the global competitiveness of the
United States aviation industry.\4\ FAMRA also directed the
Administrator to consider the recommendations from the CPS.\5\
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\4\ Public Law 112-95, section 312(c).
\5\ Public Law 112-95, section 312(b)(6).
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ARC membership represented a broad range of stakeholder
perspectives, including U.S. and international manufacturers, trade
associations, and foreign civil aviation authorities (FCAAs).
The ARC noted the prevailing view within industry was that the only
way to reduce the program risk, or business risk, associated with the
certification of new airplane designs was to avoid novel design
approaches and testing methodologies. Under existing part 23, the
certification of new and innovative products frequently requires the
FAA's use of equivalent level of safety (ELOS) findings, special
conditions, and exemptions. These take time, resulting in uncertainty
and high project costs. The ARC emphasized that although industry needs
to develop new airplanes designed to use new technology, current
certification costs inhibit the introduction of new technology. The ARC
identified prescriptive certification requirements as a major barrier
to installing safety[hyphen]enhancing modifications in the existing
fleet and to producing newer, safer airplanes.
The ARC also examined the harmonization of certification
requirements between the FAA and FCAAs, and the potential for such
harmonization to improve safety while reducing costs. Adopting
performance-based safety regulations that facilitate international
harmonization, coupled with internationally accepted means of
compliance, could result in both significant cost savings and the
enabling of safety-enhancing equipment installations. The ARC
recommended that internationally accepted means of compliance should be
reviewed and voluntarily accepted by the appropriate aviation
authorities, in accordance with a process established by those
authorities. Although each FCAA would be capable of rejecting all or
part of any particular means of compliance, the intent would be to have
FCAA participation in the creation of the means of compliance to ease
acceptance of the means of compliance.
Based on the ARC recommendations and in response to FAMRA, the FAA
initiated rulemaking on September 24, 2013. Subsequently, on November
27, 2013, Congress passed the SARA, which requires the FAA to issue a
final rule revising the certification requirements for small airplanes
by--
Creating a regulatory regime that will improve safety and
decrease certification costs;
Setting safety objectives that will spur innovation and
technology adoption;
Replacing prescriptive rules with performance-based
regulations; and
Using consensus standards to clarify how safety objectives
may be met by specific designs and technologies.
The FAA has determined that the performance-based-standards
component of this final rule complies with the FAMRA and the SARA
because it will improve safety, reduce regulatory compliance costs, and
spur innovation and the adoption of new technology. This final rule
will replace the weight-and propulsion-based prescriptive airworthiness
standards in part 23 with performance- and risk-based airworthiness
standards for airplanes with a maximum seating capacity of 19
passengers or less and a maximum takeoff weight of 19,000 pounds or
less. The standards will maintain or increase the level of safety
associated with the current part 23, while also facilitating the
adoption of new and innovative technology in general aviation (GA)
airplanes.
C. Summary of the NPRM
On March 7, 2016, the FAA issued a notice of proposed rulemaking
(NPRM) proposing to revise part 23 in response to the SARA.\6\ In the
NPRM, the FAA proposed to--
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\6\ See 81 FR 13452.
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Establish a performance-based regulatory regime; and
Add new certification standards for LOC and icing.
On May 3-4, 2016, the FAA held a public meeting to discuss the
NPRM, hear the public's questions, address any confusion, and obtain
information relevant to the final rule under consideration.\7\ The
meeting notice and the transcripts are both in the docket. The FAA
considered comments made at the public meeting along with comments
submitted by the public to docket number FAA-2015-1621.
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\7\ See 81 FR 20264.
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The comment period closed on May 13, 2016.
III. Discussion of the Public Comments and Final Rule
A. Delayed Effective Date
The FAA has decided it is necessary to delay the effective date of
this final
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rule for 8 months, until August 30, 2017.
This final rule establishes a new performance-based system that
will require additional training for both FAA and industry engineers,
as noted in the NPRM regulatory evaluation summary. Several commenters
expressed concern with the need for additional training and guidance in
order to implement the new performance-based standards. The FAA finds
that a delayed effective date will alleviate these concerns.
Delaying the effective date will provide the FAA time to conduct
the training necessary to implement this rule in a consistent manner.
Additionally, the delayed effective date provides the FAA with
sufficient time to develop guidance materials to ensure the FAA and
industry have sufficient information to implement the new performance-
based standards consistently and correctly. Furthermore, while
compliance with part 23, amendment 23-62 will remain a means of
compliance with this final rule, a delayed effective date will allow
industry time to develop new means of compliance and will facilitate
the development of harmonized means of compliance among the FAA,
industry, FCAAs.
B. Overview of Comments
The FAA received 692 comments. Of the 692 comments, individuals
submitted approximately 30 comments and industry and other foreign
authorities submitted the remaining comments. The General Aviation
Manufacturers Association (GAMA); Aircraft Electronics Association
(AEA); Experimental Aircraft Association (EAA); and Aircraft Owners &
Pilots Association (AOPA) (hereafter ``the Associations'') collected
comments from their membership and presented these jointly. The vast
majority of commenters overwhelmingly supported the proposed changes
and provided constructive feedback so the FAA could clarify the safety
intent in various sections of this rule.
The FAA did not receive comments on the proposed changes to the
following sections. These sections are adopted as proposed, and the
explanations for the changes from the former regulations are contained
in the NPRM.
Sec. 23.1515, ``Instructions for continued airworthiness''
Sec. 35.1, ``Applicability''
Sec. 35.37, ``Fatigue limits and evaluation''
Sec. 91.205, ``Powered civil aircraft with standard category
U.S. airworthiness certificates: Instrument and equipment
requirements''
Sec. 91.313, ``Restricted category civil aircraft: Operating
limitations''
Sec. 91.531, ``Second in command requirements''
Sec. 121.310, ``Additional Emergency equipment''
Sec. 135.169, ``Additional airworthiness requirements''
C. General Public Comments
1. Rule Organization and Numbering
In the NPRM, the FAA proposed a new organization and numbering
scheme for part 23. Appendix 1 to the NPRM preamble contains a cross-
reference table detailing how the current regulations are addressed in
the proposed part 23 regulations.
The FAA received several comments suggesting the FAA change the
regulation numbering scheme for proposed part 23. Commenters expressed
concern that confusion or undue complexity would result because the
proposed part 23 regulations do not correlate by section number to the
former part 23 regulations. Commenters also noted that certain sections
of the proposed rule would have shared the same section numbers as
former part 23 regulations but would have contained completely
different content.
To avoid confusion, EASA proposed a new numbering system for
Certification Specification 23 (CS 23) \8\ and part 23, where the new
regulations would not share numbers with the former regulations to
emphasize the difference in content between these two sets of
regulations. EASA suggested the numbering for subpart A begin at Sec.
23.2000, for subpart B at Sec. 23.2100, and so on, with the
regulations numbers increasing by incremental steps of 5, i.e.,
Sec. Sec. 23.2005, 23.2010, and so on.
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\8\ EASA published an Advance Notice of Proposed Amendment (A-
NPA) 2015-06 on March 27, 2015, which set forth EASA's concept for
its proposed reorganization of Certification Specification 23 (CS-
23). EASA also published a Notice of Proposed Amendment (NPA) 2016-
05 on June 27, 2016.
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The FAA agrees that the proposed numbering scheme would have caused
confusion and undue complexity. The FAA has considered EASA's
recommended new numbering scheme for part 23 and adopts it in the final
rule. This recommendation harmonizes the numbering of part 23 and CS 23
and provides new part 23 with a unique numbering scheme to avoid any
confusion with former part 23. The FAA has determined the new numbering
scheme also alleviates concerns about situations in which a
certification basis would contain a former part 23 rule and a new part
23 rule sharing the same section number, but different subject-matter.
The FAA did not propose to change or renumber Sec. Sec. 23.1457,
23.1459, and 23.1529; therefore, these sections remain as legacy rules
in the new part 23.\9\
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\9\ The prescriptive requirements of Sec. Sec. 23.1457,
23.1459, and 23.1529 are consistent in substance and numbering
across parts 23, 25, 27, and 29.
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Air Tractor, Inc. (Air Tractor) suggested that the FAA retain
former part 23, amendment 23-62, and create a new part (e.g., part 22)
for the proposed performance-based regulations. It also suggested that
proposed appendix A should remain appendix G to avoid over-writing
existing appendix A.
The FAA notes Air Tractor's recommendation to retain former part 23
and to create a new 14 CFR part for the proposed regulations. However,
this regulation is a rewrite of part 23 by replacing the prescriptive
design requirements with performance-based airworthiness requirements,
and the creation of an additional part would result in unnecessary
confusion and overlap. However, the FAA will accept the use of the
prescriptive means of compliance contained in former part 23 as one way
to show compliance with new part 23. This will not apply to the
sections containing new requirements, such as Sec. Sec. 23.2135,
23.2150, and 23.2165 (proposed in the NPRM as Sec. Sec. 23.200,
23.215, and 23.230). In addition, the FAA is issuing a policy statement
identifying the means by which the FAA has addressed errors, findings
of ELOS to various provisions of former part 23, and special
conditions. This policy should be considered in defining means of
compliance based on former part 23.
The FAA also considered Air Tractor's recommendation to not rename
appendix G. As proposed in the NPRM, the FAA removed appendixes A
through F. However, the FAA is renaming former appendix G to part 23,
as appendix A to part 23--Instructions for Continued Airworthiness,
because this final rule is a complete rewrite and beginning the
appendices at G instead of A may cause confusion.
The following table identifies each requirement, its previously-
proposed section in the NPRM, and its corresponding section in this
final rule.
[[Page 96576]]
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NPRM Title Final rule
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Subpart A--General
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Sec. 23.1............................. Applicability and definitions Sec. 23.2000.
Sec. 23.5............................. Certification of normal Sec. 23.2005.
category airplanes.
Sec. 23.10............................ Accepted means of compliance. Sec. 23.2010.
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Subpart B--Flight
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Performance
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Sec. 23.100........................... Weight and center of gravity. Sec. 23.2100.
Sec. 23.105........................... Performance data............. Sec. 23.2105.
Sec. 23.110........................... Stall speed.................. Sec. 23.2110.
Sec. 23.115........................... Takeoff performance.......... Sec. 23.2115.
Sec. 23.120........................... Climb requirements........... Sec. 23.2120.
Sec. 23.125........................... Climb information............ Sec. 23.2125.
Sec. 23.130........................... Landing...................... Sec. 23.2130.
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Flight Characteristics
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Sec. 23.200........................... Controllability.............. Sec. 23.2135.
Sec. 23.205........................... Trim......................... Sec. 23.2140.
Sec. 23.210........................... Stability.................... Sec. 23.2145.
Sec. 23.215........................... Stall characteristics, stall Sec. 23.2150.
warning, and spins.
Sec. 23.220........................... Ground and watering handling Sec. 23.2155.
characteristics.
Sec. 23.225........................... Vibration, buffeting, and Sec. 23.2160.
high-speed characteristics.
Sec. 23.230........................... Performance and flight Sec. 23.2165.
characteristics requirements
for flight in icing
conditions.
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Subpart C--Structures
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Sec. 23.300........................... Structural design envelope... Sec. 23.2200.
Sec. 23.305........................... Interaction of systems and Sec. 23.2205.
structures.
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Structural Loads
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Sec. 23.310........................... Structural design loads...... Sec. 23.2210.
Sec. 23.315........................... Flight load conditions....... Sec. 23.2215.
Sec. 23.320........................... Ground and water load Sec. 23.2220.
conditions.
Sec. 23.325........................... Component loading conditions. Sec. 23.2225.
Sec. 23.330........................... Limit and ultimate loads..... Sec. 23.2230.
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Structural Performance
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Sec. 23.400........................... Structural strength.......... Sec. 23.2235.
Sec. 23.405........................... Structural durability........ Sec. 23.2240.
Sec. 23.410........................... Aeroelasticity............... Sec. 23.2245.
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Design
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Sec. 23.500........................... Structural design............ Sec. 23.2250.
Sec. 23.505........................... Protection of structure...... Sec. 23.2255.
Sec. 23.510........................... Materials and processes...... Sec. 23.2260.
Sec. 23.515........................... Special factors of safety.... Sec. 23.2265.
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Structural Occupant Protection
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Sec. 23.600........................... Emergency conditions......... Sec. 23.2270.
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Subpart D--Design and Construction
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Sec. 23.700........................... Flight control systems....... Sec. 23.2300.
Sec. 23.705........................... Landing gear systems......... Sec. 23.2305.
Sec. 23.710........................... Buoyancy for seaplanes and Sec. 23.2310.
amphibians.
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Occupant System Design and Protection
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Sec. 23.750........................... Means of egress and emergency Sec. 23.2315.
exits.
Sec. 23.755........................... Occupant physical environment Sec. 23.2320.
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Fire and High-Energy Protection
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Sec. 23.800........................... Fire protection.............. Sec. 23.2325.
Sec. 23.805........................... Fire protection in designated Sec. 23.2330.
fire zones and adjacent
areas.
Sec. 23.810........................... Lightning protection......... Sec. 23.2335.
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[[Page 96577]]
Subpart E--Powerplant
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Sec. 23.900........................... Powerplant installation...... Sec. 23.2400.
Sec. 23.905........................... Propeller installation....... not adopted.
Sec. 23.910........................... Powerplant installation Sec. 23.2410.
hazard assessment.
Sec. 23.915........................... Automatic power or thrust Sec. 23.2405.
control systems.
Sec. 23.920........................... Reversing systems............ Sec. 23.2420.
Sec. 23.925........................... Powerplant operational Sec. 23.2425.
characteristics.
Sec. 23.930........................... Fuel system.................. Sec. 23.2430.
Sec. 23.935........................... Powerplant induction and Sec. 23.2435.
exhaust systems.
Sec. 23.940........................... Powerplant ice protection.... Sec. 23.2415.
Sec. 23.1000.......................... Powerplant fire protection... Sec. 23.2440.
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Subpart F--Equipment
----------------------------------------------------------------------------------------------------------------
Sec. 23.1300.......................... Airplane level systems Sec. 23.2500.
requirements.
Sec. 23.1305(a)(1).................... Function and installation.... Sec. 23.2505
Sec. 23.1305(a)(3),(b),(c)............ Installation and operation... Sec. 23.2605.
Sec. 23.1310.......................... Flight, navigation, and Sec. 23.2615.
powerplant instruments.
Sec. 23.1315.......................... Equipment, systems, and Sec. 23.2510.
installations.
Sec. 23.1320.......................... Electrical and electronic Sec. 23.2515.
system lightning protection.
Sec. 23.1325.......................... High-intensity Radiated Sec. 23.2520.
Fields (HIRF) protection.
Sec. 23.1330.......................... System power generation, Sec. 23.2525.
storage, and distribution.
Sec. 23.1335.......................... External and cockpit lighting Sec. 23.2530.
Sec. 23.1400.......................... Safety equipment............. Sec. 23.2535.
Sec. 23.1405.......................... Flight in icing conditions... Sec. 23.2540.
Sec. 23.1410.......................... Pressurized system elements.. Sec. 23.2545.
Sec. 23.755(a)(3)..................... Equipment containing high- Sec. 23.2550.
energy rotors.
Sec. 23.1457.......................... Cockpit voice recorders...... Sec. 23.1457.
Sec. 23.1459.......................... Flight data recorders........ Sec. 23.1459.
----------------------------------------------------------------------------------------------------------------
Subpart G--Flightcrew Interface and Other Information
----------------------------------------------------------------------------------------------------------------
Sec. 23.1500.......................... Flightcrew interface......... Sec. 23.2600.
New..................................... Installation and operation... Sec. 23.2605.
Sec. 23.1505.......................... Instrument markings, control Sec. 23.2610.
markings and placards.
New..................................... Flight, navigation, and Sec. 23.2615.
powerplant instruments.
Sec. 23.1510.......................... Airplane flight manual....... Sec. 23.2620.
Sec. 23.1515.......................... Instructions for continued Sec. 23.1529.
airworthiness.
----------------------------------------------------------------------------------------------------------------
Appendices
----------------------------------------------------------------------------------------------------------------
Appendix A to Part 23................... Instructions for Continued Appendix A to Part 23.
Airworthiness.
----------------------------------------------------------------------------------------------------------------
2. Level of Safety
In the NPRM, the FAA proposed amendments to part 23 to create an
adaptive regulatory environment that could quickly embrace new safety-
enhancing technologies and potentially increase the level of safety.
Wipaire, Inc. (Wipaire) viewed the proposal as allowing new and
emerging technologies an effective means of certification, but one
which offered little economic and certification relief to currently-
established methods and technologies.
An individual commenter noted that the proposal would allow
industry to push new techniques, materials, procedures, and targets
without being hindered by the prescriptive requirements of former part
23. However, the commenter stated that the proposal could allow subpar
designs to exist before the data suggests a failure in compliance.
The National Transportation Safety Board (NTSB), while recognizing
consensus standards provide ``a collaborative framework for standards
development,'' commented on a situation where, in its view, consensus
standards did not provide adequate protection from catastrophic
aerodynamic flutter. The NTSB expressed concern that design standards
important for safety consideration may be overlooked, and it encouraged
the FAA to refine its methodology.
The FAA understands the concerns over the level of safety required
by the performance standards. However, by leveraging the expertise of
consensus standards organizations and FAA specialists in determining
whether those standards are acceptable, those means of compliance
should provide at least the same level of safety as under the former
process.
The FAA will continue to be responsible for determining that
proposed airplane designs meet the applicable standards and ensuring
that the proposed standards provide at least the same level of safety
as did the former standards. Under new part 23, the first time an
applicant presents a new proposal for a means of compliance, the FAA
will require sufficient time and resources to determine whether it
does, in fact, meet the objectives of those standards. This is the same
process as under the former prescriptive standards. However, once the
proposed means of compliance is determined to meet these standards, the
approval process becomes more efficient. The FAA will no longer be
required to issue special conditions (or other formal processes) to
approve the means of compliance each time it is proposed, but can
accept those means of compliance immediately as it is proposed.
[[Page 96578]]
3. Accommodating Hybrid and Electric Propulsion
In the NPRM, the FAA recognized that historical general design and
performance assumptions may not be valid today. The FAA noted that
former part 23 did not account for airplanes equipped with new
technologies, such as electric propulsion systems, which may have
features entirely different from piston and turbine engines. The FAA
therefore proposed new regulations based on airplane performance and
potential risk.
With respect to allowing new technologies, the Associations and
Zee.Aero Inc. (Zee) were particularly concerned with the accommodation
of alternative engines. The Associations stated that hybrid and
electric propulsion is one of the near-term significant technological
developments which absolutely must be accommodated into the new part 23
regulations structure.
Zee also commented on the advancements in hybrid and electric
propulsion. Zee noted that new hybrid propulsion, control, and airframe
configurations are already beginning to blur the lines between the
traditional airplane categories. Zee questioned whether the FAA intends
to continue to maintain strict airplane categories and create a new
``category'' every time a new unique category configuration emerges.
Lastly, Zee noted that Sec. 21.17(b) currently captures such airplane
and wondered whether that section would become the norm for those
cases.
The regulations adopted in this final rule do allow for alternative
types of propulsion. The FAA does not intend to continue to use Sec.
21.17(b) for unique category airplanes. The FAA plans to shift these
unique airplanes from Sec. 21.17(b) to part 23. Unique airplane that
more closely resemble rotorcraft may be treated differently.
4. Impact of Rule on FAA Engineers and Designated Engineering
Representatives (DERs)
In the NPRM, the FAA proposed changes to part 23 that would
eliminate the workload of exemptions, special conditions, and ELOS
findings necessary to certificate new part 23 airplanes. The NPRM did
not specifically address the role of Designated Engineering
Representatives (DERs) in the proposed process.
Several commenters addressed the impacts of the proposed rule
changes on FAA engineers and DERs.
NetJets Association of Shared Aircraft Pilots (NJASAP) and Kestrel
Aircraft Company (Kestrel) expressed concern that the process intended
to streamline technological adoption may significantly increase the
FAA's workload. Kestrel contended the increased workload for FAA
engineers will create certification bottlenecks at the Aircraft
Certification Offices (ACOs) as their staff work to understand and
implement the changes.
The FAA recognizes workload during the transition to the new system
may increase temporarily for industry and the FAA. Under the former
part 23, the FAA had a workload of exemptions, special conditions, and
ELOS findings necessary to certificate new part 23 airplanes. However,
the FAA has determined in the long term, the workload for industry and
the FAA will be less than the workload under former part 23. As
estimated in the NPRM's regulatory evaluation summary, there will be
savings resulting from streamlining the certification process by
reducing the issuance special conditions, exemptions, and ELOS
findings. The NPRM and final rule regulatory evaluation provides
details for these cost savings and the methodology the FAA employed to
estimate the cost savings.
Other commenters expressed concerns about how the DER process will
fit in with the new regulations. Air Tractor questioned whether DERs
will find compliance with accepted means of compliance. The National
Air Traffic Controls Association (NATCA) asked whether DERs will issue
acceptance statements or approvals. NATCA asked how the FAA will change
the designee policy and asked whether the FAA intends to accept or
approve the standards. Textron Aviation (Textron) requested
clarification of the FAA's transition plan regarding Organization
Designation Authorization (ODA) and DER delegations, in particular
regarding continuity of authority from the old amendments to the new.
In response to concerns regarding the role of the DERs and ODA
engineers, the FAA is developing transition training for the FAA
engineers, ODA engineers, and the DERs. The FAA is also reviewing the
relevant orders and policies for needed changes, but does not expect
changes to the basic certification process as the FAA engineers and
industry designees will still be responsible for finding compliance to
the requirements in part 23. Furthermore, the FAA is developing a
change management plan that will include formal training for both FAA
engineers and staff and industry designees. Under existing policies and
processes, designees must demonstrate the capability to make correct
determinations of compliance with particular regulations before they
are authorized to do so. This is unchanged by this rule. To the extent
an applicant uses previously-accepted methods of compliance for which
the designee has demonstrated such capability, the FAA may delegate
compliance findings. If an applicant is proposing a new method of
compliance, the designee's authority may be limited to only
recommending a finding of compliance.
Kestrel contended standardization among ACOs would likely decrease
due to lack of clearly-defined criteria and that divergent
certification expectations would exacerbate existing issues of
inconsistent application and interpretation of requirements.
While this final rule adopts high-level performance standards, the
FAA intends to ensure consistent application through the process for
determining the acceptability of their means of compliance. The FAA's
certification standards staff will determine whether proposed consensus
standards are acceptable and, if so, will publish a notice of
availability of those standards in the Federal Register. The FAA will
also maintain a publicly-available list of consensus standards that
have been found to be acceptable as methods of compliance.\10\ For
methods of compliance submitted by individual applicants, the FAA will
continue to use the existing issue paper process, which includes full
coordination with the standards staff to ensure standardization. The
FAA recognizes the importance of having an internationally accepted
means of compliance for part 23 airplanes. The FAA believes once there
are internationally accepted means of compliance available,
manufacturers may be reluctant to bypass these harmonized means to
develop their own, unless they have an innovative process or new
technology not already addressed. In either case, the FAA's processes
should ensure flexibility and transparency to the extent permitted
without violating proprietary interests of entities developing methods
of compliance. Allowing for innovation and new technology is a major
goal of this rule.
---------------------------------------------------------------------------
\10\ As discussed in the NPRM, the FAA will have a similar
process for determining whether a previous acceptance of a method of
compliance should be rescinded, based on new information or service
experience.
---------------------------------------------------------------------------
In response to NTSB's concerns about new technology, the FAA finds
that shifting compliance emphasis to industry consensus standards is
critical to ensuring the safety of new
[[Page 96579]]
technology. This shift will allow the FAA to leverage technical experts
from across the aerospace industry and from outside the traditional
aerospace industry to develop standards for new technologies.\11\
---------------------------------------------------------------------------
\11\ National Transportation Safety Board, Auxiliary Power Unit
Battery Fire, Japan Airlines Boeing 787-8, JA829J, Boston,
Massachusetts, January 7, 2013, AIR-14/01 (Washington, DC: NTSB,
2014).
---------------------------------------------------------------------------
5. Necessity of Training
In the NPRM's regulatory evaluation, the FAA assumed that FAA and
industry part 23 certification engineers would require additional
training as a result of this rule.
Some commenters expressed concern with training needs required by a
new system. Kestrel noted the proposed rule would increase the workload
of DERs, primarily because they will require additional training and
FAA coordination to ensure proper understanding and implementation of
the new certification process. NATCA noted the significant changes to
part 23 will necessitate training of all FAA engineers, DERs, and ODA
engineers. In particular, NATCA said designees and ODAs cannot be
authorized to find compliance to part 23 until trained or demonstrated
competence. NATCA recommended the FAA amend its delegation and ODA
policy documents to reflect the changes to part 23 and implement
training as soon as possible.
The NTSB expressed concern about increased demand on FAA engineers
to evaluate new technologies as a result of the proposed changes to
part 23. It suggested the FAA may face challenges similar to those
encountered with the certification of the lithium-ion batteries in the
Boeing 787, including insufficient guidance and education to ensure
compliance with applicable requirements. The NTSB pointed to several
safety recommendations it issued to the FAA in the wake of a lithium-
ion battery incident in a Boeing 787 in 2013, which centered around
developing and providing adequate written guidance and training to
certification engineers.
The FAA agrees guidance and training are necessary and has delayed
the effective date of this rule in order to complete the training
development and implementation for ACOs, DERs, and industry. The FAA
will continue to review orders and policies for needed changes.
6. Need for Revised or New Agency Guidance and Directives
The FAA proposed Advisory Circular (AC) 23.10,\12\ Accepted Means
of Compliance, to provide applicants guidance on the process of
submitting proposed means of compliance to the FAA for consideration by
the Administrator. The FAA also indicated in the NPRM that it would
provide guidance as it determines what satisfies the performance-based
standards.
---------------------------------------------------------------------------
\12\ See docket number FAA-2015-1621.
---------------------------------------------------------------------------
NATCA requested the FAA publish new or revised Orders and policy
documents for public review and comment prior to the issuance of the
final rule. For example, how would a certification engineer recognize
what is a ``good compliance showing'' to a new part 23 requirement and
how would that engineer explain the compliance showing to an authorized
representative of the Administrator. Also, how would a certification
engineer minimize or avoid allegations from an applicant that the
engineer is being inequitable in the application of the new part 23
requirement compared to how the requirements have been applied to other
applicants.
NATCA noted applicants often use legal processes for approval of
type design changes to obtain less expensive or extensive certification
requirements for a design proposal, and that the ``number of seats''
has been used previously to finesse operating requirements
applicability. NATCA questioned whether the FAA will permit this under
new part 23 as established by the airplane certification levels and
whether there will be any check or limitation or safety judgment made
on this potential use of new part 23. NATCA requested the FAA publish
an Order or policy addressing this issue.
One commenter was concerned the FAA will eventually leave the task
of developing ACs for means of compliance to consensus bodies and
individual applicants and opposed a system where public domain guidance
must be purchased from a private entity. The commenter suggested that
even if the FAA decides to discontinue updating its guidance, it should
retain control and continue to permit the use of its existing guidance
as well as provide a list of guidance with its status.
The FAA agrees with NATCA that updated guidance is needed and is in
the process of reviewing current orders and policies and will use
existing processes to implement those changes. The FAA also recognizes
the potential that some applicants will attempt to ``finesse'' the
applicability of requirements for higher airplane certification levels
by limiting the maximum passenger capacity of their proposed designs.
This potential is inherent in any attempt to establish different levels
of safety based on the concept of the ``safety continuum.'' The
disincentive for such finessing is the reduction of functionality, and
therefore profitability, of the resulting design.
The FAA will continue to use all applicable ACs associated with
part 23. Applicants will need to use the cross-reference table in this
final rule preamble because the ACs will continue to reference the
former section numbers. The FAA will expand the guidance in these ACs
to better address the range of part 23 airplanes identified in industry
consensus standard documents. The FAA has no plans to cancel the
current ACs because they are still needed for older airplane
modifications; therefore, the applicable ACs will still be available to
applicants. Consensus standards bodies will develop means of compliance
with the new regulations. The FAA will continue to develop ACs, as
needed, to provide guidance to the public on what means of compliance
would be acceptable. These functions are distinct, but complementary.
7. Inconsistent Language
In the NPRM, the FAA proposed to remove prescriptive design
requirements and replace them with performance-based airworthiness
standards.
Some commenters expressed concern with the lack of concreteness in
the proposed regulations. Transport Canada stated the standards
required the definition of a safety objective to clarify the meaning of
some terms. The National Agricultural Aircraft Association (NAAA) was
concerned the proposed regulations could result in inconsistent
interpretations. NATCA viewed the rules as too ``stripped down'' for
non-experienced people and commented that the use of ``vague'' terms
would make it difficult to apply the new rules. Air Tractor contended
the proposed rules consolidated existing requirements into fewer
``general'' or ``vaguely'' worded rules.
Other commenters addressed perceived inconsistencies in the
language of the proposed revisions to part 23. The Associations noted
some of the proposed rules focused on the applicant while others
focused on the airplane.\13\ These commenters observed
[[Page 96580]]
it is important that the language of part 23 does not contradict part
21, which establishes the procedures for obtaining design approvals.
The commenters recommended the FAA adopt the regulatory language used
elsewhere in the airworthiness standards, which impose requirements on
the airplane design.
---------------------------------------------------------------------------
\13\ For example, some of the proposed rules stated ``the
applicant must show'' or ``the applicant must demonstrate,'' while
others stated ``the airplane must.''
---------------------------------------------------------------------------
The FAA recognizes the final rule uses high-level performance
standards, and in some cases, the requirements are not tightly
specified. However, the FAA finds that tight specification is not
needed as this final rule is consistent with the safety objectives of
the former prescriptive standards. The cross-reference table in this
final rule identifies what sections of this final rule are intended to
meet the safety objectives of the former regulations. Because this
final rule is intended to achieve at least the same level of safety as
the former regulations, this comparison may be used as a guide to the
various levels of acceptable risk associated with each section.
In response to the comment raised by GAMA and others, part 21
imposes obligations on applicants for design approvals; therefore, the
references to the applicant in this final rule are consistent.
8. Need for Additional Provisions in Part 23
NATCA recommended the FAA add several provisions to part 23,
including a requirement about loss of propeller or propeller control,
provisions defining the levels of software certification needed,
requirements that address impact protection from unmanned aircraft
systems (UAS), and provisions about the introduction of new
technologies.
The FAA considered NATCA's comments; however, the FAA declines to
adopt NATCA's recommendations at this time. The FAA is not adding
requirements about loss of propeller or propeller control and
provisions defining the levels of software needed because these are
more appropriately addressed in means of compliance. The FAA also finds
it unnecessary to include specific provisions about the introduction of
new technologies because all the regulations in new part 23 are
intended to allow the introduction of new technologies. Furthermore, it
would be outside the scope of this rulemaking to add requirements
addressing impact protection from UAS.
9. Development of Standards
In the NPRM, the FAA described how industry groups associated with
the Part 23 ARC discussed the development of consensus standards and
how the ARC selected ASTM as the appropriate organization to initiate
this effort.
NATCA expressed concerns the FAA was relinquishing standardization
and stated the FAA needed to articulate an expected minimum technology
maturity level.
The FAA's process for reviewing applicant's submissions to verify
compliance with the safety standards will address NATCA's concern
regarding technology. This review process will not change from the way
the FAA currently reviews an applicant's regulatory compliance. One of
the purposes of this rule is to provide greater flexibility to
applicants in showing they meet the objectives of the safety standards,
and thus ``standardization'' in the strictest sense goes against this
purpose. Similarly, with respect to minimum technology level, another
purpose of this rule is to spur innovation and technology adoption.
Therefore, requiring a certain technology maturity level would
contradict that purpose.
10. Restricted Category Agricultural Airplanes
In the NPRM, the FAA did not specifically address single-engine
agricultural airplanes.
The NAAA commented that AC 21.25-1, Issuance of Type Certificate:
Restricted Category Agricultural Airplanes, is currently used by the
FAA to determine which part 23 certification requirements should not be
part of an airplane's TC under Sec. 21.25. NAAA questioned how the
requirements found inappropriate for single-engine agricultural
airplanes in AC 21.25-1 will influence the certification process.
The FAA notes the cross reference table located in this final rule
correlates the sections referenced in AC 21.25-1 with the new
regulations and associated means of compliance. Long term, the FAA
recommends NAAA work with the FAA to develop means of compliance
specific to restricted category agricultural airplanes.
11. International Cooperation Efforts
In the NPRM, the FAA indicated the part 23 rulemaking was a
harmonization project between the FAA and EASA. EASA published an
Advance Notice of Proposed Amendment (A-NPA) 2015-06 on March 27, 2015,
which set forth EASA's concept for its proposed reorganization of CS
23. The FAA received several comments on harmonization.
Garmin International (Garmin) and Agencia Nacional De Aviacao Civil
Brazil (ANAC) commented on the significant differences between the NPRM
and EASA's A-NPA. Garmin encouraged the FAA and EASA to resolve all
differences before publishing their final regulations. Textron stressed
the importance of harmonizing rule language with other major global
certification authorities because a lack of harmonization would call
into question whether one set of consensus standards would be adequate
to achieve certifications worldwide. Textron expressed disappointment
that the FAA's NPRM and EASA's A-NPA were not better aligned prior to
publication. Textron explained the goal should be 100 percent
harmonization with no exceptions. Garmin and Textron both commented on
the significant costs that non-harmonized regulations would have on the
industry.
EASA commented on the importance of using, as much as possible, the
same text in CS 23 and part 23. EASA explained, however, that CS 23 was
more of a technical standard, while proposed part 23 addressed the
applicant's responsibility. To better align with CS 23, EASA suggested
that the FAA require ``the applicant's design'' to meet certain
requirements rather than ``the applicant.''
Optimal Aerodynamics Ltd (Optimal) recognized the harmonization
efforts that have taken place, but sought reassurance from the FAA that
revisions to part 23 would not lead to greater differences with other
CAA's certification standards. Assuming CS 23 aligns with part 23,
Optimal asked if it would be possible to base compliance on EASA's
revised CS 23 when applying to the FAA for certification under new part
23.
The FAA agrees that harmonization with EASA's standards is
important. While identical language is not the goal, the FAA has worked
closely with EASA to ensure the same basic requirements for part 23 and
CS 23 in order that both authorities can accept the same set of
industry means of compliance. For example, as discussed previously,
references to the applicant's obligations (``the applicant must'') are
consistent with part 21 and with EASA's counterpart requirement that
applicants ``show'' compliance. To further this effort, the FAA has met
with EASA,\14\ received comments from EASA, and submitted comments on
EASA's A-NPA. EASA incorporated many of the
[[Page 96581]]
FAA's comments on its A-NPA into its Notice of Proposed Amendment
(NPA), published on June 23, 2016. In addition, the FAA incorporated
many of EASA's comments to the NPRM into this final rule, such as
including two new sections in Subpart G.
---------------------------------------------------------------------------
\14\ See docket number FAA-2015-1621-0062.
---------------------------------------------------------------------------
12. Part 23 ARC Recommendations and the Existing Fleet
As previously discussed in more detail, the FAA chartered the Part
23 ARC in 2011 to consider the reorganization of part 23 based on
airplane performance and complexity and to investigate the use of
consensus standards. The Part 23 ARC's recommendations were published
in 2013 and are available in the docket.
Textron, Garmin, and several individuals commented on those ARC
recommendations that were not proposed in the NPRM. In particular,
these commenters requested the FAA adopt changes to 14 CFR part 21,
``Certification Procedures for Products and Articles''; part 43,
``Maintenance, Preventive Maintenance, Rebuilding, and Alteration'';
and part 91, ``General Operating and Flight Rules''; as recommended by
the ARC. These comments related to type certification procedures and
airplane maintenance and operations. Similarly, several commenters
requested the FAA adopt the ARC's recommendation to establish a
``Primary Non-Commercial Category'' (PNC), which also would have
required revisions to part 21.
Several individual commenters noted that regulations applicable to
existing airplanes make it difficult and expensive to implement safety
improvements on those airplanes. These commenters questioned whether
this rulemaking will address those issues.
While the FAA recognizes the commenters' concerns regarding the
need to minimize the certification process burden, the FAA is not
making additional changes to parts 21 or 43 because they are outside
the scope of this rulemaking. The intent of this rulemaking is to
remove the prescriptive design requirements from part 23 and replace
them with performance-based airworthiness requirements. The FAA is,
however, contemplating a future rulemaking that would make additional
changes to part 21.\15\
---------------------------------------------------------------------------
\15\ The Part 21 SMS ARC published its recommendation reports
(appendix A-G and appendix H-P) on January 14, 2015. Copies can be
downloaded from the FAA Advisory and Committee site at http://www.faa.gov/regulations_policies/rulemaking/committees/documents/.
---------------------------------------------------------------------------
The FAA also considers the commenters' recommendations to create a
PNC category for aging General Aviation (GA) airplanes to be outside
the scope of the NPRM. The FAA did not propose to create a PNC category
for aging GA airplanes, as the ARC recommended, because it is also out
of scope of this rulemaking. However, the FAA is working to address the
ARC recommendations that focused on the existing fleet and part 21
processes.
With respect to the existing fleet, the FAA does not expect the
revisions to part 23 to provide immediate benefits to older airplanes.
However, when an owner of an older airplane applies for a change to the
airplane's TC in accordance with Sec. 21.101, the applicant may choose
to use the more flexible performance-based standards. In addition, as
discussed later, the revision to Sec. 21.9 will enable expedited
approval of certain parts that will benefit the existing fleet.
13. Impacts of the Proposed Rule on the Existing Fleet and on Open/
Active Projects
The FAA received several comments on impacts to the existing fleet
and on open/active projects.
Kestrel and Garmin asked how, under the proposed rule, the FAA will
address active projects, derivative airplanes and changes to existing
models. Kestrel noted Sec. 21.101 requires regulatory compliance with
the latest amendment while permitting certification on a case-by-case
basis to an earlier amendment for changes to existing models and
derivative airplanes. Kestrel noted it is common for applicants to
receive significant compliance credit on the basis of ``similarity/
identicality.'' Kestrel asked how the FAA would grant permission for an
applicant for a derivative airplane to certify entirely to a previous
amendment.
As discussed in the NPRM, the applicant has the option of using
former part 23, amendment 23-62, as a means of compliance with new part
23 (except in the areas where this final rule raises the level of
safety, as discussed previously). Since the new rule, combined with
this accepted means of compliance, is identical to the former part 23
requirements (with exceptions noted in this preamble), methods of
showing compliance--including ``similarity/identicality''--are not
affected for changes to existing airplane models. Furthermore, Sec.
21.101 only requires regulatory compliance with the latest amendment
for airplanes weighing more than 6,000 pounds. Section 21.101 also
provides relief for airplanes weighing more than 6,000 pounds when the
change is not significant or when compliance with a later amendment
would not contribute materially to the level of safety or would be
impractical
Garmin requested more details on the changes the FAA believes would
streamline the process for design approval and lower costs and project
delays. Garmin also asked the FAA to clarify how existing special
conditions, ELOS findings, and exemptions would be handled if an
applicant wants to ``step up'' to the new amendment.
The FAA has determined the cost and time savings will result from
the greater flexibility afforded by this final rule to both applicants
and the FAA to find compliance for innovative new technologies. For
traditional designs, the FAA expects applicants will be able to use the
new part 23 in the same way older Civil Air Regulation, part 3 (CAR 3)
airplanes are modified using former part 23 regulations. The FAA will
still find compliance with the regulations, and since the new
regulations allow greater flexibility by relying on accepted means of
compliance, there should be little need for special conditions, ELOS
findings, or exemptions, all of which require additional cost and time.
An individual and Air Tractor expressed concern over third-party
modifiers of airplanes who were not part of the original certification
process. The commenters suggested a third-party modifier could propose
its own means of compliance and regard it as proprietary, which may
conflict with the means of compliance used in the original basis of
certification. The commenters were concerned an STC or field approval
could become more difficult and create more work for the FAA.
The FAA notes the situation raised by the commenters currently
exists with proprietary means of compliance, and this will not change
with the new performance-based regulations. As under the former
regulations, STC applicants will continue to be required to demonstrate
that their changes, and areas affected by the changes, comply with the
applicable regulations. The FAA anticipates no increased potential for
conflict with the original design.
NATCA recommended the FAA make changes to the general definitions
of 14 CFR 1.1 concurrently with the part 23 rewrite, including revising
the definition of ``consensus standard'' because it applies to more
than Light-Sport Aircraft (LSA), adding the definition of ``proprietary
standard,'' and reconciling the differences between the International
Civil Aviation Organization (ICAO) airplane categories and the new
definitions in part 23.
The FAA has determined there is no need to define the terms,
``consensus
[[Page 96582]]
standard'' and ``proprietary standard'' in this final rule. The current
definition of ``consensus standard,'' by its terms, applies only to
LSA. For purposes of this final rule, ``consensus standard'' has the
meaning established in SARA, as discussed previously. The FAA does not
use the term ``proprietary standard'' in the regulations adopted by
this final rule. Finally, the FAA notes the definitions of the
categories need to remain the same because this final rule does not
change their applicability to the existing fleet of airplanes. Also,
the difference between the ICAO airplane standards and part 23
categories is based on weight and this rule does not affect that
difference.
While NJASAP supported the LOC In-Flight and SLD safety
enhancements, it stated runway excursions are another significant risk.
NJASAP supported requiring secondary or emergency braking systems and
recommended a requirement for powerplant reversing systems to be
installed on all level 3 and 4 high-speed airplanes to help reduce the
top three accident types. For the goal of reducing loss-of-control
accidents, NJASAP supported--along with other aerodynamic
improvements--the FAA requiring a device that gives a trained pilot
immediate feedback on the status of the airplane's wing. NJASAP
recommended level 3 high-speed airplanes be included in the safety
enhancements required for level 4 airplanes because they will be flying
similar missions, and Original Equipment Manufacturers (OEMs) will
target the level 3 certification category and stop certifying as many
level 4 airplanes.
The FAA finds that requiring emergency braking systems and
powerplant reversing systems is beyond the scope of this rulemaking and
would add additional costs. Requiring a device that gives a trained
pilot immediate feedback on the status of the wing is also beyond the
scope of this rulemaking, but a device like this could be used (and the
FAA encourages its use) as part of the low-speed stall protection.
Furthermore, the design specific nature of these recommendations is
inconsistent with the FAA's goal of performance-based requirements in
this rule revision. The new rule structure will allow for these
alternative devices.
The FAA considered NJASAP's recommendation that level 3 airplanes
be included in the level 4 safety enhancements because of levels 3 and
4 airplanes' similar missions. In this final rulemaking, the FAA
retains the traditional approach of drawing safety distinctions based
on airplane capacity and operational risk.
The NTSB commented on the proposed rule's focus on qualitative
design methodologies, but recommends the use of both quantitative and
qualitative design methodologies as the FAA has done historically. The
NTSB pointed to proposed Sec. Sec. 23.305 and 23.1315 and the
continued reliance on the requirements of former Sec. 23.1309, which
only addresses the effects of single failures. The NTSB contended that
the consideration of multiple failures should be required in the
revised part 23 when active systems may potentially be used in
commercial operations and the airplane may be more complex.
The FAA's intent in this rule is to maintain the current level of
safety. The FAA is currently engaged in rulemaking for transport
airplanes to address the NTSB's concerns. Depending on the outcome of
that rulemaking, the FAA may consider similar rulemaking for part 23 in
the future.
14. Legal Issues
In the NPRM, the FAA proposed to accept consensus standards as a
means of compliance with the new part 23 performance-based regulations.
Abbott Aerospace SEZC, Ltd. (Abbott) and Kestrel questioned the
legality of using ASTM as a means of compliance.
Abbott stated the proposed change is illegal as the new ASTM
standards constitute de facto law despite being labelled ``advisory''
and are the only realistic path to certify an airplane. Abbott claimed
this mislabeling will lead to confusion and cause industry to incur the
cost of purchasing the ASTM standards under the belief that they
constitute law and that compliance is mandatory.
Kestrel also questioned the legality of relinquishing FAA guidance
to a private entity and of using ASTM as the single standards body.
Kestrel opposed handing over public domain guidance to a private entity
for creation of its own standards, which will be provided back to the
industry for a fee. Kestrel suggested the FAA retain control and
continue to permit the use of its existing guidance.
In light of the comments, the FAA reviewed its approach to use
consensus standards as means of compliance with this rule. On November
27, 2013, the President of the United States signed SARA whereby
Congress mandated the FAA use consensus standards to clarify how safety
objectives may be met by specific designs and technologies. SARA also
requires the FAA to comply with the ``National Technology Transfer and
Advancement Act of 1995'' (NTTAA), which directs Federal agencies to
use voluntary consensus standards in lieu of government-mandated
standards when practicable. This rulemaking also complies with the
Office of Management and Budget (OMB) Circular A-119, ``Voluntary
Consensus Standards,'' which provides guidance on how to comply with
NTTAA. OMB Circular A-119 specifically addresses the issues raised by
the commenters and establishes the policy that agencies should consider
cost to regulated entities of using consensus standards as one factor
in determining whether those standards are ``reasonably available.''
The FAA has considered the cost of ASTM standards and determined, for
purposes of this rulemaking, ASTM standards are reasonably available
because the interested parties have access to them through their normal
course of business and the price is low enough that interested parties
can easily purchase them.
In addition, ASTM will not create de facto law nor be the single
standard-setting body, or custodian of public domain documents. The FAA
expects to accept means of compliance from individuals, companies, and
other standards bodies, including ASTM. While the use of a previously
accepted means of compliance will likely expedite the certification
process, no applicant will be required to use ASTM or any other means
of compliance. Instead, an applicant may propose its own means of
compliance for acceptance, or demonstrate compliance to the new rule by
using the prescriptive provisions in former part 23 and supporting
guidance--all of which will remain publically available. As discussed
in the NPRM, the long-term benefit and cost reduction provided by this
rule is that it will allow the introduction of new technologies without
the formal processes that currently increase certification costs and
inhibit innovation.
The American Association of Justice (AAJ) commented that the new
part 23 performance standards should not preempt state tort law because
state tort law functions as a necessary adjunct to federal regulations
that impose only minimum standards of care. AAJ urged the FAA to avoid
any language that could allow the new standards to be construed as
preempting state law for defectively designed or produced airplane, or
characterizing the standards beyond what is authorized by the Federal
Aviation Act.
AAJ's comment regarding preemption of state tort law in aviation
cases was
[[Page 96583]]
not a topic of this rulemaking. Rather, it is the subject of current
litigation in federal court regarding interpretation of the FAA's
enabling legislation. The outcome of that litigation is neither the
subject of this rulemaking, nor will this rulemaking affect that
outcome. However, as noted by the Supreme Court in previous litigation,
it is the applicant's obligation to comply with airworthiness
standards; the FAA cannot guarantee such compliance.
15. Regulatory Evaluation
The FAA received comments from five commenters (four companies and
one individual) on the summary of the regulatory evaluation published
as part of the NPRM. In the NPRM regulatory evaluation, the FAA
requested that commenters include data supporting their comments, but
no commenter submitted any cost or benefit data with its comments.
a. General
Kestrel stated that all applicants will benefit from decreased
certification costs and hopes the cost savings are tangible and can be
realized in a short time frame; however, Kestrel anticipates an
increased workload after the rule is adopted to train its personnel on
the new standards. Abbott, Air Tractor, and one individual commenter
characterized the cost benefit analysis as incomplete.
In the NPRM, the FAA stated that if the proposed rule saves only
one human life--for example, by improving stall characteristics and
stall warning--that alone would result in the benefits outweighing the
costs of the rule change. Air Tractor characterized this statement as
``vacuous.'' Air Tractor went on to comment that its industry places a
high value on protecting human life and expends enormous energy,
talent, and resources to protect it.
The FAA intended this statement as a simplified break-even analysis
of the likely benefits of the proposed rule. It was not intended to
replace the costs and benefits detailed in the regulatory evaluation.
The complete regulatory evaluation, located in the docket, is more
comprehensive than the summary that appears in the NPRM preamble and
contains the estimates provided to the agency by industry.\16\
---------------------------------------------------------------------------
\16\ See Docket Number FAA-2015-1621.
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Abbott stated there was no clear indication of how the proposed
change would reduce net cost or expedite the certification process.
Abbott concluded there were ``potential significant additional'' costs
created by the proposed rule, but no obvious or defined cost reduction.
Abbott characterized the proposed regulations as having an unknown cost
impact and stated these unknown costs represent a yet-unassessed and
unavoidable cost for airplane developers. Abbott also stated that any
additional cost the proposed rule places on industry that is not offset
by cost reduction elsewhere does harm to the industry.
The FAA notes that under the proposed rule, applicants may choose
to use an industry consensus standard, the former part 23 standards
(available at no cost), or its own means of compliance accepted by the
Administrator. The FAA presumes an applicant will use these options to
make the best economic choices given the circumstances of design and
development for its product. Such choices are an inherent strength of a
performance-based standard, but cannot effectively be analyzed for
costs or benefits, especially if a design encompasses new technology
that was never subject to the former regulation. Similarly, the FAA
cannot predict the viability of the products or the financial health of
an unknown start-up company under a regulation that allows for, but
does not require, its products be used in any airplane design.
b. Impact on Small Entities
Air Tractor commented the FAA's analysis of the proposed rule
impact on small entities did not include Air Tractor and Thrush
Aircraft (Thrush).
Air Tractor was concerned that data from only 5 entities was used
in the regulatory flexibility analysis. It noted the FAA should have
included every company that has active manufacturing activities and the
data used were non-representative of the overall industry. Air Tractor
also indicated the inclusion of Thrush and itself would have doubled
the number of employees and annual revenues represented in the
analysis. Additionally, Air Tractor believed the FAA should have also
included the TC holders of small airplanes that are no longer being
manufactured but require TC support and STC holders that certificate
products to the part 23 standards.
Finally, Air Tractor concluded that the omission of non U.S.-owned
entities that ``operate'' in the United States presented a ``distorted
view of the true impact'' of the proposed rule on the general aviation
industry in the United States.
The FAA conducted its analysis in accordance with the ``Small
Business Regulatory Flexibility Act.'' For each regulatory flexibility
analysis, an agency is required to provide a description of and, where
feasible, an estimate of the number of small entities to which its
proposed rule would apply. Many, if not most, small entities do not
provide publically available information such as employment data that
would allow an agency to determine if a business qualifies as a small
entity under the guidelines of the Small Business Administration (SBA).
Nor is there publicly available revenue data for these entities that
make it possible to determine the burden of a proposed or final rule on
these entities. The FAA does not have the authority or the means to
require any entity to report its employment or revenue data.
Accordingly, the FAA does not have the requisite knowledge of every
company that still has active manufacturing activities that might be
subject to the proposed rule.
The small business entities the FAA used in its analysis had
provided data on their employment and revenue either through the
regulations of U.S. DOT Form 41, the Securities and Exchange
Commission, or through news releases that the entities made public.
Neither Air Tractor nor Thrush have such data on record, and Air
Tractor did not provide employment or revenue data for itself as part
of its comment.
The five entities examined as part of the FAA's analysis qualified
as small entities under the SBA criteria and were either actively
manufacturing airplane or were under new ownership and had publically
announced they were working toward setting up an airplane manufacturing
line that would be subject to part 23. Airplanes previously
certificated under part 23 will not be affected by the regulations
affecting new certifications, so TC holders of operating airplanes who
are not actively seeking some certification are not appropriately
excluded from the analysis. The same holds true for STC holders that
used the part 23 standards in effect at the time of these airplane
original certifications.
The regulatory flexibility analysis conducted for the proposed rule
did not include any non-U.S. entities because, similar to the domestic
firms referenced above, the employment and revenue information required
for the analysis was not publicly available.
c. Icing
Textron stated that although the FAA identified a need for improved
certification standards for operation in severe icing conditions, it
did not provide a cost benefit analysis to show that part 23 airplanes
would benefit from them.
The FAA did conduct a cost benefit analysis of the icing
requirement. Flying into icing is risky and the ARC identified part 23
airplane icing
[[Page 96584]]
accidents. The FAA contacted industry, and some Part 23 ARC members
indicated to the FAA that the new rule and standards reflect current
industry practices for detecting and exiting icing conditions.
Additionally, the rule to certify that the airplane can operate safely
in SLD is voluntary. When compliance is voluntary, or no change in
industry practice will occur from a new regulation, the FAA determines
the rule to be minimal cost. This determination was made in the initial
regulatory impact analysis and is made in the final regulatory impact
analysis.
In the NPRM, the FAA proposed that for a part 23 airplane to be
certificated to fly in known icing conditions, an applicant would have
to demonstrate operation in the icing conditions defined in part 25
appendix C. This requirement did not change from the former part 23
requirements. As a safety matter, for many years airplanes currently
certificated under part 23 have demonstrated the ability to detect and
safely exit from freezing rain and freezing drizzle conditions.
The standards and requirements for the various icing certification
levels were discussed extensively with the Part 23 Icing ARC (Icing
ARC) and the Part 23 ARC. The new rule and standards for detecting and
exiting freezing drizzle and freezing rain are consistent with and
include significant parts of the Icing ARC's recommendations.
d. Part 23 Limitation
Textron recommended the FAA change the limitation on part 23
airplanes from its proposed gross takeoff weight limit of 19,000 pounds
(maintaining the current part 23 limit) to a maximum payload limitation
of 6,000 pounds. Textron stated the change would have a dramatic
positive impact on the potential costs and benefits of the proposed
change.
This change is beyond the scope of this rulemaking for the FAA to
consider. This change was not proposed by the FAA and would be a
fundamental change to part 23 that could potentially affect
certification of airplanes under part 25.
e. Reporting and Recordkeeping Requirements
The FAA stated it expected minimal new reporting and recordkeeping
requirements would result from the proposed rule and requested comments
on this finding. The FAA received no comments on reporting or
recordkeeping requirements.
Therefore, the FAA adopts the regulations as proposed, and will
make no change to the regulatory evaluation regarding the reporting and
recordkeeping requirements.
16. Out of Scope Statement
Several commenters requested changes to regulations or to existing
FAA processes and guidance materials that are not directly related to
this rulemaking. The FAA is not addressing these comments specifically
because they are beyond the scope of this rulemaking.
D. Part 23, Airworthiness Standards
1. Legacy Rules
a. Cockpit Voice Recorders (Sec. 23.1457)/Flight Data Recorders (Sec.
23.1459)
In the NPRM, the FAA proposed to use the same cockpit voice
recorder (CVR) and flight data recorder (FDR) standards that exist in
former Sec. Sec. 23.1457 and 23.1459. The proposed rule included
revised references to other sections of proposed part 23, but no
substantive changes to those standards.
The NTSB stated it is pleased the NPRM retained the needed
prescriptive design standards in proposed Sec. Sec. 23.1457 and
23.1459. The NTSB added it would be appropriate for the FAA to include
a requirement for image recorders, which it described in its Safety
Recommendation A-13-12, dated May 6, 2013.
The FAA considered the NTSB's request to add requirements for image
recorders. No functional or operational requirements to record images
has ever been proposed or evaluated for costs and benefits. Any such
requirements would constitute significant rulemaking and require public
participation, and therefore exceeds the scope of this rule.
EASA and the Associations stated the CVR and FDR requirements stem
from ICAO annex 6 requirements, which are already based upon EUROCAE
industry standards ED-155; ED-112A, ``MOPS for Crash Protected Airborne
Recorder System;'' and ED-155, ``MOPS Lightweight Flight Recording
Systems.'' They suggested the FAA redraft the regulations to be more
performance-based and number the regulations in accordance with any new
numbering scheme, and change the references from the operating
regulations as soon as practical.
The interplay between operation and certification regulations
remains the reason for carrying the current standards unchanged into
the new part 23. Redrafting them to objective standards, as suggested
by EASA and the Associations could result in varying data sets between
operators without any discernible benefit for such variation. Changing
the standards only for part 23 airplanes certificated after a
particular date would also require significant changes to the
regulations under which the airplanes operate, adding complication
without any noted benefit.
NJASAP supported the FAA's decision to maintain the current
standards for cockpit voice recorders (Sec. 23.1457), noting that
removing the current prescriptive requirements could hinder the conduct
of future accident investigations. NJASAP did not comment on Sec.
23.1459, ``Flight data recorders''.
Commenters opposed to retaining the standards generally
characterized them as too prescriptive. While accepting the need to
maintain the numbering system to align with other regulations, EASA
found the unchanged content to be detailed, design specific, and not
providing the safety intent. The EASA-suggested language referenced
recorder systems with more generalized statements regarding
installation and technical specifications. BendixKing stated that it
``seems binary'' that the ``specifics are invoked'' only ``if recording
is required.'' It also noted that the standards use approximately 1,000
words when 100 would be adequate in stating the safety intent. It
concluded the requirement as written will hurt safety in the future by
either retarding the technology or creating an environment where
manufacturers will avoid recording. BendixKing included the identical
comment for both recorder sections.
The primary use of both CVRs and FDRs is for accident
investigation. Over the past 30 years, the FAA has worked with the NTSB
to adopt and refine the specific requirements that document both
flightcrew communication and the functions of airplane that form the
basis for airplane accident and incident investigation. The FAA adopted
the first significant flight data recorder upgrades in 1997 and made a
concerted effort to standardize the operational and certification
requirements across the operating and certification parts. The primary
requirements for recording voice and data are not contained in the
certification regulations, but in the operating regulations. When an
airplane is required by an operating rule to record voice or flight
data, the operating rule references back to the standards for the
equipment in the certification part that applies to the airplane. This
is true for large and small airplanes and for helicopters.
Airplane certification requirements do not align perfectly with
operating regulations. A part 23 airplane may be operated under part 91
or 135; therefore,
[[Page 96585]]
the requirement to have and use CVRs and FDRs may differ depending on
how the airplane is operated. But the standards for the equipment--when
required--do not differ, and are intended to function the same way
regardless of the airplane's certification basis. This consistency is
central to the needs of the NTSB and all investigative bodies. It makes
the design, certification, and function of the equipment standard for
the industry as a whole. The FAA last amended the recorder regulations
in 2008 to reflect investigative experience with the functions of newer
recorder and flight management tools.
Therefore, the FAA finds it appropriate to retain these well-known
requirements. The current integration of the operating and
certification regulations is well established and functioning as
intended. The need for investigative data following accidents and
incidents is not forecasted to change. The commenters did not specify
which of the current requirements were inappropriate or unnecessary,
but merely expressed general concerns that the standards might inhibit
safety in future designs. The FAA has long acknowledged the safety
intent of flight recorders in providing investigators with the tools to
recognize trends and malfunctions following accident and incidents.
Consistency in the equipment and data that come from the equipment
remains the goal.
BendixKing's observation that the certification rules are invoked
only when ``recording is required'' is accurate. As explained, the
certification requirements for installation and use of this equipment
are only effective when required by an operating rule. Once required,
all the equipment must function to the same standards. The fact that
recording is required under different operating regulations, and the
certification regulations referenced in those operating regulations, is
the reason for not changing them for one certification part. If an
airplane is not required by operational rule to record voice or data,
then the specificity of the certification regulations is not an issue.
The commenters did not include proposed design or functional changes
for new airplane that might affect the requirements as stated. If a
novel design is proposed in the future that affects recorder function,
before approval, the FAA would coordinate with the applicant to ensure
such design features meet the needs of accident and incident
investigation.
Textron commented on proposed Sec. 23.1457(c), which retains the
current language requiring each CVR to be installed so that specified
communications are recorded on a separate channel. The regulation
currently and as proposed specifies four separate channels--the first
channel for the first pilot, the second channel for the second pilot,
the third channel at the cockpit-mounted area microphone, and the
fourth channel for the third and fourth crewmembers. Textron commented
that these CVR channel assignments are a ``legacy'' from magnetic tape
recorders and there is no physical effect of such assignment on current
solid-state recorders. Textron stated the current channel assignments
are different and, therefore, paragraph (c) language should be revised
to allow for flexibility in channel assignment or be aligned with the
assignments manufacturers currently use. In addition, Textron noted
that a proposed rule of EASA does not specify channels, but instead
references the more detailed requirement of an ASTM standard.
Textron's comment--that the requirement for separate channels does
not reflect the reality of currently-manufactured equipment--is limited
in its view. While the regulation does require separated recording of
different voice communication channels, the rule is flexible enough to
avoid the issue raised by Textron. Regardless of an applicant's CVR
channel numbering scheme, the regulation is satisfied if the CVR is
designed to record audio sources on dedicated channels. This remains
the FAA's policy on this regulation, which includes Textron's products
already installed in airplanes that meet the former regulation.
An individual commenter noted the proposed rule seemed to
anticipate an onboard storage system that must withstand a crash.\17\
The commenter suggested that because recordings may not be stored
onboard in the future, but rather wirelessly transmitted to the ground
or a satellite, the FAA should revise the provision to reflect this
possibility rather than ``locking in old technology.''
---------------------------------------------------------------------------
\17\ See docket number FAA-2015-1621-0083. The comment was
referenced as ``23.1457 Flight Data recorder.'' Section 23.1457
covers cockpit voice recorders, while 23.1459 addresses flight data
recorders. It is unclear if the comment addressed one or both
sections, but the FAA's response would not change since both require
crash protected recording devices.
---------------------------------------------------------------------------
The FAA is aware that, at some point in the future, recordings may
no longer need to be stored on board airplane. The FAA participates in
international working groups that monitor these technology trends.
There are many technical and legal issues attached to wireless
transmission of voice and data communications. A change to allow such
transmission and storage would affect several parts of the CFR and the
functions of the NTSB, which were not proposed or discussed as part of
this rulemaking.
b. Instructions for Continued Airworthiness (Sec. 23.1529)
In the NPRM, the FAA proposed to relocate the requirements for
Instructions for Continued Airworthiness from Sec. 23.1529 to proposed
Sec. 23.1515. The FAA also proposed to remove appendixes A through F,
and rename Appendix G to Part 23--Instructions for Continued
Airworthiness, as Appendix A to Part 23--Instructions for Continued
Airworthiness.
Upon further consideration, the FAA has decided to retain the
requirements for Instructions for Continued Airworthiness in Sec.
23.1529. A change to Sec. 23.1529 would affect many other parts and
guidance documents, which reference the section. Because of the new
numbering scheme in part 23, Sec. 23.1529 is located in the ``Legacy
Regulations'' section of the final rule. The appendix for Instructions
for Continued Airworthiness is now located in Appendix A to Part 23, as
proposed.
2. Subpart A--General
a. Applicability and Definitions (Proposed Sec. 23.1/Now Sec.
23.2000)
In the NPRM, proposed Sec. 23.1 (now Sec. 23.2000) would have
prescribed airworthiness standards for issuance of type certificates,
and changes to those certificates, for airplanes in the normal
category. It also would have deleted references to utility, acrobatic,
commuter category airplanes. Proposed Sec. 23.1 also would have
included definitions for the following terms specific to part 23:
Continued safe flight and landing, designated fire zone, and empty
weight.
Air Tractor asked why it was necessary to use the term ``category''
if there is only one ``normal'' category.
The FAA notes that there is a need to retain the concept of
different categories because other parts of the FAA's regulations,
including the certification and operating rules, set certain
requirements based on an airplane's category.
An individual commenter opposed the elimination of the utility
category as related to spin training for existing airplanes. The
commenter would support elimination of the utility category if there
would be a reevaluation of the airplanes allowed to be used for spin
training. This
[[Page 96586]]
commenter also questioned whether the proposed change would result in a
revision and reformatting of the current Type Certificate Data Sheet
(TCDS) and whether the airplane would be considered not airworthy until
re-placarded to conform to the new standards.
This rule does not affect the category of existing airplanes, nor
does it require the TCDS be revised or reformatted. Airplanes currently
certified in the utility category for spin training retain that
capability under this new rule. Furthermore, the airworthiness of the
existing fleet will not be affected by this rule.
An individual commenter recommended the FAA clarify whether the
term ``continued safe flight and landing'' would not consider weather,
environmental, or surface conditions in the event of a forced landing.
The FAA agrees that it should clarify that in the event of a forced
landing, the definition of ``continued safe flight and landing'' does
not include consideration of weather, environmental, or surface
conditions beyond those already taken into account by the FAA's
operating rules. The FAA expects that a pilot will conduct his or her
flight within the FAA's operating rules and the airplane's normal
operating envelope, and finds doing so will help ensure the pilot has
safe landing options. The FAA's intent was to maintain the existing
level of safety for small airplanes. Historically, single-engine and
light twin-engine airplanes have been required to have characteristics
that minimized the resulting hazards when a loss of engine forced an
off-airport landing. The requirements for larger, multiengine part 23
airplanes are based on the requirement to continue flight back to an
airport after the loss of an engine. This rule retains this requirement
as it applies to part 23 airplanes that cannot maintain altitude after
a critical loss of thrust. The FAA will provide additional
clarification in guidance. It is not appropriate for the FAA to
establish airworthiness standards for ``continued safe flight and
landing'' that would require all airplane designs to account for
extreme conditions--such as mountainous terrain--and extreme weather,
because pilots who decide to fly over dangerous terrain or in weather
have chosen to greatly reduce their options for safe landing.
The FAA proposed including a definition of ``designated fire zone''
that was flexible enough to capture both the historical understanding
of fire zones and those areas in airplanes that incorporate novel
design concepts that merit the increased safety measures. However, the
FAA finds including a definition of ``designated fire zone'' will cause
confusion and result in less flexibility. Rather than include a
definition, the FAA will maintain the same understanding as the
historical use of the term ``fire zone,'' a well-understood term that
has been in use for decades and generally includes the areas of an
airplane in which a powerplant, or some portion thereof, resides.
Accordingly, the FAA will remove the definition from the rule and will
determine which areas are designated fire zones in the specific means
of compliance. Furthermore, specific sections of the new rule have
added the term ``fire zone'' back into the rule so there is a clear
link to means of compliance.
EASA commented the proposed definition of ``empty weight'' is too
design specific and should be eliminated. EASA noted future
technological developments would necessitate changes and future
rulemakings, which is at odds with the objective to make objective
rules change resistant for the next 20 years.
The FAA agrees the definition of ``empty weight'' is too design
specific because the list of traditional features included may not
apply to all airplanes in the future. Accordingly, the FAA deletes the
definition from the final rule and will rely on means of compliance to
address the requirements for each airplane. This will allow the FAA to
capture the appropriate features for new propulsion systems and
configurations without losing the means of compliance for traditional
airplanes.
Air Tractor recommended the FAA provide a definition for ``minimum
flying weight'' that would include the weight of the necessary crew and
the minimum fuel required for legal operation for the lightest equipped
airplane that complies with type design requirements. It asserted there
is no point in the FAA certifying an airplane as safe for operation
below the minimum weight at which the airplane can be operated.
The FAA finds Air Tractor's recommended definition of ``minimum
flying weight'' is not an appropriate substitute for empty weight.
Empty weight is used to provide a baseline for an airplane;
establishing a ``minimum flying weight'' would not work for that
purpose.
Embraer suggested the FAA include definitions for ``Aircraft Power
Unit,'' ``Fuel,'' ``Critical lightning strike,'' and ``Fuel system'' in
proposed Sec. 23.1(b).
The FAA notes Embraer's suggestion to add definitions to proposed
Sec. 23.1(b); however, these definitions are addressed in their
respective subparts. The terms ``Aircraft Power Unit,'' ``Fuel,'' and
``Fuel System'' are addressed in subpart E, and the term ``Critical
lightning strike'' is addressed in subpart D. Furthermore, adding these
definitions could lead to more confusion than clarification.
b. Certification of Normal Category Airplanes (Proposed Sec. 23.5/Now
Sec. 23.2005)
In the NPRM, proposed Sec. 23.5 (now Sec. 23.2005) would have
applied certification in the normal category to airplanes with a
passenger-seating configuration of 19 or less and a maximum
certificated takeoff weight of 19,000 pounds or less. Proposed Sec.
23.5 would have also established certification levels based on the
passenger seating configuration and airplane performance levels based
on speed. Proposed Sec. 23.5 also would have established a ``simple''
airplane classification.
Normal Category
Air Tractor and Textron questioned the imposition of a weight-based
limitation for certification in the ``normal'' category in proposed
Sec. 23.5(a). Both commenters indicated that tying the applicability
of part 23 to a maximum takeoff weight of 19,000 pounds would not meet
the FAA's objective of replacing the current weight and propulsion
divisions in small airplane regulations with performance- and risk-
based divisions. Air Tractor also commented there was no basis for
weight differentiation between normal and transport category airplanes
on the FAA's safety continuum and suggested it would be more consistent
to only use certification levels and speed categories. Air Tractor
further suggested that applicants should be free to decide between
certification under part 23 and certification under ``the greater
rigor'' of part 25. Textron recommended the FAA replace the 19,000-
pound maximum takeoff weight limit with a 6,000-pound maximum payload
limit.
The FAA notes Air Tractor's and Textron's comments to extend the
scope of the normal category. However, these comments are beyond the
scope of this rulemaking. The NPRM proposed to replace the prescriptive
airworthiness standards of part 23 with performance-based standards,
not to change the scope of applicability of part 23.
Textron recommended the FAA include considerations for airplane
functional or system complexity as a determining factor in
certification requirements.
[[Page 96587]]
The FAA notes this rule already considers system complexity during
certification. The requirements applicable to an airplane depend on
reliable indicators of complexity--the airplane's designed cruising
speed or maximum operating limit speed, and the maximum number of
passengers. The airworthiness standards accommodate all degrees of
complexity, which will specifically be addressed in accepted means of
compliance.
Airplane Certification and Performance Levels
NATCA opposed the FAA's proposal to create certification and
performance levels based on passenger capacity and airspeed in proposed
Sec. 23.5(b) and (c). NATCA noted that this approach was not
consistent with how some foreign authorities with whom the United
States has bilateral agreements ``bucket'' airplane classifications,
including EASA, which classifies certification levels based on weight.
The FAA is not required to use the same metrics to classify
airplanes as its bilateral partners. For example, Article 15 of the
Agreement between the United States of America and the European Union
on Cooperation in the Regulation of Civil Aviation Safety expressly
reserves the authority for the United States to determine the level of
protection it considers appropriate for civil aviation safety and to
make changes to its regulations, procedures, and standards.
Additionally, foreign authorities, including EASA, have been involved
in the FAA's part 23 rulemaking effort since its inception with the
Part 23 ARC. All foreign authorities involved in the part 23
reorganization effort agreed on the need to eliminate the divisions in
part 23 based on weight and propulsion. Furthermore, the FAA's actions
are consistent with EASA's actions.
NATCA also contended the FAA should retain a weight criterion
because it relates to crash energy.
The FAA notes the risk associated with operating a 19,000-pound,
level 1, low-speed airplane is accounted for in this rule by directly
addressing the technologies installed on the airplane. For example, an
airplane approved for instrument flight rules (IFR) has to meet the
reliability requirements for IFR, regardless of level. Also, the FAA's
operating rules mitigate the airplane's operational risk.
NATCA also asked the FAA to clarify that an applicant would not
qualify for a lower certification level simply by removing seats and to
publish guidance on determining certification levels.
The FAA notes, as set forth in Sec. 23.5 (now Sec. 23.2005), an
airplane's certification level depends only on its maximum passenger
seating configuration. This number does not include flightcrew. The
maximum passenger seating capacity is known during the certification
process; therefore, the airplane must comply with the standards
applicable to that certification level. An airplane operator's decision
to remove a passenger seat after certification does not affect the
standards applicable to that airplane.
NATCA also recommended the FAA review the proposed part 23
certification levels to incorporate LSA and primary category airplane
and create equivalent regulations as necessary.
The FAA notes that NATCA's suggestion is beyond the scope of this
rulemaking. This rulemaking's purpose is to replace prescriptive design
requirements of part 23 with performance-based standards, not expand
the scope of part 23's applicability. The LSA and primary category
certification processes exist as separate certification paths for
airplane that qualify as either a LSA or primary airplane.
NATCA further commented by asking--
Whether the intent is for airplane models with multiple
configurations to have each configuration listed on the TCDS;
Whether there can be dual or more categories on one TC;
and
Whether an airplane can be moved between levels and speed
definitions during operational usage and, if so, whether this needs to
be captured as different options on the TCDS.
In response to NATCA's question regarding multiple configurations,
the FAA notes that if an airplane model has multiple configurations,
the applicant will have to accept as the certification basis the
requirements of the most stringent certification and performance levels
available in the configuration list. If the applicant chooses not to
comply with the most stringent requirements applicable to the
configurations, the applicant will have to address each model
individually on the TCDS. With respect to the number of categories on a
TC, the FAA is eliminating the commuter, utility, and acrobatic
airplane categories in part 23 for the reasons explained in the NPRM.
Therefore, airplanes certified under new part 23 have only one
category: normal.
Lastly, with respect to NATCA's question regarding airplanes moving
between certification levels and speed definitions, an applicant either
accepts the most stringent certification basis or addresses each model
individually on the TCDS or by an STC. In order to move to a higher
level, it will be necessary to recertify the airplane to the higher-
level standard.
NJASAP supported the proposal to use passenger capacity and
airspeed to establish airplane certification and performance levels,
but expressed concerns the methodology may go too far in generalizing a
very diverse group of airplanes.
The FAA understands NJASAP's concern, but notes the certification
and performance levels are used to replace the weight and propulsion
divisions in the former requirements. The levels are general to allow
the accepted means of compliance to more accurately address the various
technical differences.
Kestrel supported the FAA's proposed airplane certification levels,
but expressed concern with the impact of migrating the Airplane Classes
in former Sec. 23.1309 (I, II, III, IV) \18\ to the proposed combined
airplane certification and performance levels. Kestrel noted that
Airplane Classes were currently used in the System Safety Analysis
process to establish allowable quantitative probabilities. Kestrel
asked the FAA to specify what the expected allowable quantitative
probabilities would be for each of the eight possible combinations of
certification and performance levels (i.e., low-speed levels 1-4 and
high-speed levels 1-4).
---------------------------------------------------------------------------
\18\ These Classes are described in AC 23.1309-1E, paragraph 15.
---------------------------------------------------------------------------
The FAA notes that there is no direct connection between the
systems-based airplane classes from AC 23.1309-1E \19\ and the airplane
certification and performance levels in Sec. 23.2005, which apply to
all subparts. The airplane classes reflect the safety continuum concept
in that it may be acceptable for simpler airplanes or airplanes at
lower certification levels to have a higher probability of failure for
equipment. The airplane's certification level is strictly based on the
number of passenger seats. The different means of compliance will
address the safety continuum.
---------------------------------------------------------------------------
\19\ The Airplane Class Levels from former Sec. 23.1309 are
still addressed in subpart F of this rule.
---------------------------------------------------------------------------
Air Tractor commented generally that it does not see a big
difference in the certification effort required by the different
certification and performance levels. Air Tractor suggested there could
be a difference in required levels of safety for equipment, but
indicated it was impossible to tell because the FAA had not yet defined
the levels of
[[Page 96588]]
safety.\20\ Air Tractor suggested the FAA codify the required levels of
safety because the rule preamble would not be given the weight of law.
---------------------------------------------------------------------------
\20\ Air Tractor pointed out proposed Sec. 23.1300.
---------------------------------------------------------------------------
The FAA acknowledges that Air Tractor is correct in that there
could be a difference in the required levels of safety between two
airplanes based on the FAA's safety continuum philosophy. Differences
in products and their associated risks justifies using different levels
of safety. While the high-level performance requirements are the same
for all products, the required level of safety is best addressed using
means of compliance so that each project is assigned the appropriate
level of safety. Although language in the preamble does not supersede
the language of the regulation itself, the preamble is evidence of the
FAA's contemporaneous understanding of its proposed rules, and may
serve as a source of evidence concerning contemporaneous agency
intent.\21\
---------------------------------------------------------------------------
\21\ Wyoming Outdoor Council v. U.S. Forest Service, 165 F.3d
43, 53 (D.C. Cir. 1999).
---------------------------------------------------------------------------
Several commenters questioned the meaning of ``passengers'' as used
in the descriptions of certification levels in proposed Sec. 23.5(b),
particularly for airplanes that may require 1 or 2 crew depending on
operating regulations.
The FAA elects to use the term ``passenger'' to align with the
operating rules, and because passenger count has historically
correlated to risk tolerance. The term ``passenger'' excludes
``flightcrew'' members. The FAA recognizes the concerns over confusion
because the ARC discussed this issue at length and it was again
discussed within the FAA. Based on these discussions, the FAA finds
``passenger'' is the most appropriate term. As one of the commenters
noted, the ``crew'' could include one or more ``occupants.'' Part 23
airplanes can include special use airplanes that may require multiple
flightcrew members, but have no provisions for passengers. Part 23 is
also used for airplanes that carry no ``flightcrew'' or ``passengers''
today (i.e., unmanned aircraft systems), and may also address airplanes
with passengers and no flightcrew in the future. For airplanes that
require different numbers of flightcrew for different operations, the
applicant must use the smallest number of flightcrew required for any
operation, which is typically one, the most conservative number. The
FAA finds the approach proposed Sec. 23.5 (now Sec. 23.2005) will
allow the most flexibility, least confusion, and focus on risk
tolerance, which aligns part 23 with the operating rules.
Several organizations commented specifically on the proposed
airspeed limits for the low-speed and high-speed performance levels
established in proposed Sec. 23.5(c). NATCA suggested the use of
design cruising speed (VC) and maximum operating limit speed
(VMO/MMO) may not be appropriate for untrained
persons, and recommended the FAA either define those terms or use more
common measurements. NATCA also commented that the FAA needs to clarify
what ``speed'' means (i.e., cruise speed versus some other speed
standard). NATCA expressed concerns over the use of ``common'' terms
versus speeds used for certification, which are also used in
operations.
The FAA notes both VC and VMO are defined in
14 CFR 1.2. VC means design cruising speed and
VMO/MMO means maximum operating limit speed. The
FAA finds that VC, VMO, and MMO are
appropriate for engineering determinations as they relate to structural
speeds as well as flight-testing speeds. Furthermore, the FAA clearly
states these are calibrated speeds, which typically are used in
certification.
Transport Canada commented specifically on the parameters for the
low-speed performance level in proposed Sec. 23.5(c)(1). In
particular, Transport Canada said VC and VMO
should both be less than 250 Knots Calibrated Airspeed (KCAS) for an
airplane to qualify as low speed. Therefore, Transport Canada concluded
the phrase ``VC or VMO'' in this provision should
actually read ``VC and VMO''.
The FAA agrees with Transport Canada concerning the use of ``and''
versus ``or'' and revises the rule accordingly.
Air Tractor contended that the parenthetical references to
MMO limits in proposed Sec. 23.5(c)(1) and (c)(2) are
confusing because they are not clear if these values represent either
new absolute constraints, or if they are intended to provide an
approximate context for what 250 KCAS might mean at some higher
altitude. Air Tractor noted that Mach 0.6 corresponds to 250 KCAS at
about 23,400 feet in a standard atmosphere, but wondered what
performance level would be assigned to an airplane with a VC
of 250 KCAS and an MMO of 0.65.
Garmin commented that some airplanes do not have a MMO,
but have a maximum speed of more than Mach 0.6. For example, Garmin
noted an airplane with a VMO of 240 KCAS up to its certified
ceiling of 35,000 feet and no MMO would be classified as a
low-speed airplane but will actually be going Mach 0.71 at 35,000 feet.
Garmin recommended the FAA revise the low-speed and high-speed
performance levels to remove MMO from parentheticals,
clarify that a low-speed airplane must have a VC or
VMO equal to or less than 250 KCAS and a MMO less
than or equal to Mach 0.6, and that a high-speed airplane is anything
that does not qualify as low speed.
The FAA agrees that the proposed rule was unclear and revises the
final rule to clarify that MMO is one of the criteria, not
an approximation of the KCAS cutoff. Accordingly, an airplane must
satisfy all of the VC, VMO, and MMO
requirements to qualify as low speed. If an airplane does not satisfy
all three, then it is considered a high-speed airplane. After further
review, the FAA determined that VC and VMO are
not directly parallel because VC is a structural speed and
VMO is a performance speed. For this reason, the FAA
replaces VC with VNO. VMO historically
was a performance value used by turbine-powered airplanes while
VNO historically was a performance value used by piston-
powered airplanes. By replacing VC with VNO, the
values now reflect parallel operational speeds.
ANAC commented that the FAA should use stall speed instead of
VMO and MMO to define performance levels because
it would help address loss of control and prevent an applicant from
arbitrarily limiting an airplane's VMO and MMO
below the airplane's capabilities to avoid more stringent certification
standards. ANAC asked the FAA to elaborate on the connection between an
airplane's VMO and MMO and takeoff risk.
The FAA does not agree that stall speed is the best parameter to
use for determining performance levels. Although an airplane's top
speed generally has been aerodynamically limited to a multiple of stall
speed that varied depending on propulsion, this is not true for all
airplanes and does not provide the necessary flexibility to address
airplanes that incorporate new technology. For example, there are
airplanes in development that have very low-stall speeds--the airplane
can land and takeoff in very little space, or even vertically--but may
have VNO or VMO greater than 250 KCAS, making
them a high-performance airplane.
Simple Airplane Classification
The FAA proposed to define ``simple'' airplanes to recognize the
entry-level airplane. Simple airplanes would have been limited to
airplane designs that allow no more than one passenger, are limited to
VFR operations, and have a low top speed and a low stall speed.
[[Page 96589]]
The FAA asked for comments concerning the value of creating a simple
airplane sublevel given that a simple airplane would have
characteristics very similar to a certification level 1, low-speed
airplane.
ICON, Transport Canada, BendixKing, NATCA, and two individual
commenters supported the inclusion of a separate ``simple'' airplane
classification. However, Zee and the Associations commented that the
FAA should not create a ``simple'' airplane classification, and that
each of the proposed certification and performance levels should stand
on its own based solely on performance and complexity of operations.
The commenters against inclusion of a ``simple'' category contended
that it was more appropriate to address this sort of classification in
the means of compliance.
The FAA has decided not to adopt a ``simple'' airplane
classification. The FAA finds the addition of a simple category does
not produce benefits over those already provided by the new rule. The
FAA finds it is more appropriate to address the requirements for a
level 1, low-speed airplanes. Additionally, in the NPRM, the FAA
proposed allowing simple airplanes to use non-type-certificated engines
and propellers to allow those airplanes to use electric propulsion. The
FAA can achieve the same flexibility by approving electronic propulsion
as part of an airframe for a level 1, low-speed airplane; therefore,
the FAA revises the propulsion requirements in this rule to provide
that flexibility.
Airplanes Certified for Aerobatics
The FAA proposed to eliminate the acrobatic airplane category in
part 23, but still allow a normal category airplane to be approved for
aerobatics provided the airplane was certified to address the factors
affecting safety for the defined limits for that kind of operation.
Velica S.A.S. (Velica) recommended the FAA define ``aerobatic
category'' in proposed Sec. 23.5 to include airplanes without any
maneuver restrictions, other than those shown to be necessary as a
result of required flight tests.
For the reasons explained in the NPRM, the FAA removed the
acrobatic category from part 23. The FAA agrees with Velica that the
limitations for an airplane certified for aerobatics should be based on
flight tests, but believes more specificity is warranted. Therefore,
the FAA will require airplanes certified for aerobatics to comply with
the limitations established under subpart G of part 23 in this rule.
c. Accepted Means of Compliance (Proposed Sec. 23.10/Now Sec.
23.2010)
In the NPRM, proposed Sec. 23.10 (now Sec. 23.2010) would have
required an applicant to show the FAA how it would demonstrate
compliance with this part using a means of compliance, which may
include consensus standards accepted by the Administrator. Proposed
Sec. 23.10 would have also required a person requesting acceptance of
a means of compliance to provide the means of compliance to the FAA in
a form and manner specified by the Administrator. Proposed Sec. 23.10
would have created flexibility for applicants in developing means of
compliance and also specifically identify consensus standards as a
means of compliance the Administrator may find acceptable.
General Comments
The Associations recommended the FAA revise paragraph (a) to
require an applicant to ``comply'' with part 23, rather than ``show the
FAA how it will demonstrate compliance'' with part 23, using a means of
compliance. The Associations also recommended revising paragraph (b) to
require an acceptable means of compliance to be in a form and manner
specified by the Administrator.
The Associations also argued that, without these changes, the
proposed rule could have been interpreted as requiring each applicant
to come to agreement with the FAA on acceptable means of compliance for
each certification project, when it appears the FAA intends to issue
acceptance of methods of compliance in, for example, standards that are
already deemed acceptable. The commenters also noted that part 21 does
not currently require a showing of compliance in all cases. The
commenters stated that today, and potentially more so in the future,
the FAA may accept compliance through demonstration or even a statement
of compliance. The commenters contended the above-referenced revisions
to proposed Sec. 23.10 are necessary to ensure the designs meeting
part 23 can continue to fully utilize part 21.
The FAA agrees with the commenters that proposed Sec. 23.10(a)
(now Sec. 23.2010(a)) may have had the unintended result of requiring
applicants to get approval from the FAA for each means of compliance
even when the FAA had already accepted a means of compliance. This
would have been counter to the FAA's intention that a means of
compliance, once accepted by the FAA, may be used for future
applications for certification unless formally rescinded. The FAA
adopts the commenters' recommendation for paragraph (a).
The FAA does not adopt recommendation for paragraph (b) however,
because it would not meet the intent of the requirement. Paragraph (b)
addresses the situation in which an applicant proposes its own means of
compliance, either as an alternative to an accepted means of compliance
or as a new means of compliance for new technology. The FAA intended
paragraph (b) to require applicants requesting acceptance of a means of
compliance to do so in a form and manner specified by the FAA, not to
require already-accepted means of compliance to be documented in a form
and manner specified by the FAA. In light of the comment, the FAA
revises the proposed rule language to clarify that paragraph (b)
applies to applicants who are requesting FAA review and acceptance of a
proposed means of compliance.
Air Tractor questioned the need for a new rule specifying that all
means of compliance must be accepted by the FAA and asked whether an
applicant would need to obtain FAA approval for each means of
compliance at the beginning of the process or any time prior to showing
compliance.
This final rule is necessary because Congress directed the FAA to
issue a rule that replaces the prescriptive requirements of part 23
with performance-based regulations.\22\ This change means that
applicants for a TC may use any number of unique design elements to
attempt to comply with the performance-based requirements but only the
FAA can accept these as means of compliance because the FAA is
responsible for finding that an airplane satisfies the performance-
based requirements in part 23 before issuing a TC. Although the means
of compliance process is not new, the FAA adopts Sec. 23.2010 to make
the process clear to all applicants and to highlight that applicants
have the opportunity to develop alternative approaches to complying
with the part 23 performance-based requirements. While an applicant is
not required to obtain FAA acceptance of means of compliance at the
beginning of the certification process, it is advisable to seek
acceptance as soon as possible, or preferably before, to mitigate the
risk of having to redesign the airplane should the FAA not accept the
means of compliance.
---------------------------------------------------------------------------
\22\ Small Airplane Revitalization Act of 2013 (Pub. L. 113-53,
49 U.S.C. 44704 note).
---------------------------------------------------------------------------
NATCA commented the FAA should require the accepted means of
[[Page 96590]]
compliance be included on the published certification basis so products
can be standardized and post-TC modifiers can know the certification
basis used for the underlying product. NATCA also commented that
maintenance personnel returning an airplane back to service will need
access to adequate documentation on how an airplane is compliant with
the rule so they can verify the airplane remains compliant. Assuming
the standards are listed, NATCA asked the FAA to clarify how they would
be listed in the airplane certification basis.
The FAA partially agrees with NATCA's concerns. Because many of the
detailed requirements are no longer in part 23 and will move to means
of compliance, it may be hard to know how an applicant showed
compliance. That said, many means of compliance today are proprietary,
and modifiers and maintenance personnel have no way of knowing what the
original manufacturer did to show compliance. The FAA is working with
its project support personnel to determine how much of the means of
compliance information needs to be listed on the FAA TCDS to address
concerns relating to post-TC modifiers and maintenance personnel. This
information will be included in the training currently being developed
for the ACO engineers and industry designees.
NATCA also recommended the FAA permit design change applicants to
use their own alternate means of compliance to gain approval rather
than relying on the original means of compliance used for the
underlying TC. NATCA suggested this would be in line with the FAA's
statements that it is open to a means of compliance without preferring
one over the other.
This option is currently permitted and will continue to be
permitted under the new part 23. Applicants requesting a change to type
design may propose their own means of compliance rather than using the
original means of compliance. However, the FAA will review the request
depending on the complexity of the design change or the alternative
means of compliance. While this is the current process, AC 23.2010
provides guidance on how to submit a proposed means of compliance to
part 23 for FAA acceptance.
NATCA asked the FAA to clarify how the certification basis would be
handled for industry consensus standards. NATCA also asked whether an
applicant must at least partially use industry consensus standards, or
whether an applicant may choose not to use consensus standards at all.
Finally, NATCA asked if an applicant could get a part 23 TC by only
using the standards in ACs. Air Tractor suggested the FAA revise
proposed Sec. 23.10 to mention that the standards included in ACs are
an accepted means of compliance.
The FAA notes that the certification basis will be the same as it
is today: Applicants must show compliance with part 23. An applicant
may choose not to use any consensus standards, or a combination of
consensus standards and other means of compliance, as long as the
applicant's proposed means of compliance complies with part 23 and is
accepted by the Administrator. The FAA finds it unnecessary to revise
the proposed rule language as Air Tractor suggested. An applicant may
already use ACs as means of compliance to part 23, where applicable,
under Sec. 23.2010.
Use of Applicant-Proposed Means of Compliance
Air Tractor contended the use of applicant-proposed means of
compliance standards would lead to a significant loss in transparency
of the certification process, as individual applicants may choose to
make both the results and the process of showing compliance a matter of
proprietary intellectual property. ANAC commented that the FAA should
establish a method to publicize information about approved means of
compliance that are not part of a consensus standard. To preserve
proprietary information, ANAC recommended the FAA only publish
summaries as it currently does for exemptions, special conditions, and
ELOS findings. NATCA questioned how the FAA will handle proprietary
specifications within a certification basis, arguing it is not in the
public interest to have ``secret'' certification requirements. NATCA
recommended the certification basis be published in the Federal
Register for public comment. NATCA also recommended the certification
basis for proprietary information be ``explicitly identified'' on the
TCDS or STC. Finally, NATCA asked the FAA to clarify whether the FAA
will publish FAA issue papers when an applicant uses an applicant-
proposed means of compliance and, if so, noted that several FAA orders
and policies would need to be revised.
The FAA has a responsibility to protect an applicant's proprietary
information, including a proprietary means of compliance. As such, the
FAA will not make the proprietary portions of applicant-proposed means
of compliance publicly available. The FAA plans to address applicant-
proposed means of compliance as it does today, by summarizing the
information. The FAA will identify the certification basis (i.e., the
applicable airworthiness standards) on the TCDS or STC as is done
today. The FAA has not published, and does not plan to publish, the
certification basis or FAA issue papers in the Federal Register for
public comment. Each applicant's certification basis is based on part
23 and is agreed to between the applicant and the FAA. The FAA is not
required to elicit public comment on proposed means of compliance.
Garmin asked whether the FAA will accept portions of a previously
accepted means of compliance, or whether an applicant must use that
entire means of compliance. Garmin recommended the FAA revise proposed
Sec. 23.10 (now Sec. 23.2010) to permit whole or partial
implementation of a previously-accepted means of compliance or,
alternatively, ensure AC 23.10 permits this.
The FAA agrees with Garmin and points out that this is acceptable
today. The FAA can be flexible in accepting mixed, partial, or entire
means of compliance from industry consensus standards as applicable to
the specific product. The FAA recognizes that new product innovations
will make this flexibility more important in the future. An industry
consensus standard can state that, for credit in meeting that standard,
the applicant has to meet the entire set of requirements. But the FAA
may tailor acceptable consensus standards based on what is appropriate
for the intended function.
Use of Current Part 23 as Means of Compliance
Embraer recommended the FAA revise proposed Sec. 23.10(a) (now
Sec. 23.2010(a)) to acknowledge that an applicant may use the
prescriptive requirements in former part 23 as an alternate means of
compliance. Kestrel asked whether the FAA will require issue papers to
permit the use of these former prescriptive requirements.
In the NPRM, the FAA noted it will accept the use of the
prescriptive means of compliance contained in former part 23 as
alternate means of compliance, except for those sections where the
level of safety has increased specifically for stall characteristics
and icing protection. The FAA does not need to codify this decision to
retain this flexibility and is therefore not revising the proposed
language for Sec. 23.10. For applicants relying on satisfaction of the
prescriptive requirements in former part 23, amendment 23-62, as a
means of compliance, the FAA will only require the G-1 certification
basis issue paper to list the means of compliance as ``amendment 23-
62''.
[[Page 96591]]
NATCA asked whether the FAA will permit an applicant to use older
prescriptive regulations, such as Aeronautics Bulletin, amendment 7a,
``Airworthiness Requirements for Aircraft''; CAR 3; and previous
versions of part 23, as a means of compliance. If not, NATCA asked the
FAA to clarify why those regulations are not appropriate and acceptable
for the proposed design.
The FAA will consider the use of the older, prescriptive
regulations in cases where it is appropriate for the airplane in
question. There have been instances where applicants have approached
the FAA with projects to ``remake'' new versions of vintage airplanes.
The FAA has allowed and will continue to allow the use of
appropriately-selected design standards on vintage airplanes. However,
applicants wanting to use this approach should expect to use newer
industry practices where the old standards and practices have, over
time, not proven to meet the minimum acceptable safety standard for
that class of airplane in part 23.
Manner in Which Applicant Must Present Means of Compliance
Textron asked how the FAA will document the acceptance of a non-
industry standard means of compliance and whether acceptance of a
Project-Specific Certification Plan (PSCP) is adequate proof of the
FAA's acceptance of the means of compliance.
The FAA plans to include information on the acceptance of non-
consensus standards on its Small Airplane Directorate Web site. The G-1
issue paper and agreement on the certification basis and compliance
checklist will suffice. PSCP acceptance is adequate proof of FAA
acceptance of a means of compliance if a G-1 issue paper is not used.
Textron also asked whether there would be a system set-up similar
to repair specifications where an applicant could have pre-defined
methods for making certain changes to its products, and whether there
would be a method for the FAA to accept deviations to the accepted
standards.
The Part 23 ARC did not consider and the NPRM did not propose
repair specification; therefore, it is beyond the scope of this
rulemaking effort.
Air Tractor and Kestrel contended the process proposed by draft AC
23.10--which states that an applicant should list the means of
compliance and consensus standards they intend to use to show
compliance with part 23 in a certification plan or compliance
checklist--is premature and would slow the certification process. The
details of an airplane's design are often incomplete when an
application is submitted and it can take years to obtain FAA acceptance
of a PSCP. Air Tractor suggested that establishing a means of
compliance during the process of negotiating the PSCP should be limited
to picking one or more of the following: Analysis, tests, design
review, physical inspection, etc. Air Tractor also commented that a
requirement for the FAA to review and approve of particular methods
before the analysis can be presented would be new for most regulations.
It would also require a new level of required response from the FAA
that would drastically slow the process of either establishing the
certification plan or showing compliance. Air Tractor also questioned
how this requirement compares with the FAA and Industry Guide to
Product Certification.
The FAA finds that including the means of compliance in the PSCP or
the compliance checklist will not alter the current practice for new
technology because some of the compliance requirements may not be known
at the time of application. This initial uncertainty means the agreed
compliance may remain as a draft during the development and
certification process until the specific means of compliance are
determined and agreed upon. This may be a common issue with new
technology during the first few years after the new part 23 is
implemented. It will take some time to get accepted means of compliance
into consensus standards, resulting in these means of compliance being
developed during the project. In the long term, the new approach should
shorten the time needed for an applicant to get FAA agreement on its
means of compliance.
Finally, the FAA clarified the intent of the form and manner of the
means of compliance. The FAA does not intend to ``specify'' the form
and manner of means of compliance; the form and manner only need to be
``acceptable.''
3. Subpart B--Flight
a. Weight and Center of Gravity (Proposed Sec. 23.100/Now Sec.
23.2100)
In the NPRM, proposed Sec. 23.100 (now Sec. 23.2100) would have
required an applicant to determine weights and centers of gravity that
provide limits for the safe operation of the airplane. Additionally, it
would have required an applicant to show compliance with each
requirement of this subpart at each combination of weight and center of
gravity within the airplane's range of loading conditions using
tolerances acceptable to the Administrator. Proposed Sec. 23.100 would
have also required the condition of the airplane at the time of
determining its empty weight and center of gravity be well defined and
easily repeatable.
The Associations recommended a clarifying change to proposed Sec.
23.100(a) that would require the applicant to determine limits for
weights and centers of gravity that provide for the safe operation of
the airplane, rather than determine weights and centers of gravity that
provide limits.
The FAA adopts the Associations clarifying change. Accordingly,
Sec. 23.2100(a) now requires the applicant to determine limits for
weights and centers of gravity that provide for the safe operation of
the airplane.
Additionally, the Associations recommended changing proposed Sec.
23.100(b) to require the applicant to comply with each requirement of
subpart B at critical combinations of weight and center of gravity. The
commenters explained that it is appropriate to demonstrate compliance
at critical combinations of weight and center of gravity, but showing
compliance at each combination ``would present an infinite matrix of
test points.''
The FAA also adopts the Associations recommended change to proposed
Sec. 23.100(b) (now Sec. 23.2100(b)). While proposed Sec. 23.100(b)
could have been interpreted to require an infinite matrix of test
points, this was not the FAA's intent. Accordingly, Sec. 23.2100(b)
now requires the applicant to comply with each requirement of subpart B
at critical combinations of weight and center of gravity within the
airplane's range of loading conditions using tolerances acceptable to
the Administrator.
The Associations also stated that the determination of empty weight
and center of gravity in proposed Sec. 23.100(c) is ``somewhat
confusing and potentially unnecessary.'' The commenters suggested
clarifying changes that would replace ``empty weight'' with ``weight''
and delete ``well'' and ``easily repeatable,'' thereby requiring the
condition of the airplane at the time of determining its weight and
center of gravity to be defined. Similarly, Textron recommended
deleting the terms ``well'' and ``easily'' from proposed Sec.
23.100(c) because they are vague and subject to interpretation.
The FAA is retaining the terms ``well defined'' and ``easily
repeatable'' in Sec. 23.2100(c). In the NPRM, the FAA explained
proposed Sec. 23.100 would capture the safety intent of Sec. 23.29.
Section 23.29 has contained the terms
[[Page 96592]]
``well defined'' and ``easily repeated'' since it was published in
amendment 23-0 \23\ with no challenges. Furthermore, ``easily'' is an
important modifier for ``repeatable'' because it ensures that the
condition of the airplane at the time of determining its empty weight
and center of gravity is not hard for a mechanic to reproduce.
---------------------------------------------------------------------------
\23\ 29 FR 17955, December 18, 1964.
---------------------------------------------------------------------------
The FAA also retains the term ``empty weight'' in Sec. 23.2100(c).
Determining empty weight is fundamental to baselining an airplane.
Removing this term would leave the weight value for baseline open to
any weight between empty to gross weight. The ambiguity of not defining
the baseline weight would create confusion and problems.
b. Performance Data (Proposed Sec. 23.105/Now Sec. 23.2105)
In the NPRM, proposed Sec. 23.105 (now Sec. 23.2105) would have
required--
An airplane to meet the performance requirements of this
subpart in various conditions based on the airplane's certification and
performance levels for which certification is requested;
An applicant to develop the performance data required by
this subpart at various altitudes and at high temperatures, while also
accounting for losses due to atmospheric conditions, cooling needs, and
other demands on power sources; and
The procedures used for determining takeoff and landing
distances to be executed consistently by pilots of average skill in
atmospheric conditions expected to be encountered in service.
EASA and the Associations stated that some designs may have
performance limitations at low temperatures rather than high
temperatures, such as batteries in electric propulsion systems. The
commenters recommended revising the proposed language to require
performance data for low temperatures that can be expected during
operation, if those low temperatures could have a negative effect on
performance.
The FAA agrees proposed Sec. 23.105(b) (now Sec. 23.2105(b))
should account for possible performance degradation due to the effect
of cold temperatures on electric propulsion systems. Proposed Sec.
23.105 was intended to capture the safety intent of former Sec. 23.45,
which required the determination of performance data in various
conditions that could negatively affect performance. Historically,
propulsion systems were gas powered and negatively affected by high
temperatures, which resulted in a corresponding negative effect on
performance. This explains why former Sec. 23.45 required the
determination of performance data at a temperature from standard to 30
degrees Celsius above standard, as performance degradations
historically resulted from operation at high temperatures.
As stated in the NPRM, the FAA intended the proposal to account for
airplanes equipped with new technologies, such as electric propulsion
systems. Additionally, the FAA intended proposed Sec. 23.105(b) to
account for various conditions that could affect airplane performance.
However, proposed Sec. 23.105(b) would only have accounted for
performance degradations that could result from the operation of
systems at high temperatures, as the proposed language reflected former
Sec. 23.45. Because cold temperatures, rather than high temperatures,
may have a negative performance effect on an electric propulsion system
or a hybrid system, the FAA revises the proposed language to account
for performance degradations at low temperatures. The FAA also removes
the prescriptive language that would have required the determination of
performance data at a temperature from standard to 30 degrees Celsius.
Section 23.2105(b)(2) now requires the applicant to develop
performance data at temperatures above and below standard day
temperature that are within the range of operating limitations, if
those temperatures could have a negative effect on performance. This
requirement is consistent with the NPRM as it replaces the prescriptive
design requirements from the regulation with performance-based
airworthiness standards that accommodate new technologies, such as
electric and hybrid propulsion systems. Additionally, Sec.
23.2105(b)(2) more accurately reflects the safety intent of former
Sec. 23.45 because it requires the development of performance data in
conditions that could negatively affect performance, including
conditions that account for new technologies.
As a general matter, under Sec. 23.2105(b)(2), an applicant
seeking certification of a gas-powered propulsion system must develop
performance data at temperatures above standard that are within the
airplane's operating limitations, because high temperatures could have
a negative effect on the airplane's performance. Alternatively, an
applicant seeking certification of an electric or hybrid propulsion
system must develop performance data at temperatures both above and
below standard that are within the airplane's operating limitations, if
these temperatures could have a negative effect on performance.
Garmin pointed out that limited airflow in a climb configuration
may cause non-propulsion systems to overheat during long hot climbs,
requiring a different climb speed or configuration for system cooling
than addressed in proposed Sec. 23.105(b). Garmin recommended the FAA
include the phrase ``other essential equipment'' in addition to
propulsion cooling in paragraph (b)(2).
The Associations similarly suggested that there may be some cases
where the performance of equipment other than the propulsion system may
drive cooling requirements for hot conditions. The commenters
recommended revising the proposed language to include cooling
requirements for these equipment, in situations other than climb.
The FAA understands the concerns of Garmin and the Associations,
for paragraph (b)(2) to address cooling requirements for more than the
propulsion system. However, subpart B--including Sec. 23.2105--is
intended to address airplane performance. Therefore, Sec. 23.2105
should only address systems that affect airplane performance. For
example, Sec. 23.2105 may apply to avionics that also control
propulsion, or flight controls and lift systems needed to develop
repeatable airplane performance. Traditional avionics that do not
affect performance are addressed in subpart F, which contains
requirements for equipment. Therefore, the FAA is not adopting the
phrase ``other essential equipment'' because it may be interpreted to
include systems that do not affect performance, such as oxygen or
navigation systems. This would be a new requirement that has not been
identified as a safety need, increasing the scope and possibly the cost
of this rule. For the same reasons, the FAA is not expanding the scope
of the rule to include cooling requirements for equipment other than
propulsion systems, in situations other than climb.
Nevertheless, in light of the comments, the FAA acknowledges there
may be systems associated with propulsion that are necessary for
consistent performance, such as batteries or engine controllers, that
could be affected by temperature. Section 23.2105 should address these
types of systems. Therefore, Sec. 23.2105(b)(2) will apply to systems
associated with electric or other propulsion systems if those systems
could negatively affect performance at temperatures above or below
standard.
[[Page 96593]]
c. Stall Speed (Proposed Sec. 23.110/Now Sec. 23.2110)
In the NPRM, proposed Sec. 23.110 (now Sec. 23.2110) would have
required an applicant to determine the airplane stall speed or the
minimum steady flight speed for each flight configuration used in
normal operations, accounting for the most adverse conditions for each
flight configuration, with power set at idle or zero thrust.
The Associations recommended removing the proposed requirement for
power to be set at idle or zero thrust for each determination to enable
the introduction of new technologies such as distributed propulsion
with reliable electric power. The commenters explained that proposed
Sec. 23.110 must account for distributed lift systems because the
concept of distributed lift along a wing may be used to facilitate low-
speed handling, and reliable systems of this type may dictate
operational stall speeds. The commenters asserted their recommended
change would ensure that distributed propulsion, with an appropriate
reliability level, could be used in a landing condition accounting for
a lower stall speed based upon the effects of this equipment.
The FAA agrees that proposed Sec. 23.110 (now Sec. 23.2110)
should account for distributed propulsion systems used for thrust,
flight controls, and high lift systems. However, the rule must define a
thrust level for standardization because stall speeds are important to
the development of the performance-based speeds. The FAA finds it
appropriate to require traditional designs to determine stall speeds
and minimum steady flight speeds with power set at idle or zero thrust.
Accordingly, Sec. 23.2110(a) now requires the power to be set at idle
or zero thrust for propulsion systems used primarily for thrust. To
accommodate distributed propulsion systems, the FAA is adding new Sec.
23.2110(b), which requires a nominal thrust for propulsion systems used
for thrust, flight control, and/or high-lift systems. These changes
will allow Sec. 23.2110 to accommodate the new technologies identified
by the commenters.
Additionally, the FAA revises the proposed rule language to clarify
the ``stall speed or minimum steady flight speed determination'' must
account for the most adverse conditions for each flight configuration.
This change is consistent with the proposed rule, which would have
required ``each determination'' to account for the most adverse
conditions for each flight configuration, because ``each
determination'' referred to the ``stall speed or minimum steady flight
speed determination.''
d. Takeoff Performance (Proposed Sec. 23.115/Now Sec. 23.2115)
In the NPRM, proposed Sec. 23.115 (now Sec. 23.2115) would have
required an applicant to determine airplane takeoff performance, which
would have included the determination of ground roll and initial climb
distance to 50 feet, accounting for stall speed safety margins, minimum
control speeds, and climb gradients. Proposed Sec. 23.115 would have
also required the takeoff performance determination to include
accelerate-stop, ground roll and initial climb to 50 feet, and net
takeoff flight path, after a sudden critical loss of thrust for levels
1, 2, and 3 high-speed multiengine airplanes, multiengine airplanes
with a maximum takeoff weight greater than 12,500 pounds, and level 4
multiengine airplanes.
The Associations suggested the FAA revise proposed Sec. 23.115 to
capture the performance-based standards at a ``higher objective based
level'' because the proposed section was too detailed and prescriptive.
Textron recommended the FAA adopt language similar to EASA's A-NPA
2015-06, which leaves determination of detailed standards appropriate
to airplanes with different certification and performance levels to the
means of compliance standards.
The FAA disagrees with the comment, because it is important to
ensure the consistency of takeoff performance data across part 23
airplanes. This consistency aids private pilots, who often operate a
variety of part 23 airplanes, in determining the airports from which
they may operate.
Several commenters recommended the FAA remove the 12,500-pound
cutoff in proposed Sec. 23.115(c).
The FAA agrees and removes the weight discriminator from the rule
language. Although the FAA proposed to remove the commuter category,
along with weight- and propulsion-based certification divisions, and to
replace them with divisions based on risk and performance, the FAA also
proposed to require multiengine airplanes with a maximum takeoff weight
of more than 12,500 pounds to comply with the increased takeoff
performance requirements in paragraph (c). Proposed paragraph (c) was
intended to ensure that larger business jets carrying fewer than 10
passengers, which would have been considered commuter category under
the former rule, were captured under the takeoff performance
requirements because these airplanes would not necessarily fall under
level 4. The FAA recognizes that applying paragraph (c) to multiengine
airplanes with a maximum takeoff weight of more than 12,500 pounds is
redundant. Those airplanes, which are equivalent to airplanes under the
former commuter category, are captured by applying paragraph (c) to
levels 1, 2, and 3 high-speed multiengine airplanes and to all level 4,
multiengine airplanes. Furthermore, while paragraph (c) does not apply
to levels 1, 2 and 3 low-speed multiengine airplanes, the FAA may issue
special conditions if there is a configuration that presents a higher-
than-anticipated risk.
Several commenters objected to requiring the determination of
takeoff performance for all airplanes to include the determination of
initial climb distance to 50 feet above the takeoff surface. The
commenters noted that under the former rule, takeoff distance for
commuter category airplanes and multiengine jets weighing more than
6,000 pounds required the initial climb distance be calculated using 35
feet above the takeoff surface. Textron recommended the FAA revise
proposed Sec. 23.115(b) to apply the 50-feet-above-takeoff-surface
requirement only to single-engine airplanes and levels 1, 2, and 3 low-
speed multiengine airplanes rather than to all airplanes. Textron also
recommended revising proposed Sec. 23.115(c)(2) from ``50 feet'' to
``35 feet'' above the takeoff surface, noting the 35-foot standard has
been demonstrated as safe for the classes of airplane to which it has
been applied.
The FAA agrees with the commenters and revises proposed Sec.
23.115(b) (now Sec. 23.2115(b)) to require only single-engine
airplanes and levels 1, 2, and 3 low-speed, multiengine airplanes to
include the distance required to climb to a height above 50 feet when
calculating takeoff performance. The FAA is also changing the altitude
for the initial climb in Sec. 23.2115(c)(2) to 35 feet. The service
history of airplanes that would be classified as levels 1, 2, and 3
high-speed multiengine airplanes and level 4 multiengine airplanes
under this rule, which were certified using a 35-feet-initial-climb
requirement, has been sufficiently safe to support the proposition that
the 35-feet requirement provides an adequate level of safety for high-
speed multiengine airplanes and level 4 airplanes.
The Associations suggested revising proposed Sec. 23.115(b) and
(c) to require takeoff performance to include the determination of
``ground roll distance required to takeoff,'' rather than ``ground
roll.''
The FAA notes using ``ground roll distance required to takeoff'' is
not necessary for clarity. The term ``ground
[[Page 96594]]
roll'' in the context of takeoff is well-understood.
Several commenters recommended revising proposed Sec. 23.115(b) to
include two subparagraphs in what the FAA interprets as an effort to
clarify that the applicant must provide two distances, one for ground
roll and another for the distance required for the initial climb to 50
feet.
The FAA finds it unnecessary to reorganize paragraph (b) as the
commenters proposed. The format, as proposed and adopted, is
sufficiently clear.
The Associations suggested the FAA revise the proposed rule
language in proposed Sec. 23.115(c)(1) to require the takeoff
performance determination to include the distance determination of ``an
aborted take-off at critical speed,'' rather than ``accelerate-stop.''
The FAA agrees that ``accelerate-stop'' is not as clear a
description of the objective of the maneuver as ``aborted take-off at
critical speed''. Therefore, the FAA revises paragraph Sec.
23.2115(c)(1) to reflect the commenters' recommendation.
Embraer recommended the FAA provide special consideration--
including freezing the certification bases--for previously-approved
light jets with certification bases that include special conditions
measuring the takeoff distance as the distance required to takeoff and
climb to a height of 35 feet above the takeoff surface. Embraer feared
the potential cost associated with an upgrade or modification.
The FAA finds a special consideration unnecessary. There is already
a process, prescribed by Sec. 21.101(b), that allows applicants for a
change to a TC to show that the change complies with an earlier
amendment of a regulation if the newer requirement would not contribute
materially to the level of safety of the product or would be
impractical.
ANAC recommended the FAA make it clear that takeoff airspeed and
procedures must be determined. The FAA disagrees with ANAC's comment as
such a change would be redundant with what we proposed for Sec. 23.105
(now Sec. 23.2105).
e. Climb Requirements (Proposed Sec. 23.120/Now Sec. 23.2120)
In the NPRM, proposed Sec. 23.120 (now Sec. 23.2120) would have
required an applicant to demonstrate various minimum climb performances
out of ground effect, depending on the airplane's certification level
and performance capability.
In light of comments received, the FAA revises proposed Sec.
23.120 (now Sec. 23.2120) by withdrawing paragraphs (b)(4), (b)(5),
and (c)(1), and renumbering paragraphs (c)(2) and (c)(3) as (c)(1) and
(c)(2) respectively. This section discusses these changes in more
detail.
Textron commented that regulations have historically applied to the
airplane, not to the applicant, with demonstration of compliance
through flight testing. Textron recommended the FAA offer alternative
rule language that reflected its comment. The Associations similarly
recommended the FAA change the opening of proposed Sec. 23.120 to
focus on the design rather than the applicant. These commenters also
recommended re-designating the opening as paragraph (a).
The FAA notes that, historically, the airplane-specific
requirements focused on the airplane, and the part 21 certification
requirements were targeted more to the applicant. Many sections in this
rulemaking effort tried to include applicant accountability, which was
why the proposed rule focused on the ``applicant.'' However, based on
the comments received, the FAA revises the proposed language throughout
this rule by removing ``applicant'' where the requirement is more
logically based on the airplane.
Textron commented on the proposal to apply discriminators based on
weight divisions and detailed quantitative climb criteria conflicted
with the stated intent of the rulemaking to remove weight-based
divisions and develop standards reflecting the diversity of future
airplane designs. Textron recommended the FAA adopt language similar to
proposed CS 23.120, which leaves determination of detailed standards
appropriate to airplanes with different certification and performance
levels to means of compliance. The Associations recommended the FAA
make the calculation of performances more general, to facilitate the
use of standard means of compliance, which may exist in consensus-based
standards. An individual commenter similarly stated the
prescriptiveness of proposed Sec. 23.120 was contrary to the stated
objective of the proposal. The commenter stated the text of proposed
Sec. 23.120 would be more appropriate as a standard rather than a
rule. The commenter recommended that the FAA use the language of
proposed Sec. 23.125, which would have required the determination of
climb performance in certain conditions and configuration, in proposed
Sec. 23.120. The commenter also noted the current version of the ASTM
standard for climb requirements already fully covers the language of
proposed Sec. 23.120.
In response to Textron's comment, the FAA revises proposed Sec.
23.120 so it no longer contains weight divisions. Instead, the
requirements of this section are based on certification levels,
performance levels, and number of engines. Section 23.2120 does,
however, contain quantitative climb criteria. On this topic, the FAA
did not adopt the EASA proposed CS 23.120 language as recommended by
Textron. While the idea of removing all climb gradient requirements was
discussed in the Part 23 ARC, the FAA finds it is not in the best
interest of safety to eliminate all required climb gradients.
Therefore, the FAA is including the minimum climb gradients in this
performance-based rule. But, the FAA consolidated the climb gradient
requirements of former part 23 to simplify the requirement. The FAA
finds doing so will maintain the former level of safety while reducing
the certification burden. The FAA acknowledges the ASTM means of
compliance contain the climb gradients in more detail than required
from the requirements of this section. However, the ASTM means of
compliance has not been accepted by the FAA as of the publication of
this rule.
The FAA finds that, while removing as many prescriptive
requirements as possible is important for creating a performance-based
rule, some requirements should remain because they have been proven
over decades of service and are already based on performance. The FAA
finds the climb requirements are one such case.
In response to the comment that the FAA should use the language of
proposed Sec. 23.125 (now Sec. 23.2125) in proposed Sec. 23.120 (now
Sec. 23.2120), the FAA notes that Sec. 23.2125 only requires the
performance information be determined for the airplane flight manual
(AFM). There is no minimum climb gradient in Sec. 23.2125 as with
Sec. 23.2120. The Part 23 ARC discussed this issue at length with the
objective of defining a clear, minimum performance-based metric that
would allow the prescriptive climb gradients to move to means of
compliance. The climb gradients in former Sec. Sec. 23.65 through
23.77 came from early CAR 3 and have been in place for more than half a
century, with the exception of some commuter category requirements,
which came from early part 25. Since the FAA has established
measureable gradients, any alternative approach would need to maintain
the same gradients to provide an equivalent level of safety as the
former climb requirements. The ARC considered numerous options, but in
every case the proposed metric was subjective such that the FAA may be
[[Page 96595]]
required to evaluate various other climb gradient schemes against the
former climb gradients, when the intent was to maintain the former
climb gradients. Finally, the FAA determined keeping the prescriptive
climb gradients from the former rules remains the best approach.
Furthermore, supporting this position, the FAA could not envision new
and novel configurations that could not meet these climb gradients, but
would offer the same level of safety. All the new and novel
configurations that have been shared with the FAA have performance that
will meet or exceed the minimum gradients proposed in the NPRM. For
these reasons the FAA is retaining the proposed language.
Furthermore, it may not have been clear in the NPRM that the FAA
intended proposed Sec. 23.120 to address the required minimum climb
gradients in former Sec. Sec. 23.63, 23.65, 23.67, and 23.77, and
proposed Sec. 23.125 (now Sec. 23.2125) to address the required
publication of the measured performance in former Sec. Sec. 23.66,
23.69, and 23.71. Therefore, the FAA is not including language similar
to proposed Sec. 23.125 (now Sec. 23.2125) in Sec. 23.2120, because
Sec. 23.2120 includes required climb gradients, not information
requirements.
Textron stated that proposed Sec. 23.120(a) would have applied to
the all engines operating (AEO) takeoff climb and that a common
terminology should be used. Textron recommended the FAA replace the
undefined phrase ``initial climb configuration'' in proposed paragraph
(a) with the unambiguous phrase ``takeoff configuration'', and remove
the phrase ``at takeoff'' from proposed paragraph (a)(2). Textron also
recommended the FAA remove the phrase ``at sea level'' from proposed
paragraph (a)(1) because the FAA already proposed Sec. 23.105 to
require an airplane, unless otherwise prescribed, to meet the
performance requirements of this subpart in still air and standard
atmospheric conditions at sea level for all airplanes.
The FAA notes that replacing ``initial climb configuration'' with
``takeoff configuration'' would require the design to comply with the
required minimum climb performance out of ground effect, with all
engines operating and in the ``takeoff configuration''. The FAA finds
that this change would be more stringent than the former regulations.
Former Sec. 23.65(a) allowed for the climb to be demonstrated with the
landing gear retracted, and former Sec. 23.65(b) allowed for the climb
to be demonstrated with the landing gear retracted if it could be
retracted in 7 seconds. While normalizing both former regulations might
appear relieving for airplanes certified as complying with former Sec.
23.65(b),\24\ the FAA finds that most airplanes designed in the past 2
decades incorporated landing gear that retracted in less than seven
seconds. Therefore, the FAA is retaining the phrase ``initial climb
configuration'' in paragraph (a).
---------------------------------------------------------------------------
\24\ Former Sec. 23.65(b) applied to normal, utility, and
acrobatic category reciprocating engine-powered airplane of more
than 6,000 pounds maximum weight, single-engine turbine, and
multiengine turbine airplanes of 6,000 pounds or less maximum weight
in the normal, utility, and acrobatic category.
---------------------------------------------------------------------------
The FAA agrees with Textron's recommendation to delete ``at sea
level'' from proposed Sec. 23.120(a)(1). The FAA proposed the term
because it was part of former Sec. 23.65(a). As Textron noted,
however, proposed Sec. 23.105(a) (now Sec. 23.2105(a)) would have
already required an airplane to meet the performance data of subpart B,
including Sec. 23.2120, in still air and atmospheric conditions at sea
level for all airplanes. It is therefore unnecessary for paragraph
(a)(1) to require a climb gradient ``at sea level'' of 8.3 percent for
landplanes and 6.7 percent for seaplanes and amphibians. However, the
FAA is not deleting ``at takeoff'' as recommended by Textron. The
agency is aligning the new rule with former Sec. 23.65 by using
``after takeoff'' instead of ``at takeoff.'' This requirement is
indirectly addressed in Sec. 23.2105(b); however, as proposed, the
language was not clear as to intent. By including the term ``after
takeoff'', this requirement reinforces the meaning of ``ambient
atmospheric conditions'' in Sec. 23.2105(b).
The Associations and Transport Canada noted that proposed Sec.
23.120(a) did not address climb performance for level 4 airplanes.
Transport Canada stated the FAA should specify all engine operating
climb gradient requirements for level 4 airplanes. The Associations
stated the climb gradient requirements for level 4 airplanes should be
the same as the requirement for high-speed level 1 and 2 airplanes and
level 3 airplanes.
The FAA considered the comments and in response, revises proposed
Sec. 23.120(a) to include an all engines operating climb requirement
for level 4 single-engine airplanes. The former climb requirements
required all airplanes with 10 or more passengers to have multiple
engines and meet the commuter category climb requirements, which were
focused on the ability to climb after an engine failure. These one-
engine-inoperative climb requirements were extensive. The philosophy
was that if the airplane could meet the climb requirements after one
engine failed, it would have more-than-adequate performance with all
engines operating. This is why there were no all engine operating climb
requirements for commuter category airplanes. The FAA agrees with and
continues this philosophy in the new rule for multiengine airplanes
designed for 10 or more passengers, which are level 4 airplanes under
this rule. However, because the new rule eliminates the commuter
category and allows for single-engine airplanes to carry 10 or more
passengers, there is now a need for single-engine level 4 airplanes to
have an all engines operating climb requirement.
The FAA agrees with the Associations that the climb gradient
requirements for level 4 single-engines airplanes should be the same as
the requirement for levels 1 and 2 high-speed airplanes and level 3
airplanes. This was an oversight in the NPRM and the FAA is correcting
it in this final rule. Accordingly, Sec. 23.2120(a)(2) now requires
levels 1 and 2 high-speed airplanes, all level 3 airplanes, and level 4
single-engine airplanes to demonstrate, with all engines operating and
in the initial climb configuration, a climb gradient at takeoff of 4
percent. This revision is a logical outgrowth of the notice because, as
noted by the commenters, there is no basis for distinguishing between
level 3 and level 4 airplanes for this requirement.
Transport Canada commented that the FAA should consider and
validate whether a 4 percent climb gradient for high-performance
airplanes with all engines operating is sufficient. For example, an
airplane climbing at 100 knots (approximately 400 feet per minute) may
be acceptable for a level 1 airplane, but not for anything larger.
Transport Canada noted that proposed paragraph (a)(2) may govern more
frequently, because the all-engine climb capability driven by the one-
engine-inoperative requirements has been reduced in proposed paragraph
(b)(3). Transport Canada also noted that, given the increasing
probability of airplanes with more than 4 engines, it may be more
effective to increase the all-engine climb gradient in proposed
paragraph (a)(2).
The FAA considered Transport Canada's comments, but notes the
intent with this section was to maintain the level of safety in former
part 23. Section 23.2120(b) requires the same climb gradient--4
percent--as was required for similar airplanes by former part 23. The
FAA notes that requiring more stringent climb requirements is beyond
the scope of this rulemaking.
[[Page 96596]]
Textron made several comments to proposed Sec. 23.120(b). Textron
stated the word ``the'' should replace the word ``a'' when referring to
critical loss of thrust. For proposed Sec. 23.120(b)(1), Textron
suggested referring to climb gradient the same way as in proposed Sec.
23.120(a)(2). Textron also recommended changing ``configuration'' to
``configurations'' in proposed paragraph (b)(1) because one airplane
may have multiple takeoff and approach configurations. Textron and
Kestrel requested clarification regarding the single-engine
crashworthiness requirements referred to in proposed Sec.
23.120(b)(1). Kestrel asked whether those requirements will be
established in the rule or based on an associated standard.
Regarding Textron's comment on the use of the word ``the'' in the
phrase ``the critical loss of thrust,'' the term ``the'' would assume
that everyone knows what that critical loss of thrust is. While that
may be true for traditional configurations, it may not be true for
future configurations. Therefore, the FAA is keeping the proposed
phrase ``a critical loss of thrust.'' However, the FAA agrees with
Textron concerning multiple configurations and revises the rule to
align the reference to the climb gradient in Sec. Sec. 23.2120(a)(2)
and 23.2120(b)(1) for clarity.
In response to Kestrel and Textron, Sec. 23.2120(b)(1) contains a
requirement addressing airplanes that do not meet the single-engine
crashworthiness requirements of proposed Sec. 23.600, ``Emergency
conditions'' (now Sec. 23.2270). Section 23.2120(b)(1) is intended to
capture the intent of former Sec. 23.67(a)(1), which required
airplanes with VSO of more than 61 knots to maintain a
steady climb gradient of at least 1.5 percent. Sixty-one knots was a
historic stall speed limit for single-engine airplanes and for that
reason, it was used as a division between multiengine airplanes that
could climb after the loss of one engine and other multiengine
airplanes that could not maintain altitude after the loss of one
engine. These former requirements assumed that the airplane only had
two engines. The FAA is not using the 61 knot stall speed division in
this new rule the way it was used in former Sec. 23.562, ``Emergency
landing dynamic conditions'', for crashworthiness requirements.
Instead, the FAA is basing these new regulations on actual stall speed.
The new regulations should, over time, allow several alternatives to
address occupant protection. For this reason, and because the FAA did
not intend to increase the level of safety over the former
requirements, the FAA is using the phrase ``single-engine
crashworthiness.''
Textron asserted that to obtain the best takeoff performance in
high and hot conditions, it can be advantageous to use lesser flap
settings to improve climb capability after takeoff. However, the
proposed climb requirements--defined only in terms of the approach
configuration--would have eliminated this capability, and would not
have reflected the former part 23 standards. Textron suggested the FAA
revise the proposed rule language in paragraph (b)(3) to require
multiengine level 3 high-speed airplanes and level 4 airplanes to
determine the climb gradients for weight, altitude, and temperature
combinations appropriate for takeoff in the takeoff configuration.
The FAA notes that the reason for using the ``approach
configuration'' was not that it reflected an actual configuration, but
that it was more conservative than using the ``takeoff configuration.''
The FAA elected to consolidate the climb requirements from four
configurations into one configuration. To do so, the FAA had to make
some assumptions. The major assumption used in consolidating the climb
requirements was that if the airplane could meet the second segment
climb gradient at 400 feet, then it should meet the other traditional
requirements and would provide an acceptable level of safety. However,
to provide a margin of safety in case one of the other conditions was
slightly more critical, the FAA elected to apply the discontinued
approach flap configuration, which is ``approach'' flaps, for this
requirement.
Transport Canada commented it would be more conservative to require
the four-engine climb gradient of 2.6 percent in proposed Sec.
23.120(b)(3), rather than the two-engine climb gradient of 2 percent.
The FAA explained in the NPRM that the climb gradient associated
with the loss of one engine for a two-engine airplane has provided an
acceptable safety history for this class of airplane. The historical
three- and four-engine climb gradients were based on part 25
regulations regarding gas engine technology, and may not be appropriate
for distributed electric propulsion configurations or designs. For this
reason, using those historical values may end up with a more
conservative approach than intended. This would increase the
requirements from the former part 23 regulations, which is outside the
scope of this rulemaking.
Several commenters recommended the FAA either delete, clarify, or
re-write proposed Sec. 23.120(b)(4) and (5) because the intent of
those paragraphs is unclear.
The FAA agrees that proposed Sec. 23.120(b)(4) and (b)(5) are
confusing. The FAA intended the conditions in paragraphs (b)(4) and
(b)(5) to apply to the determinations required by paragraph (b).
However, because Sec. 23.2105(a) requires an airplane to meet the
performance data of subpart B for these 2 conditions, paragraphs (b)(4)
and (b)(5) are redundant and confusing. For this reason, the FAA
withdraws paragraphs (b)(4) and (b)(5).
An individual commented that all multiengine airplanes should be
able to climb after an engine failure. The commenter stated this
performance is affordable and the FAA should not permit poor
performance because a manufacturer wants to refurbish a decades-old
design and produce it.
The FAA notes that adding the requirement for all-multiengine
airplanes to be able to climb after an engine failure is beyond the
scope of this rulemaking. The FAA finds that the current level of
safety in former part 23 regarding climb performance for multiengine
airplanes following an engine failure is adequate.
The Associations recommended the FAA revise the proposed rule
language to require the applicant to demonstrate a climb gradient of 3
percent during balked landing ``without creating undue pilot
workload.'' The commenters also recommended the FAA rewrite proposed
Sec. 23.120(c) to include a general requirement for the applicant to
determine, as applicable, climb and descent performance for all engines
operating; following a critical loss of thrust on take-off; and after a
critical loss of thrust during the enroute phase of flight.
The FAA originally determined that adding the phrase ``without
creating undue pilot workload'' in this requirement was redundant with
proposed Sec. 23.105(c); however, proposed Sec. 23.105(c) only
addressed takeoff and landing distances. The FAA also recognizes that
many of the part 23 fatal accidents happen on go-arounds or balked
landings and are attributable, at least in part, to high-pilot
workload. For this reason, the FAA is adding ``without creating undue
pilot workload'' to Sec. 23.2120(c).
The FAA also addresses the commenters' recommendation to include a
general requirement for the applicant to determine, as applicable,
climb and descent performance for all engines operating; following a
critical loss of thrust on take-off; and after a critical loss of
thrust during the enroute
[[Page 96597]]
phase of flight in Sec. 23.2125(a)(2) and (a)(3).
Textron and Transport Canada also commented on proposed Sec.
23.120(c). Textron stated that it is unclear why takeoff power is
specified for the balked landing, but not for any other minimum climb
performance requirements. Textron recommended changing the word
``configuration'' to ``configurations'' in proposed Sec. 23.120(c)(3)
because an airplane might have multiple landing configurations.
The FAA agrees with Textron that the reference to takeoff power was
not needed. Therefore, the FAA deletes the reference from proposed
Sec. 23.120(c) (now Sec. 23.2120(c)). The FAA also agrees with
Textron's recommendation to change ``configuration'' to
``configurations'' and makes this change in Sec. 23.2120(c).
Transport Canada asked that the FAA justify the reduction in the
required landing climb gradients from 3.3 percent to 3 percent.
The FAA notes that former Sec. 23.77, which governed balked
landings, required a 3.3 percent gradient for piston airplanes weighing
less than 6,000 pounds; a 2.5 percent gradient for piston engine and
single-engine turbine-powered airplanes over 6,000 pounds and for
multiengine turbine-powered airplanes weighing 6,000 pounds or less;
and a 3.2 percent gradient for multiengine turbine-powered airplanes
weighing over 6,000 pounds and commuter category airplanes. The FAA is
simplifying the former requirement by taking the average of the three
climb gradients. The FAA did not receive any negative comments
concerning the decrease or increase in climb gradient requirements, so
the FAA adopts the language as proposed.
f. Climb Information (Proposed Sec. 23.125/Now Sec. 23.2125)
In the NPRM, proposed Sec. 23.125 (now Sec. 23.2125) would have
required an applicant to determine the climb performance for--
All single-engine airplanes;
Level 3 multiengine airplanes, after a critical loss of
thrust on takeoff in the initial climb configuration; and
All multiengine airplanes, during the enroute phase of
flight with all engines operating and after a critical loss of thrust
in the cruise configuration.
Proposed Sec. 23.125 would have also required an applicant to
determine the glide performance of the airplane after a complete loss
of thrust for single-engine airplanes.
Transport Canada commented that proposed Sec. 23.125(a) appears to
lack the concept of determining climb performance at each approved
weight, altitude, and temperature. Additionally, Transport Canada
stated it is unclear why proposed Sec. 23.125(a)(2) applies only to
level 3 multiengine airplane. Transport Canada recommended the FAA
require the determination of climb performance following a critical
loss of thrust on take-off in the initial climb configuration for all
multiengine airplanes at each weight, altitude, and temperature.
The FAA agrees with Transport Canada that proposed Sec. 23.125(a)
would not have expressly required the determination of climb
performance at each approved weight, altitude, and temperature. The FAA
intended proposed Sec. 23.105(a)--which would have required levels 1
and 2 high-speed airplanes and level 3 airplanes to provide performance
data in ambient atmospheric conditions within the operating envelope--
to capture this requirement. To comply with the requirement in proposed
Sec. 23.105(a) to ``meet the performance requirements'' of subpart B,
an applicant would have had to make these determinations anyway.
However, after considering Transport Canada's comment, the FAA revises
the proposed language to make clear that Sec. 23.125(a)(2) (now Sec.
23.2125(a)(2)) requires the determination of climb performance at each
weight, altitude, and ambient temperature within the operating
limitations. This change is consistent with the NPRM, which explained
that proposed Sec. 23.125 was intended to capture the safety intent of
former Sec. Sec. 23.66 and 23.69. Both of these sections required the
determination to be made at each weight, altitude, and ambient
temperature within the airplane operating limitations.
The FAA agrees that Sec. 23.2125(a)(2) should apply to more than
level 3 multiengine airplanes; however, it should not apply to all
multiengine airplanes. Section 23.2125(a)(2) captures the safety intent
of former Sec. 23.66, which applied only to reciprocating engine-
powered airplanes of more than 6,000 pounds maximum weight and turbine
engine-powered airplanes. Under the new performance-based regulations,
the equivalent airplanes--considering the intent of former Sec.
23.66--are levels 1 and 2 high-speed multiengine airplanes and all
level 3 airplanes. Therefore, the FAA revises the proposed rule
language to include levels 1 and 2 high-speed multiengine airplanes in
addition to level 3 multiengine airplanes, to maintain the same level
of safety as former Sec. 23.66. However, because former Sec. 23.66
did not apply to commuter-category airplanes--which were considered the
equivalent of level 4 multiengine airplanes--Sec. 23.2125(a)(2) should
not apply to all multiengine airplanes as doing so would make the rule
more stringent than former Sec. 23.66.
Textron noted the continuous reference to ``a critical loss of
thrust'' in proposed Sec. 23.125 and recommended the FAA refer to it
as ``the critical loss of thrust.'' The FAA understands Textron's
comment; however, the term ``the critical loss of thrust'' assumes
there is a critical loss of thrust and that it is a known, finite
condition for all multiengine airplanes. This may not be the case. The
phrase ``a critical loss of thrust'' allows for the possibility that
there is no critical loss of thrust or that different airplane
configurations would have different critical loss of thrust conditions
based on a specific configuration.
Textron recommended deleting the undefined phrase ``initial climb
configuration'' from proposed Sec. 23.125. Textron also recommended
the FAA not require multiengine airplanes to be in the cruise
configuration during the determination of climb performance in the
enroute phase of flight. Textron explained that while the enroute phase
of flight is typically associated with a ``clean'' airplane
configuration, the applicant should be free to define this
configuration.
The FAA agrees with Textron's intent, but does not accept Textron's
recommendations. The FAA is requiring the airplane to be in the
``initial climb configuration'' in Sec. 23.2125(a)(2) and the ``cruise
configuration'' in Sec. 23.2125(a)(3). However, the FAA is not
defining ``initial climb configuration'' because a definition would be
prescriptive and inflexible for new configurations, which would be
contrary to this performance-based regulation. Paragraphs (a)(2) and
(a)(3) capture the safety intent of former Sec. Sec. 23.66 and 23.69,
respectively. Former Sec. Sec. 23.66 and 23.69 contained prescriptive
requirements pertaining to the takeoff and enroute configurations,
which were based on airplane designs over the past half-century. The
FAA finds the new rules should include traditional configurations, but
be flexible enough for new configurations in the future. These new
configurations may be different from what was traditionally required in
part 23 due to a unique propulsion, high lift, and/or flight control
configuration. Therefore, Sec. 23.2125(a)(2) and (a)(3) specify the
configuration conditions in a performance-based manner that allows
flexibility for the applicant to define what the configuration is in
means of compliance.
[[Page 96598]]
Furthermore, based on another comment from Textron, the FAA deletes
unnecessary text in paragraph (b) and moves the phrase ``single engine
airplanes'' in the same paragraph to make the rule language of Sec.
23.2125(b) read consistently with Sec. 23.2125(a).
g. Landing (Proposed Sec. 23.130/Now Sec. 23.2130)
In the NPRM, proposed Sec. 23.130 (now Sec. 23.2130) would have
required an applicant to determine the landing distance for standard
temperatures at each weight and altitude within the operational limits
for landing. The landing distance determination would start from a
height of 50 feet (15 meters) above the landing surface, require the
airplane to land and come to a stop (or for water operations, reach a
speed of 3 knots) using approach and landing speeds, configurations,
and procedures which allow a pilot of average skill to meet the landing
distance consistently and without causing damage or injury. Proposed
Sec. 23.130 would have required these determinations for standard
temperatures at each weight and altitude within the operational limits
for landing.
Transport Canada stated proposed Sec. 23.130 should require the
landing performance to account for stall speed safety margins and
minimum control speeds to maintain consistency with the take-off
requirements in proposed Sec. 23.115 (now Sec. 23.2115) and to ensure
the same level of safety as former part 23.
The FAA agrees the landing requirements of proposed Sec. 23.130
(now Sec. 23.2130) should expressly account for stall speed safety
margins and minimum control speeds consistent with the takeoff
performance requirements of proposed Sec. 23.115 (now Sec. 23.2115).
Proposed Sec. 23.130(b) would have generally required the
determination of approach and landing speeds. As explained in the NPRM,
the FAA intended proposed Sec. 23.130 to capture the safety intent of
former Sec. 23.73, which required the reference landing approach speed
to account for minimum control speed (VMC) and
VS1. The FAA's intention to account for stall speed safety
margins and minimum control speed, which would ensure the same level of
safety as former Sec. 23.73, was not clear in the proposed rule
language. Accordingly, the FAA is adding language to paragraph Sec.
23.2115(b) to clarify that an applicant must account for stall speed
safety margins and minimum control speeds when determining the approach
and landing speeds, configurations, and procedures.
Several commenters recommended clarifying changes to proposed Sec.
23.130. The Associations recommended deleting the phrases ``the
following'' and ``for landing'' in the introductory paragraph. Textron
recommended various changes to proposed Sec. 23.130(b), such as
replacing ``meet'' with ``achieve,'' specifying that the landing
distance is determined in proposed paragraph (a), and replacing
``causing damage or injury'' with ``endangering the airplane and its
occupants.''
The FAA deletes the phrase ``for landing'' from the introductory
paragraph of Sec. 23.2130. This phrase is unnecessary because the
section is about landing distance. However, the FAA retains the phrase
``the following'' for clarity. For Sec. 23.2130(b), the FAA agrees
that requiring a pilot of average skill ``to meet the landing
distance'' is unclear, but will not replace the term ``meet'' because
changing one word would not make the regulation any clearer. Instead,
the FAA revises the language in Sec. 23.2130(b) to require a pilot of
average skill ``to land within the published landing distance'' and
finds it unnecessary to specify in Sec. 23.2130(b) that the landing
distance is determined in Sec. 23.2130(a). Lastly, the FAA retains the
proposed language ``causing damage or injury'' because the commenter's
recommended change is vague and could cause the regulations to be
interpreted more stringently.
BendixKing suggested adding language to proposed Sec. 23.130(a)
that would require the speed of 3 knots for water operations to be
relative to the surface in calm atmospheric conditions. Alternatively,
the Associations recommended removing entirely the requirement for
water operations to reach a speed of 3 knots. The commenters agreed
that the term ``stop'' would differ for water and land operations, but
asserted that the difference is not as simple as stating 3 knots. The
commenters stated the appropriate method of compliance for determining
a stop for seaplanes or amphibians should be contained in accepted
standards.
The FAA agrees with the commenters and removes from the proposed
rule language the requirement for water operations to reach a speed of
3 knots. The speed of 3 knots originated from AC 23-8C, which addresses
water operations. Former Sec. 23.75, the predecessor to Sec. 23.130,
required the airplane to come to a complete stop, and left the surface
type undefined. The FAA intended to clarify rule language by specifying
the speed of 3 knots to differentiate between land and water
operations. However, in light of the comments, the proposed language
added confusion and failed to allow the flexibility necessary for water
operations. The FAA agrees with the commenters that the 3-knot
reference is more appropriate as guidance. Accordingly, Sec.
23.2130(a) now requires the applicant to determine the distance
required to land and come to a stop, starting at a height of 50 feet
above the landing surface. This change removes the need to address
whether the speed of 3 knots must be relative to the surface in calm
atmospheric conditions. The information necessary to comply with Sec.
23.2130(a) will be addressed in means of compliance.
NJASAP said that wet runway data, as well as contaminated runway
data, should be available for airplane certified to land under the
conditions set forth in proposed Sec. 23.130(a). NJASAP also suggested
the FAA adopt concepts from the Takeoff and Landing Performance
Assessment (TALPA) ARC. NJASAP pointed out that airplanes certified
under part 135 fly in all weather conditions. Finally, NJASAP stated
that runway excursions are a documented risk for these airplanes and
this opportunity offers an additional enhancement.
While the FAA supports the NJASAP recommendation to make wet runway
data available, doing so should not be a requirement. The TALPA ARC was
primarily a part 25 effort targeting transport operations, not small
airplane operations. The FAA is not adopting the TALPA ARC
recommendations because they exceed former part 23 requirements and are
therefore outside the scope of this rulemaking. The FAA recommends that
NJASAP work with industry to add wet runway conditions to the industry
consensus standards as possible means of compliance for airplanes used
in part 135 operations.
ANAC recommended the FAA require the landing procedures to allow
for a safe landing, or a transition to a balked landing configuration,
as this would cover the intent of former Sec. 23.75.
The FAA agrees that proposed Sec. 23.130 (now Sec. 23.2130)
should address the safe transition to the balked landing conditions.
The FAA intended proposed Sec. 23.130 to capture the safety intent of
former Sec. Sec. 23.73 and 23.75. Former Sec. 23.75 required a safe
transition to the balked landing conditions of former Sec. 23.77 from
the conditions that existed at the 50-foot height. The balked landing
conditions are now contained in Sec. 23.2120(c), which captures the
safety intent of former Sec. 23.77. To ensure Sec. 23.2130 contains
the same level of safety as former Sec. 23.75, the FAA revises the
proposed rule language to require an
[[Page 96599]]
applicant to determine the approach and landing speeds, configurations,
and procedures that allow for a safe transition to the balked landing
conditions specified in part 23.
The Associations also recommended the FAA clarify the introductory
sentence of proposed Sec. 23.130 by deleting ``each.'' The FAA agrees
with this comment. Requiring determinations to be made at ``each''
combination of weight and altitude within the operational limits could
be interpreted as requiring an infinite matrix of test points, which
was not the FAA's intent. Rather than requiring the applicant to
determine landing performance at ``each'' combination of weight and
altitude within the operational limits, the FAA is requiring the
determinations to be made at ``critical combinations'' of weight and
altitude. This change is consistent with the change the FAA made to
Sec. 23.2100(b).
h. Controllability (Proposed Sec. 23.200/Now Sec. 23.2135)
In the NPRM, proposed Sec. 23.200 (now Sec. 23.2135) would have
required--
The airplane to be controllable and maneuverable, without
requiring exceptional piloting skill, alertness, or strength, within
the operating envelope, at all loading conditions for which
certification is requested. This would have included during low-speed
operations, including stalls, with any probable flight control or
propulsion system failure, and during configuration changes;
The airplane to be able to complete a landing without
causing damage or serious injury, in the landing configuration at a
speed of VREF minus 5 knots using the approach gradient
equal to the steepest used in the landing distance determination;
VMC not to exceed VS1 or
VS0 for all practical weights and configurations within the
operating envelope of the airplane for levels 1 and 2 multiengine
airplanes that cannot climb after a critical loss of thrust; and
An applicant to demonstrate those aerobatic maneuvers for
which certification is requested and determine entry speeds.
Kestrel questioned whether proposed Sec. 23.200, which is intended
to capture the requirements of former Sec. 23.145, would be
interpreted to include the former requirement to show the airplane can
pitch nose downward when approaching stall, thus avoiding or recovering
from stall, or, alternatively, whether the FAA found that requirement
to be too prescriptive, representing only one possible means of
compliance with the proposed controllability requirements.
The FAA intended proposed Sec. 23.200 (now Sec. 23.2135) to
capture the safety intent of the former controllability Sec. Sec.
23.141 through 23.157 and allow for other possible means of compliance
appropriate to new or innovative designs. Therefore, proposed Sec.
23.200 was not related only to former Sec. 23.145 and was not intended
to capture the specific requirements of former Sec. 23.145, but did
intend to capture its broader safety intent. The former requirement
referenced by the commenter is prescriptive and provides a means of
compliance for traditional configuration airplanes. Because it is
possible for novel configurations and control schemes in the future to
need different means of compliance, the FAA finds that the prescriptive
language from former Sec. 23.145 is more appropriate as means of
compliance.
Textron commented on proposed Sec. 23.200(a)(2). Textron pointed
out that former Sec. 23.143(a) and the proposal from the Part 23 ARC
referenced ``all flight phases,'' which better captures the general
intent of former Sec. 23.143(a). Additionally, Textron stated that
proposed Sec. 23.215 addresses stall characteristics, making the stall
aspect of proposed Sec. 23.200(a)(2) redundant. Textron recommended
the FAA maintain language similar to former part 23 by replacing the
phrase ``low-speed operations, including stalls,'' with ``all flight
phases.''
The FAA agrees with Textron. The FAA's intent in proposed Sec.
23.200(a) (now Sec. 23.2135(a)) was to capture the safety intent of
former Sec. 23.143, which required the airplane to be safely
controllable and maneuverable during all phases of flight. The FAA
agrees that the phrase ``all flight phases'' better captures the safety
intent of former Sec. 23.143(a). Additionally, upon further review,
the language of proposed Sec. 23.200(a)(2) is confusing because, while
the FAA proposed to add requirements to essentially avoid the stall
maneuver in proposed Sec. 23.215, proposed Sec. 23.200(a)(2) would
have required controllability in the stall. While this is a desirable
and recommended condition, the FAA does not want to add confusion. The
stall requirements belong in proposed Sec. 23.215 (now Sec. 23.2150).
For these reasons, the FAA adopts Textron's recommendation.
Textron also commented on proposed Sec. 23.200(a)(3). Textron
noted that former Sec. 23.143 and the proposal from the Part 23 ARC
did not address failures other than a response to a sudden engine
failure. Textron also noted that proposed Sec. 23.1315 already covers
general airplane system or equipment failures. Textron claimed the
requirements of proposed Sec. 23.200(a)(3) could be interpreted as
requiring demonstration of all probable flight control and propulsion
failures in a flight-test environment, which the commenter said would
not be practical or safe. Textron recommended maintaining the
traditional scope of former subpart B controllability requirements,
which included normal operations and, for multiengine airplanes, the
response to critical loss of thrust, and using the methods employed for
proposed Sec. 23.1315 to evaluate responses to other failures.
In light of Textron's comment, the FAA finds it necessary to
clarify that Sec. 23.2135(a)(3) applies to ``reversible,'' which were
traditionally mechanical flight controls, not ``irreversible'' flight
controls. The FAA's intent in proposed Sec. 23.200(a) was to capture
the safety intent of former Sec. Sec. 23.145(e) and 23.147(c), which
required applicants to address mechanical control system failures.
Historically, these requirements targeted control cable failures or
push-pull tube disconnects. Former subpart F, which contained
requirements on equipment, addressed powered- and computer-controlled
flight control systems. Under this final rule, subpart F continues to
address equipment, such as powered- and computer-controlled flight
control systems, and Sec. 23.2135 addresses mechanical control system
failures, which is consistent with former Sec. Sec. 23.145(e) and
23.147(c).
The Associations and EASA also addressed proposed Sec.
23.200(a)(3).\25\ The Associations recommended the FAA delete the word
``any'' from the phrase ``any probable flight control or propulsion
system failure.'' EASA recommended the FAA replace the word
``probable'' with ``likely,'' to avoid creating ambiguity with
probability definitions.
---------------------------------------------------------------------------
\25\ EASA actually referred to proposed Sec. 23.200(a)(4) in
its comment, but the FAA assumes EASA meant to refer to proposed
Sec. 23.200(a)(3), which is where the term ``probable'' is used.
---------------------------------------------------------------------------
The FAA agrees the term ``any'' does not add value compared to the
potential for confusion coming from an absolute qualifier. The FAA
therefore deletes the word ``any'' in Sec. 23.2135(a)(3).
The FAA also agrees the term ``probable'' has specific meaning
relative to systems. Furthermore, the FAA expects a transition from
mechanical flight controls to computer-controlled flight control
systems, which are covered under the requirements in subpart F. Because
the term ``probable''
[[Page 96600]]
has the potential to create confusion between the flight test
requirements of subpart B and the systems requirements of subpart F,
the FAA is using the term ``likely,'' rather than ``probable,'' which
will reduce the potential for confusion while maintaining the intent of
the requirement. For more detailed discussion on the use of ``likely'',
please refer to the discussion on proposed Sec. 23.205 (now Sec.
23.2140).
The Associations commented on proposed Sec. 23.200(b), stating
that it does not account for preferred technologies, such as angle of
attack indicators, for executing safe approach and landing procedures.
The commenters recommended proposed paragraph (b) require the airplane
to complete a safe landing when following the landing procedures;
providing a safe margin below Vref or above angle of attack.
EASA recommended removing the configuration details and specific speed
margin from proposed Sec. 23.200(b) because future designs would not
be able to comply with them.
The FAA agrees with these comments. The FAA intended proposed Sec.
23.200(b) (now Sec. 23.2135(b)) to capture the safety intent of former
Sec. 23.153 for control during landings. The FAA agrees that
specifying a prescriptive speed of Vref minus 5 knots, which
former Sec. 23.153 required, may not be appropriate for entry-level
airplanes with very-low landing speeds and may not even apply to new
configurations. The FAA therefore removes this prescriptive speed.
Instead, the FAA is requiring a reasonable margin below Vref
or above approach angle of attack, as recommended by the Associations.
This change from what was proposed is consistent with the safety intent
of former Sec. 23.153 as it requires a safe speed margin and it
accounts for entry-level airplanes and new technology. The FAA also
deletes the phrase ``equal to the steepest used in the landing distance
determination'' and replaces it with ``steepest approved'' approach
gradient procedures as this is clarifying.
Textron recommended proposed Sec. 23.200(b) be modified to require
the airplane to land without ``endangering the airplane and its
occupants,'' rather than to land without ``causing damage or serious
injury.''
The FAA finds that Textron's recommendation does not capture the
safety intent of former Sec. 23.153, which required safe completion of
a landing. However, in light of Textron's comment, the FAA is
clarifying the term ``damage.'' As proposed in the NPRM, the rule would
not have allowed any damage, no matter how trivial. This was not the
intent of former Sec. 23.153. The FAA intended to capture the safety
intent of former Sec. 23.153 in proposed Sec. 23.200(b) (now Sec.
23.2135(b)); therefore, the FAA revises the proposed rule language by
defining the damage that could be accepted during demonstration.
Section 23.2135(b) now requires the airplane to be able to complete a
landing without causing ``substantial'' damage or serious injury.
Substantial damage is defined in 49 CFR part 830 as requiring major
repairs and effectively preclude the use of the airplane for its
intended purpose.
Textron also noted that proposed Sec. 23.200 would not have
required VMC to be determined. ANAC and Textron recommended
the FAA require VMC to be determined, because it must be
accounted for in the determination of takeoff performance. Textron
recommended adding a new paragraph to proposed Sec. 23.200. Textron
recommended the new paragraph state VMC is the calibrated
airspeed at which, following the sudden critical loss of thrust, it is
possible to maintain control of the airplane. For multiengine
airplanes, the applicant must determine VMC for each flight
configuration used in takeoff and landing operations.
The FAA agrees the rule should require VMC to be
determined. Proposed Sec. 23.200 was intended to capture the safety
intent of former Sec. 23.149, which defined and required the
determination of VMC. The FAA is adding language to Sec.
23.2135(c) that is consistent with former Sec. 23.149, but removes the
prescriptive requirements of former Sec. 23.149, such as the specific
configuration requirements. Section 23.2135(c) now states that
VMC is the calibrated airspeed at which, following the
sudden critical loss of thrust, it is possible to maintain control of
the airplane. Section 23.2135(c) also requires the applicant to
determine VMC, if applicable, for the most critical
configurations used in the takeoff and landing operations. The FAA is
requiring the applicant to determine VMC in the most
``critical'' configurations rather than in ``each'' configuration
because requiring the determination at each configuration would present
an infinite number of test points. Additionally, the FAA added the
phrase ``if applicable'' to the rule language because there are
multiengine airplanes that do not have a VMC.
ANAC recommended proposed Sec. 23.200(c) be written in a less
prescriptive manner to allow for different technology solutions. ANAC
stated that proposed Sec. 23.200(c) should contain only the safety
objective stated in the NPRM. For example, proposed Sec. 23.200 should
have stated that an airplane should not depart controlled flight at low
speeds above stall as a result of asymmetric thrust.
The Associations stated that while proposed Sec. 23.200(c)
represented a potential solution to the typical accident scenario
involving loss of control in multiengine airplanes, which are unable to
climb on a single engine, there are other solutions that may be better
depending on the design of the airplane. The commenters noted that
instead of assuring VMC is below the stall speed, solutions
might include envelope protection, increased awareness of the loss of
control condition, or automatic-power response. To ensure the rule
allows the best solution for a particular design, the commenters
recommended the FAA not adopt proposed Sec. 23.200(c). Instead, the
commenters recommended the section on loss of control, proposed Sec.
23.215, require multi-engine airplanes, not certified for aerobatics,
not have a tendency to suffer a loss of control after a likely critical
loss of thrust. Several other commenters also expressed concerns about
proposed Sec. 23.200(c) and made similar recommendations.
As explained in the NPRM, the critical safety issue that the FAA
intended proposed Sec. 23.200(c) to address was the loss of control
caused by asymmetric thrust. The FAA recognized in the NPRM concerns
regarding the effectiveness of the proposed requirement in addressing
loss of control caused by asymmetric thrust and requested comments on
the proposal. In light of the comments received, the FAA is not
adopting proposed Sec. 23.200(c). The FAA agrees with ANAC and the
Associations that the rule should allow for different technologies as
design solutions to the identified safety issue. The FAA also agrees
that Sec. 23.2150 should include the requirement to address this loss
of control issue. Therefore, the FAA adopts less prescriptive language
similar to that recommended by the commenters, which is consistent with
the intent of proposed Sec. 23.200(c). This will allow for alternative
design solutions. Section 23.2150(c) now requires levels 1 and 2
multiengine airplanes, not certified for aerobatics, to not have a
tendency to inadvertently depart controlled flight from thrust
asymmetry after a critical loss of thrust.
The Associations and EASA recommended the FAA apply this
requirement to all multiengine airplanes, rather than only levels 1 and
2. The FAA is not adopting this recommendation. As explained in the
NPRM, the FAA does not have the accident history data to support it.
The FAA encourages manufacturers of levels
[[Page 96601]]
3 and 4 multiengine airplanes to incorporate safety features that
prevent inadvertent departure as with levels 1 and 2 multiengine
airplanes.
ICON commented an airplane designed in accordance with proposed
Sec. 23.200(c) would require less skill and presence of mind during an
emergency, resulting in better safety.
While the FAA is not adopting proposed Sec. 23.200(c), new Sec.
23.2150(c) achieves the safety objective of proposed Sec. 23.200(c).
Transport Canada noted the reason for requiring VMC to
be less than the stall speed is to avoid loss of control following an
engine failure. Transport Canada suggested an airplane designed with a
large enough rudder to meet this requirement may be more prone to
inadvertent spin entries. Transport Canada recommended requiring all
multiengine airplane to have a positive climb gradient following an
engine failure.
As explained in the NPRM, while the Part 23 ARC discussed the
option that all multiengine airplanes have guaranteed climb performance
after a critical loss of thrust, the FAA ultimately rejected this
option because it could impose a significant cost on the production of
training airplanes.
i. Trim (Proposed Sec. 23.205/Now Sec. 23.2140)
In the NPRM, proposed Sec. 23.205 (now Sec. 23.2140) would have
required the airplane to maintain longitudinal, lateral, and
directional trim under various conditions, depending on the airplane's
certification level, without allowing residual forces to fatigue or
distract the pilot during likely emergency operations, including a
critical loss of thrust on multiengine airplanes.
EASA commented the text of proposed Sec. 23.205 failed to take
into account residual forces for lateral and directional control for
those level 1, 2, and 3 airplanes with ground-adjustable trim tabs.
The FAA agrees with EASA that while the FAA addressed ground-
adjustable trim tabs for level 1, 2, and 3 airplanes, the proposed rule
failed to account for residual forces in lateral and directional axes.
The FAA intended for proposed Sec. 23.205 to maintain the level of
safety found in former Sec. 23.161. Former Sec. 23.161(a), which
applied generally to all airplanes and to lateral, directional, and
longitudinal trim, stated that it must be possible to ensure the pilot
will not be unduly fatigued or distracted by the need to apply residual
control forces exceeding those for prolonged application of former
Sec. 23.143(c) in normal operations of the airplane. In light of
EASA's comment, the FAA recognizes that proposed Sec. 23.205 (now
Sec. 23.2140) would only have prohibited residual control forces from
fatiguing or distracting the pilot during likely emergency conditions.
The FAA agrees with EASA that the rule should account for residual
control forces in lateral and directional axes for levels 1, 2, and 3
airplanes. However, to maintain the same level of safety as former
Sec. 23.161, the rule should also account for residual control forces
in longitudinal axes and should apply generally to levels 1, 2, 3, and
4 airplanes. Accordingly, the FAA is adding the requirement for
residual control forces not to fatigue or distract the pilot during
normal operations of the airplane to Sec. 23.2140(c). This requirement
is consistent with former Sec. 23.161(a).
Textron noted that the reference ``normal operations'' would
require all level 4 airplanes to be able to trim in all three axes from
obstacle height to obstacle height. Textron contended that would seem
to increase the burden from the former requirements in Sec. 23.161, at
least regarding lateral and directional trim.
The FAA considered Textron's comment, but is retaining the
reference to ``normal operations'' in proposed Sec. 23.205(a)(2) (now
Sec. 23.2140(a)(2)). While Sec. 23.2140(a)(2) could be interpreted
more stringently than former Sec. 23.161(b)(2), the FAA never intended
the proposed language to increase the burden from the previous
requirements. Former Sec. 23.161 required lateral and directional trim
for commuter category airplanes, which are the equivalent of level 4
airplanes, at all speeds from 1.4VS1 to the lesser of
VH or VMO/MMO. The objective of the
proposed rule was to allow the prescriptive requirements of former
Sec. 23.161 to be addressed in means of compliance. While specific
speeds such as 1.4VS1 are appropriate as the lower speed
limit for defining ``normal operations'' for traditional configurations
of level 4 airplanes, it may not fit new airplanes with novel
propulsion, high lift, and flight control system configurations. For
this reason, the FAA finds the proposed language of ``normal
operations'' best addresses the top-level safety requirement of former
Sec. 23.161(b)(2) while allowing the appropriate speed range to be
addressed in means of compliance.
In reference not only to this section, but also to its use
throughout the proposed rule, ANAC commented that the term ``likely''
is not precise and should be clarified or replaced with more precise
terms such as ``probable'', ``remote'', or ``not extremely
improbable.''
The FAA infers that ANAC recommended using a quantitative term,
such as ``probable,'' because it is defined in guidance material. While
the FAA agrees with ANAC's comment that the term ``likely'' is not
precise, the FAA intends to allow some imprecision for the objective of
providing performance-based standards that are sufficiently flexible to
accommodate new technologies. The term ``likely'' was chosen to mean a
reasonable expectation based on the existing conditions. This is
consistent with the former usage of the term throughout part 23.
Clarification of what should or should not be considered likely for a
particular rule will be provided in the means of compliance.
Textron recommended deleting the qualifying term ``likely'' from
proposed Sec. 23.205(c) because it would be subject to interpretation.
Textron also recommended adding abnormal operations to those operations
during which residual control forces must not fatigue or distract the
pilot. Lastly, Textron recommended a few editorial changes, including
adding the term ``control'' to residual forces.
While Textron took exception to the word ``likely'' to describe
emergency operations, the FAA finds the term to be appropriate in this
case. Deleting the qualifier ``likely'' could actually lead to more
stringent interpretations of the requirement. The term ``likely''
bounds the requirement within rational and probable emergencies. Simply
using the term ``emergency'' could be construed as requiring an
applicant to address any possible emergency regardless of how
improbable it is.
The FAA agrees with Textron concerning the addition of abnormal
operations. Former Sec. 23.161 referenced the specific condition of an
engine failure, which would have been based on traditional engine
configuration on the wing. Looking ahead, that failure condition could
be considered an abnormal and/or an emergency operation depending on
the number of engines, location, and control of the engines.
Furthermore, there may be other types of failures where trim would be
important. For these reasons, the FAA finds that addressing the
situation using the performance-based terms of ``abnormal'' and
``emergency'' is appropriate and consistent with the objective of
providing performance-based standards that are sufficiently flexible to
accommodate new technologies.
The FAA also agrees with Textron's recommendation to add
``control'' to
[[Page 96602]]
residual forces. The FAA notes that former Sec. 23.161 referenced
``residual control forces,'' not ``residual forces.'' This was an
oversight in the NPRM. Accordingly, Sec. 23.2140(c) now prohibits
residual control forces from fatiguing or distracting the pilot during
likely abnormal or emergency operations.
The Associations and Textron recommended streamlining the proposed
rule language by moving a phrase that appeared twice in proposed Sec.
23.205(a)(1) and (2) to a single, earlier reference in proposed Sec.
23.205(a).
The FAA agrees with the commenters and has adopted their
recommendation. Section 23.2140(a) now requires the airplane to
maintain lateral and directional trim without further force upon, or
movement of, the primary flight controls or corresponding trim controls
by the pilot, or the flight control system, under the conditions
specified in paragraphs (a)(1) and (a)(2). This marks a change from
what was proposed in the NPRM in that paragraph (a) no longer addresses
longitudinal trim. The FAA removed the reference to longitudinal trim
in paragraph (a) because longitudinal trim is addressed by paragraph
(b).
Furthermore, the FAA is adding language to paragraph (b) that
requires the longitudinal trim to be maintained without further force
upon, or movement of, the primary flight controls or corresponding trim
controls by the pilot, or the flight control system, under the
conditions specified in paragraphs (b)(1) through (b)(4). This
requirement, which is consistent with the intent of the NPRM, ensures
Sec. 23.2140(b) maintains the same level of safety as former Sec.
23.161. Former Sec. 23.161(a) required each airplane to meet the trim
requirements of former Sec. 23.161 after being trimmed and without
further pressure upon, or movement of, the primary flight controls or
their corresponding trim controls by the pilot or the automatic pilot.
This requirement applied generally to lateral, directional, and
longitudinal trim.
j. Stability (Proposed Sec. 23.210/Now Sec. 23.2145)
In the NPRM, proposed Sec. 23.210 (now Sec. 23.2145) would have
required airplanes not certified for aerobatics to have the following
in normal operations: (1) Static longitudinal, lateral, and directional
stability, and (2) dynamic short period and combined lateral
directional stability. Proposed Sec. 23.210 would have also required
airplanes not certified for aerobatics to provide stable control force
feedback throughout the operating envelope. Additionally, proposed
Sec. 23.210 would have precluded any airplane from exhibiting any
divergent stability characteristic so unstable as to increase the
pilot's workload or otherwise endanger the airplane and its occupants.
Kestrel suggested removing the phrase ``in normal operations'' from
proposed Sec. 23.210(a)(1) because it could be interpreted to mean
that static stability is not required in abnormal operations.
The FAA understands Kestrel's concern with the phrase ``in normal
operations'' in the proposed language. However, the FAA intended
proposed Sec. 23.210(a) (now Sec. 23.2145(a)) to capture the safety
intent of the stability sections in former part 23, which did not
require demonstrations in abnormal or emergency conditions. Former
Sec. 23.171 required an airplane to show static stability in ``any
condition normally encountered in service,'' which the FAA considers to
be normal operations. The former requirements have provided an
acceptable level of safety. The FAA adopts the proposed language in
Sec. 23.2145(a)(1) as proposed.
Optimal stated that proposed Sec. 23.210(a)(2) appears to require
that all lateral modes be stable, implying that airplane need to be
spirally stable. This commenter indicated that most airplane have
divergent spiral modes and therefore could not meet this requirement as
proposed.
The FAA agrees with Optimal that the proposed requirement could be
interpreted as including spiral mode. The FAA intended proposed Sec.
23.210(a)(2) to capture the short period and Dutch-roll stability that
former part 23 required. ``Combined lateral-directional oscillations''
means ``Dutch roll.'' The FAA revises the language in Sec.
23.2145(a)(2) to replace ``combined lateral-directional stability''
with ``Dutch roll'' stability.
ANAC suggested including the terms ``adequate'' or ``appropriate''
to qualify dynamic stability in proposed Sec. 23.210(a)(2).\26\ ANAC
stated that requiring only a showing of stability may allow for the
interpretation that ``marginally stable'' is acceptable, while current
part 23 has minimum damping factors prescribed.
---------------------------------------------------------------------------
\26\ ANAC actually addressed this comment to Sec. 23.205(a)(2),
but it appears it was supposed to address Sec. 23.210(a)(2).
---------------------------------------------------------------------------
The FAA agrees with ANAC that requiring only stability without a
qualifier could allow for interpretations outside of the prescriptive
standards of former part 23. However, the FAA does not agree with
qualifying stability in Sec. 23.2145(a)(2). Under the new part 23,
applicants will have to propose a means of compliance. While this is a
significant change from the former part 23, the language in Sec.
23.2145(a)(2) will enable the FAA to accept the current prescriptive
limits as a means of compliance. Alternatively, if a new technology
requires something different, the FAA can accept what is appropriate.
NJASAP suggested the ``Dutch roll'' characteristic on the EMB505
airplane is close to the language used in proposed Sec. 23.210(b).
NJASAP sought to ensure any stability system used to comply with this
section is not so dependent on Global Positioning System (GPS)
technology that its loss or interruption could cause the electronic
augmentation system to fail.
NJASAP's comment is outside the scope of this section as the FAA
proposed Sec. 23.210 (now Sec. 23.2145) to include requirements for
flight controls, not for their underlying systems. The FAA notes,
however, that flight control systems used to comply with this section
must also meet the system requirements of subpart F, which adequately
address the commenter's concern.
k. Stall Characteristics, Stall Warning, and Spins (Proposed Sec.
23.215/Now Sec. 23.2150)
In the NPRM, proposed Sec. 23.215 (now Sec. 23.2150) would have
required an airplane to have controllable stall characteristics in
straight flight, turning flight, and accelerated turning flight with a
clear and distinctive stall warning that provides sufficient margin to
prevent inadvertent stalling. Proposed Sec. 23.215 would have allowed
for alternative approaches to meeting this requirement for levels 1 and
2 airplanes and level 3 single-engine airplanes, not certified for
aerobatics, in order to avoid a tendency to inadvertently depart
controlled flight. Proposed Sec. 23.215 would have also required
airplanes certified for aerobatics to have controllable stall
characteristics and the ability to recover within one and one-half
additional turns after initiation of the first control action from any
point in a spin, not exceeding six turns or any greater number of turns
for which certification is requested while remaining within the
operating limitations of the airplane. Proposed Sec. 23.215 would have
also precluded airplanes certified for aerobatics from having spin
characteristics that would result in unrecoverable spins due to pilot
disorientation or incapacitation or any use of the flight or engine
power controls.
Garmin commented that while the proposal contained a lengthy
discussion about requirements to improve the
[[Page 96603]]
airplane's resistance to departing controlled flight, proposed Sec.
23.215(a) would only have required the airplane to have controllable
stall characteristics in straight, turning and accelerated flight.
Garmin stated there was no mention of flight characteristics related to
control usage at the stall that does not precisely and correctly
control the stall. As an example, Garmin noted an applicant can comply
with the rule and have an airplane that is controllable through a stall
if flown correctly, but if not flown correctly, can enter an
uncontrollable spin if the airplane is allowed to stall while not
precisely coordinated. Garmin recommended the FAA change either the
rule or the preamble to be consistent with each other.
The FAA acknowledges the NPRM preamble discussion may have been
unclear. The FAA only intended proposed Sec. 23.215(b) (now Sec.
23.2150(b) to improve an airplane's resistance to departing controlled
flight. This increase in level of safety applied only to the smaller
part 23 airplanes, not all part 23 airplanes. Furthermore, the FAA
intended for proposed Sec. 23.215(a) to capture the safety intent of
former Sec. Sec. 23.201 and 23.203. Garmin's example will continue to
be true for airplanes not required to meet Sec. 23.2150(b). The FAA
notes that Sec. 23.2150(a) will not include requirements related to
conditions and control usage at the stall. While former Sec. Sec.
23.201 and 23.203 included these requirements, the FAA finds they are
better addressed in means of compliance.
The FAA notes the details from these former rules will be addressed
in the means of compliance and will remain essentially unchanged,
especially for larger, higher-performance airplanes. The reason is that
the accident history of the larger airplanes does not warrant the
change. The means of compliance for the level 1 and 2 airplanes and
level 3 single-engine airplanes is expected to allow for more
alternative approaches from what is acceptable today to meet the higher
level of safety in this rule.
Textron and the Associations commented that Sec. 23.215(b) should
not require multiengine airplanes to not have a tendency to
inadvertently depart controlled flight. The commenters explained that
loss of control accidents involving multiengine airplanes result mostly
from pilots failing to maintain directional control following a
critical loss of thrust. Textron noted that this concern is being
addressed by proposed Sec. 23.200(c), which proposes new requirements
for airplanes that cannot climb after a critical loss of thrust.
Textron also noted former Sec. 23.221 was not a requirement for
multiengine airplanes and that proposed Sec. 23.215(b) would have
represented a significant new burden with no safety justification.
The Associations stated it believed loss of control accidents
predominately involve single-engine airplanes, or multiengine airplanes
during a critical loss of thrust event. The Associations recommended
that the FAA revise proposed Sec. 23.215 to ensure the loss of control
requirements are applied in a manner that will maximize safety while
being applied in an efficient manner. The Associations specifically
recommended the FAA revise proposed Sec. 23.215 to require multiengine
airplanes, not certified for aerobatics, to not have a tendency to
suffer a loss of control after a likely critical loss of thrust. This
would be an alternative to adopting proposed Sec. 23.200(c). The
Associations also recommended the FAA revise the proposed Sec.
23.215(b) to require single-engine airplanes, not certified for
aerobatics, to not have a tendency to inadvertently depart controlled
flight.
The FAA agrees that proposed Sec. 23.215(b) (now Sec. 23.2150(b))
should apply only to single-engine airplanes. The FAA proposed to apply
paragraph (b) to level 1 and 2 multiengine airplanes in an attempt to
address the loss of control accidents in light multiengine airplanes
that can occur after an engine failure if the pilot does not maintain a
safe single-engine speed. However, as noted by Textron, the FAA
proposed Sec. 23.200(c) to address this safety issue by requiring that
Vmc not exceed Vs1 or Vso. In light of
the comments, the FAA recognizes it is more appropriate to address the
loss of control issue for light multiengine airplanes in Sec. 23.2150
rather than Sec. 23.2135 because it is redundant to address the issue
in both sections. The FAA revises Sec. 23.2150(b) in this final rule
to reflect that it only applies to single-engine airplanes in all
certification levels to be consistent with former Sec. 23.221. While
the FAA did not propose in the NPRM that level 4 single-engine
airplanes would be subject to this requirement, extending this
requirement to such airplanes is a logical outgrowth from the proposal
because the same safety benefit applies regardless of certification
level. Also, the FAA finds no valid technical basis for excluding level
4 airplanes from this requirement. The airplane categories in former
part 23 did not provide for certification of single-engine airplanes
with passenger capacities greater than nine; however, it is possible
that applicants may seek approval for such an airplane in the future.
In such cases, these airplanes will have the same level of safety as
smaller single-engine airplanes.
As discussed in the preamble discussion of Sec. 23.2135, the FAA
is withdrawing proposed Sec. 23.200(c) and adding a new Sec.
23.2150(c). Paragraph (c) requires levels 1 and 2 multiengine
airplanes, not certified for aerobatics, to not have a tendency to
inadvertently depart controlled flight from thrust asymmetry after a
critical loss of thrust. The FAA finds that paragraphs (b) and (c), as
revised, more accurately reflect the FAA's intent regarding the
prevention of loss of control accidents in both single and multi-engine
airplanes.
EASA commented that proposed Sec. 23.215(b) would not have
provided the flexibility needed for future designs. EASA recommended
the FAA allow levels 1 and 2 airplanes and level 3 single-engine
airplanes not certified for aerobatics to meet one of three
alternatives: (1) Not to have the tendency to inadvertently depart
controlled flight; (2) have a benign behavior when departing controlled
flight; or (3) have a system preventing departure from controlled
flight.
While the FAA understands EASA's recommended approach, Sec.
23.2150(b) and (c) contain the most significant safety improvements in
this rulemaking effort. Any departure from controlled flight is likely
to result in a fatal accident unless an experienced pilot demonstrating
spins in an aerobatic airplane intentionally does it. Allowing levels 1
or 2 airplanes or level 3 single-engine airplanes to have a benign
behavior when departing controlled flight would not meet the FAA's
safety objective for airplanes that are not certified for aerobatics.
The FAA notes that an airplane that can depart controlled flight with
benign behavior can inadvertently depart controlled flight.
Furthermore, having a system that prevents departure from controlled
flight may be a means of compliance for Sec. 23.2150(b). Therefore,
the FAA finds it inappropriate to offer it as an alternative in the
regulation.
The FAA did not intend Sec. 23.2150(b) to be absolute in that
``spin resistance'' is the only way to meet the rule. An airplane using
enhanced stall warnings and envelope protection could be very difficult
to depart from controlled flight and comply with Sec. 23.2150(b). That
same airplane, with some effort, could be made to spin (depart
controlled flight) and have good recovery capability and still--because
of the stall characteristics and the enhanced warning and systems
protection--comply with the new requirement. The
[[Page 96604]]
FAA is working on means of compliance that will allow numerous
combinations of airframe and systems approaches to complying with the
new requirement so that applicants have alternative ways to comply with
the regulation. Furthermore, this approach will encourage the
development of new innovative technology that targets resistance to
departure from controlled flight.
Several commenters took issue with the proposed requirement in
Sec. 23.215(b) that certain airplanes must not have a tendency to
inadvertently depart controlled flight. Air Tractor, Optimal, and an
individual commenter noted the proposal does not define this phrase.
The individual commenter asked whether this phrase includes proper use
of flight controls, improper use of flight controls, conditions beyond
and per former Sec. 23.221(a)(2) for spin resistance. Air Tractor
stated it would be difficult to prove an airplane meets this
requirement.
The FAA purposely used language that would allow flexibility in
showing compliance. The FAA recognizes the lack of clear, detailed
requirements may increase the difficulty of proving that the airplane
meets this requirement. However, the FAA finds providing clear,
detailed requirements would prevent the acceptance of alternative
approaches to this safety problem. It could also prevent the use of new
technology, which would discourage the development of even newer
technology. As explained in the NPRM, the FAA envisions numerous
alternative approaches to meeting this requirement, ranging from a
stick pusher to full spin resistance. The FAA is relying on industry to
develop acceptable means of compliance beyond these two acceptable
approaches for this requirement, should industry fully leverage the
flexibility the FAA built into the rule. The FAA is also relying on
industry to incorporate new technologies into the airplane to address
stall-based accidents. Currently, the ASTM committee is maturing an
innovative approach that incorporates many of the variables associated
with stall characteristics to prevent inadvertent departures from
controlled flights.
Air Tractor expressed concern that it may not be able to comply
with the intent of the proposed requirement because its airplanes are
designed to operate close to the ground and sometimes close to a stall.
According to Air Tractor, if it were to add some kind of substantial
departure resistance to prevent inadvertent stalls resulting in a
departure from controlled flight, as described in the NPRM, this
modification could potentially increase pilot fatigue significantly.
The FAA notes that Air Tractor's airplanes are certified in
restricted category and have the latitude to modify the part 23
requirements where necessary. For example, as Air Tractor pointed out,
its airplanes are designed to operate close to the ground and sometimes
close to a stall. For this reason, Air Tractor did not have to meet the
one-turn spin requirement from former part 23 as specified on TCDS
Number A19SW. However, because Air Tractor's airplanes are operated
close to the ground and sometimes close to a stall, characteristics or
features that prevent inadvertent departure would be desirable, unless
these characteristics or features add control forces that fatigue the
pilot or reduce maneuverability. The FAA finds these issues apply only
to a small subset of airplanes and can be addressed most efficiently
and effectively in the certification context, rather than by revising
the regulatory text. Optimal expressed concern with unintended
consequences that may result from imposing departure from controlled
flight resistance requirements. Specifically, it questioned whether
proposed Sec. 23.215(b) can be satisfied without compromising other
aspects of the airplane's performance and handling.
The FAA notes that, historically, when only using traditional
mechanical controls, there are performance and handling tradeoffs that
can come from imposing departure resistance requirements. This is one
reason the FAA has been reluctant to push for departure resistant
characteristics in the past. However, the development, availability,
and cost of new technology to address departure resistance have matured
such that the FAA believes it is time to introduce this requirement to
reduce loss of control accidents. Aerodynamics and systems combined can
address departure resistance without compromising performance and
handling. The FAA will not accept a means of compliance that has a
detrimental effect on safety.
Transport Canada questioned whether proposed Sec. 23.215(b) would
result in designs that have a significant effect on the loss of control
accident rate and asked what the flight test requirements would be for
demonstrating compliance with paragraph (b). American Champion Aircraft
Corporation (American Champion) stated the regulation should provide a
means to determine acceptable departure resistance, or a description of
an acceptable means of compliance.
The FAA recognizes that the means of compliance will be very
important in the success of this requirement to improve safety. The FAA
adopts a general performance-based requirement in Sec. 23.2150(b) to
enable numerous alternative approaches to meet the requirement. For
this reason, it is impossible to specify a single set of flight test
requirements. The flight test requirements will depend on the
applicant's approach to complying with this rule and the means of
compliance it uses. It would have been impossible to adopt requirements
for all combinations of safety features and characteristics that reduce
the tendency to inadvertently depart controlled flight in the
requirements themselves. However, applicants can still use the spin
resistance requirements from former Sec. 23.221 for spins, and a stick
pusher compliant with former Sec. 23.691 for artificial stall barrier
systems. Additionally, ASTM is developing an expandable matrix concept
that will allow credit for combinations of stall warning, stall/
envelope protection, and flight characteristics. This matrix should
result in not only encouraging manufacturers to install more safety
enhancing equipment, but more importantly, it will also encourage the
development of innovative approaches to preventing inadvertent
departure because of the speed at which new technology can be
incorporated into the certification process. To address the wide range
of airplane characteristics and solutions, the FAA is adopting a
standard that the airplane may not have tendency to inadvertently
depart controlled flight.
American Champion noted inconsistencies with the required degree of
departure resistance throughout the NPRM. For example, the commenter
noted proposed Sec. 23.215(b) stated ``must not have a tendency to
inadvertently depart controlled flight.'' Section V of the NPRM
referred to departure resistant as ``stall characteristics that make it
very difficult for the airplane to depart controlled flight,'' and
section VI states certification levels would have required
``substantial departure resistance.'' American Champion recommended the
FAA clarify the degree of departure resistance intended by proposed
Sec. 23.215(b).
The FAA notes Sec. 23.2150(b) states that single-engine airplanes,
not certified for aerobatics, ``must not have a tendency'' to
inadvertently depart controlled flight. Therefore, ``must not have a
tendency'' is the standard. The FAA acknowledges, however, that the
NPRM discussions should have been more consistent when discussing the
proposed rule language.
[[Page 96605]]
Optimal expressed concern about removing the requirement for
single-engine airplanes not certified for aerobatics to recover from a
one-turn/three-second spin at this time because pilots have been adept
at finding unanticipated ways to get spin resistant airplanes to depart
from controlled flight and because airplanes that are the most
reluctant to spin tend to be the most reluctant to recover. Optimal
recommended the FAA retain the requirement to recover from an incipient
spin until sufficient certification and operational experience has been
acquired with departure resistant airplanes.
The FAA removes the requirement for the one-turn/three-second spin
for normal category single-engine airplanes. Historically, airplanes
that were reluctant to spin tended to be reluctant to recover. This
history is based on airplanes with inherent stability and reversible
controls, which to date are all small airplanes. The FAA intentionally
focused on the prevention of the conditions that lead to an inadvertent
spin (departing controlled flight) versus the historical focus on spin
recovery. For decades, the FAA has focused on spin recovery in
certification programs only to have those same certified airplanes
depart controlled flight at altitudes so low that even experienced
pilots could not recover. For decades, this scenario has accounted for
a large percentage of fatal accidents. The FAA has to change the
approach to certification in order to reduce the number of departure
from controlled flight fatal accidents.
Kestrel expressed concern that demonstrating compliance to proposed
Sec. 23.215(d) would be prohibitively expensive and potentially
impossible. Kestrel suggested the FAA modify the proposed rule language
to read ``with any typical use of the flight or engine power
controls.''
The FAA agrees that proposed Sec. 23.215(d)(1) (now Sec.
23.2150(e)(1)) could have been interpreted as imposing an unbounded
requirement, which was not the FAA's intent. The FAA revises the
proposed rule language as Kestrel suggested.
EASA commented that proposed Sec. 23.215(d)(2) (now Sec.
23.2150(e)(2)) would have contained a flightcrew interface requirement
that does not belong in the airworthiness (design) requirements. EASA
recommended the FAA move this requirement to subpart G, which addresses
flightcrew interface requirements.
The FAA is retaining the requirement in subpart B because it
originated from former subpart B, Sec. 23.221(c). The FAA finds that
keeping it in the same subpart, in this instance, will avoid confusion.
American Champion commented that it is unnecessary to restrict
certification of dual-purpose airplanes by requiring a mechanical or
electronic change, as described in the NPRM, because airplanes can both
meet the enhanced stall characteristics and also be suitable for some
aerobatic maneuvers. The commenter noted that departure resistance,
proposed Sec. 23.215(b), does not preclude an airplane from aerobatic
maneuvering, although it may affect the ability of the airplane to
enter a spin.
The FAA proposed to restrict certification of new airplanes for
dual use to prevent inadvertent stalls, which was one of the proposal's
objectives. If an airplane can spin for spin training, then the
airplane can inadvertently stall and depart into a spin during normal
operations. In light of American Champion's comment, however, the FAA
acknowledges there may be airplanes in the future that are approved for
limited aerobatics that do not include spins. This would be similar to
military fighter airplane. The military approach has historically been
to explore thoroughly the post stall regime including spins and
departures from controlled flight that do not result in traditional
spins. This is done in the military and for civilian aerobatic
airplanes to address the situation where a mistake during a planned
maneuver results in departing controlled flight. The FAA can envision a
flight control system that could prevent departures from all approved
maneuvers. To the FAA's knowledge, the F-16 flight control system has
been very successful in preventing inadvertent departures from
controlled flight even though these airplane are frequently flown
``acrobatically.'' For these reasons, the FAA may allow certification
of a new airplane for dual use even if the airplane is not approved for
spins. However, an applicant proposing a system, such as a flight
control system that could prevent departure from controlled flight
during normal operations, should expect to work with the FAA to
thoroughly address FAA concerns for safe margins from inadvertent
departure from controlled flight.
Proposed Sec. 23.215(d) would have precluded airplanes certified
for aerobatics from having spin characteristics that would result in
unrecoverable spins due to pilot disorientation or incapacitation or
any use of the flight or engine power controls. Upon further
reflection, the FAA revises the proposed rule language to require spin
characteristics in airplanes certified for aerobatics to recover
``without exceeding limitations.'' The FAA inadvertently omitted this
clause from proposed Sec. 23.215(d) (nowSec. 23.2150(e)), which was
intended to capture the safety intent of former Sec. 23.221(c). Former
Sec. 23.221(c) required the applicable airspeed limits and limit
maneuvering load factors not to be exceeded. Additionally, including
this clause in the requirement will better align the FAA language with
EASA's NPA language.
The NTSB commented that while it supports reducing the rate of loss
of control accidents in general aviation, it is unclear how proposed
Sec. Sec. 23.200 and 23.215 would have accomplished this. The NTSB
explained that the only link it sees to reducing loss of control
accidents is the change to VMC and asked the FAA to clarify
exactly how the revisions will reduce loss of control accidents.
The FAA notes that the NPRM included a substantial discussion
explaining how the FAA envisions the rule reducing loss of control
accidents. The new rules allow alternative approaches that an applicant
may use, ranging from a stick pusher to full spin resistance. Adding
flexibility to the rule will allow alternate approaches to address
inadvertent departure by using combinations of new technology not
addressed in the former requirements. These alternatives will be
addressed in means of compliance. There is no ``exact'' approach to
meet the new rule because the objective is to encourage new approaches
to loss of control that are more effective than the ones that are
failing us today.
Additionally, the NTSB submitted detailed comments on the stall
departure characteristic exception in the ASTM standard. The FAA will
address these comments in the AC because these comments are on the
acceptability of an ASTM standard as a means of compliance rather than
on the proposed rule.
l. Ground and Watering Handling Characteristics (Proposed Sec. 23.220/
Now Sec. 23.2155)
In the NPRM, proposed Sec. 23.220 (now Sec. 23.2155) would have
required airplanes intended for operation on land or water to have
controllable longitudinal, and directional handling characteristics
during taxi, takeoff, and landing operations. Proposed Sec. 23.220
would have also required an applicant to establish a maximum wave
height shown to provide for controllable longitudinal, and directional
handling characteristics and any necessary water
[[Page 96606]]
handling procedures for those airplanes intended for operation on
water.
Textron and the Associations noted that the FAA proposed to remove
the prescriptive requirements related to establishing demonstrated
crosswind capability from former Sec. 23.233, but proposed to retain
similar requirements for water operations to establish wave height
criteria. These commenters stated that operational specificity related
to water landings should be addressed in means of compliance standards
and recommended that the FAA not adopt proposed Sec. 23.220(b).
The FAA agrees with the commenters that proposed Sec. 23.220(b)
would have been overly prescriptive for water operations and that it
would be more appropriate as a means of compliance. While proposed
Sec. 23.220(a) would have included the top-level safety requirements
for both land and water operations, proposed Sec. 23.220(b) would have
been inconsistent with the approach taken for land airplanes as it
would have contained prescriptive requirements only for airplanes
intended for operation on water. Accordingly, the FAA is not adopting
proposed Sec. 23.220(b). The information necessary to comply with
proposed Sec. 23.220(a) (now Sec. 23.2155 in its entirety) and the
method to communicate that information to the pilot will be addressed
in means of compliance with this section.
EASA also recommended that the FAA not adopt proposed Sec.
23.220(b). EASA explained that the AFM requirements in subpart G should
cover ``how-to'' information and how that information is provided to
the pilot, as proposed in the NPRM. Therefore, proposed Sec. 23.220(b)
should not require what must be included in the AFM.
The FAA agrees with EASA that the information is more appropriately
addressed in the AFM means of compliance. The AFM requirements are
located in subpart G.
m. Vibration, Buffeting, and High-Speed Characteristics (Proposed Sec.
23.225/Now Sec. 23.2160)
In the NPRM, proposed Sec. 23.225 (now Sec. 23.2160) would have--
Precluded vibration and buffeting from interfering with
the control of the airplane or causing fatigue to the flightcrew, for
operations up to VD/MD;
Allowed stall warning buffet within these limits;
Precluded perceptible buffeting in cruise configuration at
1g and at any speed up to VMO/MMO, except stall
buffeting for high-speed airplanes and all airplanes with a maximum
operating altitude greater than 25,000 feet (7,620 meters) pressure
altitude;
Required an applicant seeking certification of a high-
speed airplane to determine the positive maneuvering load factors at
which the onset of perceptible buffet occurs in the cruise
configuration within the operational envelope and preclude likely
inadvertent excursions beyond this boundary from resulting in
structural damage; and
Required high-speed airplanes to have recovery
characteristics that do not result in structural damage or loss of
control, beginning at any likely speed up to VMO/
MMO, following an inadvertent speed increase and a high-
speed trim upset.
Textron and the Associations noted that the language from which
proposed Sec. 23.220(a) originated (former Sec. 23.251) included the
term ``excessive fatigue,'' rather than ``fatigue.'' These commenters
recommended that the FAA use the term ``excessive fatigue'' in proposed
Sec. 23.220(a). Textron explained that by omitting the term
``excessive,'' any perceptible level of fatigue could be considered
unacceptable and the proposal would result in an unwarranted change in
standards for vibration.
The FAA agrees with the commenters and is adding the term
``excessive'' to Sec. 23.2160(a).
ICON contended that proposed Sec. 23.225(b) would have been fine
for landplanes, but not for seaplanes because seaplanes, with their
hull step, will always have some buffet in cruise. Additionally, ICON
noted that airplane with windows removed will have perceptible
buffeting at all speeds.
The FAA agrees with ICON that seaplanes and floatplanes routinely
operate with a limited amount of buffet during normal operation. The
FAA did not intend for proposed Sec. 23.225(b) to increase the level
of safety over former Sec. 23.251, which allowed for the limited
buffeting normal to seaplanes and floatplanes. Historically, this level
of buffeting has not interfered with the control of the airplane or
caused excessive fatigue to the pilot. Because the proposed rule
language originated from former Sec. 23.251, the FAA finds that it
does not create a new certification burden on applicants with seaplanes
or floatplanes. Accordingly, the FAA adopts the language as proposed.
Furthermore, airplanes approved for operations without doors or
windows, or those that allow the windows to open in flight, were not
intended to be addressed under this rule.
Textron and the Associations noted that the former requirement for
a high-speed trim upset (former Sec. 23.255) applied to designs with
adjustable horizontal stabilizers. However, the FAA did not specify
whether proposed Sec. 23.220(d)(2) would have been limited to
airplanes with adjustable horizontal stabilizers. Textron explained
that, as proposed, Sec. 23.220(d)(2) would have contained an
additional requirement for high-speed airplanes that did not have
trimmable horizontal stabilizers. The commenters recommended the FAA
limit the application of proposed Sec. 23.220(d)(2) to airplanes that
incorporate a flight adjustable horizontal stabilizer.
The FAA intended to keep this requirement as general as possible,
not to propose a new requirement on high-speed airplanes that lacked
trimmable horizontal stabilizer. As stated in the NPRM, the FAA
intended proposed Sec. 23.220(d)(2) (now Sec. 23.2160(d)(2)) to
address the current safety intent of former Sec. 23.255, which applied
only to airplanes that included trimmable horizontal stabilizers. The
FAA adopts language in Sec. 23.2160(d)(2) to clarify that the
requirement applies only to airplanes that incorporate trimmable
horizontal stabilizers.
n. Performance and Flight Characteristics Requirements for Flight in
Icing Conditions (Proposed Sec. 23.230/Now Sec. 23.2165)
In the NPRM, proposed Sec. 23.230 (now Sec. 23.2165) would have
required--
An applicant requesting certification for flight in icing
conditions to demonstrate compliance with each requirement of this
subpart. Exceptions to this rule would have been requirements
applicable to spins and any requirement that would have to be
demonstrated at speeds in excess of 250 KCAS, VMO or
MMO, or a speed at which an applicant demonstrates the
airframe would be free of ice accretion;
The stall warning for flight in icing conditions and non-
icing conditions to be the same.
An applicant requesting certification for flight in icing
conditions to provide a means to detect any icing conditions for which
certification is not requested and demonstrate the airplane's ability
to avoid or exit those conditions; and
An applicant to develop an operating limitation to
prohibit intentional flight, including takeoff and landing, into icing
conditions for which the airplane is not certified to operate.
Proposed Sec. 23.230 would have also added optional icing
conditions where a manufacturer may demonstrate its airplane can either
safely operate in, detect and safely exit, or avoid. Finally,
[[Page 96607]]
proposed Sec. 23.230 would have only applied to applicants seeking
certification for flight in icing.
NJASAP stated it viewed proposed Sec. 23.230 as a safety
enhancement and noted that several accidents have demonstrated a
benefit to having one stall standard--meaning the airplane should be
able to remain largely free of ice in conditions within which it is
certified to operate. The NTSB stated that adopting proposed Sec. Sec.
23.230 and 23.1405 will likely result in Safety Recommendation A-96-54
being classified as ``Closed--Acceptable Action.''
Textron and the Associations asked the FAA to clarify that proposed
Sec. 23.230(a) applies to the airplane's ice protection system when it
is operating normally, not when it is in a failed or degraded mode.
Therefore, rather than requiring the applicant to demonstrate the
requirements of proposed paragraphs (a)(1) and (a)(2), the Associations
recommended that the FAA require the normally-operating airplane ice
protection systems to include the requirements of proposed paragraphs
(a)(1) and (a)(2).
The FAA agrees with the comments made by the Associations and
Textron, and the FAA adopts language to clarify that Sec. 23.2165(a)
applies to the normal operation of an ice protection system.
Accordingly, Sec. 23.2165(a) now requires the applicant to demonstrate
the requirements of paragraphs (a)(1) and (a)(2) under the normal
operation of the ice protection system.
The FAA is also changing the language in Sec. 23.2165(a) to
clarify that Sec. 23.2165 applies to an applicant who requests
certification for flight in icing conditions defined in part 1 of
appendix C to part 25, or to an applicant who requests certification
for flight in these icing conditions and any additional atmospheric
icing conditions. This change better reflects the FAA's intent.\27\
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\27\ 81 FR 13452, 13462
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Additionally, the FAA is using the phrase ``must show'' rather than
``must demonstrate'' in Sec. 23.2165(a), because ``must demonstrate''
may be interpreted as requiring a flight test, as Textron suggested in
its comment on proposed Sec. 23.230(b) (discussed later). This change
is consistent with the NPRM, which explained that demonstration, as a
means of compliance, may include design review and/or analysis and does
not mean flight tests are required.\28\
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\28\ 81 FR 13452, 13493
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The FAA is also adding the never-exceed speed (VNE) to
the exception in Sec. 23.2165(a), under paragraph (a)(1)(ii), to
correct an inadvertent omission in the proposal. Because proposed Sec.
23.230(a)(1)(ii) was intended to apply to both piston and turbine
airplanes, the addition of VNE is necessary as the proposed
VMO/MMO would only have applied to turbine
airplanes. This change from what was proposed is consistent with the
current guidance in AC 23.1419-2D.
BendixKing, Daher,\29\ the Associations, Kestrel, and Textron all
requested clarification of the wording of proposed Sec. 23.230(a)(2),
which proposed that the applicant must demonstrate that the stall
warning for flight in the icing conditions and non-icing conditions is
``the same.'' Several of the commenters explained that the stall
warning in icing conditions needs to provide a similar notification as
the stall warning in non-icing conditions, but it does not need to
occur in the same way.
---------------------------------------------------------------------------
\29\ In its comment, Daher quoted 23.230(a)(2) but attributed
that quote to 23.300
---------------------------------------------------------------------------
Textron similarly stated that proposed Sec. 23.230(a)(2) could be
interpreted as indicating that the stall warning must be the same in
all of its aspects, which should not be the intent. Textron explained
that the stall warning system in icing conditions cannot be the same as
in non-icing conditions because some designs require a different angle
of attack schedule in icing to obtain the same airspeed margin between
stall warning and stall. Textron recommended requiring ``the means by
which stall warning is provided to the pilot'' to be the same in icing
and non-icing conditions.
In response to the comments on proposed Sec. 23.230(a)(2), the FAA
did not intend to require the stall warning to be the same in all
material aspects for flight in icing conditions and non-icing
conditions. Rather, the FAA intended proposed Sec. 23.230(a)(2) to
require the same type of stall warning, such as an artificial stall
warning system or an aerodynamic buffet. Therefore, the FAA adopts
Textron's recommendation. Accordingly, Sec. 23.2165(a)(2) now requires
the means by which the stall warning is provided to the pilot to be the
same in both icing and non-icing conditions. This change from the
proposal addresses the other commenters' concerns by clarifying that
the type of stall warning provided to the pilot, rather than the design
of the stall warning system, must be the same.
Textron recommended replacing the words ``must demonstrate'' with
the words ``must show'' in proposed Sec. 23.230(b), because the former
typically implies compliance by flight testing, whereas the latter
allows more than one means of compliance. Similarly, the Associations
commented that proposed Sec. 23.230(b) should ensure the design
includes a means to safely avoid and exit icing conditions. However,
the FAA should not require the applicant to ``demonstrate the
airplane's ability'' to avoid or exit icing conditions because the
means by which the airplane safely avoids or exits icing conditions may
not have to be demonstrated under part 21. The commenters noted that
amended designs, for example, may use similarity to a previously
approved design to show compliance.
The FAA agrees that ``must demonstrate'' in proposed Sec.
23.230(b) may be interpreted as requiring a flight test. Because the
FAA did not intend to preclude other means of compliance, the FAA
adopts the phrase ``must show,'' as recommended by Textron.
Accordingly, Sec. 23.2165(b) now requires an applicant requesting
certification for flight in icing conditions to show the airplane's
capability to avoid or exit icing conditions for which certification is
not requested.
Kestrel supports categorizing SLD as an icing condition, but noted
that guidance in AC 23.1419-2D is currently used on part 23 icing
certification programs to establish SLD detection cues and exit
procedures. Kestrel asked the FAA to clarify whether this guidance will
continue to be an acceptable means of compliance for the ice detection
requirement.
The NPRM stated ``many manufacturers already have equipped recent
airplanes with technology to meet the standards for detecting and
exiting SLD conditions in accordance with current FAA guidance.''
Although systems to detect SLD are being developed, none have been
certified. Inclusion of the pilot cues as listed in AC 23.1419-2D into
the AFM have been an acceptable means to detect SLD, and will continue
to be an acceptable means of compliance to Sec. 23.2165(b).
ANAC questioned whether proposed Sec. 23.230(c) was intended to
prohibit flight into known icing conditions or forecast icing
conditions. ANAC recommended including the term ``known'' before
``icing conditions.''
The FAA agrees with ANAC's position that only ``known'' icing
conditions should be prohibited. However, Sec. 23.2165(c) prohibits
intentional flight into icing conditions. Because the term
``intentional'' implies that the icing conditions are known, the FAA
finds it unnecessary to include the term ``known'' before ``icing
conditions.'' Accordingly, the FAA
[[Page 96608]]
adopts the language in Sec. 23.2165(c) as proposed.
An individual commenter appeared to criticize the FAA for not
requiring de-icing to work and suggested that ``[a] wind tunnel at the
far North or South may be enough for a conclusive test.'' In response
to the individual commenter, an icing tunnel is a standard means of
compliance to test ice protection systems on new airplane designs. Any
resulting intercycle, residual, or runback ice has to be accounted for
when showing compliance with the subpart B regulations in icing. No
changes are made as a result of this comment.
4. Subpart C--Structures
a. Structural Design Envelope (Proposed Sec. 23.300/Now Sec. 23.2200)
In the NPRM, proposed Sec. 23.300 (now Sec. 23.2200) would have
required the applicant to determine the structural design envelope,
which describes the range and limits of airplane design and operational
parameters for which the applicant would show compliance with the
requirements of subpart C. Proposed Sec. 23.300 would have required
the applicant to account for all airplane design and operational
parameters that affect structural loads, strength, durability, and
aeroelasticity, including structural design airspeeds and Mach numbers.
Several commenters identified concerns with the detailed
definitions of airspeeds for which applicants would be required to
account. They pointed out that, for some types of airplanes, these
airspeeds may not be appropriate in particular circumstances. EASA
recommended removal of the speed definitions for a more generic
proposal in its proposed CS 23.320.
The FAA recognizes the commenters' concerns on the various issues
in proposed Sec. 23.300(a). The FAA believes the best way to address
these comments is to adopt regulatory text similar to the text in
EASA's section CS 23.320, which removes the need to define individual
design airspeeds in the regulation. Some comments on proposed Sec.
23.300(a) recommended retaining certain methods of compliance language,
such as defining VC in terms of VH, which is in
former part 23. In keeping with the intent of this rulemaking, however,
the FAA believes these types of prescriptive standards are best moved
to means of compliance.
Air Tractor commented on proposed Sec. 23.300(b), which addressed
design maneuvering load factors for the structural design envelope. Air
Tractor raised concerns that obtaining consensus compliance from the
FAA without the prescriptive formula established by former Sec.
23.337(a) would be a protracted battle--worse than the existing issue
paper process for non-standard design.
Regarding Air Tractor's concerns, the FAA has decided to move the
prescriptive formula for determining the design maneuvering load
factors to means of compliance. The FAA also reiterates that the phrase
``service history'' is intended to mean the design maneuvering load
factors should be based on those load factors used for airplanes with
successful service histories that have similar design, operational
capabilities, and intended use. If there are no existing similar
designs, the FAA will work with the applicant to identify the most
appropriate means of compliance. In general, the FAA does not expect
applicants to measure and record maneuvering load factors on new
designs.
EASA asserted that the language in proposed Sec. 23.300(c) was too
design specific and could be replaced with the text from its proposed
CS 23.305.
The FAA finds that proposed Sec. 23.300(c) is not overly design
specific, because each of the enumerated items must be taken into
account, regardless of the applicant's design. The FAA therefore adopts
paragraph (c) as proposed.
Air Tractor recommended the FAA change ``empty weight to the
maximum weight'' to ``minimum flying weight to maximum weight,'' in
proposed Sec. 23.300(c)(1). Air Tractor stated this language applies
to all airplanes and is appropriate for certification; while ``empty
weight'' applies only to certain airplanes' operational requirements.
The FAA notes Air Tractor's recommendation that ``empty weight'' in
Sec. 23.2200(c)(1) should be replaced with ``minimum flying weight.''
However, the FAA believes that establishing a design empty weight is
necessary so that variations in the mass of properties such as fuel,
payloads, and occupants, when added to the airplane, can be accounted
for.
The Associations recommended deleting the term ``All'' from the
beginning of proposed Sec. 23.300(c)(1) and (e) for simplification.
Textron recommended changing ``All'' in proposed Sec. 23.300(c)(1) to
``Each.'' Textron stated the change would be consistent with former
part 23, which uses ``each weight'' throughout the subparts, whereas
``all'' implies an applicant would have to evaluate an infinite number
of weights rather than those that are relevant. Textron also
recommended replacing ``All'' in proposed Sec. 23.300(e) with ``Each
critical altitude,'' because ``all'' is too encompassing.
The FAA agrees with the recommendation to replace ``All'' with
``Each'' in proposed Sec. 23.300(c) and (e) and revises the language
in both paragraphs accordingly. The FAA also adds the word ``critical''
so the subsection text reads ``Each critical. . .''. In this context,
``critical'' refers to a weight or altitude that results in a maximum
or minimum structural loading condition. A ``critical weight'' will,
for example, be the weight of the airplane at its highest possible
value with no fuel in the wing. This condition will reduce the effects
of inertia in the wing and result in maximum structural loads. A
``critical altitude'' will be the altitude where the maximum pressure
differential occurs in a pressurized cabin, or an altitude where the
effects of atmospheric compressibility cause changes to the airplane
aerodynamic coefficients, resulting in maximum structural loads.
EASA commented that proposed Sec. 23.300(d) was too design
specific and should cover loads resulting from controls.
The FAA interprets EASA's comment to mean the FAA should consider
non-traditional methods of control, such as vectored thrust. The FAA
agrees and revises paragraph (d) to include non-traditional control
systems.
EASA also commented on proposed Sec. 23.300(e), stating it would
create a requirement that is not applicable to very-light aircraft
(VLA) today. EASA asserted that the intent can be covered by the new
proposal for flight loads in proposed Sec. 23.310 (now Sec. 23.2210).
While the FAA notes EASA's concern with proposed Sec. 23.300(e),
the FAA finds that paragraph (e), as proposed, would place only an
insignificant burden on an applicant using the VLA standard. The FAA
finds a simple method of compliance, such as for a maximum altitude of
14,000 feet, could be incorporated into an industry consensus standard
to meet this requirement.
b. Interaction of Systems and Structures (Proposed Sec. 23.305/Now
Sec. 23.2205)
In the NPRM, proposed Sec. 23.305 (now Sec. 23.2205) would have
provided a regulatory framework for the evaluation of systems intended
to modify an airplane's structural design envelope or structural
performance, and other systems whose normal operating state or failed
states may affect structural performance. Compliance with proposed
Sec. 23.305 would have provided acceptable mitigation of structural
[[Page 96609]]
hazards identified in the functional hazard assessments required by
proposed Sec. 23.1315.
Textron recommended removing proposed Sec. 23.305 because the NPRM
makes clear that, with or without proposed Sec. 23.305, the safety
intent of proposed Sec. 23.1315 covers the interaction of systems and
structures. Textron also objected to the use of, or reference to, non-
part 23 data. As an example, Textron cited the reference in the
preamble to FAA special condition number 25-390-SC,\30\ which the FAA
said would be an acceptable means of compliance with proposed Sec.
23.305. Textron questioned whether there was justification for this
requirement if part 23 data was not available.
---------------------------------------------------------------------------
\30\ http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSC.nsf/MainFrame?OpenFrameset.
---------------------------------------------------------------------------
In response to Textron's comment regarding the necessity of
proposed Sec. 23.305, the FAA notes the intent stated in the NPRM was
erroneous in its description of the relationship between proposed Sec.
23.305 and proposed Sec. 23.1315 (now Sec. 23.2510). The correct
intent of proposed Sec. 23.305 is to provide a requirement for those
systems intended to directly affect structural performance. An example
of this type of system is a structural load alleviation system. Former
Sec. 23.1309 and Sec. 23.2510 do not envision these types of systems
and the FAA has previously issued special conditions to address these
unique and novel systems. Therefore, the FAA retains proposed Sec.
23.305 as Sec. 23.2205 in this final rule because it provides a way
for applicants to address failures in systems intended to directly
affect structural performance by accounting for the probability of such
failures and the likely pilot reactions to them.
Also, regarding Textron's comment that the NPRM preamble referenced
a part 25 special condition that did not contain part 23 data, the FAA
notes the reference was used as an example because the wording of the
special condition was typical of others relating to Interaction of
Systems and Structure, which establish an acceptable method of
compliance with this section. The FAA has issued a part 23 special
condition (23-258A-SC).\31\ However, the FAA did not use the part 23
special condition as an example because, while it is an acceptable
method of compliance with this section, the approach used in it is not
typical of other special conditions addressing these issues.
---------------------------------------------------------------------------
\31\ 78 FR 10055, February 13, 2013.
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Textron also stated the phrase ``affect structural performance''
was too vague and should be better defined for clarity. Textron noted
every trim system, flight control system, and high lift system affects
structural performance at some level. Textron recommended either
eliminating this phrase or using the preamble to define ``structural
performance.'' Textron recommended proposed Sec. 23.305 be revised to
provide that, for airplanes equipped with systems intended to alleviate
the impact of the requirements of this subpart and affect the
structural design envelope, either directly or as a result of failure
or malfunction, the applicant must account for the influence and
failure conditions of these systems when showing compliance with the
requirements of this subpart.
The Associations commented that proposed Sec. 23.305 was intended
to address systems, which may use aerodynamic or other means to
alleviate loads in certain conditions and to ensure structural
integrity remains in the event these systems were to fail. The
commenters requested the FAA change the language to ensure the intent
of this section is clear and there are no unintended consequences, such
as creating a requirement to perform systems safety assessments on all
systems and structure interactions. The commenters asserted that this
would create a tremendous burden with no measurable benefit. The
commenters proposed Sec. 23.305 be revised to provide that, for
airplanes equipped with systems that are intended to alleviate
structural loads, the applicant must account for the influence and
failure conditions of these systems when showing compliance with the
requirements of this subpart.
The FAA agrees with Textron and the Associations that Sec. 23.2205
should address only those systems intended to affect structural
performance. In the NPRM, the FAA referred to these types of systems as
``structural systems''. The FAA referred to other types of systems as
``non-structural systems''. The FAA agrees that these non-structural
systems are adequately addressed by Sec. 23.2510. The FAA is using the
NPRM description of structural systems in rewording Sec. 23.2205 to
ensure that any airplane equipped with a system intended to affect
structural performance would be provided the same level of safety as an
airplane not equipped with such a system.
c. Structural Design Loads (Proposed Sec. 23.310/Now Sec. 23.2210)
In the NPRM, proposed Sec. 23.310 (now Sec. 23.2210) would have
required--
An applicant to determine structural design loads
resulting from an externally or internally applied pressure, force, or
moment that may occur in flight, ground and water operations, ground
and water handling, and while the airplane is parked or moored.
An applicant to determine structural design loads at all
combinations of parameters on and within the boundaries of the
structural design envelope that would result in the most severe loading
conditions; and
The magnitude and distribution of these loads be based on
physical principles and be no less than service history has shown can
occur within the structural design envelope.
The Associations recommended adding the phrase ``as applicable'' to
proposed Sec. 23.310(a) to address the varying bases to determine load
calculations. These commenters also recommended replacing the term
``any'' with the word ``likely,'' because the calculation of any
externally or internally applied pressure, force, or moment would
result in boundless design and calculation. Textron recommended the
same revisions. Textron noted that the rule implies that all airplanes
will be required to determine both ground and water loads, but not all
airplanes are amphibious.
The FAA agrees with Textron and the Associations concerning the
comments on adding the phrase ``as applicable'' and removing the word
``any'' in proposed Sec. 23.310(a). The FAA also agrees with limiting
the scope of proposed Sec. 23.310(a) by adding the word ``likely'' to
the description of the loading conditions the applicant must consider.
As explained in the discussion of proposed Sec. 23.205, ``likely''
means reasonably expected based on the conditions that may exist.
Accordingly, the FAA revises Sec. 23.2210(a) to capture these changes.
Air Tractor recommended the FAA delete the ``service history''
clause from proposed Sec. 23.310(c) because there is no ``service
history'' for most new airplanes and there is danger that the FAA will
require that service history be collected before certification is
granted for a new design. EASA also noted that a ``service history''
will not always be available for innovative designs.
The FAA partially agrees with Air Tractor regarding the meaning of
``service history'' in proposed Sec. 23.310(c). Service history, in
this sense, refers to the service history and experience gained
throughout aviation history. In Air Tractor's case, service history
would be the service history of other restricted category agricultural
airplanes of similar design. The FAA finds Sec. 23.2200(b) adequately
covers the intent of the ``service history''
[[Page 96610]]
requirement and therefore removes it from Sec. 23.2210(c).
d. Flight Load Conditions (Proposed Sec. 23.315/Now Sec. 23.2215)
In the NPRM, proposed Sec. 23.315 (now Sec. 23.2215) would have
required an applicant to determine the loads resulting from vertical
and horizontal atmospheric gusts, symmetric and asymmetric maneuvers,
and, for multiengine airplanes, failure of the powerplant unit which
results in the most severe structural loads.
EASA noted the proposed rule did not cover the objective that loads
should be considered for the operational envelope, but instead based
the requirement on measured gust statistics. EASA proposed using its CS
23.315 language because it is more objective and does not include
design details.
The FAA finds the requirement to consider loads throughout the
operational envelope is addressed by proposed Sec. 23.310(b) (now
Sec. 23.2210(a)(2)). However, the FAA agrees with EASA's comment that
the proposed rule language is too design specific. Therefore, FAA
revises the rule language to remove design specifics. In particular,
the FAA removes proposed Sec. 23.215(c), which addressed canted
lifting surfaces. The FAA finds Sec. 23.2210(c) adequately addresses
this requirement. The FAA also changes the wording of proposed Sec.
23.215(d) (now 23.2215(c)) to account for the possibility that a single
powerplant, operating two separate propellers, could develop asymmetric
thrust if one propeller system experienced a failure. This would result
in a condition similar to an engine failure in a multiengine airplane,
described in the former regulations. Although no applicant has
submitted such a design for approval to date, given the increased
flexibility this rule provides, future applicants may propose such a
design. In that case, this design will be subject to the same safety
concern and the same need to address it, as applicants for approval of
multiengine airplanes.
Air Tractor commented on proposed Sec. 23.315(a) and questioned
whether the gust velocities in former part 23 or CAR 3 were based on
``measured gust statistics.'' Air Tractor noted it has never seen a
technical report to that effect. Air Tractor also questioned whether
the FAA would deem the CAR 3 and current part 23 values sufficient, and
raised concerns that making up its own requirements to meet FAA
approval would be difficult.
The FAA changed the gust load formula in former Sec. 23.341,
amendment 23-7 \32\ to incorporate the mass parameter approach to
calculating gust loads. The mass parameter approach was developed and
calibrated against measured gust data on transport category airplanes.
The FAA does not intend for applicants for a new TC to measure gust
loadings. The former gust formula remains an acceptable method of
compliance with this regulation. The FAA developed this regulation so
certain airplanes could take advantage of alternate analysis methods,
including the power spectral density approach. Examples of these types
of airplanes include high altitude and endurance airplanes, where
dynamic response of the airplane structure must be considered in the
gust load analysis.
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\32\ 34 FR 13078, August 13, 1969.
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e. Ground and Water Load Conditions (Proposed Sec. 23.320/Now Sec.
23.2220)
In the NPRM, proposed Sec. 23.320 (now Sec. 23.2220) would have
required an applicant to determine the loads resulting from taxi, take-
off, landing, and ground handling conditions occurring in normal and
adverse attitudes and configurations.
EASA proposed using its A-NPA CS 23.325 language because it is more
objective and covers more situations, such as landing on snow or other
surfaces not covered in proposed Sec. 23.320. BendixKing asked that
the FAA delete ``sea,'' stating the word is neither required nor
accurate.
The FAA agrees with EASA's comments and revises the text in Sec.
23.2220 to include all operating surfaces, which includes, at a
minimum, snow or ice covered land and water. EASA referred to snow and
other surfaces not covered in the proposed text, presumably meaning
EASA does not consider operations on ``snow or other surfaces'' to be
operations on the ground. While the FAA is using EASA's CS A-NPA 23.325
language, the FAA finds EASA's language citing weight and velocity to
be unnecessary. These parameters are addressed in Sec. 23.2200.
Air Tractor asked whether the ``ground handling conditions'' in
proposed Sec. 23.320(a) would be different from the ``jacking and
towing conditions'' in proposed Sec. 23.320(c). If so, the commenter
asked what ``ground handling conditions'' meant. Air Tractor also asked
whether this dealt with protection from ``hangar rash.'' Finally, Air
Tractor sought clarification on whether it would now need to define the
structural loads associated with docking an airplane, or from wave
motion causing scuffing when a seaplane is moored against a dock.
The FAA notes the ``ground handling conditions'' referenced in
proposed Sec. 23.320(a) (now Sec. 23.2220) are different than the
``jacking and towing conditions'' referenced in Sec. 23.320(c) (now
Sec. 23.2220). The reference to ``handling conditions'' is intended to
cover both ground handling conditions and jacking and towing
conditions. The FAA revises Sec. 23.2220 to cover ``taxi, takeoff,
landing, and handling conditions.''
f. Component Loading Conditions (Proposed Sec. 23.325/Now Sec.
23.2225)
In the NPRM, proposed Sec. 23.325 (now Sec. 23.2225) would have
required an applicant to determine the loads acting on each engine
mount, flight control, high lift surface, and the loads acting on
pressurized cabins.
EASA commented that proposed Sec. 23.325(b) covered the loads on
components subject to earlier defined loads in proposed Sec. Sec.
23.305 through 23.320. EASA recommended the FAA simplify the
requirement to avoid different interpretations by reflecting the
relation to the previous requirements as follows:
Interaction of systems and structures
Structural design loads
Flight Load Conditions
Ground and water load conditions
The FAA finds that a separate rule for component loading conditions
is necessary to address structural loading conditions that do not fall
under the requirements for flight and ground loads. Examples of these
loading conditions include control surface jamming and pressurized
cabin loads. The FAA revises Sec. 23.2225 to clarify the types of
loads applicants must account for.
Textron and the Associations asked the FAA to revise the ``relief
valve'' language in proposed Sec. 23.325(c), which was a design-
specific solution, in favor of more performance-based language. Textron
suggested language such as ``from zero to the maximum relief pressure
combined with gust and maneuver loads.'' The Associations recommended
replacing ``valve'' with ``pressure.''
The FAA agrees with Textron and the Associations on the use of the
term ``relief valve.'' The FAA revises Sec. 23.2225(c)(1), (2), and
(3) by replacing the term ``relief valve'' with ``relief pressure.''
The FAA agrees with a comment made at the public meeting by the
Associations that proposed Sec. 23.325 should cover sudden engine
stoppage loads for turbine engines, as did former part 23. A
requirement for the design of
[[Page 96611]]
engine mounts for turbine engines to be able to withstand a sudden
engine stoppage has been in former part 23 since 1980.\33\ Former Sec.
23.361(b)(1) required, in pertinent part, that for turbine engine
installations, the engine mounts and supporting structure be designed
to withstand an engine torque load imposed by a sudden engine stoppage.
The requirement applied only to turbine engines because reciprocating
engines typically do not have significant rotational moments of
inertia. As in former part 23, reciprocating powerplants, with their
lower moments of inertia, are not included in this section of the rule.
The requirement applies only to turbines and other types of powerplants
that have significant rotational moments of inertia created by rotating
powerplant components (e.g., electric motor powerplants). Therefore,
the FAA adds protection of powerplant mounts and supporting structure
from sudden powerplant stoppage for all non-reciprocating powerplants
to Sec. 23.2225(a)(2). This change is consistent with the goal of
capturing the safety intent of former part 23, including Sec. 23.361,
as stated in the NPRM preamble, and with the performance-based nature
of this rule and its goal of more easily accommodating future designs
and technologies.
---------------------------------------------------------------------------
\33\ 45 FR 60171, September 11, 1980.
---------------------------------------------------------------------------
Finally, the FAA revises Sec. 23.2225(b) to clarify the gust loads
that must be accounted for and the meaning of ``ground operations,''
making this section consistent with the changes discussed previously
for Sec. 23.2220.
g. Limit and Ultimate Loads (Proposed Sec. 23.330/Now Sec. 23.2230)
In the NPRM, proposed Sec. 23.330 (now Sec. 23.2230) would have
described how the applicant must determine the limit and ultimate loads
associated with the structural design loads. Proposed Sec. 23.330
retained the current 1.5 safety factor for ultimate loads.
The Associations recommended the FAA revise proposed Sec. 23.330
by deleting the phrase ``special or other factors of safety are
necessary to meet the requirements of'' and replacing it with
``ultimate loads are specified in.'' These commenters noted the
section, as written, would not require the establishment of limit loads
if a special factor of safety is used to meet the requirement. Textron
recommended the same revision, explaining that proposed Sec. 23.330
need not address ``special or other factors of safety,'' other than in
some cases when an ultimate load is specified, because proposed Sec.
23.515(c) specified that limit and ultimate loads are multiplied by
special factors of safety.
The FAA agrees with the comments regarding cases where loads are
expressed only as ultimate loads. The FAA deletes the introductory
phrase ``unless special or other factors of safety are necessary to
meet the requirements of this subpart,'' in proposed Sec. 23.330. The
FAA notes Sec. 23.2265(c) specifies that limit and ultimate loads are
multiplied by special factors of safety. Furthermore, the FAA revises
Sec. 23.2230 by inserting the phrase ``unless otherwise specified
elsewhere in this part,'' which captures the intent of former Sec.
23.303.
EASA recommended the FAA should also address the former requirement
for redistribution of loads due to deflections under loads. EASA also
recommended the regulation cover the specific case where strength
specifications are expressed only in ultimate loads and permanent
deformation is accepted.
The FAA notes Sec. 23.2210(b) addresses the issue of
redistribution of loads. Specifically, 23.2210(b) requires the
distribution of loads be based on physical principles. The FAA finds
redistribution of load due to deflection is an expression of physical
principles and is retaining this requirement in Sec. 23.2210(b) of
this rule.
An individual commenter asked the FAA to remove the ``arbitrarily
prescriptive'' 1.5 factor of safety and substitute a more performance-
based approach. The commenter explained that advances in probabilistic
analysis have increased understanding of actual variables like load
predictions, material properties, and airplane operations. The
commenter proposed defining the value for structural failure more
explicitly and allowing the applicant to account for the variations to
achieve the value, allowing for more efficient designs. The commenter
suggested retaining the 1.5 factor of safety as a possible approval
approach to establish the means of compliance.
The FAA notes the 1.5 factor of safety has been used for many years
and has provided an acceptable level of safety. Probabilistic analysis
methods and the data necessary to support them are not sufficiently
mature to provide the same level of assurance of safety. As
probabilistic methods mature, the FAA will consider their use if
applicants can show they provide an equivalent level of safety.
h. Structural Strength (Proposed Sec. 23.400/Now Sec. 23.2235)
In the NPRM, proposed Sec. 23.400 (now Sec. 23.2235) would have
required an applicant to demonstrate the structure will support limit
and ultimate loads. The NPRM explained that in this context,
``demonstrate'' means the applicant must conduct structural tests to
show compliance with the structural performance requirements unless the
applicant shows that a structural analysis is reliable and applicable
to the structure.
The Associations recommended adding ``unsafe'' at the beginning of
proposed Sec. 23.400(a)(1) to clarify the intent of the requirement
and ensure it is not viewed as including expected or non-critical types
of interference, such as thrust reverser buckets making normal contact
with each other. Similarly, Textron recommended inserting the word
``safe'' before ``operation'' in proposed paragraph (a)(1) to ensure
that ``interference'' in the regulation will always be interpreted to
mean interference that would cause an unsafe condition.
The FAA agrees that inserting the word ``safe'' in the text of
proposed Sec. 23.400(a)(1) will clarify that the structure must
support limit loads without interference with the ``safe'' operation of
the airplane. This suggested change is consistent with the
corresponding requirements in former part 23, and will resolve the
Associations' concern as well. Accordingly, the FAA revises Sec.
23.2235(a)(1) to capture this change.
NJASAP asked why the FAA proposed removing time requirements (the
capability of the airplane structure to support ultimate loads without
failure for at least three seconds) in proposed Sec. 23.400.
As discussed in the NPRM preamble, the FAA considers the ``3-
second'' rule a statement of physical principles and sound testing
practices that does not need to be stated in the requirements for
structural strength. It is more appropriate for inclusion in a means of
compliance. The FAA makes no change to the regulatory text based on
NJASAP's comment.
i. Structural Durability (Proposed Sec. 23.405/Now Sec. 23.2240)
In the NPRM, proposed Sec. 23.405 (now Sec. 23.2240) would have
required an applicant to develop and implement procedures to prevent
structural failures due to foreseeable causes of strength degradation,
and to prevent rapid decompression in airplanes with a maximum
operating altitude greater than 41,000 feet. Proposed Sec. 23.405
would have also required an airplane to be capable of continued safe
flight and landing with foreseeable structural damage caused by high-
energy
[[Page 96612]]
fragments from an uncontained engine or rotating machinery failure.
The Associations said proposed Sec. 23.405 remains ``far too
prescriptive and design oriented.'' The commenters recommended language
that they believed addresses the objectives of the rule without being
so design focused. Specifically the Associations suggested the phrase
``serious or fatal injuries, loss of the airplane, or extended periods
of operation with reduced safety margins'' in Sec. 23.2240(a) be
replaced with ``unsafe conditions.''
Textron suggested that the proposed rule is too prescriptive
regarding the number of compartments for compartment floor
depressurization, as well as in prescribing the ``design'' structure
rather than specifying the required capability of the structure.
Textron suggested revising proposed Sec. 23.405 similar to that
suggested by the Associations.
An individual commenter recommended the FAA delete the phrase
``loss of the airplane'' from proposed Sec. 23.405(a). The commenter
stated this would address the long-understood interpretation that part
23 does not include certain structures for required evaluation on the
effects of fatigue failure, such as landing gear and engine support (or
hull loss, as discussed in the NPRM preamble). Without this revision,
the commenter noted the intent of the rule not to increase the burden
on certification would be nullified. In effect, the commenter found the
proposed rule would require the same structure as is currently
evaluated in part 25, which is inconsistent with former part 23. The
commenter favored incorporating a comprehensive fatigue evaluation of
structure as is currently in part 25.
The FAA agrees with the suggestion to delete the phrase ``loss of
the airplane'' in paragraph (a). The FAA finds the prevention of
serious or fatal injuries and the prevention of extended periods of
operation with reduced safety margins is the objective of Sec.
23.2240. The FAA will not adopt the Associations' recommended change to
replace the phrase ``serious or fatal injuries, loss of the airplane,
or extended periods of operation with reduced safety margins'' with
``unsafe conditions.'' The term ``unsafe condition'' is the threshold
for the FAA issuing airworthiness directives under 14 CFR part 39, and
is not an accurate term to be used in this section.
The FAA also revises paragraph (a) to reflect more completely the
requirements of the former part 23 regulations this section is
replacing.\34\ Because proposed Sec. 23.405(a) did not refer
specifically to the Airworthiness Limitations section (ALS) of the
Instructions for Continued Airworthiness (ICA) (as did former Sec.
23.575), it could be interpreted as allowing the procedures to be
placed in another part of the ICA. Therefore, the FAA revises the text
in paragraph (a) to clarify that these procedures must be in the ALS.
The FAA also clarifies that ``inspections'' developed under this
section must be included in the ALS in addition to the ``procedures''
developed under the section, because former Sec. 23.575 required both
to be in the ALS. Appendix G to former part 23, now appendix A to this
final rule, requires the FAA to approve the ALS. Finally, the FAA notes
that compliance with the ALS is mandatory under Sec. Sec. 43.16 and
91.403(c).
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\34\ Sec. Sec. 23.365(e), Pressurized cabin loads; 23.571,
Metallic pressurized cabin structures; 23.572, Metallic wing,
empennage, and associated structures; 23.573, Damage tolerance and
fatigue evaluation of structure; 23.574, Metallic damage tolerance
and fatigue evaluation of commuter category airplanes; 23.575,
Inspections and other procedures; and 23.627, Fatigue strength. (81
FR 13476, March 14, 2016).
---------------------------------------------------------------------------
EASA suggested replacing the design-specific requirements in
proposed Sec. 23.405(b) with more objective requirements from EASA's
CS 23.340(b) to allow proportionality for different airplane levels. In
particular, EASA said more objective requirements should replace the
proposed requirements related to pressurized airplanes and uncontained
engine failure.
The FAA notes the language in EASA's proposed CS 23.340 could be
interpreted as expanding the scope of the former regulations by
requiring evaluation of discrete source damage for all airplanes
certificated under part 23. As stated in the NPRM, the FAA intended
proposed Sec. 23.405(b) and (c) to capture the intent of former
Sec. Sec. 23.365(e) and 23.571(d), which only addressed airplanes with
pressurized compartments. Sudden release of pressure and operating
above 41,000 feet altitude present the same hazards to the airplane
occupants regardless of airplane category or size.
The FAA moves the content of proposed Sec. 23.405(b) and (c) to
Sec. 23.2240(c)(1) and (c)(2) in the final rule. The final rule also
adds new Sec. 23.2240(b), which addresses the requirement for level 4
airplanes. This requirement is similar to the former Sec. 23.574
requirement for damage tolerance evaluations of commuter category
airplanes. The FAA inadvertently left this requirement out of the NPRM.
The FAA agrees with the comments that proposed Sec. 23.405(b) was
overly prescriptive. The FAA deletes the detailed description of the
pressurized compartment and emphasizes the sudden release of pressure
in Sec. 23.2240(c)(1) and (c)(2). The FAA retains reference to door
and window failures as examples of the types of failures that could
result in sudden release of pressure.
EASA stated that proposed Sec. 23.405(d) is too specific to engine
rotorburst; however, other risks could be expected from new
technologies that should also be considered.
The FAA agrees with EASA's comment that paragraph (d) should
address all high-energy fragments, not just fragments from an engine
rotorburst. The FAA revises Sec. 23.2240(d) to include all high-energy
fragments. The FAA also includes turbine engines and rotating machinery
as sources of high-energy fragments.
Several other commenters also commented on proposed Sec.
23.405(d), noting that former part 23 required ``minimizing'' hazards
associated with damage from uncontained engine or rotating machinery
failures, but the NPRM would require the airplane be able to ``continue
safe flight and landing'' following such damage. The commenters
asserted that there is no way to eliminate all the risks that will
prevent the ``continued safe flight and landing,'' and asked the FAA
maintain the requirement to ``minimize'' these hazards as in former
Sec. 23.903(b)(1).
The FAA agrees that proposed Sec. 23.405(d) is inconsistent with
the description in the NPRM preamble. Therefore, the FAA agrees with
the commenters' recommendation to adopt the term ``minimize'' in Sec.
23.2240(d). The FAA does not intend for applicants to incorporate all
possible design precautions against rotorburst hazards, especially
those that are resource prohibitive or have a negligible impact on
safety. The FAA expects an applicant's compliance with Sec. 23.2240(d)
to incorporate all practical design precautions to minimize the hazards
due to high-energy fragments.
j. Aeroelasticity (Proposed Sec. 23.410/Now Sec. 23.2245)
In the NPRM, proposed Sec. 23.410 (now Sec. 23.2245) would have
required an airplane to be free from flutter, control reversal, and
divergence at all speeds within and sufficiently beyond the structural
design envelope, for any configuration and condition of operation,
accounting for critical
[[Page 96613]]
degrees of freedom, and any critical failures or malfunctions. Proposed
Sec. 23.410 would have also required an applicant to establish
tolerances for all quantities that affect flutter.
Air Tractor and Transport Canada raised concerns about the phrase
``sufficiently beyond the structural design envelope'' in proposed
Sec. 23.410(a)(1). Transport Canada said the wording is subjective and
does not convey a performance requirement and suggested complementing
the phrase ``sufficiently beyond'' with safety objective requirements.
Air Tractor noted the existing regulations do not extend beyond the
design envelope. Air Tractor asked for clarification on what is
considered ``sufficiently beyond.''
Regarding Air Tractor's assertion that the former regulations did
not extend beyond the design envelope, the FAA intended proposed Sec.
23.410 to capture the safety intent of former Sec. Sec. 23.629,
23.677, and 23.687 without introducing the inflexibility created by the
former regulations. Former Sec. 23.629(c) required that flutter
analysis show freedom from flutter, control reversal, and divergence up
to 20 percent above dive speed. Existing part 25 rule language requires
flutter analysis to show this up to 15 percent above dive speed. This
is to account for uncertainties inherent in analytical techniques. Part
25 requires a smaller margin above dive speed due to its more rigorous
analytical requirements. Additionally, former Sec. 23.629(b)(4)
precluded any large or rapid reduction in damping as dive speed is
approached in flight tests.
As for Air Tractor's comment requesting clarification on what is
considered ``sufficiently beyond'' in proposed Sec. 23.410(a)(1), the
former part 23 requirements for margins on analyses and flight tests
worked together to ensure a momentary inadvertent excursion above dive
speed in operation, or combined variations in quantities that may
affect flutter, did not result in a catastrophic flutter event. Thus,
the FAA required a sufficient margin above dive speed in former part 23
for many years. The phrase ``sufficiently beyond the structural design
envelope'' is intended to require a sufficient margin consistent with
the requirements of former part 23. However, as technology and
analytical techniques evolve and improve, the new language will allow
room for the methods of compliance to adapt and possibly change the
appropriate margin needed for safe operations. This language is also
harmonized with EASA's proposed rule language.
Several commenters raised concerns about the use of the term
``any'' in proposed Sec. 23.410(a). The Associations asked the FAA to
revise proposed Sec. 23.410(a)(2) to require the airplane to be free
from flutter, control reversal, and divergence for ``approved''
configurations and conditions of operation, rather than for ``any''
configuration and condition of operation. Textron recommended the FAA
require the airplane to be free from flutter, control reversal, and
divergence for ``any likely'' configuration and condition of operation.
Similarly, the Associations suggested removing the term ``any'' from
proposed Sec. 23.410(a)(4).
The FAA notes the commenters concerns about the term ``any'' in
Sec. 23.2245(a)(2) and (a)(4). In the NPRM, the FAA explained that
Sec. 23.2245 would capture the safety intent of former Sec. 23.629.
Former Sec. 23.629(a) has required the airplane to be free from
flutter, control reversal, and divergence for ``any condition of
operation'' since 1978. This terminology originated from CAR 3.311, the
predecessor to former Sec. 23.629, was adopted in 1947 and required
the wings, tail, and control surfaces to be free from flutter,
divergence, and control reversal for ``all conditions of operation.''
The FAA recognizes it is impossible to evaluate an infinite number of
data points, but that is not the intent of Sec. 23.2245 nor was it the
intent of its predecessor regulations. Rather, the FAA interprets the
term ``any'' in Sec. 23.2245(a)(2) as requiring the applicant to
exercise due diligence by accounting for a sufficient number of data
points that would enable the applicant to state the entire envelope has
been evaluated and is safe. This interpretation is consistent with the
way the FAA has interpreted CAR 3.311 and former Sec. 23.629. Because
the FAA has used the terms ``any'' and ``all'' in its flutter
requirements for decades, the FAA is retaining the term ``any'' in
Sec. 23.2245(a)(2) and (a)(4). This maintains harmonization with
EASA's proposed rule language.
Several commenters raised concerns with terminology in proposed
Sec. 23.410(b). Textron and the Associations suggested the FAA require
the applicant to establish and account for ``sensitivities'' rather
than ``tolerances'' because the term ``tolerances'' has a very specific
meaning and a proper flutter analysis is a collection of flutter
sensitivity analyses.\35\ The Astronautics Corporation of America
(Astronautics) sought clarification of the term ``quantities'' in
proposed Sec. 23.410(b) and offered alternative regulatory language in
an attempt to clarify its meaning. Textron proposed replacing
``quantities'' with ``parameters.''
---------------------------------------------------------------------------
\35\ Textron specifically noted that proposed Sec. 23.2245(b)
``would require the applicant to specify a +/-X% tolerance on things
such as cross sectional properties (torsional GJ), cross sectional
moments of inertia, or other qualities that affect flutter but
aren't intended to have a +/-X% tolerance.''
---------------------------------------------------------------------------
Regarding Textron, the Associations and Astronautics' comments on
the use of ``tolerances'' and ``quantities'' in proposed Sec.
23.410(b), the FAA is retaining the terms ``tolerances'' and
``quantities'' in Sec. 23.2245(b). The FAA intends Sec. 23.2245 to
capture the safety intent of former Sec. 23.629, which has contained
the terms ``tolerances'' and ``quantities'' since 1978.\36\ The FAA has
interpreted them consistently from that time, and will continue to do
so in Sec. 23.2245. This language is also harmonized with EASA's
proposed rule language.
---------------------------------------------------------------------------
\36\ See 43 FR 50592, October 30, 1978.
---------------------------------------------------------------------------
Textron recommended removing the word ``establish'' from the
proposed language. The commenter noted that you cannot account for
something without establishing it first.
The FAA agrees with Textron that it would be redundant to require
an applicant to establish and account for tolerances. For that reason,
the FAA retains the word ``establish'' and deletes the words ``and
account for'' from Sec. 23.2245(b) in the final rule. This change
emphasizes the necessity of fully analyzing these tolerances and
harmonizes with EASA's proposed rule language.
k. Design and Construction Principles (Proposed Sec. 23.500/Now Sec.
23.2250)
In the NPRM, proposed Sec. 23.500 (now Sec. 23.2250) would have
required--
An applicant to design each part, article, and assembly
for the expected operating conditions of the airplane;
The design data to adequately define the part, article, or
assembly configuration, its design features, and any materials and
processes used;
An applicant to determine the suitability of each design
detail and part having an important bearing on safety in operations;
and
The control system to be free from jamming, excessive
friction, and excessive deflection when the control system and its
supporting structure are subjected to loads corresponding to the limit
airloads when the primary controls are subjected to the lesser of the
limit airloads or limit pilot forces, and when the secondary controls
are subjected to loads not less than those corresponding to maximum
pilot effort.
[[Page 96614]]
The Associations recommended the FAA change the title of proposed
Sec. 23.500 from ``Structural design'' to ``Design and construction
principles.''
The FAA concurs with the recommendation by the Associations to
change the title of Sec. 23.2250 to ``Design and construction
principles.'' The FAA agrees the suggested title is a better descriptor
and will harmonize with EASA's proposed title for this section, and
adopts it for this rule.
Several comments addressed proposed Sec. 23.500(d). Air Tractor
recommended that the FAA revise the wording of proposed Sec. 23.500(d)
to specify that it applies to flight controls. Air Tractor further
noted that it appears that the definition of ``maximum pilot effort''
has been untethered from former Sec. Sec. 23.397(b) and 23.143(c),
making it necessary for every applicant ``to re-invent the wheel.''
Regarding Air Tractor's comment proposing to add the term
``flight'' to further define ``control system'', the term ``control
system'' has been used consistently for many years in this context in
the former regulations, and is understood to refer to ``flight''
controls. This text also harmonizes with EASA's proposed rule language.
Therefore, the FAA adopts the language as proposed in the NPRM.
As for Air Tractor's concern that maximum pilot effort has been
untethered from former Sec. Sec. 23.397(b) and 23.143(c), the FAA
notes that under the new performance-based regulations, applicants will
be free to use former part 23 or other accepted means, such as industry
consensus standards, as a means of compliance. These accepted means of
compliance will detail how the airplane will meet the performance-based
requirements.
The Associations stated that it is appropriate for means of
compliance to specify how airframe and control system interactions will
be tested up to limit loads and that, depending on the nature of the
control system, it may be more or less appropriate to perform such a
test. These tests ensure the appropriate level of testing is always
applied to traditional flight controls and also to future systems,
which may include fans or thrusters. The commenters suggested the level
of detail be contained in accepted standards. Additionally, the
commenters recommended the FAA consider revising proposed Sec.
23.500(d) by deleting paragraphs (1), (2), and (3) and adding the
phrase ``the airplane is subjected to expected limit airloads'' to the
end of paragraph (d). EASA also recommended the FAA remove details in
proposed Sec. 23.500(d) that describe what parts of the system should
be subject to which loads because this is design specific and should be
covered in the means of compliance.
The FAA agrees with EASA and the Associations to revise proposed
Sec. 23.500(d)(1), (d)(2), and (d)(3) and adds the phrase ``the
airplane is subjected to expected limit airloads'' to the end of Sec.
23.2250(d). This change aligns with EASA's recommendation and assists
in harmonization with EASA's proposed rule. The FAA considers these
suggestions to be more in line with the original intent of the
performance standards. Therefore, the FAA adopts the changes proposed
by the commenters.
Textron suggested the FAA remove the Sec. 23.500(d)(1) requirement
that the supporting structure is loaded with limit airloads while the
control system is loaded, which the commenter noted has historically
never been a part 23 requirement. Textron further suggested the FAA
change the phrase ``controls are'' in both subparagraphs (2) and (3) to
``control system is'' to further specify that this is a control system
test. Textron commented that the word ``controls'' could imply
something other than the entire system is the intent.
As noted above in this section, the FAA removes paragraphs
paragraph (d)(1), (d)(2) and (d)(3). The FAA adopts the terminology
``control system'' in the revised proposed Sec. 23.500(d).
EASA also suggested the FAA consider moving the general principle
for doors, canopies, hatches, and access panels from proposed Sec.
23.750(f) to a new Sec. 23.2250(e).
The FAA concurs with EASA's recommendation to move the general
principle for doors, canopies, hatches, and access panels from proposed
Sec. 23.750(f) to a new Sec. 23.2250(e). The requirement is more
appropriate in this section because it states a general design
principle rather than a requirement relating to emergency evacuation.
The FAA also notes that making this change further helps to harmonize
FAA and EASA regulations.
l. Protection of Structure (Proposed Sec. 23.505/Now Sec. 23.2255)
In the NPRM, proposed Sec. 23.505 (now Sec. 23.2255) would have
required an applicant to protect each part of the airplane, including
small parts such as fasteners, against deterioration or loss of
strength due to any cause likely to occur in the expected operational
environment. Proposed Sec. 23.505 would have also required each part
of the airplane to have adequate provisions for ventilation and
drainage and would require an applicant to incorporate a means into the
airplane design to allow for required maintenance, preventive
maintenance, and servicing.
Textron recommended clarifying the intent of proposed Sec.
23.505(a) by including a reference to specific sources of damage
because it is unclear whether the proposed rule would be an increase
from what was previously required.
The FAA considered Textron's comment. However, as far back as 1949
(Sec. 3.295, ``Protection''), the regulations required all members of
the structure to be ``suitably protected against deterioration or loss
of strength in service due to weathering, corrosion, abrasion, or other
causes. . . .'' The CAR 3 requirement was included in the 1965
recodification as former Sec. 23.609, which included a non-exhaustive
list of possible causes of deterioration. In the NPRM, the FAA removed
the listed examples, but maintained the requirement to account for
deterioration or loss of strength due to ``any cause likely to occur.''
Textron further stated that it is unclear whether the phrase
``expected operational environment'' is intended to include any
environment that might occur during failure conditions, or just the
environment during normal operating conditions. Textron recommended
replacing the phrase ``expected operational environment'' with
``intended operational environment'' or ``normal operational
environment.''
The FAA considered Textron's recommendation to change ``expected
operational environment'' to ``intended operational environment'' or
``normal operational environment.'' The FAA did not intend to limit
this requirement only to the normal operational environment because, if
the failure conditions are an expected environment, then an applicant
should consider those conditions and protect the structure.
Deterioration or loss of strength due to corrosion, weathering, and
abrasion are all examples of failure conditions because capability has
been degraded. For many years, the rule has expressly required
consideration of these causes. It was an expected environment for items
to be corroded, weathered, and abraded, but applicants had to consider
any other causes too.
m. Materials and Processes (Proposed Sec. 23.510/Now Sec. 23.2260)
In the NPRM, proposed Sec. 23.510 (now Sec. 23.2260) would have
required--
An applicant to determine the suitability and durability
of materials used for parts, articles, and assemblies, the failure of
which could prevent continued safe flight and landing, while accounting
for the effects of likely
[[Page 96615]]
environmental conditions expected in service; and
The methods and processes of fabrication and assembly used
to produce consistently sound structures and, if a fabrication process
requires close control to reach this objective, an applicant would have
to perform the process under an approved process specification.
Additionally, proposed Sec. 23.510 would have required an
applicant to justify the selected design values to ensure material
strength with probabilities, accounting for--
The criticality of the structural element; and
The structural failure due to material variability, unless
each individual item is tested before use to determine that the actual
strength properties of that particular item would equal or exceed those
used in the design, or the design values are accepted by the
Administrator.
Proposed Sec. 23.510 would have required a determination of
required material strength properties to be based on sufficient tests
of material meeting specifications to establish design values on a
statistical basis. Proposed Sec. 23.510 would have also required an
applicant to determine the effects on allowable stresses used for
design if thermal effects were significant on an essential component or
structure under normal operating conditions.
Textron commented that, as proposed, the regulatory text in
paragraph (a) was unclear as to whether an applicant must account for
the effects of likely environmental conditions expected in service on
parts, articles, and assemblies. Textron proposed combining the two
sentences in paragraph (a) to clarify the FAA's intent for the effect
of specific environmental conditions on parts, articles, and assemblies
to be considered in determining the suitability and durability of
materials.
The FAA concurs with Textron's comment regarding the lack of
clarity in paragraph (a), and revises the regulation accordingly.
Although the revision creates a slight disharmony with EASA's proposed
rule language, the intent of the two regulations remains the same, and
the change helps to clarify the FAA's intent.
Textron also requested the FAA to replace the word ``essential''
with the word ``critical''. The commenter stated the word ``essential''
has not been used or defined historically in part 23 structural
compliance, whereas the word ``critical'' is used more frequently and
is better defined.
Based on Textron's comment for clarity, the FAA revises Sec.
23.2260(e) to replace the word ``essential'' with the word
``critical'', since ``critical'' is a more common and widely used term
of art amongst structural engineers than ``essential.'' Specifically,
the failure of a critical component or structure is potentially
catastrophic.
In the public meeting, Aspen Avionics asked the FAA to clarify
whether the requirement in proposed paragraph (b) to perform the
process under an ``approved process specification'' refers to an FAA-
approved process specification or an accepted industry standard or some
other approved process specification. Aspen Avionics also commented on
proposed paragraph (d), which stipulates that if material strength
properties are required, a determination of those properties must be
based on sufficient tests of material meeting the specifications. Aspen
Avionics questioned whether this requirement applies to the applicant
or whether the applicant can rely on statements from a manufacturer--
i.e., Aspen asked the FAA to clarify who has to do what testing for the
materials. Aspen also asked whether the testing requirement applies to
primary, secondary, or tertiary structure.
Regarding Aspen Avionics' request for clarification of what
constitutes an approved process specification for paragraph (b), the
FAA does not intend any change from current practices under former
regulation Sec. 23.605(a), where nearly identical language was used.
The process specification is ``approved'' by the FAA, and the FAA
expects to have access to the specification in order to review and
determine whether it contains sufficient control to substantiate
compliance with the regulation. The specification may be proprietary to
the OEM or sub-contractor, but should have formal document approval and
control procedures like other engineering reports, documents and
drawings necessary for the type design.
As for Aspen Avionics' question regarding the test requirements and
whether the requirement is for primary, secondary, or tertiary
structure, the FAA does not intend any change from current practices
under former regulation Sec. 23.613(a), where nearly identical
language was used. The TC holder is responsible for data used to
substantiate its type design. Whether the required testing is performed
by the OEM or a sub-contractor does not matter as the FAA holds the OEM
responsible, and expects the data to be available for FAA review to
ensure compliance with the regulation. This requirement for
statistically based material properties applies to any airplane primary
structure. Existing published FAA guidance and widely used industry
practices should be consulted for the finer divisions of structure,
such as secondary and tertiary, and the material properties typically
used.
n. Special Factors of Safety (Proposed Sec. 23.515/now Sec. 23.2265)
In the NPRM, proposed Sec. 23.515 (now Sec. 23.2265) would have
required an applicant--
To determine a special factor of safety for any critical
design value that was uncertain, used for a part, article, or assembly
likely to deteriorate in service before normal replacement, or subject
to appreciable variability because of uncertainties in manufacturing
processes or inspection methods;
To determine a special factor of safety using quality
controls and specifications that accounted for each structural
application, inspection method, structural test requirement, sampling
percentage, and process and material control; and
To apply any special factor of safety in the design for
each part of the structure by multiplying each limit load and ultimate
load by the special factor of safety.
The Associations recommended changing Sec. 23.515(a) by requiring
special factors of safety be ``established and applied'', rather than
determined, by the applicant. Additionally, they suggested the language
of the regulation focus on critical design values ``affecting
strength.''
The FAA has used ``determine'' in numerous other places in the
NPRM. The commenters' suggested change would not imply a different
meaning. As for the commenters' suggestion that the term ``critical
design value'' should be limited to those values ``affecting
strength,'' there may be other critical design values aside from
strength that warrant the use of special factors of safety. For
example, former part 23 specified bearing factors for certain
applications. These were intended to account for not only strength, but
also for durability and consideration of possible dynamic loading. In a
performance-based standard where these factors are not specified, it is
necessary to make sure that future designs, materials, and
applications, not yet envisioned, account for any critical ``design
values,'' in the same way the former regulations account for known
critical values in those applications today. The FAA adopts Sec.
23.2265(a) with minor modifications.
[[Page 96616]]
Air Tractor commented that proposed Sec. 23.515(b) added
unwarranted specificity and is worded such that the special factor must
account for each inspection method, whether or not it is critical. Air
Tractor further commented that certain conditions, such as structural
test requirements, sampling percentages, and process and material
controls, would be defined in a quality system approved under a
production certificate (PC), not as part of a type design. Air Tractor
contended that a type design should be approved independently of any
quality system or production system requirements.
The FAA agrees with Air Tractor that conditions, such as structural
test requirements, sampling percentages, and process and material
controls, would be defined in a quality system that is approved under a
PC. However, there are instances where those items are defined by type
design or inspection methods in an approved type design. As with the
former Sec. 23.621, ``Casting factors,'' special casting factors of
safety are to be applied to any structural casting, not just critical
ones. The specific casting factor used in all those cases is
inseparably tied to the applicable tests and inspections, both of which
include sampling percentages specified for the part being produced.
Former Sec. 23.621(a) required these factors to be defined in the type
design, and they are in addition to whatever tests and inspections are
required for foundry quality control. Therefore, proposed Sec.
23.515(b) is not substantively different from the former regulations.
The FAA generally agrees with Air Tractor's comment that approval
of a type design is independent of any quality system or production
system requirements. However, as explained previously in this section,
the special factor of safety used to substantiate the type design is
approved for use based completely on the part criticality, inspections,
tests, and sampling percentages specified for a particular part.
Additionally, the Associations recommended changing proposed Sec.
23.515(b)(1) by replacing ``structural'' application with ``kind of''
application. The commenters contended it would ensure that special
factors of safety continue to be applied in the same manner as they are
applied in the former rule, while also providing for more flexibility
for new materials and construction techniques.
The FAA agrees with the Associations that the term ``structural''
in proposed Sec. 23.515(b)(1) should be revised. However, the FAA
believes the words ``type of'' is more accurate than ``kind of'' in
this application, and revises the text of Sec. 23.2265(b) accordingly.
The Associations recommended changing proposed Sec. 23.515(c) to
require a factor of safety established under proposed Sec. 23.330(b)
to be multiplied by the highest pertinent factor of safety established
under proposed Sec. 23.515(b). The commenters explained that this
change would ensure special factors of safety are applied in the same
manner as they are applied in the former rule, while also providing for
more flexibility for new materials and construction techniques.
The FAA disagrees with the Associations as such a change has led to
convoluted regulations in the past. Further, the limit and ultimate
loads are clearly defined in this subpart, so this cross-reference is
unnecessary.
Additionally, EASA noted that although the strict wording in former
part 23 and CS 23 did not require special factors to be applied to
ultimate loads that do not have corresponding limit loads (e.g.,
emergency landing conditions), this is not reflected in the NPRM.
Referring to proposed Sec. 23.515(c), EASA noted that former part 23
and CS 23 use the highest pertinent special factor, instead of any
special factor as proposed in the NPRM. EASA suggested that
coordination is necessary for harmonization.
The FAA does not agree with EASA's assertion that a narrow
interpretation of former part 23 would not require special factors of
safety to be applied to ultimate loads that do not have corresponding
limit loads. Former Sec. 23.625(d) required the attachments of seats,
berths, and safety belts and harnesses to multiply the inertia loads in
the emergency landing conditions in former Sec. 23.561 by a special
factor of safety (i.e., fitting factor) of 1.33. However, the FAA
concurs with EASA that new part 23 should require the use of the
``highest pertinent'' special factor of safety, and not ``any'' special
factor of safety. Therefore, the FAA revises Sec. 23.2265(c)
accordingly.
Additionally, upon further review, the FAA finds that the proposed
wording in Sec. 23.515(c) appears to require an applicant to multiply
not only each ultimate load by the special factor of safety, but also
each limit load by the same factor even though sometimes there is no
corresponding limit load. Therefore, the FAA also revises Sec.
23.2265(c) to state that the special factor of safety is applied
regardless of whether there is a limit load condition corresponding to
the ultimate load condition. Although the FAA's language may not be
harmonized with EASA's NPA, the intent is the same.
o. Emergency Conditions (Proposed Sec. 23.600/Now Sec. 23.2270)
In the NPRM, proposed Sec. 23.600 (now Sec. 23.2270) would have
required--
The airplane, even if damaged in emergency landing
conditions, to provide protection to each occupant against injury that
would preclude egress;
The airplane to have seating and restraints for all
occupants, consisting of a seat, a method to restrain the occupant's
pelvis and torso, and a single action restraint release, which meets
its intended function and does not create a hazard that could cause a
secondary injury to an occupant;
The airplane seating, restraints, and cabin interior to
accommodate likely flight and emergency landing conditions and should
not prevent occupant egress or interfere with the operation of the
airplane when not in use;
Each baggage and cargo compartment be designed for its
maximum weight of contents and for the critical load distributions at
the maximum load factors corresponding to the determined flight and
ground load conditions; and
Each baggage and cargo compartment to have a means to
prevent the contents of the compartment from becoming a hazard by
impacting occupants or shifting, and to protect any controls, wiring,
lines, equipment, or accessories whose damage or failure would affect
operations.
Air Tractor, commenting on proposed Sec. 23.600(a), said the NPRM
preamble suggested that future certification endeavors will require
more effort (e.g., possibly full-scale crash testing of the fuselage)
to meet necessary requirements. Air Tractor also noted that inertial
loads likely to occur in an emergency landing were not defined.
Additionally, Air Tractor presumed the conditions defined in former
Sec. 23.561 would be accepted, but doing so would not make things
under the proposed rule any easier, faster, or less expensive. Air
Tractor also claimed that should some other inertial loads likely to
occur in an emergency landing be proposed, the applicant should expect
a protracted discussion with the FAA to defend any differences.
The FAA disagrees that future certification endeavors will require
more effort and possibly full-scale crash testing of the fuselage to
meet the requirements. Existing conditions of current static and
dynamic testing would remain as a means of compliance. Proposed Sec.
23.600(a) would
[[Page 96617]]
not have required full-scale crash testing of the fuselage. The FAA's
intent was to allow for an evaluation of a ``crash landing''
considering the performance of the entire airframe, safety equipment,
and occupant. The former requirements only required evaluation of the
seat from the floor up, and the restraints, using generic floor
impulses independent of airframe reaction. Additionally, the FAA did
not define inertial loads because one of the goals of creating
performance-based standards was to move away from mandated prescriptive
standards, which inhibit innovation and safety enhancing technology
adoption. The inertial loads likely to be encountered will be contained
in the means of compliance. An applicant may propose inertial loads
other than those contained in industry standards already accepted by
the Administrator, and substantiate why they are adequate,
representative, and equally safe as accepted loads. This rule will
allow applicants to evaluate crash landing conditions considering the
entire airplane and its performance, instead of limiting applicants to
just these tests.
The NTSB noted the NPRM stated that proposed Sec. 23.600 would
capture the safety intent of former Sec. Sec. 23.561 and 23.562, which
the FAA described as containing prescriptive design standards. The NTSB
disagreed that former Sec. Sec. 23.561 and 23.562 are prescriptive
design standards, and stated former Sec. Sec. 23.561 and 23.562 were
performance-based standards that do not specify any elements of the
design, but instead prescribed a test and measureable levels of
performance needed to ensure safety.
The NTSB shared the FAA's concern regarding consideration of
occupiable space in a post-crash situation, and agreed former standards
do not address these issues. However, the NTSB disagreed with the FAA's
suggestion that analysis techniques available in the automotive
industry are transferable to new airplane designs. The NTSB said it is
likely that differences between airframe and automotive structures will
require a significant number of full-scale aircraft crash tests before
analytical techniques have been validated to the point they can be used
as means of compliance. Pointing to NTSB Safety Recommendation A-11-3,
which it issued in 2011 after conducting a study of the performance of
airbags in general aviation airplane, the NTSB recommended the FAA
consider the variation in the sizes and anthropometry of airplane
occupants when evaluating a proposed means of compliance.
The FAA understands the NTSB's comments, but does not agree. Former
Sec. Sec. 23.561 and 23.562 assessed only the seat, attachment,
restraints, and head strike. The generic floor impulse used did not
take into account the variables inherent to the airplane, such as the
ability to protect the survivable volume, crushable airplane structure,
or features that absorb impact energy or offer the ability to evaluate
how all of these variables can work together to enhance
crashworthiness. This rule will allow a more holistic approach to
crashworthiness. Not prescribing a specific seat test opens the door
for future technology and advances in analytical techniques to
demonstrate equivalent and even enhanced safety, utilizing all advances
available to the engineer. At the same time, until these enhanced
techniques become available and proven, the existing seat test methods
are still acceptable for showing compliance with this rule and will be
contained in a means of compliance.
Additionally, the FAA will accept the former regulations as an
acceptable method of compliance, despite their limitations. Testing in
accordance with the former regulations has provided a certain level of
safety for many years; therefore, continuing to accept them for future
designs will maintain that level of safety. However, the FAA contends
that having a prescriptive set of tests in the rule has prevented the
industry from moving beyond this one standard of protecting occupants.
This is because the former regulations required a very specific seat
sled test; detailing seat mounting misalignment, impulse force peak and
rise times, and maximum forces allowed to be experienced by the
restraint system, and the occupant's lumbar spine among other things.
Due to the rule specifying all these details, it is nearly impossible
for the FAA to find equivalency in applicants proposed alternatives. By
changing the requirement from a prescriptive test to the safety intent
behind the test, the FAA will only need to evaluate whether new methods
meet the safety intent, and not have to evaluate their relative safety
against the former requirements. The determination that likely crash
scenarios do not generate loads on the occupants that exceed the limits
of human injury was the basis of the former rule language, and how the
test and crash impulse was derived. It was a combination of various
scenarios, represented by one specific set of tests. The new rule will
allow a holistic approach to enable designs to achieve occupant
protection more effectively.
While the automotive industry generally has a more-developed
crashworthiness analysis capability than that used in the aviation
industry, the FAA wants to allow for incorporation of holistic
crashworthiness in addition to conventional compliance. The FAA notes
the NTSB's concern that automotive technology will not directly
transfer to aerospace applications because it requires significant
numbers of full-scale aircraft crash tests for validation to yield the
confidence in the analytical techniques. However, the FAA disagrees.
The FAA has not yet determined how much and what type of validation
will be required for a given crash scenario. This determination will
depend on the particular design and what the validation is attempting
to demonstrate. The automotive and other industries have gained a lot
of knowledge on what is needed to demonstrate valid models using
dynamic transient analysis. The FAA believes that the knowledge from
these industries can be leveraged to reduce or eliminate the need for
full-scale aircraft crashes for validation. For example, there may be
scenarios where only a small part needs validation for demonstration of
its energy absorption. This rule will provide an applicant with the
option to examine the performance of more than just the seat and
restraints, and avoids defining methods of restraint. This will allow
consideration of a myriad of ways to protect an occupant in an
emergency landing, such as using airbags.
Also, the FAA notes the NTSB's recommendation that the FAA consider
the variation in the sizes and anthropometry of airplane occupants when
evaluating a proposed means of compliance. This would be an increase in
the burden to the manufacturers, and this burden has not been
justified.
Several organizations commented on proposed Sec. 23.600(b).
Kestrel noted that proposed Sec. 23.600(b)(1) referred to impact at
stall speed, but did not specify the configuration and atmospheric
conditions associated with this stall speed. Kestrel also requested
clarification on whether applicants must design for stall speed in
icing conditions.
The FAA revises the proposed rule language. The configuration and
atmospheric conditions will be located in the means of compliance based
on a determination of the conditions that are likely to occur.
In discussing proposed Sec. 23.600(b)(1), ICON questioned whether
industry can deliver on this ``new requirement.'' Textron noted that
proposed Sec. 23.600(b) referred to the emergency landing conditions
specified in paragraph (a), which would mean the items of mass
[[Page 96618]]
specified in paragraph (a) must meet the dynamic conditions specified
in paragraph (b). Textron noted this is a significant departure from
the former rule and assumed it was not the FAA's intent to require
dynamic conditions for items of mass. Similarly, the Associations
commented that Sec. 23.600(b) would be a new requirement without
foundation. They believed the FAA intended to apply the requirement
only to occupant restraint systems.
The FAA agrees with Textron and others that an unintentional new
requirement would have been imposed by the proposed wording of
paragraph (b)(1). The FAA did not intend to apply dynamic loading
requirements to items of mass that previously required accounting only
for static loads. The FAA modifies the text of paragraph (b) to refer
only to subparagraphs (a)(1) and (a)(2) instead of all of paragraph
(a), thereby eliminating reference to items of mass.
EASA said the ``dynamic'' condition specified in paragraph (b)(1)
should be in the means of compliance, not in the rule. ICON noted that
proposed Sec. 23.600(b)(1) would require a very long list of variables
be considered in an impact, which seems prohibitively difficult to
achieve with any degree of confidence.
The FAA agrees with ICON and EASA. The long list of variables is
reduced to simply ``emergency landing'' conditions, which can then be
further detailed as part of the means of compliance.
Transport Canada said the requirement in proposed Sec.
23.600(b)(2) appeared inaccurate. It noted that what must not exceed
established injury criteria for human tolerance are the loads
experienced by the occupant, not the emergency landing conditions.
Transport Canada recommended a rewrite of paragraph (b)(2) that would
state that the occupants would not experience loads which exceed
established injury criteria for human tolerance due to restraint or
contact with objects in the airplane.
The FAA agrees with Transport Canada. The FAA adopts the
recommended language and revises the rule to clarify it is the loads
experienced by the occupant, not the emergency landing conditions that
should not exceed the established injury criteria for human tolerance.
BendixKing suggested replacing the word ``restraints'' with
``protection'' in the two instances the word occurs in proposed Sec.
23.600(c). BendixKing suggested this change is appropriate because the
intent of the rule is to ensure crash protection for the occupant,
which may or may not be what is understood to be restraint. BendixKing
also stated it is important not to assume a particular solution, but to
focus on the safety intent or occupant protection from harmful motion
during an impact. Therefore, it suggested words used in proposed Sec.
23.600(d) like ``restraint,'' ``pelvis,'' ``torso,'' be replaced with
language like ``protection'' or ``securing the occupant from harm.''
EASA commented that proposed Sec. Sec. 23.600(c) and (d) should be an
accepted means of compliance, not regulatory requirements. The
Associations commented that the language in proposed Sec. 23.600(d)
should be aligned with current DOT practices related to automobile
safety. The commenters noted the proposed language may preclude some
better methods of safety in crashworthiness and might unnecessarily
restrict design capabilities.
The FAA agrees with BendixKing that using design-specific solution
terminology such as ``restraints'' is not appropriate for a
performance-based regulation. While the occupant needs to be
restrained, restraints should be considered on a broader basis. The FAA
also agrees with EASA that the portions of Sec. Sec. 23.600(c) and (d)
that use design-specific terminology should be in the means of
compliance. As such, the FAA will use more generic terms like
``protection'' or ``occupant protection system'' in lieu of the design-
specific terms proposed in paragraphs (c) and (d), to allow for other
methods of compliance to meet the safety intent of the rule. Finally,
due to these word changes, the FAA moved the consideration of ``ground
loads'' from paragraph (d) to paragraph (c).
Transport Canada noted the reference to water loads is missing in
paragraphs (d) and (e)(1). Transport Canada recommended those
paragraphs be modified by adding the word ``water'' in the phrase ``For
all flights and ground loads.''
The FAA considered Transport Canada's comment, but one of the goals
of adopting performance-based regulations is to remove some of the
specificity, to enable the flexibility to adapt to changing
technologies and environments. Specifying every possible landing
surface would not align with this goal. Therefore, the FAA is not
incorporating Transport Canada's changes into the final rule.
Transport Canada also commented that proposed Sec. 23.600(e)
should provide a performance-based standard for the requirements in
former Sec. 23.787(b) for baggage or cargo sharing the same
compartment as passengers.
The FAA agrees baggage and cargo sharing the same compartment with
passengers should be restrained. However, a change to the proposed rule
is not necessary to address this. Section 23.2270(a) of this rule
requires restraint of items of mass within the cabin utilizing static
inertial loads, including baggage or cargo that is in the cabin.
The Associations and Textron addressed the requirement in proposed
Sec. 23.600(e)(3) that baggage and cargo compartments must protect
controls, wiring, lines, equipment, or accessories whose damage or
failure would ``affect operations.'' Textron noted that any kind of
damage or failure would arguably ``affect operations,'' making it
difficult to comply with the rule. Textron recommended the FAA qualify
the requirement by adding the word ``safe'' in front of ``operations.''
The Associations recommended the FAA delete the word ``any'' in front
of ``controls,'' delete the word ``affect,'' and add the words ``limit
safe'' in front of ``operations.''
The FAA agrees with the comments from Textron and the Associations
and is adding ``safe'' to modify ``operations.'' Adopting this change
will harmonize the text with EASA's proposed rule language. The FAA
will not adopt the other recommended changes as they would not have a
substantive effect on the rule.
Daher commented generally on Sec. 23.600, indicating the phrase
``rolling and pitching'' would be more appropriate than ``pitching and
yawing.'' Daher did not indicate where these phrases were, but the FAA
believes it is referring to a statement made in the NPRM preamble
discussion of proposed Sec. 23.600 that stated dynamic seat testing
requirements address the ability of seat assemblies to remain attached
to the floor, even when the floor shifts during impact. Pitching and
yawing of the seat tracks during dynamic seat tests demonstrates the
gimbaling and flexibility of the seat.
Furthermore, the FAA believes Daher was specifically inferring that
``rolling and pitching'' would be more appropriate in Sec.
23.2270(b)(1) because the rule language in former Sec. 23.562 required
the seat rails to be misaligned by 10 degrees in the ``pitch'' and
``roll'' axis, not the ``pitch'' and ``yaw'' axis. The FAA's intent was
not simply to mimic the original Sec. 23.562 misalignment
requirements, but to identify static airplane orientation at impact in
order to assess the level of airframe crushing and energy absorption.
However, based on other comments on proposed Sec. 23.600, the FAA has
removed specific references to
[[Page 96619]]
the terms ``flight path angle,'' ``flight pitch angle,'' ``yaw,'' and
``airplane configuration.'' These parameters will be included in the
means of compliance.
An individual commenter in the seatbelt manufacturing industry
suggested putting a life limit of 10 years on seatbelts, because the
webbing loses its strength due to exposure to UV lights and heat. The
FAA notes that a seat belt life limit is not within the scope of this
rulemaking. The details of seat belts and seat belt webbing materials
are controlled by industry standards and Technical Standard Orders
(TSOs). Additionally, specifying those types of design-specific
solutions is counter to performance-based regulations.
5. Subpart D--Design and Construction
a. Flight Control Systems (Proposed Sec. 23.700/Now Sec. 23.2300)
In the NPRM, proposed Sec. 23.700 (now Sec. 23.2300) would have
required an applicant to design airplane flight control systems to
prevent major, hazardous, and catastrophic hazards. Proposed Sec.
23.700 would have required an applicant to design trim systems to
prevent inadvertent, incorrect, or abrupt trim operation. In addition,
proposed Sec. 23.700 would have required an applicant to design trim
systems to provide a means to indicate--
The direction of trim control movement relative to
airplane motion;
The trim position with respect to the trim range;
The neutral position for lateral and directional trim; and
For all airplanes except simple airplanes, the range for
takeoff for all applicant requested center of gravity ranges and
configurations.
Proposed Sec. 23.700 would have also required an applicant to
design trim systems to provide control for continued safe flight and
landing when any one connecting or transmitting element in the primary
flight control system failed, except for simple airplanes.
Additionally, proposed Sec. 23.700 would have required an applicant to
design trim systems to limit the range of travel to allow safe flight
and landing, if an adjustable stabilizer is used.
Furthermore, proposed Sec. 23.700 would have required the system
for an airplane equipped with an artificial stall barrier system to
prevent uncommanded control or thrust action and provide for a
preflight check. The FAA also proposed requiring an applicant seeking
certification of a level 3 high-speed or level 4 airplane to install a
takeoff warning system on the airplane, unless the applicant
demonstrates that the airplane, for each configuration, could takeoff
at the limits of its trim and flap ranges.
In light of comments received, the FAA revises proposed Sec.
23.700 to withdraw paragraphs (a)(1) and all its subparagraphs, rename
proposed paragraph (a)(2) as (a)(1), add new paragraph (a)(2), withdraw
proposed paragraphs (b)(3), (b)(4), and paragraphs (c) and (d) and all
their subparagraphs. This section discusses these changes in more
detail.
Textron and Kestrel questioned how the term ``prevent'' was
intended to be used with the system safety analysis terms ``major,''
``hazardous,'' and ``catastrophic.''
The FAA acknowledges the term ``prevent'' caused confusion in
proposed Sec. 23.700(a)(1), and replaces ``prevent'' with ``protect
against'' in Sec. 23.2300(a)(2). The FAA did not intend to require
additional safety analysis in this section, as suggested by these
comments.
The Associations, Kestrel, Air Tractor, and Textron expressed
concern that proposed Sec. 23.700 appears to require that applicants
perform System Safety Assessments (SSAs) for traditional mechanical
flight control systems that have never been subject to this requirement
in the past. They note this would impose substantial new costs on
applicants. The commenters acknowledge that SSAs would be appropriate
for unconventional designs, such as fly-by-wire systems.
The FAA did not intend to imply that a safety analysis would be
required for all flight control systems, including simple mechanical
flight control systems in proposed Sec. 23.700(a). The FAA deletes the
terms that could have been associated with safety analysis and revises
Sec. 23.2300(a)(2) to require the applicant to design airplane flight
control systems to protect against likely hazards. The FAA intends
``protect against likely hazards'' to be a high-level requirement to
consider potential hazards to the flight control system, and
incorporate features in the design to protect against these hazards.
One way for a traditional flight control system to satisfy this would
be to use the former part 23 regulations, which addressed hazards such
as jamming, chafing, interference, incorrect assembly, asymmetric
flaps, control system lock inadvertent engagement in flight, etc.
The FAA agrees with the comments stating that safety analysis is
necessary, as required by Sec. 23.2510 (proposed as Sec. 23.1315),
for fly-by-wire flight control systems, powered flight control systems,
and automatic flight control systems. The FAA withdraws the safety
analysis requirement in Sec. 23.2300 because Sec. 23.2510 adequately
addresses the requirement for safety analysis. The FAA notes the
applicability of the Sec. 23.2510 safety analysis requirements will be
addressed as a means of compliance, similar to the current practice in
AC 23.1309-1E.
The Associations and Textron recommended the FAA eliminate proposed
paragraph Sec. 23.700(a)(1)(iii), which lists ``flutter'' as one of
the possible major, hazardous or catastrophic hazards, because it is
redundant and unnecessary as the safety intent of flutter is covered in
the aeroelastic section, proposed Sec. 23.410 (now Sec. 23.2245). The
FAA agrees because Sec. 23.2245 ``Aeroelasticity'' adequately
addresses flutter for normal operation, exceedances and failure
conditions. The FAA also withdrew the other examples of hazards in
proposed Sec. 23.700(a)(1) so that they can be addressed more
completely in means of compliance.
The Associations and Textron also questioned the use of the term
``misconfiguration'' in proposed Sec. 23.700(a)(1)(v). Textron asked
the FAA to clarify whether the term refers to items like rigging and
installation or items like wing configurations (e.g., flaps, speed
brakes) and trim. The Associations recommended ``misconfiguration'' be
replaced with ``misrigging'' for clarity and anticipated the
traditional misrigging practices would continue to apply. Proposed
Sec. 23.700(a)(1)(v) was intended to address the requirement from
former Sec. 23.685(d) that each element of the flight control system
must have design features, or must be distinctively and permanently
marked, to minimize the possibility of incorrect assembly that could
result in malfunctioning of the control system. The FAA agrees that
``misrigging'' incorporates the intent of this requirement more clearly
than ``misconfiguration.'' However, the FAA has decided to remove
proposed Sec. 23.700(a)(1)(v) from the final rule as discussed.
With the withdrawal of the list in proposed Sec. 23.700(a)(1), the
FAA renumbers proposed Sec. 23.700(a)(2) as Sec. 23.2300(a)(1) and
adds a new paragraph (a)(2).
Textron commented that proposed Sec. 23.700(a)(2) could seem
reasonable for all systems and recommended moving the paragraph to
proposed Sec. 23.1305 (now Sec. 23.2505).
The FAA disagrees with applying proposed Sec. 23.700(a)(2) to all
systems and equipment because the requirement to ``operate easily,
smoothly and positively enough to allow normal operation'' does not
apply to all
[[Page 96620]]
systems. For example, evaluating a flight data recorder for
``smoothness'' would not make sense. The FAA revises Sec.
23.2300(a)(1) to be consistent with former Sec. 23.671(a) because it
states the intent of the requirement more clearly.
The Associations proposed revising Sec. 23.700(b) to state ``the
trim systems must . . .'' instead of ``[t]he applicant must design trim
systems to.'' They made a similar comment on proposed Sec. 23.700(a).
The FAA used ``the applicant must design . . .'' throughout the
NPRM. The FAA retains this wording because it's consistent with part 21
to impose the obligation on the applicant.
Textron noted that proposed Sec. 23.700(b)(1) was a general
concept that should actually apply to all systems, and therefore
recommended changing the word ``trim'' to ``system,'' and moving
proposed Sec. 23.700(b)(1) to proposed Sec. 23.1305. Textron also
questioned whether the term ``prevent'' in proposed Sec. 23.700(b)(1)
meant ``meet the associated requirements of a system safety
assessment.'' Textron recommended rewriting proposed paragraph (b)(1)
to provide that the applicant must design trim systems to meet system
safety requirements, according to the assessment mandated by proposed
Sec. 23.1310, and that the evaluation of the system shall include
hazards caused by inadvertent (uncommanded) trim operation and
incorrect (motion in the opposite direction than commanded) trim
operations.
The FAA notes the requirement to ``prevent inadvertent, incorrect,
or abrupt system operation'' would not be appropriate for some systems.
For example, evaluating a flight data recorder for ``abrupt system
operation'' would not make sense. Therefore, the FAA did not
incorporate Textron's recommendation in this rule. The FAA also
declines to move the regulation to proposed Sec. 23.1305 (now Sec.
23.2505) because that section applies to all systems, while this
requirement is only intended for flight control trim systems. In light
of Textron's comment, the FAA has changed ``prevent'' to ``protect
against'' for consistency with Sec. 23.2300(a)(2). However, the FAA
did not incorporate Textron's recommendation to change proposed Sec.
23.700(b)(1) because this section does not require safety analysis.
This section applies to all trim systems while Sec. 23.2510 does not
apply to trim systems that are considered ``flight control surfaces and
their simple systems'' as discussed in AC 23.1309-1E.
Several organizations commented on proposed Sec. 23.700(b)(3). The
Associations recommended deleting proposed paragraph (b)(3). They
stated that addressing the loss of any single flight control link with
traditional mechanical flight controls has provided a substantial level
of safety and as new stability and fly-by-wire systems are discussed,
it will be increasingly important to develop adequate means of
compliance in acceptable documents.
EASA asserted the proposed requirement to have a trim system as a
means of control in case of failure of a connecting or transmitting
element was too prescriptive and should be captured by the intent that
a flight control system must prevent major, hazardous, and catastrophic
hazards for likely failure conditions.
The FAA agrees that proposed Sec. 23.700(b)(3) was too
prescriptive because means other than trim could be used to safely
control the airplane when any one connecting or transmitting element in
the primary flight control system fails. The requirement to protect the
airplane from loss of control when any one connecting or transmitting
element in the primary flight control system fails is captured in Sec.
23.2300(a)(2) at a high level. Therefore, the FAA withdraws proposed
Sec. 23.700(b)(3). In addition, the FAA adds ``if installed'' to Sec.
23.2300(b) in light of the comments that future designs may not use
trim systems.
Transport Canada observed that VLA rules permit trim systems that
do not provide safe flight and landing following failure of the primary
control system. Transport Canada said it did not believe this
alleviation should be carried into the part 23 revisions, even for
small airplanes. Transport Canada recommended the level of safety for
trim system failures be raised for simple airplanes.
As discussed elsewhere, the FAA has decided to withdraw the simple
category, proposed in Sec. 23.5(d), and also to withdraw proposed
Sec. 23.700(b)(3) because Sec. 23.2300(a)(2) captures the
requirement. The FAA has determined that the level of safety for trim
system failures should not be raised for entry-level airplanes. One of
the goals of the NPRM was to provide appropriate standards for ``entry-
level airplanes'', and the FAA finds Sec. 23.2300(a)(2) meets that
goal. As discussed in this section, Sec. 23.2300(a)(2) requires the
applicant to design airplane flight control systems to protect against
likely hazards. While the FAA's intent is that flight control systems
that meet the former part 23 requirements adequately protect against
the likely hazard of failures in any one connecting or transmitting
element in the primary flight control system, those airplanes certified
under EASA's Certification Specification--Very Light Aeroplanes (CS-
VLA), were not certified under part 23. Rather, they were imported to
the U.S. and certificated as special class airplanes in accordance with
Sec. 21.17(b). Under Sec. 23.2300(a)(2), these airplanes could be
certified under part 23, using the CS-VLA to meet the requirements.
Upon further consideration of proposed Sec. 23.700(b)(4), the FAA
decided the safety intent of the requirement to limit the range of
travel to allow safe flight and landing, if an adjustable stabilizer is
used, is already incorporated in the regulations through the
requirement for the applicant to design airplane flight control systems
to protect against likely hazards. The proposed requirement was
prescriptive and may not be appropriate for non-traditional airplane
designs. Therefore, the FAA withdraws proposed Sec. 23.700(b)(4).
The Associations asserted including specific information for the
verification of stall barrier systems in proposed Sec. 23.700(c) is
not beneficial because the issue being addressed is already covered by
``flight control reliability aspects.'' The commenters also noted the
simple checks being specified may not be appropriate for all stall
barrier systems and that addressing stall barrier flight controls would
be better detailed in means of compliance. The commenters recommended
deleting proposed Sec. 23.700(c).
The FAA agrees that there is no benefit to including Sec.
23.700(c) because Sec. 23.2510 adequately addresses stall barrier
system failure conditions and checks for latent failures. Therefore,
the FAA withdraws Sec. 23.700(c).
Textron, ANAC, and Air Tractor commented that proposed Sec.
23.700(d) would require a takeoff warning system without explanation of
what it would be, and this could increase complexity.
The FAA withdraws proposed Sec. 23.700(d) because the safety
requirement of warning a pilot who is attempting to takeoff with the
trim or flaps in an unsafe configuration is adequately addressed in
Sec. 23.2605(c).
b. Landing Gear Systems (Proposed Sec. 23.705/Now Sec. 23.2305)
In the NPRM, proposed Sec. 23.705 (now Sec. 23.2305) would have
required--
The landing gear and retracting mechanism be able to
withstand operational and flight loads;
An airplane with retractable landing gear to have a
positive means to keep the landing gear extended and a secondary means
for extending the
[[Page 96621]]
landing gear that could not be extended using the primary means;
A means to inform the pilot that each landing gear is
secured in the extended and retracted positions; and
Airplanes, with retractable landing gear, except for
airplanes intended for operation on water, to also have a warning to
the pilot if the thrust and configuration is selected for landing and
yet the landing gear is not fully extended and locked.
Furthermore, if the landing gear bay is used as the location for
equipment other than the landing gear, proposed Sec. 23.705 would have
required that equipment be designed and installed to avoid damage from
tire burst and from items that may enter the landing gear bay. Proposed
Sec. 23.705 would have also required the design of each landing gear
wheel, tire, and ski account for critical loads and would require a
reliable means of stopping the airplane with kinetic energy absorption
within the airplane's design specifications for landing. For level 3
high-speed multiengine and level 4 multiengine airplanes, proposed
Sec. 23.705 would have required the braking system to provide kinetic
energy absorption within the design of the airplane specifications for
rejected takeoff as the current rules do for multiengine jets over
6,000 pounds and commuter category airplanes.
Several commenters argued that proposed Sec. 23.705 was too design
specific and recommended the FAA replace specific design elements such
as brakes, wheels, and tires with objectives that would work for a wide
array of technologies.
In light of comments received, the FAA revises proposed Sec.
23.705 to withdraw proposed paragraphs (a)(1) through (d), to be
replaced with new paragraphs (a)(1), (a)(2), (b), (c)(1) and (c)(2).
This section discusses these changes in more detail.
The FAA reassessed the need for the language of proposed Sec.
23.705(a)(1) and (b) and decided not to adopt the proposed paragraphs.
The FAA has determined these requirements are adequately addressed by
proposed Sec. Sec. 23.310 (now Sec. 23.2210), 23.320 (now Sec.
23.2220), and 23.400 (now Sec. 23.2235). Section 23.2210 requires
structural design loads to be determined that result from likely
externally or internally applied pressures, forces or moments, that may
occur in flight, ground and water operations, ground and water
handling, and while the airplane is parked or moored. This includes
operational and flight loads on the landing gear and retracting
mechanism, including the wheel well doors specified in the FAA's
proposed Sec. 23.705(a)(1). Section 23.2235 requires the structure to
support these loads. Section 23.2220 requires the applicant to
determine the structural design loads resulting from taxi, takeoff,
landing, and ground handling conditions occurring in normal and adverse
attitudes and configurations. This includes the critical loads on
wheels, tires, and skis specified in proposed Sec. 23.705(b). Section
23.2235 requires the structure to support these loads.
Commenters noted proposed Sec. 23.705 diverged from EASA's
proposed CS 23.425, and recommended the FAA work with EASA to achieve
harmonization. Several commenters recommended the FAA reject the
language originally proposed for Sec. 23.705 and replace it with the
language from EASA's proposed CS 23.2325.
The FAA agrees that it should harmonize Sec. 23.2305 as much as
possible with CS 23.2325, and has done so where appropriate.
The Associations recommended the FAA revise proposed paragraph (a),
which would define landing gear. Textron recommended the FAA add a
requirement to provide stable support and control to the airplane
during ground operation. The commenters noted the change to paragraph
(a) would harmonize with EASA.
The FAA finds the recommended language for paragraph (a)
unnecessary. The FAA also finds the accepted means of compliance will
describe what is considered landing gear for a particular airplane
design. The FAA notes the recommended language is overly broad and can
be read to encompass rudder systems and other systems that do not
directly interact with the ground, but are necessary to control the
airplane during surface operation. The FAA notes rudder systems and
other systems are adequately addressed elsewhere.
The FAA revises Sec. 23.2305(a)(1) to adopt CS 23.2325(b)(1) by
requiring the landing gear to be designed to provide stable support and
control during surface operation. Although the NPRM did not
specifically address this requirement, the FAA intended for the revised
regulations to capture the safety intent of the former part 23
regulations. This also harmonizes with EASA.
The FAA will not adopt the landing gear loads and energy absorption
requirements in CS 23.2325(b)(2) and (b)(3) because these requirements
are adequately addressed in Sec. Sec. 23.2210, 23.2220, and 23.2235.
The FAA notes the airplane has to be designed for the anticipated
loads, and energy absorbed by the landing gear affects the airframe
loads, which are addressed in these sections. Additionally, proper
function of any systems related to absorption of energy in the landing
gear is addressed in Sec. 23.2505.
The FAA adopts CS 23.2325(b)(4) as Sec. 23.2305(a)(2), requiring
the landing gear to be designed to account for likely system failures
and likely operation environment, including anticipated limitation
exceedances and emergency procedures. As a result of this revision, the
FAA withdraws proposed Sec. 23.705(a)(3).
Although the NTSB supported proposed Sec. 23.705(a)(3), the FAA
notes proposed Sec. 23.705(a)(3) only addressed tire failures on
airplanes with retractable landing gear based on the assumption that
tire burst and foreign object risk is greater on airplanes with
retractable landing gear. This is generally true for traditional
airplane designs. The risk is generally more severe on airplanes with
large numbers of passengers, flight critical systems near the landing
gear, complex systems, and high-speed operation on the ground. These
factors generally exist on airplanes with retractable landing gear, but
they could exist on airplanes with fixed landing gear. Conversely, the
risk is generally less severe on airplanes with no passengers, no
flight critical systems near the landing gear, simple systems and low-
speed operation on the ground. These factors generally exist on
airplanes with fixed landing gear, but they could exist on airplanes
with retractable landing gear (e.g., powered gliders). Therefore, the
proposed Sec. 23.705(a)(3) assumption that airplanes with retractable
landing gear should be protected from the risks of tire failures and
foreign objects, but airplanes with fixed landing gear should not be
protected, may not be correct for future designs.
Section 23.2305(a)(2) applies to all landing gear and requires
landing gear failures to be considered more generally. The FAA finds
Sec. 23.2305(a)(2) will allow traditional designs to comply using
current practices as means of compliance, with the flexibility to
develop new means of compliance more appropriate for potential future
designs. This furthers the goal of moving to performance-based
requirements.
The FAA notes Sec. 23.2305(a)(2) captures the intent of former
Sec. Sec. 23.721, 23.729, 23.735, and 23.1309, which required that
applicants account for likely landing gear failures. It also captures
the intent of former Sec. Sec. 23.603, 23.721, 23.729, 23.735,
23.1301, and 23.1309, which required that applicants account for likely
operation environments, and/or anticipated
[[Page 96622]]
limitation exceedances and emergency procedures.
The commenters recommended that the FAA move the substance of
proposed Sec. 23.705(a) for airplanes with retractable landing gear to
proposed Sec. 23.705(c) and replace the proposed language with CS
23.2325(d), which deals with airplanes that have a system that actuates
the landing gear.
The FAA has considered the comments and has decided to adopt CS
23.2325(d)(1) and (4) as Sec. 23.2305(c)(1) and (2). CS 23.2325(d)(1)
and (4) require a positive means to keep the landing gear in the
landing position and an alternative means available to bring the
landing gear in the landing position when a non[hyphen]deployed system
position would be hazardous. The FAA adopts Sec. 23.2305(c)(1) because
it is less prescriptive than proposed Sec. 23.705(a)(2)(i). The FAA
notes the recommended phrase ``in the landing position'' is less
prescriptive than ``extended'' and better expresses the intent of the
requirement. Moreover, Sec. 23.2305(c)(1) does not increase the burden
on traditional designs; provides flexibility to allow new designs to be
certified because it applies to all landing gear actuated by a system,
not just retractable landing gear; and assists in harmonization.
The FAA adopts the language of CS 23.2325(d)(4) as Sec.
23.2305(c)(2), with one minor change. The FAA is using the phrase ``a
hazard'' instead of ``hazardous'' to avoid confusion with former Sec.
23.1309's use of the phrase ``hazardous failure condition.'' The
language of CS 23.2325(d)(4) better captures the safety intent of
former Sec. 23.729(c), which did not require a secondary means for
landing gear that could be extended manually, and is less prescriptive
because it only requires an alternative means to bring the landing gear
to the landing position if a non-deployed position would be a hazard.
Additionally, moving the location of this requirement has no technical
impact and harmonizes with CS 23.2325.
The FAA does not adopt proposed Sec. 23.705(a)(2)(iii) or the
language from CS 23.2325(d)(2) and (d)(3) because the FAA considers
both proposals to be adequately addressed by proposed Sec. 23.1500(b)
(now Sec. 23.2600(b)). Section 23.2600(b) requires the applicant to
install flight, navigation, surveillance, and powerplant controls and
displays so qualified flightcrew can monitor and perform defined tasks
associated with the intended functions of systems and equipment. The
systems and equipment design must minimize flightcrew errors which
could create additional hazards. Section 23.2600(b) incorporates the
safety intent of previous requirements for landing gear indications and
effectively requires the pilot to be informed of the landing gear
position (secured in extended or retracted position) should the pilot
need that information.
Textron recommended the FAA remove the requirement for a secondary
means of extending the landing gear in proposed Sec. 23.705 and rely
instead on the requirements of proposed Sec. 23.1315.
The FAA disagrees as Textron's recommendation does not capture the
intent of the former regulation, which was a specific requirement for a
secondary means of deploying landing gear. Furthermore, this
requirement in proposed Sec. 23.705 was not covered by the general
systems failure requirements of proposed Sec. 23.1315.
Several commenters recommended deleting proposed Sec.
23.705(a)(2)(iv), in part, because it was too prescriptive. One
commenter recommended rewriting the rule as a performance[hyphen]based
regulation to encourage alternate--and perhaps better--means of
detecting wrong configurations for landing.
The FAA agrees that proposed Sec. 23.705(a)(2)(iv) is too
prescriptive, and finds it is adequately addressed by the requirements
of new Sec. 23.2605(c), which requires information concerning an
unsafe system operating condition must be provided in a timely manner
to the crewmember responsible for taking corrective action.
Accordingly, the FAA withdraws proposed Sec. 23.705(a)(2)(iv).
Textron recommended the FAA add the word ``essential'' before
``equipment'' in proposed Sec. 23.705(a)(3),\37\ asserting that non-
essential equipment is not important to protect in the landing gear
bay.
---------------------------------------------------------------------------
\37\ Textron referenced ``the 2nd line of the 2nd paragraph,''
but the FAA infers they intended to reference proposed Sec.
23.705(a)(3) because this is the provision that would require
protection of equipment.
---------------------------------------------------------------------------
The FAA disagrees with Textron's recommendation as it is possible
that failures of non-essential equipment like a fuel line for a
combustion heater may result in hazards more severe than the loss of
the non-essential function. Therefore, the FAA is not adopting this
change in the final rule.
Textron recommended rewording proposed Sec. Sec. 23.705(c) and (d)
to limit their applicability to airplanes with wheels, asserting these
paragraphs required airplanes without wheels to have brakes.
Alternatively, Textron suggested moving the requirement to proposed
Sec. 23.1300(a) (now Sec. 23.2500(a)) because an airplane with wheels
will need a braking system to meet proposed Sec. 23.1300(a), making
Sec. 23.705(c) redundant. Other commenters recommended the FAA replace
proposed Sec. 23.705(c) and (d) with the CS 23.2325(c), which
addresses kinetic energy absorption.
The FAA concurs with the recommendation to replace proposed Sec.
23.705(c) and (d) with CS 23.2325(c). The FAA notes CS 23.2325(c) has
the same meaning as proposed Sec. 23.705(c) and (d), but harmonizes
with EASA's NPA 2016-05. The FAA has determined the removal of the
phrase ``within the airplane's design specifications for landing'' and
replacement with ``sufficient . . . to account for landing'' has no
technical impact. The FAA adopts the change as Sec. 23.2305(b).
The FAA disagrees with Textron's recommendation to reword Sec.
23.705(c) and (d) to limit their applicability to airplanes with
wheels. The FAA notes proposed paragraphs (c) and (d) would not require
brakes. While the FAA has considered Textron's alternative
recommendation, the specific energy absorption requirement of proposed
Sec. 23.705(c) is not adequately addressed by the general system
performance requirements of proposed Sec. 23.1300(a). Therefore, the
FAA is not adopting this change in the final rule.
Textron suggested the FAA should harmonize its proposed regulations
on this topic with CS 23.600 by removing language related to brakes as
a subset of meeting the requirements of proposed Sec. 23.1300(a).
The FAA agrees with harmonizing with EASA wherever possible.
However, specifically requiring a reliable means of stopping the
airplane is not excessively prescriptive and provides clarity to the
regulation. Furthermore, Textron's suggested text would not harmonize
with CS 23.2325.
EASA recommended eliminating the reference to level 3 and 4
airplanes in proposed Sec. 23.705(d), and replacing it with a
reference to airplanes ``required to demonstrate aborted take-off
capacity,'' which links the requirement to takeoff performance.
Similarly, all of the comments on this section recommended making
proposed Sec. 23.705(d) applicable to the same airplanes covered by
proposed Sec. 23.115(c)(1) (now Sec. 23.2115(c)(1)).\38\ Textron also
suggested directly referencing proposed Sec. 23.115 to prevent the
link between the two
[[Page 96623]]
requirements from being inadvertently broken.
---------------------------------------------------------------------------
\38\ Proposed Sec. 23.115(c)(1) would have applied to ``levels
1, 2, and 3 high-speed multiengine airplanes, multiengine airplanes
with a maximum takeoff weight greater than 12,500 pounds and level 4
multiengine airplanes.''
---------------------------------------------------------------------------
The FAA agrees with the recommendation to make Sec. 23.2305(b)
applicable to the same airplanes as Sec. 23.2115(c)(1) for several
reasons. First, in order to comply with Sec. 23.2115(c)(1), applicants
must design airplanes with a means to decelerate the airplane after a
rejected takeoff, regardless of the requirements in Sec. 23.2305(b),
so adopting the recommended change would not increase the burden on
applicants. Second, making the applicability of Sec. 23.2305(b)
different from Sec. 23.2115(c)(1) could cause confusion, especially
because the proposed applicability would have included airplanes
excluded from Sec. 23.2115(c)(1). In former Sec. Sec. 23.55 and
23.735(e), the FAA applied the requirement to determine the distance
for an aborted takeoff at critical speed to the same airplanes required
to provide kinetic energy absorption in the brakes for a rejected
takeoff, and there is no reason to discontinue this practice.
Additionally, adopting this recommendation harmonizes the FAA
requirement with CS 23.2325(c).
c. Buoyancy for Seaplanes and Amphibians (Proposed Sec. 23.710/Now
Sec. 23.2310)
In the NPRM, proposed Sec. 23.710 (now Sec. 23.2310) would have
required airplanes intended for operations on water to provide buoyancy
of 80 percent in excess of the buoyancy required to support the maximum
weight of the airplane in fresh water. Proposed Sec. 23.710 would have
also required airplanes intended for operations on water to have
sufficient watertight compartments so the airplane will stay afloat at
rest in calm water without capsizing if any two compartments of any
main float or hull are flooded.
The FAA noted in the NPRM that it was proposing to remove the
requirement that each main float must contain at least four watertight
compartments of approximately equal volume because it was a specific
design requirement that would be addressed by the proposed performance-
based standard.
All of the comments on this section noted a problem with the
prescriptive design specificity of proposed Sec. 23.710(b); in
particular, the requirement to have watertight compartments. The
commenters noted an erroneous assumption that all airplanes intended
for operations on water would have watertight compartments. The
commenters noted that manufacturers could employ a different solution--
such as foam-filled floats--eliminating the need for compartments, and
still meet the buoyancy intent. BendixKing commented that the buoyancy
requirement needs to be ``more generic to address the core safety
intent, which is adequate floatation in the event of a failure.'' The
Associations and Textron offered alternative regulatory language that
would remove the requirement to have watertight compartments and
provide a general performance-based standard for demonstrating
buoyancy.
The FAA agrees that proposed Sec. 23.710(b) is excessively
prescriptive. The FAA recognizes there are other ways to meet the
safety goal of protecting the airplane from capsizing. Therefore, the
FAA revises proposed Sec. 23.710(b) to establish a more performance-
based standard for demonstrating buoyancy.
ICON noted that hull type and float seaplanes were treated
differently in former part 23, and recommended that they be treated
differently in the new part 23 as well, because they deal with a loss
of buoyancy in different ways. In particular, ICON noted differences in
the rate of capsizing, the ability to detect an intrusion of water, and
the pilot's ability to remove the water while operating the airplane.
ICON asked the FAA to eliminate the separate compartment requirements
for hull[hyphen]type seaplanes.
The FAA agrees that, as proposed, the combination of hulls and
floats into one regulation would have imposed a requirement on hulls
that is more stringent than the requirements in former part 23. The FAA
revises the proposed language to remove the prescriptive requirement
for watertight compartments. As such, Sec. 23.2310 contains a more
general standard for buoyancy that is appropriate for both floats and
hulls.
d. Means of Egress and Emergency Exits (Proposed Sec. 23.750/Now Sec.
23.2315)
In the NPRM, proposed Sec. 23.750 (now Sec. 23.2315) would have
required--
The airplane cabin exit be designed to provide for
evacuation of the airplane within 90 seconds in conditions likely to
occur, excluding ditching, following an emergency landing. For
ditching, proposed Sec. 23.750 would have required the cabin exit for
all certification levels 3 and 4 multiengine airplanes be designed to
allow evacuation in 90 seconds;
Each exit to have a simple and obvious means, marked
inside and outside the airplane, to be opened from both inside and
outside the airplane, when the internal locking mechanism is in the
locked position; and
Airplane evacuation paths to protect occupants from
serious injury from the propulsion system, and require that doors,
canopies, and exits be protected from opening inadvertently in flight.
Proposed Sec. 23.750 would have precluded each exit from being
obstructed by a seat or seat back, unless the seat or seat back could
be easily moved in one action to clear the exit. Proposed Sec. 23.750
would have also required airplanes certified for aerobatics to have a
means to exit the airplane in flight.
The Associations, BendixKing, Textron, and EASA recommended the FAA
remove the 90-second evacuation requirement in proposed Sec. 23.750(a)
and replace it with less prescriptive language. EASA stated that the
90-second evacuation time was not contained in the former part 23
regulations and would not be reasonable for all airplanes. EASA stated
that leaving the acceptable design solutions to an acceptable means of
compliance would be better. As alternatives to the proposed language,
BendixKing suggested a requirement for ``adequate and timely''
evacuation, Textron suggested a requirement for ``rapid'' evacuation,
and the Associations suggested a requirement for ``rapid and safe''
evacuation.
The FAA agrees and removes the airplane 90-second evacuation
requirement because specifying the time limit in the regulation is
unnecessarily prescriptive. The FAA replaces the evacuation requirement
with the requirement to ``facilitate rapid and safe evacuation of the
airplane in conditions likely to occur following an emergency landing,
excluding ditching for level 1, level 2, and single-engine level 3
airplanes.'' This harmonizes more closely with EASA's proposed CS
23.2335.
The Associations specifically proposed revisions to the regulatory
text, which appeared to align with EASA's proposed regulation. In
accordance with their recommendation, the FAA revises the beginning of
proposed Sec. 23.750(a) to move a portion of its content into Sec.
23.2315(a)(1). Section 23.2315(a) is revised to read: ``With the cabin
configured for take-off or landing, the airplane is designed to,''
followed by more detailed requirements in the subparagraphs. The FAA
believes this change more clearly preserves the intent of former
regulations. It also harmonizes with EASA's proposed regulation.
Textron also commented that the FAA should either replace the word
``likely'' in proposed Sec. 23.750(a) or ensure the
[[Page 96624]]
``likely conditions'' referred to in paragraph (a) are clearly defined
in the ASTM standards. The FAA intends the term ``likely'' to be
nonprecise or within a mathematical certainty. As explained in the
discussion of proposed Sec. 23.205, the FAA finds the most appropriate
location for defining ``likely conditions'' is in a means of
compliance, because these conditions may vary for different airplanes;
therefore, the FAA retains the word ``likely'' in paragraph (a).
Textron also noted that proposed Sec. 23.750(a) specifies ``likely
conditions,'' but excludes ditching for all but levels 3 and 4
multiengine airplanes. However, Textron stated that ditching as a
likely condition associated with emergency evacuation had not been
required previously. It recommended the FAA add a requirement to
proposed Sec. 23.750, to require a means on levels 3 and 4 multiengine
airplanes to evacuate the airplane safely following a ditching event.
The FAA notes the requirement to safely evacuate the airplane
during ditching is already addressed generally in Sec. 23.2315(a)(1).
The methods for meeting this requirement will be in a means of
compliance.
Textron further commented on using former Sec. 23.807(e) as a
means of compliance to show that occupants have a means available to
safely evacuate the airplane. Textron stated that former Sec.
23.807(e) only prescribes one exit on each side of the airplane to be
above the waterline or alternative methods must be employed.
The FAA agrees that providing one exit on each side of the airplane
above the waterline is an acceptable means of compliance. While this
may be one means of compliance that is acceptable for traditional
designs, the FAA's goal in this rule is to use means of compliance,
developed by industry or individuals, to allow for non-traditional
designs.
Transport Canada commented on proposed Sec. 23.750(a), noting that
cabin exit design is just one of several elements that affect
evacuation performance. Transport Canada also noted that the
expectation to meet the evacuation performance with the airplane's
maximum certified occupancy should be made explicit. Transport Canada
suggested a revision to proposed paragraph (a) stating that the
airplane design, including the cabin exit design, must provide for
evacuation of the airplane of the maximum number of occupants within 90
seconds in conditions likely to occur following an emergency landing.
The FAA agrees that cabin exit design is just one of several
elements that affect evacuation performance and that rapid evacuation
with the airplane's maximum certified occupancy is required, but the
regulation does not have to explicitly include this requirement.
Section 23.2315 addresses generally all the likely conditions that
affect emergency evacuation, which would include an airplane with
maximum certificated occupancy. Therefore, the FAA is not adopting the
language proposed by Transport Canada.
The Associations recommended the following revisions to proposed
Sec. 23.750(a), which deleted or combined portions of proposed
paragraphs (a), (b), (c), (d) and (f) into a new paragraph (a), and
renumbered paragraph (e) as paragraph (b). Their proposed paragraph
(a)(1) appears to correlate with proposed Sec. 23.750(a). They
proposed a revision to proposed paragraph (a)(1) stating that, with the
cabin configured for take-off or landing, the airplane is designed to
facilitate rapid and safe evacuation of the ``aeroplane'' in conditions
likely to occur following an emergency landing, excluding ditching for
level 1, level 2, and single-engine level 3 airplanes.
The FAA adopts this language as Sec. 23.2315(a)(1), except for
spelling ``aeroplane'' as ``airplane.'' This is better organized and
more understandable than the proposed language, while still retaining
the intent of former regulations and harmonizes the regulations between
FAA and EASA.
Textron commented that the phrase ``when the internal locking
mechanism is in the locked and unlocked position'' in proposed Sec.
23.750(b) is not necessary and should be deleted. The FAA agrees and
removes the phrase because this is a detailed design consideration,
which is more appropriately addressed in means of compliance.
Textron also recommended the FAA add a requirement similar to the
requirement for auxiliary locking devices in former Sec. 23.783(c)(6),
which would provide, in pertinent part, that auxiliary locking devices
that are actuated externally to the airplane may be used but such
devices must be overridden by the normal internal opening means.
Textron's view was that auxiliary locking devices used to secure the
airplane would likely be needed to prevent unauthorized entry into the
airplane when it is left unattended.
The FAA disagrees with Textron's recommendation as the suggested
text because it is more appropriate for a means of compliance.
The Associations proposed revisions to proposed Sec. 23.750(a)(2)
that coincidently address Textron's comment on internal locking
mechanisms. They suggested adding language stating that, with the cabin
configured for take-off or landing, the airplane is designed to have
means of egress (openings, exits or emergency exits), that can be
readily located and opened from the inside and outside. The means of
opening must be simple and obvious.
The FAA adopts this language as Sec. 23.2315(a)(2), except the
proposed marking requirement is retained. This revision captures the
safety intent of the former regulations more clearly and harmonizes
regulations between the FAA and EASA.
The Associations recommended deleting proposed Sec. 23.750(c). The
FAA agrees because paragraph (a)(1), as revised, already addresses
similar requirements, rendering paragraph (c) redundant.
Textron commented on proposed Sec. 23.750(d) by recommending the
FAA address obstructions more generally (i.e., not just seat backs),
and offered the language stating that each exit must not be obstructed
unless the obstruction can be easily moved in one action to clear the
exit.
Transport Canada similarly suggested the requirement should more
generally address that any component of the interior should be
considered as a potential obstruction, and also address temporary
obstructions during flight. Transport Canada proposed a revision to
proposed paragraph (d) stating that each exit must not be obstructed by
any interior component during taxi, take-off or landing. In addition, a
seat or seat back may obstruct an exit if the seat or seat back can
[be] easily moved in one action to clear the exit.
The FAA considered Transport Canada's proposed wording, but moving
a seat back easily in one motion to reach an emergency exit is more
appropriate as a means of compliance. The FAA agrees with Textron's and
Transport Canada's comments on proposed Sec. 23.750(d) that
obstructions that could potentially block exits should be addressed
more generally and not limited to seat backs, because other items could
block exits and impair evacuation. The FAA revises the regulation
accordingly as Sec. 23.2315(a)(3).
The Associations proposed a revision to proposed Sec. 23.750(a)(3)
stating that, with the cabin configured for take-off or landing, the
airplane is designed to have easy access to emergency exits when
present.
The FAA is incorporating this suggestion in Sec. 23.2315(a)(3).
The new language captures the safety intent of the former regulations
more generally
[[Page 96625]]
and harmonizes the FAA language with the EASA NPA language.
The Associations recommended to renumber proposed Sec. 23.750(e)
as proposed Sec. 23.750(b) (now Sec. 23.2315(b)). The FAA agrees and
adopts the proposed renumbering. This relocation will not change the
substantive content of the paragraph, but matches with EASA's numbering
and will lessen confusion.
The Associations recommended deleting proposed Sec. 23.750(f).
EASA commented that the requirement in proposed Sec. 23.750(f) for
doors, etc. is too design-specific and can be covered by generic
principles covered in Sec. 23.2250 (proposed as Sec. 23.500).
The FAA understands EASA's comment, but requiring doors, canopies,
and exits to be protected from opening inadvertently in flight is a
general requirement that does not limit possible design solutions.
However, the FAA moves this requirement to Sec. 23.2250(e) to
harmonize the location of the requirement with EASA's rule.
Upon further review, the FAA is replacing the word ``approved'' in
proposed Sec. 23.750(e) (now Sec. 23.2315(b)) with the word
``certified''. This change does not affect the original intent of
paragraph (e), but harmonizes the language with EASA.
e. Occupant Physical Environment (Proposed Sec. 23.755/Now Sec.
23.2320)
In the NPRM, proposed Sec. 23.755 (now Sec. 23.2320) would have
required an applicant to design the airplane to allow clear
communication between the flightcrew and passengers and provide a
clear, sufficiently undistorted external view to enable the flightcrew
to perform any maneuvers within the operating limitations of the
airplane. Proposed Sec. 23.755 would have also required an applicant
to design the airplane to protect the pilot from serious injury due to
high-energy rotating failures in systems and equipment, and protect the
occupants from serious injury due to damage to windshields, windows,
and canopies.
Additionally, proposed Sec. 23.755 would have required, for level
4 airplanes, each windshield and its supporting structure directly in
front of the pilot to withstand the impact equivalent of a two-pound
bird at maximum approach flap airspeed and allow for continued safe
flight and landing after the loss of vision through any one panel.
Furthermore, proposed Sec. 23.755 would have required any
installed oxygen system to include a means to determine whether oxygen
is being delivered and a means for the flightcrew to turn on and shut
off the oxygen supply, and the ability for the flightcrew to determine
the quantity of oxygen available. Proposed Sec. 23.755 would have also
required any installed pressurization system to include a
pressurization system test and a warning if an unsafe condition exists.
EASA commented the requirement in proposed Sec. 23.755(a)(2) for
the airplane design to provide a clear, sufficiently undistorted
external view should be covered in the ``crew interface'' paragraph.
The FAA agrees with EASA that the Sec. 23.755(a)(2) flightcrew
visibility requirement is more directly related to flightcrew interface
than occupant environment. The FAA is including the words ``including
pilot view'' in Sec. 23.2600(a). This change harmonizes Sec.
23.2600(a) more closely with proposed CS 23.2600(a).
Similarly, the FAA relocates the proposed Sec. 23.755(b)(2)
requirement to Sec. 23.2600(c), because this change harmonizes Sec.
23.2600(c) more closely with EASA's proposed CS 23.2600(d).
Additionally, the FAA adopts the language in EASA's proposed CS
23.2600(d), except for the spelling of ``aeroplanes'' versus
``airplanes'' for improved clarity and harmonization.
The Associations suggested the FAA delete the word ``any'' from the
phrase ``any maneuvers within the operating limitations of the
airplane,'' in proposed Sec. 23.755(a)(2). The commenters did not
provide a rationale for this suggestion.
The FAA disagrees as removing the word ``any'' could unduly
restrict the scope of the rule. The FAA's intent is that adequate
visibility must be provided to perform any maneuvers within the
operating limitations of the airplane. Therefore, the FAA adopts Sec.
23.2600(a) as proposed in the NPRM.
The Associations, Transport Canada, EASA, and ANAC questioned
proposed Sec. 23.755(a)(3), which would require the airplane design to
protect the pilot from serious injury due to high-energy rotating
failures. The Associations stated there may be new systems which may
include high amounts of energy that is not the result of rotating
equipment. The commenters suggested proposed Sec. 23.755(a)(3) be
broadened to include the new systems, such as high voltage systems.
EASA similarly suggested amending the protection of pilots against
serious injury due to high-energy rotating failures to include any
high-energy risks.
The FAA has considered the commenters' suggestion to change
proposed Sec. 23.755(a)(3) as recommended. However, the FAA has
concluded that the safety requirements contained in Sec. 23.2510,
``Equipment, systems and installations,'' (proposed as Sec. 23.1315)
of this rule adequately address hazards from high-energy sources.
Therefore, no change is being made to the final rule based on the
commenters' suggestion.
ANAC referenced former Sec. 23.1461(d) and asked the FAA to
explain why proposed Sec. 23.755(a)(3) excluded protection for
airplane occupants other than the pilot from certain hazards.
Additionally, Transport Canada commented the proposed language requires
protecting the pilot from high-energy rotating failures, which suggests
a lower level of safety for the other airplane occupants. It
recommended replacing the word ``pilot'' with ``occupants''.
The FAA agrees with ANAC and Transport Canada that proposed Sec.
23.755(a)(3) would effectively lower the level of safety because it did
not protect all occupants from high-energy rotor failures. It also did
not protect the airplane from high-energy rotor failures, and allowed
the pilot and pilot controls to be in the inboard propellers' plane of
rotation. The FAA intended to incorporate the safety intent of former
Sec. Sec. 23.771(c) and 23.1461.
Therefore, the FAA adopts Sec. 23.2550 to better capture the
safety intent of former Sec. 23.1461. Section 23.2550 requires
equipment containing high-energy rotors to be designed or installed to
protect the occupants and airplane from uncontained fragments. The FAA
also revises Sec. 23.2320(a)(2) (proposed as Sec. 23.755(a)(3)) to
capture the safety intent of former Sec. 23.771(c). Section
23.2320(a)(2) will require the pilot and flight controls be protected
from propellers.
Textron and NJASAP commented on the requirement in proposed Sec.
23.755(b)(1) for level 4 airplanes to ensure that the windshield and
its supporting structure directly in front of the pilot can withstand
the impact equivalent of a two-pound bird. Textron noted the 14 CFR
part 33 engine requirement for medium bird ingestion is based on a 2.5-
pound bird and questioned why the FAA did not use 2.5-pounds in
proposed Sec. 23.755(b)(1). Textron also recommended the FAA consider
language from CS 23.440(a) with weight/type specifics being defined in
the industry standards.
The FAA notes NJASAP's and Textron's comment on the weight of the
bird in proposed Sec. 23.755(b)(1). Former Sec. 23.775(h)(1) required
windshield panes directly in front of pilots in the normal conduct of
their duties, and the supporting structure for these panes, to
withstand, without penetration, the
[[Page 96626]]
impact of a two-pound bird when the velocity of the airplane (relative
to the bird along the airplane's flight path) is equal to the
airplane's maximum approach flap speed for commuter category airplanes.
The FAA codified this requirement in part 23, amendment 23-49.\39\ The
preamble of the NPRM \40\ for amendment 23-49 explains that the two-
pound bird requirement was based on ICAO bird strike data that occurred
on airplanes of 19,000 pounds or less from 1981 through 1989. Also,
this requirement is well established in the former regulations and has
provided an acceptable level of safety. Therefore, the FAA retains the
two-pound bird requirement.
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\39\ Final Rule, Airworthiness Standards; Systems and Equipment
Rules based on European Joint Aviation Requirements, 61 FR 5151,
5166 (Feb. 9, 1996).
\40\ NPRM, Airworthiness Standards; Systems and Equipment Rules
based on European Joint Aviation Requirements (59 FR 37620, July 22,
1994).
---------------------------------------------------------------------------
NJASAP commented the methodology used to discriminate between level
3 and 4 airplanes will motivate OEMs to certify more airplanes within
level 3. The commenter also noted that airplanes in this category have
experienced fatal accidents due to bird strikes. NJASAP recommended the
FAA apply the requirements of proposed Sec. 23.755(b)(1) to level 3
high-speed airplanes.
The FAA acknowledges the requirement in former Sec. 23.775(h)(1)
applied to commuter category airplanes, while the proposed requirement
would have applied only to level 4 airplanes. Under the former
regulations, a commuter category airplane was limited to multiengine
airplanes with a seating configuration, excluding pilot seats, of 19 or
less and a maximum certificated weight of 19,000 pounds or less.\41\
Additionally, a normal category airplane was limited to those airplanes
that had a seating configuration, excluding pilot seats, of nine or
less, a maximum certificated takeoff weight of 12,500 pounds or less,
and intended for nonacrobatic operation.\42\ Under the proposal, level
4 airplanes would be airplanes with a maximum seating configuration of
10 to 19 passengers. Thus, the proposal would have the effect of
providing relief to a percentage of part 23 airplanes with a maximum
certified takeoff weight more than 12,500 pounds, but have fewer than
10 passengers seating configuration.
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\41\ See Sec. 23.3(d), amendment 23-62.
\42\ See Sec. 23.3(a), amendment 23-62.
---------------------------------------------------------------------------
Under NJASAP's proposal, this requirement would apply to airplanes
with 7 to 9 passengers and a maximum certified takeoff weight of 12,500
pounds or less, which would increase the certification requirements of
former Sec. 23.775(h)(1). This regulation has proven to be an
acceptable level of safety. Additionally, adding level 3 airplanes
would increase the cost for a number of these airplanes that weigh less
than 12,500 pounds.
Transport Canada and ANAC noted that former Sec. 23.831 addresses
smoke, which was not included in proposed Sec. 23.755(c). Transport
Canada recommended the FAA add the phrase ``and solid or liquid
particulates'' after the word ``vapors'' in proposed paragraph Sec.
23.755(c) because smoke is a collection of airborne solid and liquid
particulates and gases.
The FAA agrees with Transport Canada and ANAC and revises Sec.
23.2320(c) to require the air provided to each occupant be free of
hazardous concentrations of smoke during normal operations and likely
failures. The FAA intended proposed Sec. 23.755(c) to incorporate the
safety intent of former Sec. 23.831(b), which requires the ventilating
air in the flightcrew and passenger compartments to be free of harmful
or hazardous concentrations of gases and vapors in normal operations
and in the event of reasonably probable failures or malfunctioning of
the ventilating, heating, pressurization, or other systems and
equipment. It also requires smoke evacuation be accomplished quickly if
accumulation of hazardous quantities of smoke in the cockpit area is
reasonably probable.
The FAA chose the term ``smoke'' instead of ``solid or liquid
particulates'' because it is a more common term. Section 23.2320(c)
requires air at a breathable pressure, free of hazardous concentrations
of gases, vapors, and smoke, to be provided to each occupant during
normal operations and likely failures.
ANAC questioned whether general rules (like proposed Sec. 23.1315)
would address the concern of smoke evacuation capability and requested
the FAA clarify how airplane manufacturers would be driven to develop a
smoke evacuation system in case there is no explicit requirement, just
general ones.
The FAA considers Sec. 23.2320(c) to be an explicit requirement
for cockpit smoke evacuation but general regulations may also require
smoke evacuation to be considered. A pressurized airplane design that
cannot evacuate smoke from the cockpit sufficiently to allow the
flightcrew to safely perform their duties, does not provide each
occupant with air at a breathable pressure, free of hazardous
concentrations of gases, vapors and smoke, during normal operations and
probable failures. Therefore, an effective smoke evacuation system is
necessary to comply with Sec. 23.2320(c) of this rule.
The Associations recommended reordering proposed Sec. 23.755(d)
and (e) to place the oxygen requirements after the pressurization
requirements. The FAA agrees with the recommendation and notes this
change harmonizes with EASA's regulation. In EASA's regulation,
pressurization system requirements precede the oxygen systems
requirements.
Textron commented that the FAA should remove proposed Sec.
23.755(e)(1), as it covers the same subject area as proposed Sec.
23.1305(c). Proposed Sec. 23.1305(c) would have required information
concerning an unsafe system operating condition to be provided in a
timely manner to the crewmember responsible for taking corrective
action. Presentation of this information must be clear enough to avoid
likely crewmember errors.
The FAA agrees with Textron's comment, as both sections would
require the crewmembers to be made aware of unsafe conditions.
Therefore, the FAA adopts Sec. 23.2605(c) as proposed and withdraws
proposed Sec. 23.755(e)(1).
Proposed Sec. 23.755(e)(2) would have required pressurization
systems, if installed, to include a pressurization system test. The FAA
intended to capture the safety intent of former Sec. 23.843,
``Pressurization system tests,'' which required specific tests for
demonstrating compliance with safety requirements. Upon further review,
the FAA finds that proposed Sec. 23.755(e)(2) contains prescriptive
requirements, which is inconsistent with the FAA's goal of establishing
performance-based requirements as was set forth in the NPRM. Therefore,
the FAA withdraws proposed Sec. 23.755(e)(2).
The FAA reviewed the former regulations related to proposed Sec.
23.755 to determine if it inadvertently omitted any safety requirements
for pressurization systems. As a result of this review, the FAA has
identified the following omissions, which are addressed in this rule.
This final rule now requires pressurization systems, if installed,
to be designed to protect against decompression to an unsafe level,
which captures the safety intent of former Sec. Sec. 23.841(c), (d)(2)
and (d)(3). This final rule also requires pressurization systems, if
installed, to be designed to protect against excessive differential
pressure, which captures the safety intent of Sec. Sec. 23.841(b)(1),
(b)(2), (b)(3) and (b)(8).
[[Page 96627]]
Section 23.2320(e)(1) specifically requires that if an oxygen
system is installed in the airplane, it must effectively provide oxygen
to each user to prevent the effects of hypoxia and be free from hazards
in itself, in its method of operation, and its effect upon other
components. This requirement captures the safety intent of former
Sec. Sec. 23.1441(a) and (d); 23.1443, and 23.1447(a), (b), (c), (d),
(e), and (g). These provisions require pressure/demand oxygen equipment
for the crew on high altitude airplanes; minimum oxygen flowrates and
pressures at specified conditions; standards for oxygen mask and
cannula effectiveness; ease of donning, retention, and accessibility;
and standards for crew communication while using oxygen equipment.\43\
The FAA revises 23.2320(e)(1) to capture the safety intent of these
former regulations, but without their prescriptive requirements, by
requiring that if an oxygen system is installed in the airplane, it
must effectively provide oxygen to each user to prevent the effects of
hypoxia.
---------------------------------------------------------------------------
\43\ These specifications were intended to protect against
hypoxia.
---------------------------------------------------------------------------
The FAA has also decided to add the specific language from former
Sec. 23.1441(b) into Sec. 23.2320. Requiring an oxygen system, if
installed, to be free from hazards in itself, in its method of
operation, and its effect upon other components restates former Sec.
23.1441(b) verbatim and captures the safety intent of former Sec. Sec.
23.1441(b) and (e), 23.1445, 23.1447(f), 23.1449, 23.1450(b), 23.1451,
and 23.1453. These provisions required--
A means for the crew to turn on and shut off oxygen supply
at the high-pressure source in flight;
Materials that could be used for oxygen tubing to be
considered;
A means to reserve oxygen for the flightcrew if a source
is shared with passengers;
A manual means to deploy passenger oxygen masks (or other
units) for high-altitude airplanes;
A means to allow the crew to determine whether oxygen is
being delivered;
Hazards from chemical oxygen generator temperature and
pressure to be addressed;
Protection of oxygen equipment and lines from fire
hazards; and
Protection against overload, unsafe temperatures, and
hazards in a crash landing.
The FAA withdraws proposed Sec. 23.755(d)(1) as it is rendered
redundant by adopted Sec. 23.2600(b).\44\ Furthermore, by making the
revisions described previously, the FAA is able to eliminate proposed
Sec. 23.755(d)(2) and (3) as redundant. Proposed Sec. 23.755(d)(2)
and (3) would have required oxygen systems to include a means to
determine if oxygen is being delivered and a means to permit the
flightcrew to turn on and shut off the oxygen supply at any high-
pressure source in flight. The FAA considers these requirements
redundant because failure to deliver oxygen to a user who needs oxygen
for protection against hypoxia with no way to determine that oxygen is
not flowing is a hazard in the oxygen system; and an oxygen leak that
cannot be shutoff at the high pressure source is a hazard in the oxygen
system. If oxygen is needed for the survival of the pilots or
passengers and it is turned off at the high-pressure source
(intentionally or inadvertently), the inability to turn it on would be
a hazard in the oxygen system.
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\44\ Proposed Sec. 23.755(d)(1) would have required oxygen
systems to include a means to allow the flightcrew to determine the
quantity of oxygen available in each source of supply on the ground
and in flight. Adopted Sec. 23.2600(b) requires the applicant to
install displays so qualified flightcrew can monitor and perform
defined tasks associated with the intended functions of systems and
equipment.
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f. Fire Protection (Proposed Sec. 23.800/Now Sec. 23.2325)
In the NPRM, proposed Sec. 23.800 (now Sec. 23.2325) would have
required the--
Insulation on electrical wire and electrical cable outside
designated fire zones be self-extinguishing;
Airplane cockpit and cabin materials in certification
levels 1, 2, and 3 be flame-resistant;
Airplane cockpit and cabin materials in level 4 airplanes
be self-extinguishing;
Airplane materials in the baggage and cargo compartments,
which are inaccessible in flight and outside designated fire zones, be
self-extinguishing; and
Electrical cable installation that would overheat in the
event of circuit overload or fault be flame resistant.
Additionally, proposed Sec. 23.800 would have precluded thermal
acoustic materials outside designated fire zones from being a flame
propagation hazard. Proposed Sec. 23.800 would have also required
sources of heat that are capable of igniting adjacent objects outside
designated fire zones to be shielded and insulated to prevent such
ignition.
Proposed Sec. 23.800 would have required airplane baggage and
cargo compartments, outside designated fire zones, to be located where
a fire would be visible to the pilots, or equipped with a fire
detection system and warning system, and--
Be accessible for the manual extinguishing of a fire;
Have a built-in fire extinguishing system, or
Be constructed and sealed to contain any fire within the
compartment.
Proposed Sec. 23.800 would have required a means to extinguish any
fire in the cabin, outside designated fire zones, such that the pilot,
while seated, could easily access the fire extinguishing means, and for
levels 3 and 4 airplanes, passengers would have a fire extinguishing
means available within the passenger compartment. Where flammable
fluids or vapors might escape by leakage of a fluid system, proposed
Sec. 23.800 would have required each area, outside designated fire
zones, be defined and have a means to make fluid and vapor ignition,
and the resultant hazard, if ignition occurs, improbable. Additionally,
proposed Sec. 23.800 would have also required combustion heater
installations outside designated fire zones be protected from
uncontained fire.
EASA commented that the fire protection outside designated fire
zones requirements proposed in Sec. 23.800 were design solutions
instead of objectives. EASA contended these proposed provisions would
hamper the development of different, but acceptable future designs.
EASA recommended the FAA follow the A-NPA text from CS 23.445.
The FAA does not share EASA's view that the proposed Sec. 23.800
requirements were design specific solutions. For the foreseeable
future, there will be wiring, cabling, insulating, and covering
materials used in airplane cabins, cockpits, and baggage and cargo
compartments. The performance standard requires certain materials be
self-extinguishing, flame resistant, etc., in order to prevent the
initiation or propagation of a fire. The way to demonstrate compliance
with the performance standard is now moved to accepted methods of
compliance instead of being specified in rule language or appendices.
Additionally, the former part 23 regulations for commuter category
airplanes, and the proposed regulations for level 4 airplanes, intended
for personnel to be alerted to the presence of a fire and a way to
extinguish it. Based on the FAA's understanding of the current
technology available, for the foreseeable future, fire detection
systems and extinguishers are the methods to achieve this. The FAA is
not prescribing the technology and design of those systems.
[[Page 96628]]
Additionally, the FAA finds that following the A-NPA text from CS
23.445 would be a new approach to achieving the safety intent of
preventing the initiation or propagation of a fire, which was not set
forth for notice and comment. Further, the FAA has concerns whether
EASA's proposed rule language would meet the same level of safety as
provided for in the former part 23 regulations, as EASA's proposed text
would require minimization of the risk of ``fire initiation'' and
``fire propagation''. The word ``minimize'' has not historically been
used in this safety standard where specific tests were used with
specific pass/fail criteria. The FAA also finds using the word
``minimize'' may introduce ambiguity in the rule. While the FAA is not
adopting EASA's recommendation, the FAA contends the requirement in
Sec. 23.2325 harmonizes with EASA's requirements because the effect is
the same.
Embraer recommended modifying the title of proposed Sec. 23.800 to
remove the word ``designated,'' as well as removing the phrase
``Outside designated fire zones'' from the lead sentence of the
proposed rule.
The FAA agrees with Embraer's comment that it is unnecessary to
state ``designated'' in the title. The FAA eliminates the phrase ``fire
zones'' as well because the term may lead to confusion. This revision
aligns the final rule with the safety intent of former regulations and
has the benefit of aligning the title with EASA's proposed title.
Furthermore, the FAA changes the title of Sec. 23.2325 to ``Fire
protection'' and deletes the lead-in sentence ``Outside designated fire
zones:''. Finally, the FAA adds ``. . . in the fuselage . . .'' to
subparagraph (c) so as not to expand the applicable area of the rule.
Transport Canada recommended the FAA define several terms used in
this section, specifically, ``self-extinguishing,'' ``flame
resistant,'' and ``flame propagation hazard'', because this section
would otherwise be subject to a wide range of interpretation. Transport
Canada stated the performance statement, as expressed, may not ensure
the level of safety of former Sec. 23.853.
The FAA finds that defining these terms is not necessary, nor that
this rule will be subject to a wide range of interpretation. Putting
the parameters necessary to precisely define these terms would mean
specifying test standards, which is contrary to the rule's intent to
move away from prescriptive standards. The specifications for meeting
these requirements will be contained in an accepted means of
compliance. One means of compliance accepted by the FAA is to use the
former prescriptive means of compliance contained in former part 23,
together with a policy statement issued by the FAA identifying means by
which the FAA has addressed errors, ELOS findings to various provisions
of former part 23, and special conditions (i.e., ``prescriptive
means''). The performance standard, plus this accepted means of
compliance, will ensure the same level of safety as former Sec.
23.853. The FAA notes that to be acceptable, any future proposed means
of compliance would have to provide at least an equivalent level of
safety.
Transport Canada questioned whether proposed Sec. 23.800(a) would
cover components located in between the fuselage skin and the
compartment liners that were explicitly covered under former Sec.
23.853. The commenter recommended the FAA consider these components.
The FAA finds it unnecessary to list these specific parts in the
rule since all materials in those compartments must meet the standards
specified for that compartment. The FAA notes, just as under former
Sec. 23.853(d)(3)(ii), items behind compartment liners are considered
materials that exist in those compartments.
In level 4 airplanes, proposed Sec. 23.800(a)(3) would have
required materials in the cockpit, cabin, and baggage and cargo
compartments be self-extinguishing. NJASAP stated level 3 high-speed
airplanes should also be required to have self-extinguishing cockpit
and cabin materials. NJASAP noted many business jets that fly at high
altitude will fall into the level 3 high-speed category in the future.
NJASAP indicated if a fire were to break out in this airplane type, it
could take several minutes to detect it and to make an emergency
landing.
The FAA notes under the former Sec. 23.853(d), only commuter
category airplanes needed to meet the self-extinguishing requirement
for these specified items. In the NPRM, the FAA correlated level 4
airplanes to the commuter category. Therefore, adding the requirement
to make cockpit and cabin materials self-extinguishing for level 3
airplanes would impose requirements beyond those imposed under former
Sec. 23.853 and would be beyond the scope of the notice. Furthermore,
the FAA is unaware of service experience with level 3 airplanes that
would justify the increased cost associated with the NJASAP's comment.
Textron and the Associations requested clarification regarding the
use of ``or'' in proposed Sec. 23.800(b)(2) with respect to circuit
overload or fault. The Associations asked whether the FAA intends to
allow some electrical systems, such as high-reliability primary power
wires in electrically-powered airplanes, to use reliable design
practices in place of circuit protection for some wires. Textron
thought the use of ``or'' meant both overload and failure of the
protective device do not need to be considered and asked whether the
intent is to allow some circuits without overload protection, such as
main start cables.
The FAA notes the focus of this rule is fire protection rather than
circuit design. The FAA's intent is to make certain electrical cable
installations that could overheat are flame resistant, regardless of
whether this is due to a circuit overload or fault. Proposed Sec.
23.800 nearly mirrors former Sec. 23.1365(b), which used the same
phrase ``. . . circuit overload or fault . . . .'' \45\ The FAA did not
intend to change the meaning of former Sec. 23.1365(b). To address the
commenters' concerns, the FAA revises Sec. 23.2325 to reflect the
language as stated in former Sec. 23.1365(b).
---------------------------------------------------------------------------
\45\ See 61 FR 5151, February 9, 1996.
---------------------------------------------------------------------------
Also, the FAA noted a typographical error in proposed paragraph
(c). A slash (``/'') between ``thermal'' and ``acoustic'' was missing.
The absence of the ``/'' indicate only insulation that was both thermal
and acoustic must comply. The FAA's intention was either thermal or
acoustic, as required under the former Sec. 23.856. The FAA has
corrected this inadvertent omission in this rule.
Textron and the Associations submitted comments on proposed Sec.
23.800(d), which would have required sources of heat that are capable
of igniting adjacent objects, to be shielded and insulated to prevent
such ignition. Textron noted the proposed rule broadened the scope of
the former requirement from ``cargo and baggage compartments'' to
anything that is not a designated fire zone. Textron recommended the
FAA modify proposed Sec. 23.800(d) to include the phrase ``located in
the cargo and baggage compartments'' after ``Sources of heat.'' Textron
also commented that preventing hot equipment from starting fires in
normal operation is needed, but in the case where materials and
proximities are controlled by type design (i.e., other than the cargo
and baggage compartments), this is sufficiently addressed by proposed
Sec. 23.1300 (now Sec. 23.2500). The Associations recommended
modifying proposed Sec. 23.800(d) by adding the
[[Page 96629]]
phrase ``located in the cargo compartment.''
The FAA agrees the proposed rule would have unintentionally
broadened the prior requirements. The FAA revises the rule language to
add ``within each cargo and baggage compartment''. The FAA also agrees
with Textron that other regulations in subpart F sufficiently address
the issue of preventing hot equipment from starting fires in normal
operation where materials are located in places other than the cargo
and baggage compartments.
The Associations proposed removing the word ``any'' in front of
``fire'' from proposed Sec. 23.800(e)(2) and (f). The commenters did
not provide a reason for the proposal. Although ``any'' is implied, the
FAA prefers to leave the word in the rule language to be explicit.
Regarding proposed Sec. 23.800(g)(2),\46\ Textron asked whether
the probability of the leak is considered (i.e., the ``improbable''
requirement is for ignition and hazard after a leak). Textron
recommended the FAA clarify whether the requirement presumes a leak.
Transport Canada commented that the language of proposed Sec.
23.800(g)(2) was not consistent with AC 23.1309-1E. An individual
commenter submitted a similar comment. Transport Canada recommended the
FAA revise this provision to be consistent with AC 23.1309-1E, thereby
changing the qualitative probability to be remote, extremely remote, or
extremely improbable.
---------------------------------------------------------------------------
\46\ Textron cited proposed ``Sec. 23.2325(a)(2)'', but it
appears the commenter intended to refer to Sec. 23.2325(g)(2).
---------------------------------------------------------------------------
The FAA agrees the wording of proposed Sec. 23.800(g)(2) was
problematic because the term ``improbable'' was associated with
quantitative failure rates in former Sec. 23.1309. The FAA did not
intend to require an assessment of the probability of a flammable fluid
leak or ignition of a flammable fluid leak. The FAA's intent is that
reasonable design precautions are used to reduce (i) the likelihood of
flammable fluid leaks, (ii) the likelihood of flammable fluid ignition,
and (iii) the severity of flammable fluid ignition. The FAA agrees that
since the proposed rule would have required ignition to be assumed, it
does not make sense to make the hazard improbable ``if'' ignition
occurs.
The FAA intended to capture the safety intent of the requirement in
former Sec. 23.863. The FAA considered the suggestions for revising
proposed Sec. 23.800(g), and is using the text of former Sec.
23.863(a). Former Sec. 23.863(a) was a performance-based requirement
and former Sec. 23.863(b) and (c) provided details on how former Sec.
23.863(a) must be addressed. New Sec. 23.2325(g)(2) requires a means
to minimize the probability of ignition of the fluids and vapors and
the resultant hazard if ignition does occur in each area where
flammable fluids or vapors might escape by leakage of a fluid system.
``Minimize'' means to reduce the probability and consequences of
occurrence to the extent practical. It does not establish a
probabilistic requirement, but rather requires application of sound
engineering judgment to use effective means to achieve the safety
objective.
g. Fire Protection in Designated Fire Zones and Adjacent Areas
(Proposed Sec. 23.805/Now Sec. 23.2330)
In the NPRM, proposed Sec. 23.805 (now Sec. 23.2330) would have
required--
Flight controls, engine mounts, and other flight
structures within or adjacent to designated fire zones be capable of
withstanding the effects of a fire;
Engines inside designated fire zones to remain attached to
the airplane in the event of a fire or electrical arcing; and
Terminals, equipment, and electrical cables, inside
designated fire zones, used during emergency procedures, be fire-
resistant.
Embraer recommended modifying proposed Sec. 23.805 to change the
title from ``Fire protection in designated fire zones'' to ``Fire
protection in fire zones and adjacent areas.''
The FAA agrees with the recommendation to add ``and adjacent
areas'' to the title for clarification. The FAA notes that Sec.
23.805(a) references flight controls, engine mounts, and other flight
structures adjacent to a designated fire zone.
However, ``designated fire zone'' has a particular meaning. Embraer
viewed this proposed definition as prescriptive and recommended the FAA
use the definition of ``fire zone'' contained in the draft of AC
25.863-1. That definition stated a fire zone means a ``zone that
contains a nominal ignition source and may be exposed to a flammable
fluid/material as a result of a failure.'' The FAA reviewed the
definition of ``fire zone'' in AC 25.863-1 and determined this
definition would impose requirements beyond those in the former part 23
regulations.
Embraer also recommended removing the modifying phrase ``inside
designated fire zones'' contained in the proposed regulation. Embraer
stated that ``former Sec. 23.1181 defined the `hot' parts of an engine
installation is an ignition source and considering that there are fuel,
oil, and hydraulic fluids being carried around such areas, they shall
be considered a fire zone, and then the term `designated' would apply,
which means that it is not necessary [for] further analysis to define
if it is a flammable fluids zone or a fire zone.''
The FAA agrees with Embraer's recommendation and removes the
modifying phrase from the first line of the proposed text for Sec.
23.805(b). The FAA will clarify within each requirement if it applies
in designated fire zones, or designated fire zones and adjacent areas.
EASA stated that proposed Sec. 23.805(b) reflects current design-
specific requirements that should be amended to cover other ``new''
designated fire zones, such as for batteries. Proposed Sec. 23.805(b)
would have required engines inside designated fire zones to remain
attached to the airplane in the event of a fire or electrical arcing.
EASA recommended revising proposed Sec. 23.805(b) to read: ``A fire in
a designated fire zone must not preclude continued safe flight and
landing''.
The FAA finds EASA's proposal is beyond the scope of the NPRM. The
FAA intended proposed Sec. 23.805 to capture the safety intent of
former Sec. Sec. 23.865 and 23.1359(b). Former Sec. 23.865, in part,
required engine vibration isolators to incorporate suitable features to
ensure the engine is retained if the non-fireproof portions of the
vibration isolators deteriorate from the effects of a fire. The FAA
finds this requirement is still applicable to engines that use
flammable fuels and should be retained. However, the FAA agrees
proposed Sec. 23.805(b) reflected current design-specific requirements
that would not be applicable to other potential designs that do not use
flammable fuels for propulsion. Therefore, the FAA is making this
requirement only applicable to engines in designated fire zones. The
FAA also withdraws the proposed requirement for engines to remain
attached to the airplane in the event of electrical arcing, because the
FAA finds that the threat of electrical arcing causing structural
failure is addressed adequately in the electrical systems requirements
in subpart F.
Embraer commented that the word ``engine'' should be replaced with
the phrase ``power unit'' in proposed Sec. 23.805(b). The FAA
understands Embraer's rationale, but the FAA's authority to issue TCs
refers to ``aircraft engines,'' not power units (49 U.S.C. 44704(a)(1))
so the term ``aircraft engines'' needs to be retained. Therefore, the
FAA is not adopting EASA's recommendation in the final rule.
[[Page 96630]]
Textron recommended the FAA replaces ``terminals, equipment, and
electrical cables'' with the word ``equipment'' in proposed Sec.
23.805(c). Paragraph (c) would have required terminals, equipment, and
electrical cables inside designated fire zones, that are used during
emergency procedures, be fire resistant. Textron stated that if this
provision is supposed to apply to anything in a fire zone that gets
used in an emergency, it is potentially misleading.
The FAA disagrees with Textron's comment. The FAA intended proposed
Sec. 23.805(c) to capture the safety intent of former Sec.
23.1359(b), which stated ``Electrical cables, terminals, and equipment
in designated fire zones that are used during emergency procedures must
be fire-resistant.'' Accordingly, the FAA is not making any change to
the language proposed in Sec. 23.805(c) (now Sec. 23.2330(c)).
h. Lightning Protection (Proposed Sec. 23.810/Now Sec. 23.2335)
In the NPRM, proposed Sec. 23.810 (now Sec. 23.2335) would have
precluded primary structure failure caused by exposure to the direct
effects of lightning, that could prevent continued safe flight and
landing for airplanes approved for IFR. Proposed Sec. 23.810 would
have required airplanes approved only for VFR to achieve lightning
protection by following FAA-accepted design practices found in FAA-
issued ACs and in FAA-accepted consensus standards.
Air Tractor and Transport Canada commented that ``FAA-accepted
design practices'' does not establish a performance standard in
proposed Sec. 23.810(b). Air Tractor also noted this proposed
regulation would make the ACs required and regulatory. Transport Canada
further stated that specifying ``FAA'' in the rule is not conducive to
harmonization between authorities and recommended replacing ``FAA-
accepted design practices'' with a performance-based requirement in the
form of a safety objective.
The FAA agrees that proposed Sec. 23.810(b) is not consistent with
the goal to develop performance-based standards and to spur innovation.
The FAA recognizes new methods of protecting the airplane from
catastrophic effects from lightning may be developed that are not
currently FAA-accepted design practices and these methods should be
permitted if found acceptable to the FAA.
In light of the comments received for this section, the FAA
revisited the goal of proposed Sec. 23.810. The FAA intended to
capture the safety intent of the former lightning regulations in former
Sec. 23.867. Former Sec. 23.867(a) was a high-level performance-based
requirement requiring the airplane to be protected against catastrophic
effects from lightning. Former Sec. 23.867(b) and (c) were means of
compliance with Sec. 23.867(a). Former Sec. 23.867(b) specified how
metallic components must be designed to protect the airplane against
catastrophic effects from lightning, while former Sec. 23.867(c)
specified how non-metallic components must be designed to protect the
airplane from catastrophic effects from lightning. The FAA also
intended to establish safety requirements for direct and indirect
effects of lightning on all systems and structure in proposed
Sec. Sec. 23.810, 23.930, and 23.1320. Proposed Sec. 23.810 would
have addressed protection of structure, proposed Sec. 23.930 would
have addressed protection of fuel systems, and proposed Sec. 23.1320
would have addressed protection of electrical and electronic systems.
However, upon review, proposed Sec. 23.810 did not address all
structure and proposed Sec. 23.1320 did not address all systems and
equipment.
The FAA has determined that retaining the language of former Sec.
23.867(a) would more appropriately capture the FAA's intent for Sec.
23.2335 because it applies to the entire airplane including all
systems, equipment and structure. Therefore, the FAA revises Sec.
23.2335 to require the airplane to be protected against catastrophic
effects from lightning, which is a performance standard. The FAA finds
this revision addresses Air Tractor's and Transport Canada's remaining
concerns.
The FAA also identified an error in the proposed correlation table
in the NPRM. Former Sec. 23.867(b) was correlated with proposed Sec.
23.1320, ``Electrical and electronic system lightning protection'', and
not proposed Sec. 23.810, ``Lightning protection of structure''. This
reference was incorrect because proposed Sec. 23.1320 did not address
all aspects of protecting the airplane against catastrophic effects
from lightning for metallic components. The FAA corrected the
correlation in the table provided in this final rule.
EASA commented that the requirement of lightning protection of the
structure should relate to the type of environment that causes the
risk, instead of the type of operation. EASA recommended replacing IFR
with instrument meteorological conditions (IMC), and replacing VFR with
visual meteorological conditions (VMC).
The FAA agrees with EASA's comment that the requirements for
lightning protection should be related to the risk of lightning. Rather
than drawing a distinction between IFR and VFR, or IMC and VMC, the
language provided in this final rule now reflects a performance-based
standard. The standard will be met by an accepted means of compliance.
The FAA finds this approach provides greater flexibility to allow
development of means of compliance that are appropriate for different
types of airplanes and different types of operation depending on the
risk of lightning.
6. Subpart E--Powerplant
a. General Discussion
In the NPRM, the FAA proposed substantial changes to former subpart
E based on two considerations. First, the FAA stated many of the former
regulations could be combined to provide fewer regulations that
accomplish the same safety intent. Second, the FAA also stated part 23
overlaps with the requirements in parts 33 and 35.
Textron noted that subpart E appeared to be missing performance
requirements for key propulsion aspects. Textron recommended the FAA
include rules that address engine controls, powerplant accessories and
components, and powerplant instruments and indicators as set forth in
former Sec. Sec. 23.1141, 23.1163, and 23.1225 of appendix E of the
Part 23 ARC Report.
The FAA reviewed each requirement mentioned by the commenter and
finds those requirements have been addressed in the final rule using
less prescriptive language. In most cases several regulations, rather
than any single rule, capture the intent of the former regulations
referenced by the commenter. Requirements contained in regulations for
powerplant installation, airplane level systems, and flightcrew
interface combined with more specific requirements found in regulations
for powerplant fire protection, instrument markings, control markings,
and placards, address the specific requirements noted by the commenter.
An individual commenter stated the FAA's removal of all references
to part 33 and part 35 from proposed part 23 was inappropriate. The
commenter contended the FAA's conclusion that those references are
redundant because the requirements are already addressed during the
certification of the engine or propeller is incorrect. The commenter
noted that compliance with specific performance standards for engines
and propellers is only ensured by requiring a product to be approved to
a specific
[[Page 96631]]
amendment level of part 33 or 35, before it is eligible for
installation on a particular airplane. The commenter also noted that
engines and propellers approved prior to a specific part 23 amendment
level may not have met a specific installation level requirement
specified by that amendment. For example, the commenter noted that
former Sec. 23.903 required minimum engine ingestion performance by
the installation of an engine certified to a specific amendment level
of part 33, thereby ensuring that any installed turbine engine had met
a minimum performance level mandated by the FAA through that amendment
level.
The individual commenter also stated engine and propeller
limitations are established during the type certification of the engine
or propeller, and that these limitations are required to be included in
the TCDS and associated installation manuals. The installer must comply
with these limitations. The commenter further implied that, if the
installed engine or propeller limitations cannot be complied with, safe
operation of the product cannot be ensured. For example, the commenter
stated that former Sec. Sec. 23.1041 through 23.1047 required the
engine installation to be designed such that the temperature
limitations--established under part 33 for the engine--are maintained
in the installed configuration.
The individual commenter also noted that some components of an
engine or propeller are approved at both the engine or propeller level
and at the airplane level, but that all components require approval at
the airplane level. According to the commenter, the approval of the
engine or propeller TC can include items such as a propeller reversing
system or a turbocharger, and this data can be used for approval of
these systems at the airplane level. If an applicant prefers approval
at the airplane level only, this commenter noted, the former rule
provided a reference to the requirements contained in part 33 or 35, as
appropriate. Without the inclusion of these references in proposed part
23, certification may require special conditions.
The commenter recommended the FAA include--
References to parts 33 and 35 for type certificated
engines and propellers being installed and consider the inclusion of
similar standards when the installation of non-type certificated
engines or propellers are permitted;
A specific rule stating the powerplant installation design
must be such that all installed type certificated engines and
propellers remain within their respective approved limitations and
installation manual requirements and that a similar provision be
included when the installation of non-type certificated engines and
propellers is permitted; and
Reference in the proposal to the applicable provisions of
parts 33 and 35 for engines, propellers, and any related components of
those products being installed only at the airplane level.
The FAA agrees with the general intent of the commenter. The FAA
notes that while some requirements in the former part 23 indeed overlap
with those of parts 33 and 35, the FAA did not intend to imply that
compliance with those requirements necessary for type certification of
an engine or propeller were no longer applicable to the certification
of the installed configuration of a type certificated engine or
propeller. Historically, TCs have been required for engines and
propellers installed in airplanes certificated under part 23 and this
rule retains this requirement for all airplanes certificated under part
23, with the exception of level 1 low-speed airplanes.\47\ Essentially,
this requirement makes the requirements in parts 33 and 35 for type
certificated engines and propellers applicable to the certification of
airplanes under part 23, because the part 33 and 35 requirements must
be met in order to install these engines and propellers on part 23
airplanes. As a result, data used to show compliance for an engine or
propeller TC is considered FAA approved, and can be used to show
compliance with any applicable part 23 requirement. In many cases, this
permits a single showing of compliance such that a re-showing of
compliance at the airplane installation level may not be required.
Approval of some components, such as propeller controls or
turbocharges, have been permitted at the airplane level by referencing
the applicable part 33 or 35 requirements and using those requirements
as an acceptable means of compliance. This certification approach will
continue to remain acceptable.
---------------------------------------------------------------------------
\47\ Discussed in the preamble discussion for Sec. 23.2400.
---------------------------------------------------------------------------
The FAA does not intend to accept a means of compliance for an
engine or propeller installation that would result in a level of safety
lower than that set forth in a part 33 or 35 amendment level
specifically referenced in former part 23.
Limitations set forth in the approval of an engine or propeller
must be maintained in the installation on the part 23 airplane. These
operating limitations are established in accordance with Sec. Sec.
33.7 and 35.5. Installation instructions are provided to the installer
in accordance with Sec. Sec. 33.5 and 35.3. This regulation does not
change this approach.
Additionally, the FAA is adding a requirement from existing Sec.
23.901(e) to Sec. 23.2400, requiring installed powerplant components--
which include engines and propellers--to meet the FAA-approved
component limitations and installation instructions, or be shown not to
create a hazard. This requirement will ensure that any operating
limitations and installation instructions applicable to the engine or
propeller remain applicable to the certification of the airplane.
In the NPRM, an exception permitting the installation of non-type
certificated engines and propellers as part of the airplane was
proposed for simple airplanes. The proposal mirrors the precedent
established for the certification of airplanes under EASA CS-VLA. The
rule slightly expands the relief provided by the proposal, and permits
the certification of engines as part of the airplane for level 1 low-
speed airplanes. This change encompasses the same class of airplanes as
originally proposed while removing the restriction that these airplanes
be limited to VFR-only operations.\48\
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\48\ Discussed in the preamble discussion for Sec. 23.2400.
---------------------------------------------------------------------------
In response to the individual commenter's concerns that the
proposal does not require certain engines to meet a specific amendment
level of part 33, as set forth in former regulations, and the
commenter's specific concern that engine ingestion performance was not
specifically addressed, the FAA notes those sections of former subpart
E that required compliance with a specific amendment level for an
engine installation are addressed in this performance-based rule. The
engine ingestion requirements of former Sec. 23.903(a)(2), for
example, are addressed by the performance-based requirements of Sec.
23.2400(c). The former rule specified that an applicant must construct
and arrange each powerplant installation to account for likely
operating conditions including foreign object threats and likely
hazards in operation. Although Sec. 23.2400(c) does not refer to a
specific requirement or amendment level of part 33, the FAA expects the
means of compliance with this regulation will include provisions for
certificating engines with acceptable foreign object ingestion
performance as required by former Sec. 23.903(a)(2), which may include
references to different amendment levels of part 33 where appropriate.
Additionally, the FAA
[[Page 96632]]
intends to accept part 23 through amendment 23-62, which contained
references to specific requirements in part 33, as a means of
compliance to the performance-based requirements of this rule. The FAA
will only accept a means of compliance for a performance-based
regulation that encompasses the safety intent of a former regulation
requiring compliance with a particular amendment level of part 33 or
35, if that means of compliance provides a level of safety equivalent
to the level of safety found in former part 23.
b. Powerplant Installation and Propeller Installation (Proposed
Sec. Sec. 23.900 and 23.905/Now Sec. 23.2400)
In the NPRM, proposed Sec. Sec. 23.900 and 23.905 (now Sec.
23.2400) would have clarified, for the purpose of this subpart, that
the airplane powerplant installation must include each component
necessary for propulsion, affects propulsion safety, or provides
auxiliary power to the airplane. Proposed Sec. 23.900 would have
required the applicant to construct and arrange each powerplant
installation to account for likely hazards in operation and
maintenance, and, except for simple airplanes, each aircraft engine
would have to be type certificated. Proposed Sec. 23.905 would have
retained the requirement that each propeller be type certificated,
except for propellers installed on simple airplanes. Proposed Sec.
23.905 would have retained the requirement that each pusher propeller
be marked so it is conspicuous under daylight conditions.
EASA commented that design-specific requirements for propeller
installations should be covered by proposed Sec. 23.900, not proposed
Sec. 23.905.
The FAA adopts the regulatory approach taken by EASA for propeller
installation. Under this approach, the FAA includes the requirements
for propeller installation within Sec. 23.2400. Specifically, the
requirements of proposed Sec. 23.905(a) are addressed by Sec.
23.2400(b), proposed Sec. 23.905(b) are addressed by Sec.
23.2400(c)(3), and proposed Sec. 23.905(c) are addressed by Sec.
23.2400(c)(4). These revisions also clarify that a propeller
installation must not deviate from any limitations or installation
instructions as required by Sec. 23.2400(e). Addressing propeller
installation requirements in the section of the rule that establishes
powerplant installation requirements also results in closer
harmonization of the rule with EASA's proposed requirements in NPA
2016-05.
The FAA received numerous comments regarding the issue of whether
``power units'' should be certified under part 23 as part of the
airplane type certification. The Associations noted the proposed
language would allow engine and propellers that meet required standards
to be certified as part of the airframe, provided the airplane is
certificated as a simple airplane. The commenters contended the ability
to certificate these components as part of an airframe should be based
on the complexity of the components rather than on the certification or
performance levels of the airplane in which they are installed. The
commenters supported permitting the certification of engine and
propellers that comply with traditional engine and propeller type
certification requirements either through the issuance of a standalone
TC or through the certification process for the airframe. The
commenters also noted since electric propulsion is ``on the threshold
of becoming mainstream'', the ability to certify engines and propellers
as part of the airframe is critical to the successful and safe
integration of that technology.
EASA asserted the need to type certify an engine should be
addressed by part 21; therefore, the powerplant either could be type
certificated or certified as part of the airplane. EASA noted the type
certificate-related design and production controls that are part of the
current type certification process are also expected to be applicable
for other components such as batteries and converters. EASA stated
certification of the engine should not be related to the size or speed
of the airplane; therefore, EASA did not support limiting the
installation of propulsion systems that are not individually type
certificated to airplanes classified as simple airplanes.
Textron noted the purpose of the proposed rule is to enhance the
ability to introduce new technology efficiently, and contended that
treating each powerplant installation (e.g., electric propulsion) using
a unique ELOS finding would not be an effective way to address the
issue. Textron recommended either adding the requirements for
certifying the power unit as part of the airplane, or changing and
including the specific requirements in the industry standard to avoid
the need for unique ELOS findings. Additionally, Textron recommended
adopting proposed CS 23.500(b), which would not restrict the
installation of non-type certificated engines that meet an industry
standard to simple level 1 airplanes.
An individual commenter expressed support for the proposal to not
require certified engines for ``simple'' airplanes, but suggested
expanding the definition of ``simple'' to at least four-seat airplanes
with VS0 < 55kts and permitting IFR operations. The
commenter stated certain airplanes should not require a type-certified
engine with all of the associated costs, paperwork, and outdated
technology. The commenter also noted the requirement for a certified
engine in most airplanes precludes the use of electric propulsion in
anything but ``simple'' airplanes, since part 33 does not allow for the
certification of electric motors. The commenter also suggested
revisions to part 33 aimed at realizing the same kind of cost
reductions and to allow certain technologies on small airplane engines
without requiring full authority digital engine control (FADEC) levels
of ``design assurance.'' Additionally, other commenters specifically
recommended the proposed regulation be revised to permit all power
units installed in airplanes certificated in accordance with part 23 to
be type certificated or meet accepted specifications.
Air Tractor questioned whether alternative types of powerplant
units would receive a TC specific to that unit ``from within part 23''
and distinct from the airplane in which it is installed. If so, Air
Tractor expressed concern this approach would create a series of rules
for the purpose of issuing a TC for an unconventional powerplant design
and stated part 23 rules should not be applied to the certification of
unconventional powerplants. Air Tractor also recommended all engines
and propellers be either ``type certified'' or ``possess a type
certificate.''
NATCA noted if neither the engine nor the propeller would be
required to be type certified when installed on a simple airplane, it
is unclear how those products would be approved. Furthermore, NATCA
noted by allowing non-certificated engines on simple level 1 airplanes,
it was unclear how an airworthiness directive would be issued if an
unsafe condition were found to exist on the engine. NATCA also
recommended the FAA specify the minimum level of engineering safety
certification testing necessary to demonstrate how the engine and
propeller for simple airplanes could be approved, if they were not type
certificated.
The FAA notes the recommendation to expand the scope of proposed
Sec. 23.900 to permit all engines and propellers installed in
airplanes certificated under part 23 to be certificated under the TC of
the airplane in which the engine or propeller is installed. The FAA
evaluated the commenters' recommendations to base the need for an
engine or propeller TC on the complexity of the powerplant
[[Page 96633]]
system rather than on the complexity of the airplane. The FAA has
established standards in parts 33 and 35 that ensure an acceptable
level of safety and adequate standardization for certification of all
aircraft engines and propellers. Certification of an engine or
propeller with the airplane instead of requiring a separate engine or
propeller TC essentially requires a showing of compliance equivalent to
the airworthiness standards contained in part 33 for aircraft engines
or part 35 for propellers. The FAA finds that placing these
requirements in part 23 and using an accepted standard as a means of
compliance (with the limited exception for airplanes that can be
certificated as level 1 low speed), would not significantly reduce the
regulatory burden on engine and propeller manufacturers. Additionally,
at this time the FAA does not want to place the administrative
responsibility for the certification of all engines and propellers
installed in part 23 airplanes on two separate Aircraft Certification
Directorates, with the ensuing risks of delaying implementation of the
significant changes set forth in this final rule and creating the
possibility of differing interpretations or regulatory requirements.
The FAA is, however, open to revisit this option in the future. If, for
example, actual certifications or advances in technology indicate that
expanding this approach to include larger airplanes would provide a
manufacturer certification efficiencies, the FAA would be willing to
consider this expanded approach.
The FAA notes the Engine and Propeller Directorate (EPD) has been
responsible for establishing standards for engines and propellers and
continues to remain the best source for developing policy and guidance
for determining compliance with those standards, to include standards
for the certification of electric engines. While many commenters
believe the introduction of electric engines is imminent, and shifting
the responsibility for the certification of all engines and propellers
installed in airplanes that meet the airworthiness standards of part 23
from the EPD to the Small Airplane Directorate (SAD) would facilitate
certification of those engines, the FAA finds such action could delay
both the certification of electric engines and other more conventional
engine designs. Such a realignment of certification responsibilities
would increase the burden on both applicants and the FAA as the
involvement of two directorates would be required during the
certification process for aircraft engines and propellers.
Additionally, certification of an engine or propeller with the airplane
increases the burden of showing compliance when the product is
installed in multiple airplane models, as compliance with the basic
engine and propeller requirements must be shown for each specific
airplane model installation.
Accordingly, the FAA retains the basic approach discussed in the
NPRM requiring that all engines and propellers require a separate TC
except for those engines and propellers installed in airplanes that can
be certificated as level 1 low speed. Those standards permit the
certification of the engine and propeller with the airplane and do not
require those products possess a separate TC. However, the FAA has
slightly revised the proposal to expand the approval of aircraft
engines and propellers under the airplane TC from simple airplanes, as
originally proposed to all level 1, low-speed airplanes. Section
23.2400 will allow level 1 airplanes with engines not separately type
certificated to be used for both VFR and IFR operations. Additionally,
the FAA has added language that indicates an acceptable standard for
the certification of an engine or propeller, contains airworthiness
criteria the Administrator has found appropriate and applicable to the
specific design and intended use of the engine or propeller, and
provides a level of safety acceptable to the FAA. This language mirrors
the language contained in former Sec. 21.17(f)(1) for primary category
aircraft whose engines and propellers are certificated under the
airplane TC. This approach allows some streamlining for the engine
approval based on a specific installation verses the generic engine TC
which might be more thorough to account for the possible installation
variables. The FAA's concept of the safety continuum in this context
bases certification requirements on potential risk and considers the
number of potential passengers and the performance of the airplane,
rather than the complexity of the engine or propeller installed.
As future aircraft engines and energy sources become available,
both SAD and EPD may utilize ELOS findings, special conditions, and
exemptions to establish appropriate certification standards. These
processes will assist the agency in developing standards to address new
and novel technology, and can be applied regardless of whether the
design approval for an engine or propeller occurs as the part of the
airplane or as a separate engine or propeller approval. Additionally,
in response to those commenters concerned with the approval of electric
aircraft engines, part 33 airworthiness standards will be developed to
address those products as they are presented to the FAA for type
certification. Currently those standards do not exist in part 33,
therefore, special conditions will likely be used to establish
standards for the issuance of a TC before those standards have been
promulgated.
In response to commenters' concerns related to uncertainty as to
what minimum level of testing would be required for approval of engines
not separately type certificated and how potential airworthiness
concerns would be addressed for those products, the FAA expects any
engine or propeller will meet standards that provide a level of safety
at least equivalent to that achieved with the certification of those
products today. The FAA may accept or reject any means of compliance
proposed for acceptance and will only accept a means of compliance that
ensures the design meets the performance standards set forth in part
23. An applicant intending to use this approach would have to re-
establish compliance for the specific non-type certificated product in
accordance with an applicable FAA accepted standard under the TC of
each airplane model in which the product is installed rather than only
once as would occur with an engine or propeller TC. As stated earlier,
this provision permitting the type certification of both the engine and
propeller under the airplane TC is limited to level 1 low-speed
airplanes. Any unsafe condition related to ``non-TC'd'' engines or
propellers will be addressed by issuance of an airworthiness directive
requiring corrective action against the airplane TC under which those
engines or propellers have been approved.
Textron questioned whether proposed Sec. 23.900(c) includes
auxiliary power units, as those units are not type certificated, but
instead meet a TSO. Textron requested proposed Sec. 23.900(c) be
clarified to indicate it would apply to each aircraft power unit ``used
for propulsive power.'' Embraer, however, suggested including an
alternate means of compliance in proposed Sec. 23.900(c) for electric
engines, auxiliary power units, and other alternate sources of
propulsion.
The FAA revises the rule to ensure APUs may be approved under the
airplane TC in accordance with a standard accepted by the FAA, such as
a TSO. The FAA does not intend to require a TC for these units.
The Associations stated the proposal should include provisions to
address propulsion-specific hazards. The provisions include
environmental issues
[[Page 96634]]
unique to propulsion systems; ingestion of foreign object debris (FOD);
and the dangers of propulsion aspects to ground personnel. To address
their concerns, the commenters recommended revising proposed Sec.
23.900 to specifically require an applicant to account for all likely
operating and environmental conditions, including foreign objects
threats; sufficient clearance of moving parts to other airplane parts
or their surroundings; and likely hazards in operation, including
hazards to ground personnel.
The FAA agrees with the commenters and revises the rule to
specifically require all likely operating conditions (which include
environmental conditions), including foreign object threats; sufficient
clearance of moving parts to other airplane parts and their
surroundings; and likely hazards in operation, including hazards to
ground personnel are accounted for in each powerplant installation.
Proposed Sec. 23.900(b) referred to these conditions as ``likely
hazards in operation and maintenance,'' but the FAA finds that
specifically enumerating them will facilitate development of acceptable
means of compliance. The FAA also notes that former subpart E required
that applicants address these conditions.
To ensure compatibility between the airplanes and the power unit
design, as well as the safe operation of the power unit, ANAC
recommended including language, which would require the powerplant
installation comply with the limitations and installation instructions
provided by the power unit manufacturer. The Associations requested the
proposed section include additional requirements specifying the
installation of powerplant components that deviate from the component
limitations or installation instructions be safe and applicable
powerplant installations account for vibration and fatigue.
The FAA agrees with the commenters' intent to ensure the safe
operation of the powerplant and has added paragraph (e) to Sec.
23.2400 to specifically require powerplant components comply with their
component limitations and installation instructions or be shown not to
create a hazard. This requirement applies to the engine, propeller, and
any other components of the powerplant installation. The rule is also
revised to require powerplant installations account for vibration and
fatigue. The FAA notes component limitations and an installation manual
should be included as part of any powerplant installation. The
evaluation of the powerplant installation should also include an
evaluation of propeller vibration and compliance with proposed
installation manual limits, as the installed propeller is a component
of the powerplant installation.
Textron stated proposed Sec. 23.900 does not address automatic
power reserve (APR) systems. Textron recommended revising proposed
Sec. 23.900 based upon proposed CS 23.500. Textron also suggested
including specific language from appendix E from the final Part 23 ARC
Report, which states that an APR system that automatically advances the
power or thrust on the operating engine(s), when any engine fails
during takeoff, must comply with the applicable requirements of the
subpart. The FAA notes proposed Sec. 23.915 addressed the requirements
for APR systems referenced by the commenter and the FAA adopted these
requirements in Sec. 23.2415 of this rule.
Textron contended the proposed rule language does not include
critical items from current part 23 or redefines current requirements.
For instance, Textron noted proposed Sec. 23.900(b) appears to change
the current requirement that the powerplant installation be accessible
for preflight inspection and maintenance and adds a hazard assessment
requirement. Textron recommended revising proposed Sec. 23.900(b) to
state each powerplant installation must ensure safe operation and be
accessible for preflight inspection and maintenance.
The FAA has determined the performance-based regulations set forth
in the proposal, as revised by the changes made in this rule, address
all critical items in current part 23. With regard to Textron's
specific comments, the FAA did not intend to remove the requirement for
the powerplant installation to be accessible for preflight inspection
or require a new hazard assessment. The FAA intends that Sec.
23.2400(c) capture the current requirement that the powerplant
installation be accessible for preflight inspection. Likely hazards
include those that could result from lack of adequate preflight or
maintenance, which includes inspection. Additionally, the regulation
has not introduced a requirement to complete any hazard assessments not
required under current regulations.
An individual commenter noted the proposed rules in subpart E only
appear to address a design review that considers failures and hazards.
The commenter elaborated by stating that unlike the current rules, the
proposed rules do not require a design review for proper operation in
the normal non-failed condition. The commenter stated this change is
not discussed in the NPRM and appears to leave gaps in the traditional
certification effort where the airplane is certified to operate
properly within the approved operating envelope. The commenter
recommended including an additional requirement to ensure all
powerplant components and systems remain within all limitations and
function properly when operated within the approved airplane operating
envelope.
The FAA agrees the proposed regulatory language was not
sufficiently clear and revises proposed Sec. 23.900 (now Sec.
23.2400) to clarify the powerplant installation must be constructed and
arranged to account for likely operating conditions, likely hazards,
and all component limitations are maintained or otherwise shown to not
create a hazard throughout the approved operating envelope.
Textron noted proposed Sec. 23.900(b) should require not just
powerplants, but rather all systems, and particularly those installed
in future airplanes, to account for likely hazards in operation and
maintenance. Accordingly, Textron recommended removing the specific
provisions of the proposal referring to powerplants from proposed Sec.
23.900 and revising proposed Sec. 23.1305 to address all systems.
While the FAA agrees all systems should be designed to account for
likely hazards, the FAA notes powerplant installations have unique
requirements that may not directly apply or would be burdensome when
applied to the design of other systems. Accordingly, the FAA is not
expanding the applicability of this specific regulation to address all
systems.
In the NPRM, the FAA proposed replacing the term ``engine'' with
``power unit,'' which would have included ``auxiliary power unit''
(APU). This change was intended to ensure new requirements would be
clearly applicable to various power sources, such as those using liquid
fuel or electrical power, and to other power sources not yet
envisioned. After further review, the FAA has determined it would be
more appropriate to retain the term ``engine'' in the final rule
because ``engine'' is used throughout 14 CFR, TCs are specifically
issued for aircraft engines, and the term ``aircraft engine'' is
specifically defined in 49 U.S.C. 40102 and 14 CFR 1.1. The operating
regulations also refer to required engine indicators and engine
maintenance, and Airworthiness Directives issued for aircraft engines,
as opposed to ``power units.'' Introducing the term ``power unit''
could lead to unnecessary confusion and potential disagreements
regarding the applicability of specific
[[Page 96635]]
regulatory requirements. Additionally, the FAA notes the term
``engine'' includes any device that converts any form of energy into
force that propels an airplane. The FAA finds the term ``engine'' can
be used to address both current and new sources of propulsion and
accordingly has replaced the term ``power unit'' with ``engine'', or
``auxiliary power unit'', where appropriate in this rule. The intent of
this change is to clarify the requirements of this subpart are
applicable to any device that propels an airplane regardless of its
source of power and to avoid potential conflicts with both the
statutory and regulatory definitions of the term ``aircraft engine.''
The FAA has also added paragraph (d) to address the hazardous
accumulation of fluids, vapors or gases. This paragraph is virtually
identical to proposed CS 23.2430(b), ``Energy storage and distribution
system hazard mitigation,'' and corresponds to the safety intent of
former Sec. 23.1193(b) that addressed cowling drainage. It is designed
to ensure the hazards resulting from the accumulation of these
materials can be isolated from the airplane and personnel compartments
and these materials can be either safely contained or discharged.
c. Powerplant Installation Hazard Assessment (Proposed Sec. 23.910/Now
Sec. 23.2410)
In the NPRM, proposed Sec. 23.910 (now Sec. 23.2410) would have
required an applicant to assess each powerplant separately and in
relation to other airplane systems and installations to show that a
failure of any powerplant system component or accessory will not--
Prevent continued safe flight and landing;
Cause serious injury that may be avoided; and
Require immediate action by crewmembers for continued
operation of any remaining powerplant system.
Several commenters expressed concern that proposed Sec. 23.910
would have been impossible to meet for certain existing airplane
designs. The FAA response to these comments is below.
The Associations stated that proposed Sec. 23.910 should apply to
the ``likely'' failure of powerplant systems. The commenters asserted
that applying the proposed requirements to any failure would require
complete redundancy, which cannot be achieved in traditional single-
engine airplanes and smaller twin-engine airplanes. The commenters
contended the slower stall speeds and higher levels of crashworthiness
in the designs of these airplanes mitigate all but ``unlikely''
powerplant failures. These commenters recommended the FAA require the
applicant to assess each powerplant separately and in relation to other
airplane systems and installations to show that ``hazards resulting
from a likely failure of any powerplant system component or accessory
are minimized.''
Textron stated proposed Sec. 23.910 was ``too high level'' and
would not have established adequate performance-based requirements for
an applicant to demonstrate compliance. As an example, Textron
contended that proposed Sec. 23.910(a) would have been an impossible
requirement to meet, especially for a single-engine airplane. Textron
recommended replacing the language of proposed Sec. 23.910 with
language from EASA CS 23.510, ``Powerplant Hazard Mitigation''
EASA, Garmin, and Air Tractor stated the requirements of proposed
Sec. 23.910(a) would have been applicable to single-engine airplane
certification. Garmin stated, however, that a single-engine airplane
cannot meet proposed Sec. 23.910(a) unless the FAA clarifies the loss
of the thrust from the propulsion unit will not necessarily prevent
continued safe flight and landing. Garmin recommended the FAA either
revise proposed Sec. 23.910 or revise the definition of ``continued
safe flight and landing'' to allow for failure of the engine or
propeller in a single-engine airplane.
Air Tractor stated proposed Sec. 23.910(a) would have ruled out
the certification of single-engine airplanes. Air Tractor observed, for
example, that under the proposed rule, if a fuel line or hose were
considered a ``system component,'' then the failure of one fuel line
that feeds the engine would certainly result in an engine failure. Air
Tractor noted that there may be similarly insurmountable scenarios
involving the controls for an engine. Air Tractor stressed the need for
clearly-written rules to prevent unforeseen interpretations of
provisions that have the potential to make the design and certification
of light airplanes much more difficult than previously, or even
impossible.
An individual commenter stated that proposed Sec. 23.910(a)
appears to be a derivation of former Sec. 23.903(c)(1), which only
applied to multiengine installations and only required continued safe
operation of the remaining engines. The commenter asserted the proposed
rule would have increased the requirement from ``ensuring continued
safe operation of the remaining engines'' to ``ensuring continued safe
flight and landing of the airplane.'' The commenter further noted
proposed Sec. 23.910 would have applied to single-engine airplanes
with no justification and could have resulted in elimination of some
airplanes from certification, such as large single-engine or
multiengine airplanes where rotor non-containment effects on the
remaining engine cannot be eliminated. The commenter also stated the
proposed rule would have made ``continued safe flight and landing'' a
part of the regulation, where previously it only existed in guidance
material. The commenter indicated this may make it difficult to provide
a conditional definition of the term. To ensure safe design of
multiengine airplanes, the commenter recommended using the wording of
former Sec. 23.903(c)(1) rather than requiring a system safety
approach to powerplant installation that does not permit single
failures. The commenter also recommended using the term ``minimize''
when specifying the evaluation criteria for powerplant installations.
The commenter noted that term has been used for many years, is well
understood, and best describes the regulatory intent for those
powerplant unique systems where a single failure cannot be reasonably
eliminated from the design.
Another individual commenter said compliance with proposed Sec.
23.290 would neither be practical nor possible in all situations that
may result in a forced landing; therefore, the proposed rule should not
include a requirement for completely eliminating hazards, which the
commenter asserted is not achievable. The commenter asserted that
replacing a standard based on minimization with an absolute standard is
not an acceptable alternative. Ultimately, the commenter recommended
revising the definition of ``continued safe flight and landing'' to
allow for catastrophic outcomes of forced landings, and to either
maintain the minimization standard, or withdraw the requirement. The
commenter further noted that compliance with the proposed requirement
of absolute prevention of hazards would be impractical or impossible
for many conventional multiengine airplane configurations regarding
rotor non-containment. This is also true for all single-engine and many
multiengine airplanes regarding a propeller blade loss--especially
since the proposed rule applies to uncontained engine failure and
engine case burn-through failures for which former Sec. 23.903(b)(1)
only required the design to minimize the hazard.
Embraer observed that for turbine or reciprocating engine rotor
failure and/or
[[Page 96636]]
burn-through events, there is no way to eliminate all the risks that
will prevent continued safe flight and landing. Embraer recommended
revising the language to clarify certain proposed provisions and to add
additional provisions that would require applicants to show operating
limitations, which may adversely affect rotating component structural
integrity that would not be exceeded in service. Embraer's revisions
would require design precautions to minimize hazards to the airplane in
the event of an uncontained engine rotor or rotating component failure
or a fire originating within the engine, which burns through the engine
case.
The FAA concurs with the commenters' recommendations to revise
proposed Sec. 23.910 to make its requirements only applicable to
likely failures and to permit minimization of certain hazards, which
could prevent continued safe flight and landing. The FAA notes the
inclusion of the term ``likely'' in the requirement for the applicant
to address hazards resulting from failures is intended to place
reasonable and prudent bounds on the scope of analysis necessary to
meet the requirement and not to require consideration of all possible
failures, however remote. The scope of this analysis will be set forth
in accepted means of compliance for this regulation.
In response to commenters' concerns that the term ``minimize'', or
the philosophy encompassed by the use of the term, will be included in
the rule, the FAA notes that the term ``minimize'' has been included in
Sec. 23.2410(a) to permit the applicant to address those hazards,
which may prevent continued safe flight and landing of an airplane,
that cannot reasonably be eliminated. The FAA will consider
incorporation by an applicant of all practical design precautions,
which minimize hazards to the airplane, associated with a particular
failure acceptable in complying with this regulation. The FAA has
historically accepted this compliance approach when a minimization of
hazards has been required. This approach provides a simple means to
continuously improve airplane safety as new technologies and design
approaches evolve. It also permits acceptance of existing designs that
cannot reasonably eliminate hazards resulting from certain failures,
even if accepted design precautions have been incorporated into the
airplane's design. Such failures could include rotor non-containment,
engine case burn-through, and engine failures on single-engine
airplane. This change specifically addresses a concern expressed by all
commenters that the proposed regulation would make it impossible for an
applicant to show compliance with the regulation for many existing
airplane designs. Additionally, the rule will continue to permit the
use of simple parts, such as fuel lines and control cables, in airplane
designs. The FAA has traditionally considered their use acceptable
without requiring redundancy where it is neither practical nor likely
that a failure of the component would occur. The FAA's revisions to the
proposed regulation account for the normal use of these types of simple
components.
In response to the commenter who noted the term ``continued safe
flight and landing'' in proposed Sec. 23.910(a) appears to be based on
former Sec. 23.903(c), which only applied to multi-engine airplanes,
the FAA agrees that proposed Sec. 23.910(a) does not properly address
certain failures on single-engine airplanes. The FAA believes the
revisions discussed above addresses the individual's concerns.
Textron also recommended the FAA withdraw proposed Sec. 23.910, as
its subject area overlaps with proposed Sec. 23.1315 (now Sec.
23.2510).
The FAA revises proposed Sec. 23.910 to clarify that any failure
resulting in the loss of a single powerplant on an airplane with
multiple powerplants cannot result in the failure of other powerplants
unless those failures cannot be reasonably eliminated, in which case
the hazards must be minimized. So, while Sec. 23.2510 does apply to
all powerplant systems, the FAA notes Sec. 23.2410 includes an
exception to the general requirement of Sec. 23.2510 to account for
certain powerplant failures that may prevent continued safe flight and
landing or for which use of a traditional system safety compliance
approach may not be appropriate. Examples of such failures include
engine rotor non-containment and fire. Therefore, the FAA does not
adopt Textron's recommendation to withdraw proposed Sec. 23.910.
Garmin commented that proposed Sec. 23.910(b) seemed highly
subjective and recommended eliminating paragraph (b).
The FAA notes Sec. 23.2410(b) requires consideration of failures
affecting passenger safety such as a fan disconnect on fuselage
embedded engines or exhaust heat exchanger failures that may allow
hazardous fumes to enter the occupant compartment. The FAA finds
withdrawing paragraph (b) would eliminate the requirement for an
applicant to assess potential causes of serious injury to airplane
occupants. Additionally, it serves as the underlying requirement for
the development of a more-detailed means of compliance. Therefore, the
FAA adopts the language in Sec. 23.2410(b) as proposed.
ANAC observed that there is no requirement in proposed Sec. 23.910
to ensure powerplant-driven components, necessary for airplane
operation, are suitable for installation in airplanes certificated
under part 23, and the powerplant installation requirement in proposed
Sec. 23.900 (now Sec. 23.2400) is related only to components that
affect propulsion safety. ANAC noted the rule does not capture the
design precautions established in the former Sec. Sec. 23.933 and
23.1155. The commenter also asserted that while proposed Sec. 23.910
addresses hazard mitigation in the event of powerplant systems failure,
compliance with proposed Sec. 23.910 for turbine engines would be
directly related to protection against inadvertent thrust reverser
deployment.
The FAA notes ANAC's concerns; however, as discussed in the
preamble for Sec. 23.2400, the FAA has added paragraph (e) to Sec.
23.2400 to address powerplant component installation. Additionally, the
FAA addresses the design precautions of former Sec. Sec. 23.933 and
23.1155, which provided reversing system requirements for turbojets,
turbofans, and propellers, in the performance-based requirements
contained in Sec. 23.2420, ``Reversing systems'' (proposed as Sec.
23.920).
d. Automatic Power or Thrust Control Systems (Proposed Sec. 23.915/Now
Sec. 23.2405
In the NPRM, proposed Sec. 23.915 (now Sec. 23.2405) would have
required a power or thrust augmentation system that automatically
controls the power or thrust on the operating powerplant to provide an
indication to the flightcrew when the system is operating, provide a
means for the pilot to deactivate the automatic functions, and prevent
inadvertent deactivation.
Textron commented the requirements of proposed Sec. 23.915 could
easily be addressed by revising proposed Sec. 23.900 to state that
state an automatic power reserve (APR) system that automatically
advances the power or thrust on the operating engine(s), when any
engine fails during takeoff, must comply with the applicable
requirements of the subpart. Textron noted that this language is
included in Appendix E of the Part 23 ARC Report. Also, Textron
recommended deleting the prescriptive requirement in proposed Sec.
23.915(a) for the system to provide an indication that it is operating,
stating that such a requirement and other high level requirements are
redundant.
[[Page 96637]]
The FAA finds the adoption of the proposed Part 23 ARC language, as
recommended by Textron, would limit the scope of this rule to existing
APR type systems. The FAA also finds the intent of the ARC language is
better captured in this rule, which can apply to a wider range of
potential future automatic power or thrust control systems. The FAA
partially agrees with the commenter's request to remove the requirement
for annunciation from proposed Sec. 23.915(a). Although the proposal
did not specifically state there must be an annunciation of the
system's status, it did require the system to provide an indication of
the status. The proposal has been revised to require a means to
indicate the system is in an operating condition. The FAA finds this
revision will provide applicants with more flexibility in designing a
system to provide the flightcrew with information regarding the
operational status of this critical safety system.
ANAC stated the proposed requirements of this section are too
prescriptive and the requirements of proposed Sec. Sec. 23.1310,
23.1500, and 23.910, which address system reliability, status
monitoring, flightcrew interface, and warning indications, provide
equivalent requirements that eliminate the need for a specific
regulation to address APR systems.
The FAA does not find the provisions of proposed Sec. 23.915 are
adequately addressed by the requirements in proposed Sec. 23.900. The
requirements in Sec. 23.2405 (proposed Sec. 23.915) provide
additional specific requirements the FAA considers necessary for the
certification of APR systems in airplanes. The FAA does not find the
requirements of Sec. 23.2400 (proposed Sec. 23.900) alone would
adequately address the requirements necessary for approval of an
automatic power control system. The specific requirements in the rule
for the system to provide indication to the flightcrew that it is
operating are necessary given the critical nature of both existing and
future APR systems that may vary thrust or power to provide airplane
control during the failure of an engine. In response to ANAC's comment
that Sec. 23.915 could be replaced with a more general rule covering
system reliability, crew interface, monitoring, and warning, the FAA
finds attempting to address too many systems under a general system
safety requirement may result in the excessive application of non-
standard performance requirements across the industry. Accordingly, for
systems where basic performance requirements can be established,
without requiring specific knowledge of the system's design, those
requirements will be contained in a specific rule. This concept is
further discussed under Sec. 23.2420.
EASA suggested the FAA address auto power control systems and
reverser systems (proposed Sec. Sec. 23.915 and 23.920) in a single
requirement that would address other systems such as those that use
asymmetric thrust to provide directional control. EASA recommended
changing the title of the proposed section to ``Propulsion Augmentation
Systems'' to ensure systems that augment propulsion in any direction
(drag, thrust, direction, lift) are addressed.
The FAA notes the basic performance requirements for automatic
power control systems are different from those required for reverser
systems. Additionally, the FAA also notes adopting the term
``augmentation'' implies that only a system's use of additional thrust
or power would be addressed, whereas systems are envisioned that may
also reduce power on an operating propulsion system or use aerodynamic
means to respond to power or thrust abnormalities. The FAA considers an
automatic power or thrust control system to be a system that
automatically intervenes and provides direct or modified control to
each engine, leaving the pilot indirectly in control or possibly not in
control for an automatic recovery type function. Reversing systems
simply change the direction of thrust or power at the direct control of
the pilot. As these systems are significantly different, the FAA has
determined it is necessary to retain a specific section for both
automatic power or thrust control systems and reversing systems.
The FAA reviewed the draft language of CS 23.2405, Propulsion
augmentation systems, and found it directly applicable to automatic
power or thrust control systems. Its provisions also address many of
the commenters' concerns, especially with respect to the certification
of airplanes with advanced automatic control systems. This language is
consistent with, but less prescriptive than, the requirements of former
appendix H to part 23. Accordingly, the FAA revises proposed Sec.
23.915 by adopting the language from CS 23.2405(b) through (e) in Sec.
23.2405(a) through (d).
Textron noted it was unclear if the proposed rule was attempting to
address ``auto throttle'' applications exclusively.
The FAA did not intend proposed Sec. 23.915 to address
autothrottle or autothrust systems unless the system has the capability
to command a change to power or thrust that is not directly commanded
by movement of the primary power setting control. Such a system might
vary power on multiple powerplants to maintain level flight or add
thrust beyond that commanded by the throttle when an engine failure is
detected.
Garmin and the Associations suggested eliminating proposed Sec.
23.915(b). Garmin stated that emerging technology may include systems
that have sufficient design integrity and provide enough safety benefit
that permitting deactivation as required by proposed Sec. 23.915(b)
could have the unintended effect of reducing safety. The Associations
noted in the event the automatic power control systems of less
reliability are used, compliance with proposed Sec. 23.910 should
result in designs that achieve the risk mitigations intended by the
requirements of proposed Sec. 23.915(b).
The FAA agrees that requiring a means for a pilot to deactivate the
automatic function may have an adverse effect on safety. The FAA also
agrees emerging technology may result in the development of a system
with sufficient integrity the flightcrew does not directly control the
thrust of each engine, but rather the power control system takes
commands from the flightcrew and automatically controls each engine to
execute that command, in both normal conditions and in the event of a
failure of an engine. Accordingly, the FAA revises the rule to account
for the possibility of a broader range of automatic power or thrust
control systems and has removed the requirement for pilot deactivation
of the automatic function of these systems where a system failure is
shown to be extremely remote. The type of system that would have this
level of authority is envisioned to be similar to an automated flight
control or fly-by-wire system, and an applicant would be expected to
show the system has sufficient design integrity to meet this standard.
To provide applicants with greater design flexibility, the FAA also
revises the proposal to require the flightcrew to be able to override,
rather than deactivate systems with lower design integrity. It is
intended this requirement will apply to those systems whose failure can
be reasonably detected by the flightcrew and for which overriding the
automatic function would not have an adverse effect on safety. Such a
situation typically exists with traditional automatic power reserve
systems.
ANAC suggested the requirement to maintain the maximum thrust/power
increment limit be specifically retained in the regulation and not
serve as a possible means of compliance. ANAC
[[Page 96638]]
believes that although it is arbitrary, the 10 percent limit for the
APR is considered in the current regulation to be a straightforward and
acceptable decrement from a safety standpoint in limiting both runway
critical takeoffs and degradation of all-engine climb performance
factors that are not addressed by former part 23 Appendix H, paragraphs
H23.4(b) and (c).
The FAA notes any automatic power or thrust control system will be
required to meet all applicable regulations including Sec. 23.2415,
which requires that failures that would prevent continued safe flight
not result from a single failure or from a likely combination of
failures. In addition, the FAA notes that takeoff performance is
determined considering a critical loss of thrust. Although the 10
percent value referred to by ANAC may be considered an arbitrary limit
on the additional thrust that can be provided by an APR system, the FAA
considers it unlikely an APR design would be proposed that reserves a
significant amount of thrust for use only in the event of an engine
failure during takeoff. Yet given the broader scope of this rule,
limiting automatic power control thrust to 10 percent may not
realistically permit system designs intended to augment lift, control,
or stability through the propulsion system. Therefore, the FAA has
decided not to include the 10 percent limit in the rule.
Kestrel questioned whether the proposed section would permit
alternate automatic power control systems (such as those without thrust
lever drivers) that could meet the intent of proposed Sec. 23.1500
(now Sec. 23.2600) without an ELOS finding or an issue paper. Kestrel
noted former Sec. 23.779 requires commanded engine thrust and actual
engine thrust agree, which the commenter said has historically been
accomplished by the thrust levers being mechanically driven to the
actual engine thrust position.
The FAA notes that Sec. 23.2600 does not specifically require a
throttle lever, only powerplant controls. Therefore, if a design were
proposed that allowed a qualified flightcrew member to perform all
tasks associated with the intended powerplant control functions, an
ELOS finding would not likely be required to obtain approval of that
automatic power control system.
NJASAP supported the language of proposed Sec. 23.915 and noted
automatic power control system technology will be available to more
airplanes in lower certification categories in the not-too-distant
future.
e. Reversing Systems (Proposed Sec. 23.920/Now Sec. 23.2420)
In the NPRM, proposed Sec. 23.920 (now Sec. 23.2420) would have
required an airplane to be capable of continued safe flight and landing
under any available reversing system setting.
Textron stated the proposed language is too ``high-level'' and does
not provide adequate performance-based requirements for an applicant to
show compliance with the rule. Textron also stated the rule was ``a bit
severe'' and noted the rule could be interpreted to mean that a single-
or multiengine turboprop may now need a reverser lock out system for
flight. Textron also claimed the flight testing required to demonstrate
compliance with the proposed requirement may be complicated and
dangerous. To address its concerns, Textron recommended using the
language from CS 23.505.
Air Tractor commented that it seems impossible to expect an
airplane to be capable of safe flight and landing with application of
full reverse thrust. Air Tractor suggested the proposed language
expected the airplane to ``know'' the difference between a pilot
command for reverse thrust when the airplane is on the ground versus
when it is in air, and to overrule the pilot command if the airplane is
still flying. Air Tractor observed that while this might be an easy
control issue when combined with a squat switch, many airplanes with
spring steel fixed landing gear do not have squat switches. Air Tractor
also noted that it has not been a safety issue to have reverse thrust
capability on certain types of single-engine turboprop airplanes, all
of which employ multiple means to prevent inadvertent selection of the
reverse range and warn when that range is selected.
The Associations noted the proposed rule could be misconstrued to
indicate the FAA will no longer permit throttle gates, which are
traditionally used on turboprop designs. The commenters contended this
would necessitate the development of weight on wheels lockouts and
other complex designs that were not required by the former rule, and
for which there is no measurable safety data to indicate this was an
area of safety concern. The commenters recommended revising the rule to
state the airplane must be capable of safe flight and landing under any
``easily selectable'' reversing system setting, rather than ``any
available'' reversing system setting.
ICON asked for clarification as to whether proposed Sec. 23.920
was intended to mean that if a reversible pitch setting exists on a
propeller, an airplane must be able to continue flight even with
selection of full reverse pitch. ICON also believed the proposed rule
could be interpreted to require a demonstration of safe flight and
landing at full reverse power.
The FAA notes that numerous commenters expressed concern with the
proposed requirement that the airplane must be capable of continued
safe flight and landing under any available reversing system setting.
The FAA recognizes this language did not account for many airplane
designs that do not incorporate a system that detects when the airplane
is on the ground, which can be used to lockout or prevent manual
inflight reversal. Additionally, the FAA recognizes the proposed rule
did not provide a basic performance requirement to ensure safe
operation of the reverser system under normal operating conditions, and
the airplane is capable of continued safe flight and landing after
failures of the reversing system.
As explained in the NPRM, proposed Sec. 23.920 (now Sec. 23.2420)
was intended to capture the safety intent of former Sec. 23.933(a) and
(b). Therefore, given the variety of the commenters' concerns, the FAA
revises proposed Sec. 23.920 based on former Sec. 23.933 to address
the comments. The FAA intends Sec. 23.2420 to address the requirements
for propeller, turbojet, and turbofan reversing systems specified in
former Sec. 23.933. Section 23.2420 now requires each reversing system
to be designed so that the airplane is capable of continued safe flight
and landing after any single failure, likely combination of failures,
or malfunction of the reversing system. This rule accounts for existing
reversing system designs that use a mechanical throttle gate to prevent
inadvertent in-flight reversing system operation that could result in
an unsafe condition. For turbofan or turbojet engine reversing systems
intended for ground use only, the FAA notes that a reverser lock out
system for flight is not specifically required by the rule. However,
the FAA expects that in the event of an inflight reverser deployment,
the engine will revert to idle thrust, and the reverser can be restowed
as required by former Sec. 23.933(a)(1). The FAA also notes that Sec.
23.2420 should result in the inclusion of these features in airplane
designs, as the FAA finds they are currently the only likely means to
prevent the occurrence of an unsafe condition and permit continued safe
flight and landing after a failure resulting in a reverser deployment
in flight. In addition to basing the revisions to the proposed rule on
former Sec. 23.933(a)(1) and (b) for ground use only reversing
systems, the
[[Page 96639]]
FAA has included in Sec. 23.2420(a) the requirement from former Sec.
23.933(a)(2) for reversing systems intended for use in-flight that no
unsafe condition result during normal operation. The FAA finds this
action responds to commenters' concerns and will readily permit future
approval of systems intended for use in-flight, which incorporate new
technology.
Regarding Textron's recommendation that the FAA adopt requirements
for reversing systems proposed by EASA in CS 23.505, proposed CS 23.505
combines requirements for reverser systems, thrust augmentation
systems, and automatic power controls in a single regulation. For the
reasons discussed in responding to this comment in the context of Sec.
23.2405, the FAA determines the requirements for a reversing system
should remain separate from those for thrust augmentation or automatic
power or thrust control systems (referred to as automatic power reserve
systems in former regulations), and that the basic performance
requirements for these systems are significantly different.
Additionally, Sec. 23.2405, ``Automatic power or thrust control
systems,'' applies to future systems that may automatically adjust
thrust to manage airplane control and stability. Such a system might
operate upon a single command from the flightcrew and automatically
manage multiple powerplants to perform a requested action. For this
type of system, in-flight reversing of a particular propulsion unit may
occur (as commanded by a flight management system) even though the
flightcrew may not have specifically requested application of reverse
thrust. For certification of this type of system as part of an
airplane's design, the FAA envisions the requirements of both
Sec. Sec. 23.2420 and 23.2405 will apply.
Both Embraer and Garmin expressed concern the proposed requirement
would not permit the use of a system safety approach for a reverser
system under certain conditions that may prevent continued safe flight
and landing, as long as those conditions are shown to be extremely
improbable. Embraer recommended replacing the phrase ``under any
available reversing system setting'' in proposed Sec. 23.920 with the
phrase ``at normal operating conditions and the failures not shown to
be extremely improbable.'' Garmin recommended revising the proposed
rule to permit the use of a safety analysis to demonstrate that certain
conditions, which would potentially prevent safe flight and landing,
are extremely improbable.
In response to Garmin's and Embraer's concern, the FAA notes that
Sec. 23.2420, as revised, permits the use of a system safety approach
for certification of an airplane with a reverser system.
NJASAP believed a thrust reverser must have an override or the
ability to emergency stow in the unlikely event of inflight deployment.
The FAA notes NJASAP's recommendation to reintroduce the
requirement to stow reversers after inadvertent deployment; however,
specifically requiring a system to have the capability to restow a
reverser in-flight may limit or prevent the certification of certain
acceptable reversing system designs. As noted in Garmin's comment, for
a reverser system that cannot be shown to result in safe flight and
landing of the airplane after an in-flight deployment, an applicant may
include a robust control and monitoring system in its design that could
be shown to make an in-flight deployment extremely improbable and not
resulting from any single failures. Including this capability could
prevent the system from complying with the requirement that no single
failure prevent continued safe flight and landing.
f. Powerplant Operational Characteristics (Proposed Sec. 23.925/Now
Sec. 23.2425)
In the NPRM, proposed Sec. 23.925 (now Sec. 23.2425) would have
required the powerplant to operate at any negative acceleration that
may occur during normal and emergency operation within the airplane
operating limitations. Proposed Sec. 23.925 would have required the
pilot to have the capability to stop and restart the powerplant in
flight. Proposed Sec. 23.925 would have also required the airplane to
have an independent power source for restarting each powerplant
following an in-flight shutdown.
Embraer commented that although the preamble indicated that
proposed Sec. 23.925 intended to address the requirements of former
Sec. 23.939(a) and (b), proposed Sec. 23.925 did not appear to
require evaluation of traditional operational characteristics and did
not address the adverse effects evaluation of air inlet distortion,
powerplant handling, operating characteristics, and other adverse
effects of an installed engine or power unit. Textron and ANAC had
similar concerns. Embraer recommended the FAA revise proposed Sec.
23.925(a) to require the powerplant handling and operating
characteristics to be investigated in flight to determine that no
adverse characteristics are present, to a hazardous degree, during
normal and emergency operation within the range of operating
limitations of the airplane and of the aircraft power unit. Textron
also noted the intent of former Sec. 23.939 was to require
demonstration of proper operation of the powerplant, as installed.
Textron stated it was inappropriate to claim that the tests necessary
to meet part 33 requirements will demonstrate proper operation of the
powerplant as installed, which the NPRM preamble seemed to imply.
Textron also suggested engine vibration requirements be incorporated
into Sec. 23.2425.
Additionally, ANAC stated that proposed Sec. 23.910 addressed
hazard mitigation in powerplant failure conditions and proposed Sec.
23.900 addressed ``likely hazards in operation.'' ANAC noted the term
``hazards in operation'' might be construed to mean external threats to
the engine from foreign object ingestion or a crosswind, causing
confusion for applicants seeking to meet the proposed requirements and
making it difficult to accurately interpret proposed Sec. 23.925. To
remedy this concern, ANAC recommended that proposed Sec. 23.925
include a requirement for an applicant to demonstrate the proper
functioning of the powerplant in normal operation within the range of
operating limits of the power unit.
In light of these comments, the FAA revises proposed Sec.
23.925(a) (now Sec. 23.2425(a)) to require the installed powerplant to
operate without any hazardous characteristics during normal and
emergency operation within the range of operating limitations for the
airplane and the engine. The FAA finds this change from what was
proposed indicates that evaluation of all traditional operational
characteristics required by former regulations is also required by
Sec. 23.2425(a). The FAA has added the term ``installed'' before
``powerplant,'' in response to Textron, to clarify that Sec.
23.2425(a) applies to the operation of the powerplant, as installed.
The FAA notes if the installation of powerplant components do not
remain within established limits, Sec. 23.2400 requires any deviation
from the component limitations or installation instructions must be
shown to not create a hazard. Additionally, the requirement to evaluate
the powerplant installation for vibration and fatigue characteristics
is contained in Sec. 23.2400.
Textron also recommended the FAA revise proposed Sec. 23.925(a) to
require the powerplant to operate at any condition, including negative
acceleration. The Associations suggested the FAA remove the term
[[Page 96640]]
``negative acceleration'' from paragraph (a) and replace it with
``acceleration or deceleration.''
In response to Textron and the Associations, the FAA has removed
the term ``negative acceleration'' from the regulation because the more
general reference to ``normal and emergency operation'' in the revised
language includes ``negative acceleration.'' Additionally, the FAA
notes that Sec. 23.2400(c) requires an applicant to construct and
arrange each powerplant installation to account for likely operating
conditions and likely hazards in operation. This requirement addresses
all components and systems that comprise the powerplant installation,
such as the oil and fuel systems, and establishes a requirement for the
applicant to address all likely conditions and hazards, which may not
be specifically encountered in the approved operating envelope. The
original intent of former Sec. 23.943 was to ensure no hazardous
condition resulted when a powerplant or APU is exposed to negative
accelerations expected in flight. The FAA finds that Sec. 23.2425(a),
together with Sec. 23.2400(c), adequately address this need.
The Associations also submitted comments regarding proposed Sec.
23.925(c), which would have required an airplane have an independent
power source for restarting the engine after an in-flight shutdown.
These commenters contended the FAA's intent in drafting Sec. 23.925(c)
was to ensure that engines can be reliably restarted in flight
following an in-flight shutdown. However, these commenters noted while
an independent power source may be an adequate solution for some
designs, there are many designs for which an independent power source
would be inappropriate. For example, the Associations stated that
electric propulsion systems may include a single power source that
manages many cells, which start and stop in flight, but will not have
independent sources of power to restart them. As written, the
commenters suggested proposed Sec. 23.925(c) could be interpreted to
require that a two[hyphen]engine airplane needs three batteries for
restarting (one main and an independent source for each powerplant). To
address these concerns, the commenters recommended the FAA require the
airplane to have a ``reliable'' power source, rather than an
``independent'' power source.
Textron, Garmin, and an individual commenter had similar concerns
regarding proposed Sec. 23.925(c). Garmin recommended either
withdrawing proposed Sec. 23.925(c) or clarifying its intent. Textron
commented that proposedSec. 23.925(c) was ``too high level'' and did
not provide adequate performance-based requirements for an applicant to
demonstrate compliance. Textron recommended the FAA revise proposed
Sec. 23.925(c) based upon language contained in appendix E of the
ARC's final report.'' The individual commenter noted that proposed
Sec. 23.925(c) would appear to require multiengine airplanes to have
multiple and possibly duplicate electronic distribution systems for in-
flight restarts by battery power. The commenter suspected this was an
unintended expansion of the requirements of former Sec. Sec. 23.903(g)
and (or alternatively) Sec. 23.1165. The commenter stated this
unintended consequence would impose cost and weight penalties beyond
former part 23 requirements, which the commenter maintained were not
addressed in the regulatory analysis or the preamble to proposed Sec.
23.925(c), or otherwise justified by service experience. The individual
commenter recommended the FAA either withdraw proposed Sec. 23.925(c)
or clarify its intent.
In response to the significant number of comments the FAA received
regarding the proposed requirement that each airplane have an
independent power source for restarting the engine after an in-flight
shutdown, the FAA withdraws Sec. 23.925(c). The FAA's intent in
drafting proposed Sec. 23.925(c) was to ensure a power source,
independent from any power generated by a particular engine shutdown in
flight, be available for restarting the powerplant. This requirement
was originally adopted as former Sec. 23.903 to address ignition
systems on turbine engines and to ensure a source of ignition energy
for in-flight engine restarting exists in the event of a loss of
combustion in all engines during flight. The requirement in Sec.
23.2425(b), which requires the pilot have the capability to stop the
powerplant in flight and restart the powerplant within an established
operational envelope, establishes the performance-based requirement the
prescriptive requirements of proposed Sec. 23.925(c) were intended to
address. The FAA's intent was not to require redundant electrical
power; rather, the intent was to require power independent from that of
the engine-driven electrical power generating system to be available if
insufficient power was available at the minimum windmilling restart
speed. If an engine power generating system is capable of providing
sufficient power to operate all required systems at the minimum
windmilling restart speed, or in a normal shutdown state, an
independent power source would not be required.
In recognition that an aircraft engine may not be able to be
restarted within an airplane's entire flight envelope, the FAA revises
proposed Sec. 23.925(b) (now Sec. 23.2425(b)) to require restart
capability within an established operational envelope, which in
accordance with Sec. 23.2620 (proposed as Sec. 23.1510), must be
documented in the AFM.
g. Fuel Systems (Proposed Sec. 23.930/Now Sec. 23.2430)
In the NPRM, proposed Sec. 23.930 (now Sec. 23.2430) would have
required that each fuel system provide an independent fuel supply to
each powerplant in at least one configuration and avoid ignition from
unplanned sources. It would have required that each fuel system provide
the fuel required to achieve maximum power or thrust plus a margin for
likely variables in all temperature conditions within the operating
envelope of the airplane and provide a means to remove the fuel from
the airplane. Finally, proposed Sec. 23.930 would have required each
fuel system to be capable of retaining fuel when subject to inertia
loads under expected operating conditions and prevent hazardous
contamination of the fuel supply.
The Associations asserted that proposed Sec. 23.930 does not
permit the certification of electric propulsion systems. These
commenters recommended the FAA delete the word ``fuel'' from the title
of proposed Sec. 23.930 and adopt the provisions of proposed CS
23.530. Additionally, the commenters suggested replacing ``fuel'' with
``energy'' to clarify the requirements of this regulation are
applicable to all energy sources and not just traditional petroleum-
based fuels.
EASA, while recognizing that the term ``fuel'' covered other energy
sources, stated it believed a more independent set of design
requirements would be needed to address all energy systems, rather than
those that are more appropriate for propulsion systems and APUs.
Additionally, EASA specifically recommended adoption of its set of
requirements for energy supply systems, set forth in A-NPA 2015-06,
which provided useful requirements for a variety of systems, including
fuel, electric, and hybrid systems. EASA also noted that its A-NPA
2015-06 created several new subparagraphs to address particular
functions of an energy system.
The FAA did not intend to preclude the certification of electric
propulsion systems or other non-fossil-fuel-based propulsion systems in
part 23. The FAA
[[Page 96641]]
agrees the use of the term ``fuel'' rather than the term ``energy''
could lead individuals to reach this conclusion. However, the FAA is
concerned that adoption of the term ``energy'' in this rule, and
throughout this subpart, could lead to confusion, because the term
``energy'' is used in numerous regulations and in guidance material to
address requirements for other systems and components (i.e., braking
systems and rotating machinery) and also to describe environmental
conditions (i.e., those involving lightning). Therefore, the FAA
retains the term ``fuel'' in the regulation, but notes the term
``fuel'' in this subpart includes any form of energy used by an engine
or powerplant installation, such as provided by carbon-based fuels or
electrical potential. Fuel systems will also include the means of
energy storage for the power provided (i.e., batteries that provide
power to an electric motor) or devices that generate power for
propulsion (i.e., solar panels or fuel cells). Furthermore, while the
FAA agrees with many of the provisions proposed by EASA, the FAA is
electing to retain the requirements for energy systems under a single
section, titled ``Fuel system.'' While Sec. 23.2430 and EASA's
proposed language may not be identical, the FAA finds Sec. 23.2430
harmonizes with the intent of EASA's requirements.
The FAA notes EASA's recommendation to adopt EASA's proposed
language to address powerplant support systems to replace its current
regulatory requirements for induction and exhaust section systems. The
FAA has decided to retain a specific section to address powerplant
induction and exhaust systems. The FAA will address future energy
systems that incorporate systems such as converters or battery cooling
as part of the powerplant installation. The FAA notes the requirements
for those future systems will be adequately addressed in Sec. Sec.
23.2400, 23.2410, and 23.2430.
ANAC stated that proposed Sec. 23.930 does not address the
requirements of former Sec. 23.951(d), which required fuel systems for
turbine engine airplanes to meet the fuel venting requirements of part
34. ANAC stated the former requirement applied to airplanes and not
engines, and should therefore be specifically included in the rule.
ANAC also recommended the reference in the former rule to part 34,
which prevents intentional fuel venting, be included in the new rule.
The FAA notes part 23 historically provided only a reference to
part 34, and those requirements continue to remain applicable to the
certification of any airplane. Sections 21.17 and 21.101 require part
34 to be always included in the certification basis of airplanes.
Requirements such as fuel venting will therefore continue to apply to
the certification of these airplanes.
Textron suggested deleting the term ``avoid'' and inserting the
phrase ``prevent hazardous'' in proposed Sec. 23.930(a)(2), which
addressed the avoidance of ignition from unplanned sources. Textron
noted that using the term ``prevent'' would be consistent with the use
of the term in other sections of part 23.
An individual commenter also raised concerns about the undefined
term ``avoid'', and questioned whether the term was an absolute,
probability, or minimize requirement, or whether it covers single or
multiple failures. Presuming the proposed requirement covered fuel
ignition by lightning strikes addressed in former Sec. 23.954, the
commenter requested the proposed rule not be more stringent than the
former rule, which imposes an absolute requirement to prevent ignition
hazards but only for certain types of strikes and strike locations. The
commenter noted the FAA did not discuss the rationale, interpretation,
or intent of this requirement in the NPRM preamble. The commenter also
noted that the draft ASTM standard was identical to former Sec.
23.954, and remarked that it was unclear why proposed Sec. 23.910 did
not address this requirement. The commenter agreed with Textron and
recommended inserting the term ``hazardous'' before ``ignition'' in
paragraph (a)(2) to better clarify the proposed requirement.
Embraer and other commenters raised concerns about use of the term
``unplanned sources'' in proposed Sec. 23.930(a)(2). Embraer noted
there are no ``planned'' ignition sources, making compliance with the
rule impossible. Embraer proposed revising the requirement to account
for ignition sources not shown to be extremely improbable, and proposed
the rule require that each fuel system be demonstrated that it is
designed and arranged to prevent catastrophic ignition from sources not
shown to be extremely improbable; taking into account flammability,
critical lightning strikes, and failures within the fuel system.
Textron noted the NPRM preamble discussion for ``unplanned sources'' or
``unknown sources'' was impossible to design for because it was too
vague.
The FAA agrees the proposed requirement for unplanned sources was
vague and could result in numerous interpretations. Section
23.2430(a)(2) is intended to prevent catastrophic effects resulting
from ignition of an airplane's fuel source due to lightning, or from
corona or streamering at fuel vent outlets, as former Sec. 23.954
required. It is not intended to impose additional requirements to
protect the fuel system from other ignition sources. The FAA revises
Sec. 23.2430(a)(2) based upon former Sec. 23.954 to more accurately
convey this requirement and to ensure its application to any fuel used
to power an airplane. This revision also addresses the commenters'
concerns regarding the meaning of ``avoid'' and ``unplanned sources''
by using the phrase ``prevent ignition'' and by enumerating the
specific ignition sources that must be addressed.
Embraer also stated the phrase ``margin for likely variables'' in
proposed Sec. 23.930(a)(3) could generate confusion as to what margins
must be observed when providing the fuel required to provide maximum
power or thrust. The commenter explained that ``margin'' is usually
used to define a rate higher than what is required for an engine's
proper operation in the expected envelope and for the expected life of
operation, but stated the meaning of the term ``likely variables'' is
not clear. The commenter noted that the former rule considered a
determination of the worst fuel rate for proper operation. Embraer
suggested using text similar to that found in former Sec. 23.951(a).
The FAA agrees with Embraer's comment that proposed Sec.
23.930(a)(3) could generate confusion as to what margins must be
observed when providing the fuel required to provide maximum power or
thrust. Therefore, the FAA revises paragraph (a)(3) to require the fuel
system provide fuel necessary to ensure proper operation of each
powerplant and APU, in all likely operating conditions. This
requirement ensures adequate fuel can be provided for proper operation
of any powerplant or APU. The FAA notes an applicant's means of
compliance with this requirement should consider the worst case
conditions for fuel flow, including any additional demand due to
expected efficiency losses, consumption by other systems, or secondary
requirements such as engine cooling.
Embraer stated that it understood proposed Sec. 23.930(a)(4)
required a means to remove fuel and referred to fuel storage.
Therefore, Embraer suggested the FAA move the requirement in proposed
paragraph (a)(4) to Sec. 23.930(b), which addressed fuel storage
systems. Embraer suggested that the cross-reference table be updated
[[Page 96642]]
accordingly for former Sec. 23.971 and Sec. 23.999.
An individual commenter requested the proposed regulations include
a requirement for determining or indicating usable or unusable fuel or
energy quantities, as was formerly required. This commenter noted that
because fuel starvation is ``always'' cited as one of the top reasons
for off-field landings in general aviation accidents, it should be
adequately addressed by a specific performance requirement in part 23.
The FAA agrees with the recommendation to add a requirement to the
final rule to ensure the flightcrew is provided with information on the
total useable fuel available. The FAA adds this requirement as Sec.
23.2430(a)(4), corresponding to the requirement in former Sec.
23.1337(b), which required a means to indicate to the flightcrew
members the quantity of usable fuel in each tank. The intent of this
revision is to require applicants to both determine the usable quantity
of fuel that can be stored and provide information to the flightcrew
regarding the remaining useable fuel in the airplane.
The FAA has decided not to move proposed paragraph (a)(4) as
Embraer suggested. Since different types of fuel systems could be
certificated under the rule, the FAA has added the term ``isolate'' in
Sec. 23.2430(a)(5). The FAA recognizes that certain fuel sources may
not be removable from the system, and that isolating the fuel from the
system will provide the appropriate minimum level of safety.
Additionally, the FAA clarifies Sec. 23.2430(a)(5) to require the
fuel system be designed to retain fuel under all likely operating
conditions and minimize hazards to the occupants during any survivable
emergency landing. The FAA also includes a requirement in Sec.
23.2430(a)(6) that these failures be taken into account, consistent
with former Sec. 23.967. For the certification of level 4 airplanes,
the paragraph also provides that any failure due to an overload of the
landing system is taken into account in airplanes equivalent to those
currently certificated in the commuter category, consistent with former
Sec. 23.721.
An individual commenter asked the FAA to revise proposed Sec.
23.930(a)(6), which would require the fuel system prevent hazardous
contamination of the fuel supply, to specify that the requirement was
intended to prevent hazardous contamination of fuel delivered to
engines. The commenter noted this revision was necessary if, as the
preamble indicated, this requirement replaces former Sec. 23.997. The
proposed requirement could be interpreted to require prevention of
contamination of fuel within the fuel tank, which would be more
stringent than the former rule and of questionable practicality. The
former rules only required removal of contamination from the fuel being
provided to the engine, and not necessarily from the fuel in the tank.
The FAA agrees with the commenter and revises Sec. 23.2430 to
require removal of hazardous contamination from the fuel supplied to
each powerplant and APU. This requirement is now in new Sec.
23.2430(a)(7).
Embraer recommended the FAA revise proposed Sec. 23.930(b)(1) to
require fuel storage systems to also withstand without failure, the
vibration, inertial loads, and pressures under expected operating
conditions.
The FAA agrees with Embraer that fuel storage systems must be able
to withstand loads and pressures under expected operating conditions
without failure and has added the term ``without failure'' to paragraph
(b)(1). However, the FAA does not add specific references to vibration,
inertia, fluid, and structural loads as the FAA believes the use of
``loads under likely operating conditions'' addresses all applicable
loads, including those resulting from vibration and other sources.
The FAA revises Sec. 23.2430(b)(2) to require the fuel storage
system be isolated from personnel compartments and protected from
hazards due to unintended temperature influences. The FAA recognizes
that it did not adequately address these requirements in the NPRM. This
revision addresses the requirements of former Sec. 23.967(c) and (d),
which restricted installation of fuel tanks around engine compartments
and firewalls, and required fuel systems to be isolated from personnel
compartments. It is also consistent with the provisions of CS
23.2465(b)(2), which requires each energy storage and supply system to
be installed in such a way to be protected against hazards due to
unintended temperature influence.
Air Tractor requested adding the term ``significant'' after
``prevent'' in proposed Sec. 23.930(b)(2). Embraer concurred with this
revision because it would allow for small amounts of fuel loss through
vent lines, such as when the tanks are full and there is normal
``sloshing'' during taxi or takeoff, or when fuel expands as it warms.
An individual commenter also requested revising proposed Sec.
23.930(b)(2) to specify the fuel storage system must prevent hazardous
fuel loss during maneuvers. The commenter believed the proposal would
require the prevention of even minor fuel loss from vents, which is
more stringent than the former standard. The commenter believed the
more stringent standard was of questionable utility and practicality,
and noted it was not justified in the preamble.
An individual commenter requested the FAA delete proposed Sec.
23.930(b)(3), which would require each fuel storage system to prevent
discharge when transferring fuel, because other proposed regulations
would address any potential hazards associated with fuel transfer. The
commenter further stated it was unclear if the proposed requirement
would apply to fuel returned from the engine to other than the
specified tank. This commenter explained that some multiengine
airplanes feature fuel-transfer cross feeding, which can result in a
fuel discharge if the receiving tank is full. This approach has both
advantages and disadvantages, but should not be prohibited by
regulation. The commenter also noted this proposal was not justified in
the preamble or addressed in the Regulatory Analysis, was more
stringent than the former rule, and would require additional hardware
or revised architecture for some designs.
The FAA agrees with the recommendation to delete the requirement in
proposed paragraph (b)(3) that each fuel storage system prevent
discharge when transferring fuel. The FAA recognizes it has approved
the design of certain fuel systems under former regulations that may
result in a non-hazardous discharge of small amounts fuel when fuel is
transferred between fuel tanks or fed from a specific fuel tank and
returned to another tank under certain conditions. To ensure the
continued acceptability of these systems under the new rule, the FAA
has combined proposed paragraph (b)(2) and (b)(3) into paragraph (b)(3)
in this final rule. Paragraph (b)(3) now requires the fuel system to be
designed to prevent significant loss of stored fuel from any vent
system due to fuel transfer between storage or supply systems under
likely operating conditions.
One commenter stated the proposed rule did not specifically address
the potential of water in the airplane's fuel system, and the commenter
proposed it should contain a requirement to include fuel tank water
sensors. The commenter noted that water accumulates in fuel tanks in a
number of ways, such as when temperature changes or when air enters a
tank from which fuel has been consumed.
The FAA notes the specific hazard associated with water in
petroleum-based fuels is addressed generally in
[[Page 96643]]
Sec. 23.2430(a)(7), which requires the prevention of hazardous
contamination of the fuel supplied to the powerplant. Additionally, the
FAA notes that a compound such as water may not necessarily be
considered a contaminant or hazard in certain future fuel systems. The
commenter's proposal would introduce specific language that may not be
appropriate for future fuel systems and has therefore not been adopted.
Finally, the FAA revises Sec. 23.2430(c) to remove the restrictive
language applicable only to pressure refueling systems. The rule now
applies to fuel storage refilling and recharging systems. This revision
will establish more appropriate requirements to accommodate the
introduction of new propulsion systems such as electric motors.
Accordingly, the FAA adopts performance-based requirements that will
require prevention of improper refilling or recharging, prevention of
stored fuel contamination during likely operating conditions, and the
prevention of the occurrence of any hazard to the airplane or to
persons during refilling or recharging.
h. Powerplant Induction and Exhaust Systems (Proposed Sec. 23.935/Now
Sec. 23.2435)
In the NPRM, proposed Sec. 23.935 (now Sec. 23.2435) would have
required the air induction system to supply air needed for each power
unit and its accessories under expected operating conditions, and
provide a means to discharge potential harmful material.
EASA recommended removal of the design-specific requirements in
proposed Sec. 23.935 because those requirements should be addressed as
a means of compliance. Textron requested a complete rewrite of proposed
Sec. 23.935, stating the section was ``too high level'' and did not
provide adequate performance-based requirements for an applicant to be
able to demonstrate compliance. Textron asked the FAA to derive the
language for proposed Sec. 23.935 from appendix E of the final Part 23
ARC Report.
The FAA notes EASA's recommendation to remove Sec. 23.935 based on
its contention the section appears to be a means of compliance instead
of a performance-based requirement. However, the FAA finds the
provisions of the rule set forth performance-based requirements for
induction and exhaust systems that are appropriate for inclusion in
this rule. Rather than stipulating a specific means of compliance,
these requirements serve as high-level performance-based requirements
for which a number of alternative means of compliance could be
developed by applicants.
The FAA partially agrees with Textron's comment that the rule is
``too high level.'' Accordingly, the FAA revises Sec. 23.2435 based on
the requirements for powerplant induction and exhaust systems contained
in former Sec. Sec. 23.1091, 23.1121, 23.1123, 23.1125, and the final
Part 23 ARC Report. Section 23.2435 now sets forth performance-based
requirements that encompass these prescriptive regulations and the Part
23 ARC's proposed requirements. The FAA notes while it is adding all of
the ARC's proposed requirements for exhaust and induction systems in
this rule, not all of its recommendations for revisions to this section
were appropriate. Some of the ARC's recommendations are more
appropriately addressed by other sections of this rule. For example,
the ARC's proposed requirement for the system that supplies air to the
cabin to prevent hazardous quantities of toxic gas from entering the
cabin is addressed by Sec. 23.2400(d) while the engine accessory
component cooling requirements are addressed by Sec. 23.2400(e), which
requires powerplant components to comply with their limitations and
installation instructions, or be shown not to create a hazard.
Embraer requested the FAA revise proposed Sec. 23.935 to clarify
the design and induction system must prevent distortion as described in
former Sec. 23.939(c). Embraer also recommended the FAA revise the
proposal to include a requirement that the air induction system for
each power unit and its accessories must not, as a result of airflow
distortion during normal operation, cause vibration harmful to the
power unit.
The FAA notes that former Sec. 23.939(c) addressed distortion as a
cause of vibration and required the air inlet not, as a result of
distortion during normal operation, cause vibration harmful to the
engine. Embraer's general concerns are addressed by Sec.
23.2435(a)(1), which requires the air induction system for each
powerplant or auxiliary power unit and its accessories to supply the
air required under likely operating conditions. Embraer's specific
concern that the air induction system not cause ``vibration harmful to
the power unit'' is addressed by the powerplant installation
requirements contained in Sec. 23.2400(c)(4), which requires the
applicant to ``construct and arrange each powerplant installation to
account for . . . vibration and fatigue,'' which occur as a result of
distortion.
Air Tractor and ANAC raised concerns about whether proposed Sec.
23.935(b) was intended to address exhaust systems or air induction
systems. Air Tractor stated it did not believe the FAA intended
proposed Sec. 23.935(b) to mandate the use of an inertial bypass
particle separator (as proposed Sec. 23.935(b) could have been
interpreted to require), and recommended the FAA clarify proposed Sec.
23.935(b) to indicate the requirement applies only to exhaust systems.
ANAC commented that proposed Sec. 23.935(b) should require the exhaust
system to ensure safe disposal of exhaust gases, as the former rule
required.
The FAA agrees with Air Tractor and ANAC's concern that proposed
Sec. 23.935(b) is unclear because it only appears to discuss induction
systems (whereas the title of proposed Sec. 23.935 includes exhaust
systems). Accordingly, the FAA has modified Sec. 23.2435 to clearly
indicate the requirements of paragraph (a) apply to induction systems
and the requirements of paragraph (b) apply to exhaust systems. This
makes it clear the rule does not require use of an inertial bypass
particle separator as a means for the induction system to discharge
potential harmful material.
If a complete rewrite of proposed Sec. 23.935 is not adopted,
Textron requested clarification as to whether the proposed requirements
were intended to address the cooling air requirements for powerplant
accessories in former Sec. Sec. 23.1041 through 23.1047, and the
intent of former Sec. 23.1091. If proposed Sec. 23.935 was intended
to match the provisions of former Sec. 23.1091, Textron commented that
the proposed section was adequate. However, if proposed Sec. 23.2435
was intended to address Sec. Sec. 23.1091 and 23.1041 through 23.1047,
Textron asked for clarification of the proposed section's requirements.
Textron also specifically recommended revising the regulatory text to
clarify the intent of the proposed requirements were ``to ensure proper
operation within established limitations'' of the air induction system
for each power unit and its accessories.
The FAA notes the engine cooling requirements are not specifically
addressed in Sec. 23.2435, other than in a requirement that the
induction system be designed to supply the air required by each
powerplant or auxiliary power unit and its accessories under likely
operating conditions. However, the powerplant cooling requirements are
addressed more directly by Sec. 23.2400(e), which requires powerplant
components to comply with their limitations and installation
instructions, or be shown not to create a hazard. This requirement
[[Page 96644]]
ensures an applicant addresses engine cooling.
Additionally, the FAA revises proposed Sec. 23.2435(b) to
specifically indicate exhaust systems include exhaust heat exchangers
for each powerplant or APU. Specifically referencing these systems as
part of the airplane exhaust system continues the FAA's practice of
applying exhaust system requirements to exhaust heat exchangers. The
FAA also revises requirements for exhaust systems by adding paragraph
(b)(2) to ensure these systems are designed to prevent likely hazards
from heat, corrosion, or blockage. These requirements address the
specific requirements of former Sec. 23.1121(a) and (h) and Sec.
23.1123(a).
i. Powerplant Ice Protection (Proposed Sec. 23.940/Now Sec. 23.2415)
In the NPRM, proposed Sec. 23.940 (now Sec. 23.2415) would have
required the airplane design to prevent foreseeable accumulation of ice
or snow that would adversely affect powerplant operation. Proposed
Sec. 23.940 would have also required the powerplant design to prevent
any accumulation of ice or snow that would adversely affect powerplant
operation, in those icing conditions for which certification is
requested.
Textron recommended withdrawing proposed Sec. 23. 940, as it
believed the requirement to protect engines could be adequately
addressed in proposed Sec. 23.910 by including language that would
ensure safe powerplant operation under all likely operating conditions
or enable satisfactory powerplant functioning in icing conditions.
Alternatively, Textron proposed consolidating the requirements of
proposed Sec. 23.940 by removing paragraph (b) and revising paragraph
(a) to require the airplane design prevent ``any accumulation''--rather
than ``foreseeable accumulation''--of ice or snow that adversely
affects powerplant operation in those icing conditions for which
certification is requested.
The FAA does not agrees that eliminating proposed Sec. 23.940 (now
Sec. 23.2415) and adding a requirement to proposed Sec. 23.910 (now
Sec. 23.2410) would result in designs that would prevent the
accumulation of ice or snow that could adversely affect powerplant
operations. Including Textron's proposed regulatory language in Sec.
23.2410 as part of the powerplant installation hazard assessment could
permit designs that only address ice accretion as part of a powerplant
installation assessment, and not airframe ice accretion that may pose
an ice shed hazard. Additionally, Textron's proposal could be
interpreted to only require the powerplant's performance be evaluated
for the environmental icing conditions for which certification is
requested, and not for other conditions that may be conducive to ice
accretion in reciprocating engine induction systems. In contrast, the
FAA finds Sec. 23.2415 establishes specific requirements that will
apply to all airplane designs, to include those for which certification
in icing conditions was not requested, and adds requirements that will
apply to powerplant designs for airplanes intended for certification
for flight in icing conditions.
The FAA also finds Textron's recommendation to revise proposed
Sec. 23.940(a) and withdraw paragraph (b) would specifically eliminate
the applicability of the requirement to the powerplant design. By only
setting forth a requirement for the airplane design and not the
powerplant design, Textron's proposed revision would neither ensure an
independent assessment of the adequacy of the engine design for icing
conditions, nor require an evaluation of the engine's tolerance for ice
ingestion. Additionally, it would not apply to propellers, which are
considered powerplant components. The FAA's intent in paragraph (b) is
to require an applicant to assess the adequacy of the engine's
certification basis for installation in an airplane, the engine's
service history of ice ingestion, and propeller design.
The FAA expects that an acceptable means of compliance would
specify an evaluation of the engine's tolerance for ice ingestion that
would not be limited to the conditions specified in part 25, appendix
C, and that such an evaluation would show that it meets, or exceeds,
those standards prescribed in former Sec. 23.903(a)(2).
Textron also commented that proposed Sec. 23.940 does not address
ice accretion that could affect the performance of cooling air inlets
for the engine and its accessories.
In light of Textron's comment, the FAA is adding the term
``installation'' to proposed Sec. 23.940(b) to clarify the regulation,
like former Sec. 23.929, applies to ``other components of complete
engine installations,'' which include cooling air inlets. Accordingly,
Sec. 23.2415(b) now requires the ``powerplant installation design'' to
prevent any accumulation of ice or snow that adversely affects
powerplant operation, in those icing conditions for which certification
is requested. This change from what was proposed is consistent with the
NPRM, which explained that powerplant design in proposed Sec.
23.940(b) refers to the engine, propeller, and other powerplant
components such as cooling inlets.
Additionally, the FAA is inserting the phrase ``including the
induction and inlet system'' after ``airplane design'' to clarify that
Sec. 23.2415(a) is intended to address the engine induction ice
protection requirements found in former part 23. This change from what
was proposed is consistent with the NPRM, which explained that the
airplane design in proposed Sec. 23.940(a) refers to the engine
induction system and airframe components on which accumulated ice may
shed into the powerplant. The FAA also reiterates that paragraph (a)
applies to all airplanes regardless of whether certification for flight
in icing conditions is sought, and requires applicants to address ice
accretion anywhere on the airplane that may pose a threat to the
powerplant if that ice is shed. ``Foreseeable'' accumulation of ice and
snow, rather than ``any'' accumulation as recommended by Textron, is
used in paragraph (a). The icing and snow conditions to be evaluated
are not simply the icing conditions for which the airplane is to be
certified, as in paragraph (b). For example, on non-icing certified
airplanes, conditions to be evaluated range from carburetor icing on
reciprocating powered airplanes to part 25, Appendix C icing on turbine
powered airplanes.
j. Powerplant Fire Protection (Proposed Sec. 23.1000/Now Sec.
23.2440)
In the NPRM, proposed Sec. 23.1000 (now Sec. 23.2440) would have
required a powerplant be installed in a designated fire zone and would
have required an applicant to install a fire detection system in each
designated fire zone for levels 3 and 4 airplanes. Proposed Sec.
23.1000 would have also required an applicant to install a fire
extinguishing system for levels 2, 3, and 4 airplanes with a powerplant
located outside the pilot's view that uses combustible fuel.
Additionally, proposed Sec. 23.1000 would have required each
component, line, and fitting carrying flammable fluids, gases, or air
subject to fire conditions to be fire resistant, except components
storing concentrated flammable material would have to be fireproof or
enclosed by a fireproof shield. Proposed Sec. 23.1000 would have also
required an applicant to provide a means to shut off fuel or flammable
material for each powerplant, while not restricting fuel to remaining
units, and prevent inadvertent operation.
EASA noted the proposed regulation contained too many design
details,
[[Page 96645]]
which are better addressed as means of compliance. EASA contended that
the sole objective of proposed Sec. 23.1000 should be to require a
means to isolate and mitigate hazards to the airplane in the event of a
powerplant system fire or overheat in operation.
Although the FAA concedes that some of the proposed requirements
are prescriptive in nature, the FAA has determined that inclusion of
these requirements for fire protection are critical to safety and
should be retained to prevent any potential degradation of safety.
Fire, while not a common occurrence, greatly reduces the likelihood of
survival when occurring in flight. Detection, isolation, and
extinguishing have historically provided an acceptable means for
mitigating hazards from powerplant-related fires. Accordingly, the
final rule retains what the FAA considers to be sufficient prescriptive
requirements to ensure the existing level of fire protection. In
response to EASA's comment, as discussed in more detail later, the FAA
has added a requirement in Sec. 23.2440(b), requiring each designated
fire zone provide a means to isolate and mitigate hazards to the
airplane in the event of a powerplant system fire or overheat.
Zee questioned whether the requirement in proposed Sec. 23.1000(a)
for all powerplants to be installed in a designated fire zone is
appropriate. The commenter noted electric propulsion systems can be
designed and installed with no flammable liquids or materials, thus
eliminating the need for fire protection. Zee requested the FAA revise
proposed paragraph (a) to indicate installation in a fire zone is not
required if not applicable. The Associations also recognized the same
issue and proposed revising the requirement to only apply to flammable
powerplant components. Embraer recommended the FAA delete proposed
Sec. 23.1000(a).
ANAC observed that the intent to define ``designated fire zones''
in the proposal is to identify areas of the airplane in which a high
degree of safety precautions must be taken, recognizing that fire will
occur in these regions because of the presence of both ignition sources
and flammable fluid. ANAC contended proposed Sec. 23.1000 could be
interpreted as the region where a powerplant is to be installed must
first be evaluated for ignition sources and flammable fluids. ANAC
noted the proposed requirement could also be interpreted as the
powerplant can only be installed in regions that already contain
ignition sources and flammable fluids. Embraer contended that former
Sec. 23.1181 defined the ``hot'' parts of an engine installation as
ignition sources, and considering that there are fuel, oil, and
hydraulic fluids being carried around such areas, they should be
considered fire zones. Thus the term ``designated'' would apply,
obviating further analysis.
The FAA has considered the comments regarding the requirement to
install all powerplants in proposed Sec. 23.1000(a) (now Sec.
23.2440(a)) in a designated fire zone. The FAA notes that while
virtually every kind of powerplant (to include electric motors) may
present a potential fire hazard, some types of powerplants may not
present a likely fire hazard or require installation in a designated
fire zone. Accordingly, the FAA revises Sec. 23.2440(a) to require a
powerplant be installed in a designated fire zone only if it includes a
flammable fluid and an ignition source for that fluid. The term
``flammable fluid'' includes any flammable substance such as liquids,
gases, or gels that are capable of flowing. This change is intended to
alleviate the need to install powerplants that do not present a likely
fire hazard in a designated fire zone. The FAA also adds the term
``combustion heater'' to Sec. 23.2440(a), which are required to be
located in designated fire zones under former Sec. 23.1181. The
devices were inadvertently omitted from consideration under the fire
and high-energy protection requirements of proposed subpart D.
ANAC noted the NPRM preamble discussion indicated that fire must be
evaluated in the powerplant installation hazard assessment required
under proposed Sec. 23.910. ANAC expressed concern the dedicated
requirement for powerplant fire protection in proposed Sec. 23.1000
could be interpreted to require evaluation of fire hazards beyond the
scope of proposed Sec. 23.910. ANAC recommended the FAA include a
requirement for a firewall that ensures a fire originating in any fire
zone will not be a hazard to the airplane.
The FAA did not intend to require the use of a hazard assessment
process in proposed Sec. 23.1000 (now Sec. 23.2440). The FAA notes
the purpose of the firewall discussion in proposed Sec. 23.1000 is to
determine if a particular component or system would need to be placed
in a designated fire zone. If a component is required to be located in
a fire zone by a rule other than Sec. 23.2410, such as Sec.
23.2440(a), that requirement must be complied with regardless of the
results of any hazard assessment. The FAA revises Sec. 23.2440(a) to
require that a powerplant, APU or combustion heater, that includes a
flammable fluid and an ignition source for that fluid, be installed in
a designated fire zone. In response to ANAC's recommendation to add a
requirement for a firewall that ensures a fire originating in any fire
zone will not be a hazard to the airplane, the FAA notes Sec.
23.2440(b) requires each designated fire zone provide a means to
isolate and mitigate hazards to the airplane in the event of a
powerplant system fire or overheat. Isolation of a designated fire zone
is typically accomplished by use of a firewall or other equivalent
means.
An individual commenter raised concerns that proposed Sec.
23.1000(b) fails to address critical fire protection requirements and
only requires components carrying flammable liquid to be fire
resistant. Specifically, the commenter noted that former Sec.
23.1141(f) required powerplant controls required to operate in the
event of a fire to be fire resistant, former Sec. 23.1189 required
shutoff valves to be outside the fire zone, former Sec. 23.1203
required certain fire detector components to be fire resistant, and
former Sec. 23.1201 required fire extinguisher components in the fire
zone to be fireproof. To resolve this, the commenter recommended
implementation of basic system performance requirements for fire
protection, preserving the former fire protection standards, but not
compromising future designs. Another commenter noted the proposed rule
did not capture some of the specific fire protection requirements for
items such as powerplant controls, shutoff valves, fire detectors and
extinguishers.
The FAA agrees the proposed language was not sufficiently
comprehensive to establish clear requirements necessary for the
prevention of hazards resulting from fire. The FAA revises proposed
Sec. 23.1000(b) and renumbers it as Sec. 23.2440(c) to ensure
adequate fire protection is maintained for those noted components,
along with any other components determined critical to safety. The FAA
adds paragraph (c)(1) to ensure the design of components and the
placement within the airplane not only prevent fire hazards but also
account for the effects of fire in adjacent fire zones. This
requirement addresses the requirements in former Sec. 23.1183(a) to
ensure flammable fluid-carrying components be shielded, or located to
safeguard against the ignition of flammable fluid. These requirements
are also consistent with the provisions of former Sec. 23.1182.
Embraer recommended the FAA revise proposed Sec. 23.1000(c) to
allow for the flow of quantities of fuel that are
[[Page 96646]]
small enough not to be hazardous to enter into the powerplant. Textron
similarly asserted proposed Sec. 23.1000(c) was unnecessary and could
be addressed by proposed Sec. 23.910. Textron recommended the FAA
revise its proposal to conform with CS 23.510(e), or Sec. 23.906(i) in
appendix E of the Part 23 ARC Report.\49\ Alternatively, Textron
recommended revisions to proposed Sec. 23.1000(c), (d), and (e).
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\49\ In each area or component where flammable fluids or vapors
might escape by leakage of a fluid system, there must be means to
minimize the probability of ignition of the fluids and vapors, and
the resultant hazard if ignition does occur and prevent the
introduction of hazardous toxic gases into the cabin.
---------------------------------------------------------------------------
The FAA agrees with Embraer's comment that small amounts of fuel
may still enter a powerplant after a shutoff means has been activated.
The FAA revises paragraph (c) and paragraph (d) to require that the
applicant provide a means to prevent hazardous quantities of flammable
fluid from flowing into the designated fire zone. Accordingly, this
revision will permit the flow of small amounts of residual flammable
fluid if it is shown not to present a hazard, after activation of any
shutoff means.
With respect to Textron's comment, the FAA finds the requirements
for a means to shut off fuel or flammable material for each powerplant
necessary. The FAA has determined Sec. 23.2410 does not adequately
address this requirement because Sec. 23.2410 sets forth the
requirements for a powerplant hazard assessment in which an applicant
could feasibly conclude that a means to shut off fuel flow for each
powerplant would not be necessary to comply with the stated
requirement. At this time, the FAA does not intend to permit the
certification of airplanes without a means to shut off fuel to their
powerplants.
The FAA also considered Textron's recommendation to revise proposed
Sec. 23.1000 to conform to CS 23.510(e) or the Part 23 ARC's proposed
Sec. 23.906(i). The FAA finds the hazard minimization requirements
contained in these provisions do not specifically preclude the
certification of an airplane without a means to shut off fuel flow to
each powerplant, a requirement the FAA considers essential for hazard
mitigation. Accordingly the FAA does not adopt that recommendation, and
considers such action to be outside the scope of this rulemaking
effort.
Textron recommended the FAA revise the introductory text of
proposed paragraph (c) to require the applicant to provide a means to
shut off both fuel and flammable material for each powerplant. Textron
recommended changing ``or'' to ``and''; otherwise, the language would
suggest there is no requirement to shut off other flammable fluid flow.
Textron also requested the FAA to clarify that the applicant must only
demonstrate that the means of shut off, and not each powerplant, meets
the requirements of proposed paragraphs (c)(1) and (c)(2).
The FAA agrees with Textron's concern that proposed Sec. 23.1000
could be interpreted to require shutoff of either fuel or flammable
material, which could permit a design that does not shutoff all
flammable materials to the fire zone. Therefore, the FAA removes the
term ``fuel'' from the requirement. Section 23.2440(d) now requires
prevention of all hazardous quantities of flammable fluid from entering
a fire zone. This is consistent with former Sec. 23.1189(a)(1). During
review of the existing shutoff requirements, the FAA also determined a
critical flammable fluid shutoff valve fire performance requirement was
not included in the proposed rule. Therefore, the requirement of former
Sec. 23.1189(a)(4) is included in the final rule as Sec.
23.2440(d)(3).
The FAA notes that proposed Sec. 23.1000(d) included a qualifier
that required only powerplants that use a combustible fuel to have a
fire extinguishing system. Based on the commenter's concerns, the FAA
removes this specific requirement and revises Sec. 23.2440(a) to
require any powerplant or APU that includes a flammable fluid source
and an ignition source for that fluid be located in a fire zone. This
regulatory approach is consistent with former requirements for
designated fire zones that contain a flammable fuel and an ignition
source where any leakage of flammable fluid would likely result in a
fire. Concerns relating to possible electrical engine fires are noted,
but not considered likely such that they would require installation in
a designated fire zone. Electric motors are commonly used on airplanes,
although not for propulsion, and have not required the protection of a
designated fire zone.
Additionally, the FAA adds paragraph (d)(3) to the final rule. The
revision requires the applicant to provide a means to prevent hazardous
quantities of flammable fluids from flowing into, within, or through
each designated fire zone located outside the fire zone unless an equal
degree of safety is provided with a means inside the fire zone. This
revision is based on the provisions of former Sec. 23.1189(a)(4) and
intends to ensure the specific requirements of that section are met by
an applicant.
Textron also reiterated the concept that fire protection actually
applied to all systems and recommended removing proposed Sec.
23.1000(c)(2) and broadening its applicability to all systems by
placing the requirement in proposed Sec. 23.1305.
While the FAA understands Textron's comment that fire protection
applies to all systems, the FAA notes the fire protection for areas
outside of fire zones are addressed by Sec. 23.2325 of the final rule.
The requirements for fire protection in fire zones are more extensive
than those for other areas of the airplane. The FAA requires designated
fire zones, and their corresponding extensive fire protection
requirements, for those areas where both nominal ignition sources and
flammable fluids must be co-located such that a single failure is
likely to result in a fire. Zones of the airplane that are outside a
fire zone should not contain both nominal ignition sources and
flammable fluids. Because there is a lower likelihood of fire in these
areas, they have correspondingly less extensive requirements.
Textron also recommended revising proposed Sec. 23.1000(d) because
it believed the proposal would limit the applicability of the
requirement for a fire extinguishing system to those powerplants
``outside the pilot's view'' and those powerplants that use
``combustible fuels.'' The commenter believed the intent of the
proposal was not clear, and recommended the FAA consider the need for
extinguishing systems in hybrid electric configurations where fire
extinguishing systems may be needed to address an electrical fire.
Textron also did not believe the rule's requirement should be limited
to level 3 and 4 airplanes. Textron recommended the FAA retain the
provisions of former Sec. 23.1195, which required extinguishing
systems for ``all airplanes with engine(s) embedded in the fuselage or
in pylons on the aft fuselage.'' Textron also recommended the FAA
incorporate additional provisions from the Part 23 ARC Report, which
recommended requiring that fire extinguishing systems be installed in
all airplanes with engines embedded in the aft fuselage or in pylons on
the aft fuselage, and for an APU, if installed. The systems must not
cause a hazard to the rest of the airplane.
Textron asserted that fire detection systems should not be
mandatory for all level 3 and 4 airplanes as proposed in Sec.
23.1000(e), but rather should be required based upon the type and
location of engines used in the airplane. The commenter recommended
using the
[[Page 96647]]
proposed requirements from the Part 23 ARC Report, which describes the
top level safety requirements and then would allow the industry
standard to provide more specifics as to what engine types and
configurations would require a fire detection system. Textron further
commented that proposed Sec. 23.1000(e) should be revised to only
require fire detection systems for those airplanes that have the
characteristics specified in former Sec. 23.1203(a).
An individual commenter also noted that proposed Sec. 23.1000(d)
and (e) were inconsistent with the requirements of the former rule and,
in some cases, would impose more stringent requirements without
providing justification. Specifically, the commenter stated that, as
proposed, a level 1 or 2 airplane with the engine located outside the
view of the pilot could be required to have a fire extinguisher, but
not a fire detector. The commenter also noted a single-engine level 3
or level 4 airplane, such as a Cessna 208 or Pilatus PC-12, was not
required to have a fire detection system under the former rule, but
would be required to have such a system under the proposed rule. The
commenter further noted that the requirements of former Sec. 23.1203
were based on designs determined to be at greater risk for fire (e.g.,
multiengine turbines and reciprocating engines with turbochargers),
which justified inclusion of a fire detection system. The commenter
also noted the former rule addressed other designs and required fire
extinguishing systems for all commuter category airplanes, whereas the
proposed rule lacks these specific requirements. The commenter
recommended the FAA revise proposed Sec. 23.1000(d) and (e) to ensure
no additional burden would be placed on future designs unless justified
and to ensure the former level of fire protection would be retained.
The FAA agrees with the commenters that proposed Sec. 23.1000(d)
and (e) were confusing and inconsistent with former fire extinguishing
and detection requirements. The FAA revises those paragraphs, now
located in Sec. 23.2440(e) and (f), to be consistent with former
requirements by removing the language limiting the applicability of the
requirements to only level 3 and level 4 airplanes, and basing the need
for a fire extinguishing system on the location of a fire zone instead
of on the location of the powerplant. However, the FAA retains the
specific requirement for a means to extinguish fires within fire zones
on level 4 airplanes, because these airplanes are functionally
equivalent to airplanes currently certificated in the commuter
category. These changes make Sec. 23.2440(e) and (d) consistent with
the requirements of former Sec. Sec. 23.1195, ``Fire extinguishing
systems,'' and 23.1203, ``Fire detector system.''
Finally, Air Tractor also recommended adding ``if installed'' after
``fire detection system'' in proposed Sec. 23.1000(f) and (g) to avoid
the perception a fire detection system is a requirement.
The FAA notes that, if a particular system is not required and not
installed on the airplane, any specific requirements related to that
system will not be applicable. Therefore, the FAA does not add the text
proposed by Air Tractor to the final rule.
7. Subpart F--Equipment
a. General Discussion
The FAA proposed substantial changes to former subpart F. The
thirty-seven former system sections were consolidated into eight
sections. An effort was made to maintain the safety intent of the rules
while removing the prescriptive nature of these rules which were based
on technology available at the time the rule was introduced. This was
intended to increase future flexibility to facilitate the installation
of systems that enhance safety as new technology becomes available.
EASA recommended the FAA add an additional requirement to proposed
subpart F that describes what system and equipment information should
be determined. EASA further suggested subpart G cover how this
information is displayed.
The FAA finds EASA's recommendation to add a new requirement for
system and equipment information unnecessary because this information
is already addressed in several requirements, including proposed Sec.
23.1305 (now Sec. 23.2505), Function and installation; proposed Sec.
23.1400 (now Sec. 23.2540), Safety Equipment; proposed Sec. 23.1505
(now Sec. 23.2605), Installation and operation; proposed Sec. 23.1310
(now Sec. 23.2615), Flight, navigation and powerplant instruments; and
proposed Sec. 23.1515 (now Sec. 23.1529), Instructions for continued
airworthiness. The FAA agrees, however, that subpart G should address
how the information is presented.
b. Airplane Level Systems Requirements (Proposed Sec. 23.1300/Now
Sec. 23.2500)
In the NPRM, proposed Sec. 23.1300 (now Sec. 23.2500) would have
required equipment and systems required for an airplane to operate--
Safely in the kinds of operations for which certification
is requested;
Be designed and installed to meet the level of safety
applicable to the certification and performance levels of the airplane;
and
Perform their intended function throughout the operating
and environmental limits specified by an applicant.
Proposed Sec. 23.1300 would have also mandated that
non[hyphen]required airplane equipment and systems, considered
separately and in relation to other systems, be designed and installed
so their operation or failure would not have an adverse effect on the
airplane or its occupants.
NATCA observed the requirements of proposed Sec. 23.1300 and Sec.
23.1305 (now Sec. 23.2505) appeared similar and requested the FAA
combine the two sections.
While the FAA agrees there is some similarity between Sec. 23.2500
and Sec. 23.2505, the requirements of Sec. 23.2500 are at the
airplane level and create a distinction between ``required'' and ``non-
required'' equipment and systems. In contrast, the requirements of
Sec. 23.2505 are at the system level and apply to all installed
equipment, regardless of whether it is required.
Garmin asked the FAA to clarify whether proposed Sec. Sec. 23.1300
and 23.1305 are of general applicability and do not supersede other
specific part 23 requirements. Garmin noted that CS 23.600(a) includes
such clarifying language concerning CS 23.600 and CS 23.605, and that
the FAA's decision to omit similar wording from proposed Sec. 23.1300
makes it unclear whether the FAA agrees with EASA in this respect or
not.
In light of Garmin's comment, the FAA revises proposed Sec. Sec.
23.1300 and 23.1305 to clarify the requirements of these sections apply
generally to installed equipment and systems. However, the requirements
do not apply if another section of part 23 imposes specific
requirements on a particular piece of installed equipment or systems.
The FAA finds this revision is consistent with the NPRM. The FAA
intended proposed Sec. Sec. 23.1300 and 23.1305 to capture the safety
intent of former Sec. 23.1309. Former Sec. 23.1309 was a regulation
of general requirements that did not supersede any requirements
contained in other part 23 sections. Sections 23.2500 and 23.2505 are
harmonized with CS 23.600 and CS 23.605.
Air Tractor stated proposed Sec. 23.1300(a)(l) failed to define a
standard for the required level of safety for systems.
[[Page 96648]]
The FAA is construing Air Tractor's comment as referring to the
qualitative levels of safety for systems, which were previously
contained in former Sec. 23.1309(c). These qualitative levels of
safety are now contained in Sec. 23.2510 (proposed as Sec. 23.1315),
which provides system-level requirements. The FAA notes Sec.
23.2500(a)(1) provides airplane-level requirements, and does not
specify the level of safety because the acceptable level of safety
varies depending on the certification level of the airplane. Former
part 23 is one acceptable means of compliance for the new part 23.
Therefore, applicants may use as a means of compliance the levels of
safety defined in figure 2 of AC 23.1309-1E, ``System Safety Analysis
and Assessments for Part 23 Airplanes'', which were a means of
compliance to former Sec. 23.1309 and varied depending on the
certification class of airplane. Alternatively, applicants--individuals
or organizations--may assist in the development of industry-consensus
standards, or propose their own means of compliance to Sec.
23.2500(a)(1).
ANAC commented the phrase ``operating and environmental conditions
specified by the applicant'' in proposed Sec. 23.1300(a)(2) could lead
to misinterpretation. ANAC asserted these conditions may not be
adequate or achieve the minimum requirements for certification. ANAC
suggested using the phrase ``conditions for which the airplane is
certified.''
The FAA agrees with ANAC and revises the proposed rule language for
clarity. Accordingly, Sec. 23.2500(a)(2) now requires the equipment
and systems required for an airplane to operate safely, in the kinds of
operations for which certification is requested, to be designed and
installed to perform their intended function throughout the operating
and environmental limits ``for which the airplane is certificated.''
Several commenters commented on the use of the phrase ``non-
required'' in proposed Sec. 23.1300(b). EASA stated that the proposed
provisions of Sec. 23.1300(a) and (b) raised ambiguity regarding what
systems and equipment are ``required.'' EASA recommended clarifying the
distinction between ``required'' and ``non-required'' in paragraphs (a)
and (b), respectively, by revising the proposed rule language in
paragraph (b) to make clear ``non-required'' systems and equipment are
those not covered by paragraph (a). The Associations recommended the
FAA clarify what non-required systems and equipment include and offered
rule language similar to that proposed by EASA. Lastly, ANAC
recommended replacing ``non-required'' with ``each'' in proposed Sec.
23.1300(b) because the requirements should apply to all systems and
equipment.
The FAA agrees the distinction between proposed Sec. 23.1300(a)
and proposed Sec. 23.1300(b), which would have applied to ``non-
required'' equipment, was unclear. The FAA adopting EASA's recommended
rule language, which clarifies the distinction between the two
requirements by linking them together. Accordingly, Sec. 23.2500(b)
(proposed as Sec. 23.1300(b)), now requires the systems and equipment
not covered by Sec. 23.2500 (a) to be designed and installed so their
operation does not have an adverse effect on the airplane or its
occupants.
While the FAA agrees with ANAC that both ``required'' and ``non-
required'' equipment and systems must be designed and installed so
their operation does not have an adverse effect on the airplane or its
occupants, the FAA finds it unnecessary to apply new Sec. 23.2500(b)
to ``required'' equipment, because Sec. 23.2500(a) (proposed as Sec.
23.1300(a)) already covers this requirement. Required equipment and
systems that are designed and installed to meet the level of safety
applicable to the certification and performance level of the airplane,
in accordance with Sec. 23.2500(a)(1), and that perform their intended
function, in accordance with Sec. 23.2500(a)(2), will not have an
adverse effect on the airplane or its occupants. Furthermore, the FAA
is intentionally making a distinction between ``required'' and ``non-
required'' equipment in Sec. 23.2500(a) and (b) because ``non-
required'' equipment and systems should not always be required to
perform their intended function throughout the entire operating and
environmental limits of the airplane.
Air Tractor suggested the FAA compare former Sec. 23.1309 and
proposed Sec. 23.1300(b). They noted the proposed rule may make it
easier to certify non-required equipment; however, the proposed rule
still seemed to require a Functional Hazard Assessment (FHA) and System
Safety Assessment (SSA). Air Tractor suggested the FAA relieve the
undue burden associated with the required system safety analysis for
non-required equipment and systems.
The FAA has determined some method of assessment is necessary to
ensure that equipment and systems installed on an airplane meet an
acceptable safety level. The safety assessment must show that a logical
and acceptable inverse relationship exists between the average
probability per flight hour and the severity of failure conditions
effects. The depth and scope of the safety assessment will depend on
the types of functions performed by the systems, the severity of
failure conditions, and whether the system is complex. For simple and
conventional systems with well-established designs, the safety
assessment may be satisfied by a qualitative assessment such as the
single-failure concept and experience based on service-proven designs
and engineering judgment. Former guidance for complex systems relied on
industry standards such as ARP 4761, ``Guidelines and Methods for
conducting the Safety Assessment Process on Civil Airborne Systems and
Equipment,'' and ARP 4754A, ``Guidelines for Development of Civil
Aircraft and Systems,'' as well as AC 23.1309-1E, to define an
acceptable means of compliance. As explained in the NPRM, former part
23 and associated guidance may be used as one means of compliance with
the new part 23. Alternatively, applicants may rely on industry
consensus standards, or develop their own methods of compliance
appropriate to the various airworthiness certification levels.
Garmin stated it was unclear what the phrase ``or failure does not
have an adverse affect'' in proposed Sec. 23.1300(b) means and that
failures would be covered under proposed Sec. 23.1315. Garmin implied
that proposed Sec. 23.1300(b) was redundant with proposed Sec.
23.1315, which already addressed the failure of a non-required system
as it would have provided the basis for assessing the implications of
any failure for installed equipment. The commenter requested that the
FAA delete ``or failure'' from the proposed rule.
The FAA agrees with Garmin and deletes the words ``or failure''
from the proposed rule language. Section 23.2510 (proposed as Sec.
23.1315) addresses failure conditions of all equipment. Therefore,
proposed Sec. Sec. 23.1300 and 23.1315 would have been redundant by
requiring the same showing of compliance. Additionally, the phrase
``failure does not have an adverse effect on the airplane or its
occupants'' could have been misinterpreted as requiring the failure to
have no effect on the airplane. For example, if the equipment was
installed to provide a benefit, although not required, it could have
been wrongly interpreted that the failure of that benefit would have an
``adverse effect'' on the airplane.
c. Function and Installation (Proposed Sec. 23.1305/Now Sec. 23.2505)
In the NPRM, proposed Sec. 23.1305 (now Sec. 23.2505) would have
required each item of installed equipment to
[[Page 96649]]
perform its intended function, be installed according to limitations
specified for that equipment, and the equipment be labeled, if
applicable, as to its identification, function, or operation
limitations, or any combination of these factors. Proposed Sec.
23.1305 would have required a discernable means of providing system
operating parameters required to operate the airplane, including
warnings, cautions, and normal indications to the responsible flight
crewmember. Proposed Sec. 23.1305 would have also required information
concerning an unsafe operating condition be provided in a clear and
timely manner to the crewmember responsible for taking corrective
action.
In light of comments received, the FAA revises proposed Sec.
23.1305 to withdraw paragraph (a)(2), merge paragraph (a) and (a)(1)
into new paragraph (a), and relocate paragraphs (a)(3) through (c) to
new Sec. 23.2605 in subpart G. This section discusses these changes in
more detail.
The Associations, Textron, and ANAC commented on proposed Sec.
23.1305(a)(1). Textron commented that proposed Sec. 23.1305(a) appears
to be redundant with proposed Sec. 23.1300(a) and asked the FAA to
clarify whether proposed Sec. 23.1305(a)(1) would apply to the non-
required equipment addressed in proposed Sec. 23.1300(b).
ANAC recommended that the FAA remove proposed Sec. 23.1305(a)(1)
because the requirement is adequately addressed in Sec. 23.1300(a)(2)
for required equipment. ANAC explained that proposed Sec.
23.1305(a)(1) would contradict the requirement for non-required
equipment in proposed Sec. 23.1300(b). The Associations, noted that
one of the reasons for distinguishing ``required'' and ``non-required''
equipment in proposed Sec. 23.1300 was to alleviate the issues with
requiring non-required equipment to prove their intended function. The
commenters contended the rule should only require non-required
equipment and systems (which are not required for safe flight) to
verify their operation or failure does not interfere with required
equipment. The commenters recommended confining the proposed
requirement of Sec. 23.1305(a) to ``required'' systems and equipment.
The FAA considered the comments to proposed Sec. 23.1305(a)(1) and
recognizes the confusion between Sec. Sec. 23.1300 (now Sec. 25.2500)
and 23.1305. The FAA notes Sec. 23.2505 applies to both required and
non-required equipment. All equipment, when installed, should function
as intended to maintain a minimum level of safety. The requirement of
Sec. 23.2505 is not addressed by Sec. 23.2500(a)(2) as Sec. 23.2505
applies to both required and non-required equipment when the equipment
is installed on the airplane. Section 23.2500(a)(2) applies only to
required equipment in operation. The FAA finds Sec. 23.2505(a) does
not contradict the requirement of Sec. 23.2500(b), which applies to
non-required equipment during airplane operations once in service. As
explained in the NPRM, Sec. 23.2500(b) would not require non-required
equipment and systems to function properly during all airplane
operations once in service, provided all potential failure conditions
do not affect safe operation of the airplane. However, the non-required
equipment or system would have to function in the manner expected by
the manufacturer's operating manual for the equipment or system when
installed. To clarify the FAA's intent and better harmonize with EASA,
the FAA is merging proposed paragraph (a) with (a)(1) to revise Sec.
23.2505 to require each item of equipment, when installed, to function
as intended.
The Associations also maintained that proposed Sec. 23.1305(a)(2)
and (3) were unnecessary because installed equipment needs to operate
safely despite any markings.\50\ The commenters recommended the FAA not
adopt paragraphs (a)(2) and (a)(3). Alternatively, EASA recommended
moving the pilot interface issues of proposed Sec. 23.1305(a)(3)
through (c) to subpart G, which covers flightcrew interface. Textron
recommended the FAA move the labeling requirement to proposed Sec.
23.1300(a)(3). Transport Canada recommended clarifying proposed Sec.
23.1305(a)(3) to provide the criteria to determine the applicability of
the labeling requirement.
---------------------------------------------------------------------------
\50\ The commenters actually stated they believe proposed Sec.
23.1305(a)(1) and (2) were unnecessary. However, based on the rest
of their comments and the recommendation to delete paragraphs (a)(2)
and(a)(3) (and retain (a)(1)), the FAA assumes the commenters meant
to state that Sec. 23.1305(a)(2) and (3) are unnecessary.
---------------------------------------------------------------------------
The FAA withdraws proposed Sec. 23.1305(a)(2) as it is redundant
of paragraph (a)(1). In order to function as intended, the equipment
would have to meet its limitations. As previously noted, the FAA has
revised proposed Sec. 23.1305 by merging paragraph (a) with (a)(1).
The FAA agrees with EASA's recommendation to move certain flightcrew
interface requirements to subpart G and is relocating the requirement
of proposed Sec. 23.1305(a)(3) to subpart G, Sec. 23.2605(a) in this
rule. The commenters are correct that while a system needs to operate
safely despite any markings, markings related to identification,
function, and limitations are necessary to aid the aircrew and other
personnel to safely operate the systems. The requirement for equipment
to be labeled, if applicable, dates back to CAR 3.652 effective
December 7, 1949. If further criteria to determine the applicability of
the labeling requirement are found to be necessary, additional guidance
will be developed either by the FAA or in an industry consensus
standard.
After further analysis, the FAA finds the proposed requirements to
provide system operating parameters, including warnings and cautions,
were not adequately covered in proposed subpart G. Based on this and
EASA's comments, the FAA relocates the pilot interface requirements of
proposed Sec. 23.1305(b) and (c) to new Sec. 23.2605 in subpart G to
adequately address these issues.
Garmin, Textron, and ANAC commented on the second sentence of
proposed Sec. 23.1305(c). Garmin recommended the FAA delete the phrase
``presentation of'', as it could be interpreted as requiring a light or
other visual alert. Textron recommended the FAA replace the phrase
``clear enough to avoid likely crewmember errors'' with the phrase
``designed to minimize crewmember errors.'' ANAC contended the term
``likely'' is ambiguous and recommended the FAA replace the phrase ``to
avoid likely crewmember errors'' with the phrase ``to minimize
crewmember errors, which could create additional hazards.''
The FAA agrees with the commenters as the FAA did not intend to
limit the presentation to visual displays only. Warning information can
include visual, aural, tactile, or any combination. The FAA deletes
``presentation of'' in the proposed Sec. 23.1305(c). Although both
``minimize'' and ``likely'' may be ambiguous, as was the concern from
ANAC, the term ``minimize''--associated with the mitigation of hazards
in the rule language--can be traced back to CAR 3, effective December
7, 1949. Although using a new term such as ``likely'' may be
interpreted as a new requirement or standard for the minimization of
errors, this was not the FAA's intent. Therefore, the FAA replaces the
term ``minimize flightcrew errors'' in place of ``avoid likely
crewmember errors'' in Sec. 23.2600(b).
Embraer noted that the cross-reference table in the proposal stated
that the intent of former Sec. 23.1023 is addressed in proposed Sec.
23.935(b)(1); however, there is no Sec. 23.935(b)(1) in the proposed
rule. To address this mistake, Embraer suggested including a similar
[[Page 96650]]
requirement from former Sec. 23.1023 in proposed Sec. 23.1305, which
would apply to any equipment. Specifically, Embraer recommended an
addition to proposed Sec. 23.1305(a)(4) stating equipment be able to
withstand without failure, the vibration, inertia and loads (including
fluid pressure loads) to which it would be subjected in operation.
Embraer stated that it understood that part 33 would not address
all the concerns if the radiator is installed by the airframer, and
noted that its same comment applies to former Sec. Sec. 23.1013 and
23.1015.
The FAA has corrected and updated the table to accurately reference
the relationship between the former rule and the final rule. Also, the
FAA does not adopt Embraer's recommendation to add a requirement to
Sec. 23.2505 to address specific environmental conditions equipment
must be able to withstand. The FAA notes Embraer was describing a
specific failure mode, which is covered by Sec. Sec. 23.2500(a)(2) and
23.2510.
d. Flight, Navigation, and Powerplant Instruments (Proposed Sec.
23.1310/Now Sec. 23.2615)
In the NPRM, proposed Sec. 23.1310 (now Sec. 23.2615) would have
required installed systems to provide the flightcrew member who sets or
monitors flight parameters for the flight, navigation, and powerplant
information necessary to do so during each phase of flight. Proposed
Sec. 23.1310 would have required this information include parameters
and trends, as needed for normal, abnormal, and emergency operation,
and limitations, unless an applicant showed the limitation would not be
exceeded in all intended operations. Proposed Sec. 23.1310 would have
prohibited indication systems that integrate the display of flight or
powerplant parameters to operate the airplane or are required by the
operating rules of this chapter, from inhibiting the primary display of
flight or powerplant parameters needed by any flightcrew member in any
normal mode of operation. Proposed Sec. 23.1310 would have required
these indication systems be designed and installed so information
essential for continued safe flight and landing would be available to
the flightcrew in a timely manner after any single failure or probable
combination of failures.
In light of comments received, the FAA renumbers Sec. 23.1310 to
Sec. 23.2615, and moves this section to Subpart G. The section for
Sec. 23.2615 in Subpart G discusses these changes in more detail.
e. Equipment, Systems, and Installation (Proposed Sec. 23.1315/Now
Sec. 23.2510)
In the NPRM, proposed Sec. 23.1315 (now Sec. 23.2510) would have
required an applicant--
To examine the design and installation of airplane systems
and equipment, separately and in relation to other airplane systems and
equipment, for any airplane system or equipment whose failure or
abnormal operation was not specifically addressed by another
requirement in this part;
To determine if a failure of these systems and equipment
would prevent continued safe flight and landing, and if any other
failure would significantly reduce the capability of the airplane or
the ability of the flightcrew to cope with adverse operating
conditions; and
To design and install these systems and equipment,
examined separately and in relation to other airplane systems and
equipment, such that each catastrophic failure condition is extremely
improbable, each hazardous failure condition is extremely remote, and
each major failure condition was remote.
In light of comments received, the FAA revises proposed Sec.
23.1315 (now Sec. 23.2510) by withdrawing paragraph (a), merging
paragraph (b) into the introductory sentence, and renaming paragraphs
(b)(1), (b)(2) and (b)(3) as Sec. 23.2510(a), (b) and (c),
respectively. This section discusses these changes in more detail.
Garmin commented that proposed Sec. 23.1315 should be located with
the other general rules applicable to all systems and equipment.
The FAA agrees with Garmin's comment and is placing the regulation
with the other general rules at the beginning of subpart F.
Textron commented the intent of proposed Sec. 23.1315 is not as
clearly written as CS 23.600 and 23.605 and an AC will be needed to
determine the meaning of the proposed rule. The commenter recommended
using the wording of CS 23.600 and 23.605. In contrast, The
Associations preferred the FAA's proposed Sec. 23.1315 to the EASA's
A-NPA language, which they stated may unduly tie means of compliance to
an objective-based rule. EASA suggested that proposed Sec. 23.1315
show the inverse relationship between probability and severity in an
illustration.
To clarify the intent of the rule, the FAA revises the proposed
rule language to require each system and equipment to be designed and
installed such that ``there is a logical and acceptable inverse
relationship between the average probability and the severity of
failure condition.'' This change is consistent with the NPRM, which
explained that proposed Sec. 23.1315 (now Sec. 23.2510) would require
an engineering safety analysis to identify possible failures,
interactions, and consequences, and require an inverse relationship
between the probability of failures and the severity of consequences.
The logical inverse relationship should be proportionate and flexible
with respect to risk levels. The FAA notes that if the FAA provided
more detail and graphics in the rule, future interpretation of the rule
may be more restrictive than intended. The FAA finds the additional
information provided in EASA's A-NPA is more suitable for guidance
similar to AC 23.1309-1E and is not adding this to the rule.
The Associations recommended the FAA add a new paragraph to
proposed Sec. 23.1315 that would allow the FAA to accept a higher
failure probability for functionality that enhances the safety of the
airplane beyond the required minimum functionality. The commenters
noted such a provision would allow for safety-enhanced equipment to be
treated in a less stringent manner that accounts for the significant
benefits it could have. The commenters explained this would ensure the
lowest cost of this equipment without sacrificing the safety-enhancing
benefits. Garmin similarly noted that system safety analysis and design
assurance are focused on system and equipment failures rather than the
safety benefit such systems and equipment can provide. For example,
TSO-C151, ``Terrain Awareness and Warning System (TAWS),'' equipment
specifies a major failure classification, but no credit is given for
the offsetting safety benefit provided for installation of TAWS with
its corresponding reduction in Controlled Flight into Terrain (CFIT)
accidents. Garmin asked the FAA to consider adopting a requirement that
allows for design assurance certitude for systems that provide an
increased safety benefit.
The FAA has determined adding a new requirement to proposed Sec.
23.1315 (now Sec. 23.2510) would create a special class of equipment
in the rule, which is contrary to the FAA's intent. The objective of
this rulemaking is to provide clear safety objectives without
prescribing design solutions. The objective of proposed Sec. 23.1315
is to require each system and equipment to be designed and installed
such that there is a logical and acceptable inverse relationship
between the average probability and the severity of failure conditions.
This applies to all
[[Page 96651]]
equipment whether required or non-required, safety-enhancing or not.
The rule does not specify a required numeric probability of failure.
The rule is written to allow a proportionate and flexible numerical
value to the probabilities regarding risk levels of the equipment and
airplane. System safety assessment standards will be relied on to
provide a suitable approach for the different risk levels, similar to
what is currently found in AC 23.1309-1E for the various classes of
airplanes. Section 23.2510 provides a proportionate and flexible
structure for future technology implementation.
Garmin and the Associations recommended the FAA use the term
``failure condition'' rather than ``failure'' to ensure the rule
addresses the broader impacts of failures, rather than just those that
occur within the equipment that may have failed. Garmin explained that
by using ``failure condition,'' the rule would address combinations of
failures in the system and equipment and other systems and equipment.
ANAC stated the use of ``failure'' in paragraph (a) and use of
``failure condition'' in paragraph (b) may add confusion.
The FAA agrees with the commenters and revises proposed Sec.
23.1315 (now Sec. 23.2510) to use ``failure condition'' throughout the
section.
Textron noted some simple systems were exempt from former Sec.
23.1309. Textron asked if there was a list of systems exempt from
proposed Sec. 23.1315 (now Sec. 23.2510), or if the FAA intended to
apply the regulation to all systems. Textron specifically asked for
confirmation that propulsion, fuel systems, fire protection systems,
exits, landing gear, flight navigation, powerplant instruments, system
power generation, storage, and distribution and flight controls were
exempt from proposed Sec. 23.1315 (now Sec. 23.2510), since they each
have their own rules dealing with failures.
This final rule does not contain a list of systems exempt from
proposed Sec. 23.2510 (proposed as Sec. 23.1315). Consistent with
former Sec. 23.1309, proposed Sec. 23.1315 (now Sec. 23.2510)
applies generally to installed equipment and systems, except that Sec.
23.2510 does not apply if another section of part 23 imposes
requirements for specific equipment or systems. The FAA is not
providing a list of systems exempt from the rule, as Textron requested,
because such a list would be based on today's technology and would be
overly prescriptive and inflexible over time. This would conflict with
the goal of allowing coverage for future unforeseen technological
advancements.
Textron asked the FAA to clarify the intent of the safety
requirements in proposed Sec. 23.1315. In particular, Textron noted
that paragraph (a) simply stated ``determine'', while paragraph (b)
stated ``design and install'' to achieve safety goals that have no
connection with those stated in paragraph (a). Textron asked for
clarification of the relationship between the two paragraphs, as well
as the overall intent of the rule. Textron recommended using the
language in CS 23.605(a), which would have required each equipment and
system to be designed and installed so there is a logical and
acceptable inverse relationship between the average probability and the
severity of failure condition effects. ANAC similarly noted that no
clear safety objective was stated in proposed Sec. 23.1315(a); rather,
an applicant needed only determine if conditions (1) and (2) were
examined. Embraer suggested the FAA remove proposed Sec. 23.1315(a),
asserting that the intent of proposed Sec. 23.1315(b) would be
sufficient to meet compliance.
EASA asserted the terminology in proposed Sec. 23.1315(a) may be
confusing. Phrases such as ``continued safe flight and landing'' and
``significantly reduce the capacity of the airplane'' or ``the ability
of the flightcrew to cope with adverse operating conditions,'' are not
as clear as terms ``catastrophic,'' ``hazardous,'' and ``major'' in
describing the failure condition.
In light of these comments, the FAA withdraws proposed paragraph
(a). Proposed Sec. 23.1315(a) could have been interpreted as an
element of the means of compliance to paragraph (b) in that the
determinations of the potential consequences of failures is necessary
to establish whether the probability of their occurrence is acceptable.
Additionally, the FAA adopts Textron's recommendation and revises the
proposed rule language to require each system and equipment to be
designed and installed so there is a logical and acceptable inverse
relationship between the average probability and the severity of
failure condition effects. To comply with Sec. 23.2510(a), applicants
must account for airplane systems and equipment, separately and in
relation to other airplane systems and equipment.
Textron indicated that the terms used in proposed Sec. 23.1315(b)
were not defined in the regulations.
The FAA did not define the terms ``catastrophic failure
condition,'' ``hazardous failure condition,'' and ``major failure
condition'' in the regulations because the terms are better addressed
in guidance. These terms are currently defined in AC 23.1309-1E.
Furthermore, the rule language is consistent with the historical rule
language of former Sec. 23.1309.\51\
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\51\ See 55 FR 43306, October 26, 1990.
---------------------------------------------------------------------------
ANAC commented that proposed Sec. 23.1315(b) implied specific
classification and probability terms that may be considered
prescriptive. The commenter noted that, as written, this may prevent an
applicant from using a means of compliance that employs different
hazard categories or terminology.
The FAA notes the terms used in proposed Sec. 23.1315 (now Sec.
23.2510) are already defined in guidance (i.e., AC 23.1309-1E) and
originated from former Sec. 23.1309, and should not prevent an
applicant from using a means of compliance that employs different
hazard categories or terminology. The FAA may accept a means of
compliance standard that uses different hazard categories or
terminology, if they align with the failure condition effects in
paragraphs (a) through (c) so the requirements of proposed Sec.
23.1315 (now Sec. 23.2510) are met.
Rockwell Collins noted that former Sec. 23.1309(c)(1) required
each catastrophic failure condition to be extremely improbable and not
result from a single failure. However, proposed Sec. 23.1315(b)(1),
which was intended to capture the safety intent of former Sec.
23.1309, would have required only that each catastrophic failure
condition be extremely improbable. It would not have prohibited single-
point catastrophic failures. Rockwell Collins asked the FAA to retain
the phrase ``and not result from a single failure'' in the regulation,
because the commenter believed the FAA's intent was not to propose
changes with regard to single-point catastrophic failures.
The FAA notes the ARC recommended the FAA require systems and
equipment to be designed and installed so there is a logical acceptable
inverse relationship between the average probability and the severity
of failure condition effects whether the result of a single failure or
multiple failures. With the advancement of technology and increased
integration of systems, it is virtually impossible to eliminate all
theoretical potential single-points of failure. The rule will allow in
some cases, as is true today with some portions of the airplane, to
have the potential of single-point failures if the risk and probability
of such failure is acceptable. The FAA adopts the rule language as
proposed in Sec. 23.1315(b)(1).
Noting that key pieces of FAA guidance are critical to design and
certification, Kestrel asked whether AC
[[Page 96652]]
23.1309 would remain the primary guidance for SSA. If not, Kestrel
asked what the recommended guidance would be.
Guidance for proposed Sec. 23.1315 may consist of existing FAA
guidance, such as AC 23.1309, future FAA-generated guidance, and FAA-
accepted industry standards.
Textron noted the NPRM stated applicants who use the means of
compliance described in the existing special conditions would be able
to use data developed for compliance with proposed Sec. 23.1315.
Textron recommended the FAA revise the statement to clarify the FAA was
referring to special conditions for part 25 airplanes.
The statement in the NPRM is correct. Applicants who use the means
of compliance described in the existing special conditions for parts
23, 25, 27, or 29 may use data developed for compliance with Sec.
23.2510.
f. Electrical and Electronic System Lightning Protection (Proposed
Sec. 23.1320/Now Sec. 23.2515)
In the NPRM, proposed Sec. 23.1320(a) would have required, for an
airplane approved for IFR operations, that each electrical or
electronic system that performs a function, the failure of which would
prevent the continued safe flight and landing of the airplane, be
designed and installed such that--
The airplane system level function continues to perform
during and after the time the airplane is exposed to lightning; and
The system automatically recovers normal operation of that
function in a timely manner after the airplane is exposed to lightning,
unless the system's recovery conflicts with other operational or
functional requirements of the system.
Proposed Sec. 23.1320(b) would have required each electrical and
electronic system that performed a function, the failure of which would
reduce the capability of the airplane or the ability of the flightcrew
to respond to an adverse operation condition, to be designed and
installed such that the function recovers normal operation in a timely
manner after the airplane is exposed to lightning.
Several commenters raised concerns with the term ``system'' in
proposed Sec. 23.1320(a)(1). BendixKing explained that the proposed
phrase ``airplane system level function'' may lead to multiple
interpretations of the regulation. BendixKing asked the FAA to delete
``system'' from the proposed rule language because the rule addresses
failure at the airplane level. The Associations recommended the FAA
require the function, rather than the airplane system level function,
to comply with the requirement in paragraph (a)(1).
Garmin stated that there has been much discussion in the GAMA HIRF
(High-Intensity Radiated Fields) ad-hoc meetings regarding the
interpretation of the term ``system.'' Garmin explained the rule
language could be interpreted as requiring all redundant systems, which
perform the same function, to meet the lightning requirements. Garmin
explained that not all redundant systems should be required to meet the
catastrophic requirements to prevent potentially catastrophic failure;
proposed Sec. 23.1320(a) should apply to the function level only.
Garmin recommended alternative regulatory language would prevent
catastrophic, major, or hazardous failure conditions at the airplane
level.
The FAA agrees proposed Sec. 23.1320(a)(1) (now Sec.
23.2515(a)(1)) could have been misinterpreted due to the confusion
surrounding the phrase ``airplane system level function.'' The FAA
intended to require the function at the airplane level to meet the
requirements of paragraph (a)(1), consistent with proposed Sec.
23.1325(a)(1) (now Sec. 23.2520). Thus, the FAA intended proposed
Sec. 23.1320(a)(1) to require the function at the airplane level not
to be adversely affected during and after the time the airplane is
exposed to lightning. This means if multiple systems perform the same
function, only one of those systems is required to provide the function
under Sec. 23.2515(a)(1). Therefore, not all redundant systems are
required to meet the requirements of Sec. 23.2515(a)(1). The FAA
deletes the term ``system'' from the phrase ``airplane system level
function,'' as several commenters recommended to ensure the FAA's
intent is clear. The FAA revises the rule language to make clear that
the requirements of proposed Sec. 23.1320(a)(1) (now Sec.
23.2515(a)(1)) apply to the function at the airplane level.
Garmin noted that the proposed Sec. 23.1320 rule language was
essentially the same as former Sec. 23.1306, which was overly
burdensome for low-end part 23 airplanes. Garmin stated that proposed
Sec. 23.1320 is contrary to the goal of the part 23 reorganization and
explained the objective should be to prevent catastrophic, hazardous,
and major failure conditions for the airplane. Garmin suggested
revising proposed Sec. 23.1320 to be more general and to allow the
ASTM standards to provide the necessary means of compliance, which
should consist of a tiered compliance approach for different airplane
certification levels.
The FAA does not agree to make Sec. 23.2515 more general. Section
23.2515 is intended to address catastrophic, hazardous, and major
failure condition at the airplane level due to the effects of lightning
on systems. Critical functions that would prevent continued safe flight
and landing (catastrophic) should remain available to the crew
throughout a lightning exposure. How to maintain the function, whether
with redundant systems or non-susceptible systems, is a means of
compliance and is not specified. Likewise, systems that perform a
function, the failure of which would significantly reduce the
capability of the airplane (hazardous), must recover normal operation
of that function. A means of compliance is not specified and could
include redundancy. The FAA has revised the rule to state more clearly
that the concern for catastrophic failure conditions is at the airplane
level. Furthermore, the rule already allows a tiered compliance
approach based on the environment the airplane is likely to see.
Several commenters raised concerns with applying proposed Sec.
23.1320 to airplanes approved for IFR operations. The Associations
noted the FAA has recently approved required equipment for use in IFR
airplanes, without the need for lightning testing based on the history
of lightning strikes in the general aviation fleet. However, these
commenters indicated the proposed rule would have prohibited airplanes
with a low probability of lightning strikes from benefiting from such
an approach. These commenters asked the FAA to revise the proposed rule
language to ensure the rule does not apply to airplanes with a low
probability of lightning strike.
Garmin noted that former Sec. 23.1306 required both VFR and IFR
airplanes to meet lightning requirements for systems with catastrophic
failure conditions. However, while proposed Sec. 23.1320 would have
removed the requirement for VFR airplanes, the burden for industry is
primarily IFR airplanes as there are very few VFR airplanes, if any,
that have systems with catastrophic failure conditions. Garmin
recommended revising the proposed rule language by removing the
language that would have made proposed Sec. 23.1320 applicable to
airplanes approved for IFR operations.
EASA also asked the FAA to remove the language that would have made
proposed Sec. 23.1320 applicable to airplanes approved for IFR
operations. EASA explained that this revision
[[Page 96653]]
would permit credit for reliable systems that allow for avoidance of
thunderstorms, as these systems would make exposure to lightning
unlikely.
In light of these comments, the FAA recognizes the proposed rule
language would not have adequately relieved the burden of former Sec.
23.1306, which required all airplanes regardless of their design or
operational limitations meet the same requirements for lightning
regardless of the potential threat. As explained in the NPRM, the FAA
intended to relieve this burden by applying the lightning requirements
to airplanes with the greatest threat of lightning. The FAA proposed to
meet this objective by making the rule applicable to airplanes approved
for IFR operations. Because airplanes approved for IFR operations may
also have a low probability of lightning exposure, the proposed rule
language did not meet the FAA's objective. Accordingly, the FAA adds an
exception to the rule language for applicants who can show that
exposure to lightning is unlikely. This change from what was proposed
is more consistent with the FAA's intent as it relieves an airplane
approved for IFR operations from complying with Sec. 23.2515 if it is
shown the airplane has a low probability of lighting exposure. The
method of compliance is not specified in the rule and could be system,
operational, or environment based.
Garmin and the Associations recommended the FAA revise proposed
Sec. 23.1320(b) to make the requirement only applicable to levels 3
and 4 airplanes approved for IFR operations.
The FAA disagrees. Section 23.2520(b) is a general safety objective
with compliance tailored to the specific design intent. Exposure to
lightning is an environmental threat not directly associated with
airplane certification levels and therefore could apply to all
airplanes. The intent is to set requirements appropriately to the
design. Therefore, the FAA adds an exception to the rule language for
applicants who can show that exposure to lightning is unlikely.
Daher, Textron, and the Associations suggested the FAA, in proposed
Sec. 23.1320(a)(1) (now Sec. 23.2515(a)(1)), require the function to
not be ``adversely affected'' during and after the time the airplane is
exposed to lightning, but require the function to ``continue to
perform.'' Daher and Textron explained that requiring the function to
not be ``adversely affected'' would be more consistent with the
language of proposed Sec. 23.1325 (now Sec. 23.2520). The
Associations asserted that this revision would permit equipment
installations that may be affected by lightning, provided the loss of
equipment does not result in catastrophic events. Textron further noted
this revision would ensure harmony with EASA's proposed CS 23.620.
In response to these comments, the FAA revises the proposed rule
language to require the function at the airplane level to not be
``adversely affected'' during and after the time the airplane is
exposed to lighting. As explained in the NPRM, the FAA intended
proposed Sec. 23.1320(a)(1) (now Sec. 23.2515(a)(1)) to capture the
safety intent of former Sec. 23.1306. Former Sec. 23.1306(a)(1)
required the function to not be ``adversely affected'' during and after
the time the airplane is exposed to lightning. Because the proposed
language could be interpreted as an increase in burden, which would not
meet the intent of former Sec. 23.1306, the FAA is reverting back to
the former rule language. It should be noted that ``adversely
affected'' was not previously limited to catastrophic events as
suggested by the commenters, but included hazardous and major failure
conditions as well.
Textron questioned if crew action could be involved in the recovery
of the function or must recovery be automatic. Textron asked the FAA to
clarify whether proposed Sec. 23.1320(a)(2) would permit crew action
in recovery of the function. Garmin recommended the FAA not adopt
proposed Sec. 23.1320(a)(2).
Based on Textron's comment, the FAA clarifies paragraph (a)(2) by
removing the term ``automatic'' from the proposed rule to allow either
flightcrew action or automatic recovery. One of the goals of the
proposal was to remove prescriptive design solution for the
airworthiness standards and replace them with performance-based rules.
Automatic reset of a system is a design solution, while the safety
objective is the function be usable to the flightcrew in a timely
manner such that the intermittent loss or malfunction does not have an
adverse effect on the safety of the flight. Therefore, the recovery of
the function may be automatic or manual. While Garmin recommended that
the FAA not adopt proposed Sec. 23.1320(b) (now Sec. 23.2515(b)), the
FAA believes the safety intent of former Sec. 23.1306, which addressed
catastrophic and hazardous failure condition due to the effects of
lightning on systems, must be retained.
Transport Canada noted that proposed Sec. 23.1320(a)(2) would
benefit from inclusion of a specific safety objective. The commenter
suggested revising the proposed rule language to require the system to
automatically recover normal operation of the function in such time as
to allow a safety objective to be achieved.
The FAA notes the safety objective of paragraph (a)(2) is ``the
timely recovery of the system's function.'' Additionally, the rule
language existed in former Sec. 23.1306(a)(2). Based on this, the FAA
does not adopt the change proposed by Transport Canada in the final
rule.
Textron requested the FAA insert ``significantly'' before
``reduce'' in proposed Sec. 23.1320(b), because any reduction in
capacity would trigger this rule.
The FAA agrees with Textron and revises the language in proposed
Sec. 23.1320(b) (now Sec. 23.2515(b)) accordingly. This change is
consistent with former Sec. 23.1306, which used the phrase
``significantly reduce.'' Also, this change is necessary because
without the term ``significantly'', the language could be interpreted
as imposing requirements on each electrical and electronic system that
performs a function, the failure of which would reduce--no matter how
minimal--the capability of the airplane or the ability of the
flightcrew to respond to an adverse operating condition. This would
increase the burden from former part 23, which was not the FAA's
intent.
g. High-Intensity Radiated Fields (HIRF) Protection (Proposed Sec.
23.1325/Now Sec. 23.2520)
In the NPRM, proposed Sec. 23.1325 (now Sec. 23.2520) would have
required electrical and electronic systems that perform a function
whose failure would prevent the continued safe flight and landing of
the airplane, to be designed and installed such that--the airplane
system level function is not adversely affected during and after the
time the airplane is exposed to the HIRF environment. Proposed Sec.
23.1325 would have also required these systems automatically recover
normal operation of that function in a timely manner after the airplane
is exposed to the HIRF environment, unless the system's recovery
conflicts with other operational or functional requirements of the
system.
For airplanes approved for IFR operations, proposed Sec.
23.1325(b) would have required the applicant to design and install each
electrical and electronic system that performs a function--the failure
of which would reduce the capability of the airplane or the ability to
the flightcrew to respond to an adverse operating condition--so the
function recovers normal operation in a timely manner after the
airplane is exposed to the HIRF environment.
[[Page 96654]]
Several commenters raised concerns about the term ``system'' in
proposed Sec. 23.1325(a)(1). Textron stated the phrase ``airplane
system level'' \52\ could be interpreted to mean that if multiple
systems provide a redundant function, each system needs to work through
the threat although only one is required. Textron asked the FAA to
clarify if proposed Sec. 23.1325(a)(1) was intended to require a means
to provide the airplane level function for continued safe flight and
landing. BendixKing similarly commented that the failure being
addressed in proposed Sec. 23.1325(a)(1) is at the airplane level, but
the proposed phrase ``airplane system level function'' would lead to
multiple interpretations of the regulation. Textron and BendixKing
suggested deleting the term ``system'' from proposed Sec.
23.1325(a)(1) to clarify the requirement applies to the airplane level.
---------------------------------------------------------------------------
\52\ Safety requirements exist at the airplane, system, and item
level. SAE International, ARP 475A Guidelines for Development of
Civil Aircraft Systems, 4.1.3 Introduction to Hierarchical Safety
Requirements Generated from Safety Analyses (2010).
---------------------------------------------------------------------------
Garmin noted there has been much discussion in the GAMA HIRF ad-hoc
meetings regarding the definition of a ``system.'' Garmin asked the FAA
whether ``system'' means each individual redundant system or all
redundant systems. Garmin explained that proposed Sec. 23.1325(a)(2)
could be interpreted to impose additional requirements to the extent
that all redundant systems must meet the catastrophic failure
requirements of paragraph (a). Garmin suggested that not all redundant
systems should be required to meet the catastrophic requirements and
proposed Sec. 23.1325(a) should apply only to the function level.
Garmin recommended alternative regulatory language that reflected its
comments.
The FAA agrees that proposed Sec. 23.1325(a)(1) (now Sec.
23.2520(a)(1)) could be misinterpreted due to the confusion surrounding
the phrase ``airplane system level function.'' As explained in the
NPRM, the FAA intended the proposed rule language to clarify the
failure consequence of interest is at the airplane level. Thus, the FAA
intended paragraph (a)(1) to require the function at the airplane level
not to be adversely affected during and after the time the airplane is
exposed to the HIRF environment. This means if multiple systems perform
the same function, only one of those systems is required to provide the
function under paragraph (a)(1). Therefore, in response to Garmin's
comment, the FAA notes not all redundant systems are required to meet
the requirements of paragraph (a)(1). To clearly reflect the intent of
proposed Sec. 23.1325(a)(1) (now Sec. 23.2520(a)(1)), the FAA deletes
the term ``system'' from the phrase ``airplane system level function,''
as recommended by Textron and BendixKing, and revises the proposed rule
language to clarify that the requirements of paragraph (a)(1) apply to
the function at the airplane level.
Furthermore, in light of Garmin's comment, the FAA revises the
proposed rule language in Sec. 23.1325(a) (now Sec. 23.2520(a)) to
clarify that ``each'' electric and electronic system that performs a
function--the failure of which would prevent the continued safe flight
and landing of the airplane--must be designed and installed such that
the requirements of Sec. 23.2520(a)(1) and Sec. 23.2520(a)(2) of this
section are met.
Garmin recommended the FAA delete proposed Sec. 23.1325(a)(2) and
explained that proposed Sec. 23.1325(a)(2) is unnecessary because
proposed Sec. 23.1325(a)(1) already prohibits systems from preventing
safe flight and landing after a HIRF event. The commenter maintained
paragraph (a)(1) would be sufficient to ensure a tiered means of
compliance could be developed based on the criticality of the HIRF
event. Garmin stated that proposed Sec. 23.1325(a)(2) contains design
information, which is contrary to the goal of the part 23
reorganization, and explained the objective should be to prevent
catastrophic, hazardous, and major failure conditions for the airplane.
Garmin suggested revising proposed Sec. 23.1325 to be more general and
allow the ASTM standards to provide the necessary means of compliance.
The FAA disagrees with the commenter's recommendation to delete
proposed Sec. 23.1325(a)(2) and to make paragraph (a) more general.
The FAA agrees with a tiered means of compliance approach for hazardous
and major failure conditions, which are addressed in Sec. 23.2520(b).
However, for catastrophic failure conditions addressed in Sec.
23.2520(a), the FAA finds it necessary to require each system that
performs a function, the failure of which would prevent the continued
safe flight and landing of the airplane, to be able to recover normal
operation of the function. Paragraph Sec. 23.2520(a)(2) is not design
specific; it captures the safety intent of former Sec. 23.1308(a) at a
high level, allowing for means of compliance other than appendix J to
part 23--``HIRF Environments and Equipment HIRF Test Levels''.
Textron asked the FAA to clarify whether proposed Sec.
23.1325(a)(2) would permit flightcrew action in recovery of the
function.
The FAA is removing the term ``automatically'' from the proposed
rule language to clarify that flightcrew action is permitted in
recovering the normal operation of the system's function. The FAA
intended proposed Sec. 23.1325 to capture the safety intent of former
Sec. 23.1308, which required the system to ``automatically'' recover
normal operation of the function in a timely manner. Automatic reset of
a system is a design solution. The safety objective of former Sec.
23.1308(a) is that the function be usable to the flightcrew in a timely
manner such that the intermittent loss or malfunction does not have an
adverse effect on the safety of the flight. The FAA finds that
permitting the flightcrew to manually recover normal operation of the
system's function in a timely manner would maintain the level of safety
found in former Sec. 23.1308(a). Therefore, the recovery of the
function may be automatic or manual under Sec. 23.2520(a)(2).
The Associations commented that current policy and guidance may
apply HIRF requirements differently to part 23 products than in other
areas and suggested that the IFR discriminator in paragraph (b) may not
be as valid as using airworthiness level. The commenters recommended
the FAA restrict paragraph (b) to level 3 and 4 airplanes that are
approved for IFR operations.
Mooney International (Mooney) questioned the intent of including
IFR-related HIRF requirements in paragraph (b). Mooney contended that
HIRF is related to environments from ground-based transmission of RF
energy from radars, radios, etc., which is unrelated to IFR
environmental operations.
The FAA has considered the comments on inconsistent application of
HIRF requirements, but notes the hazardous and major failure conditions
of paragraph (b) should apply to airplanes certificated for IFR
operations regardless of airworthiness level. The different types of
operations an airplane may be certificated for are Day VFR, Night VFR,
and IFR. Airplanes certified for only VFR operations are restricted
from operating under IFR, which includes flight into IMC. IFR-certified
airplanes, however, are not prohibited from flight into IMC. The
severity of a HIRF event is greater in IMC. Therefore, the FAA finds it
necessary to apply the hazardous and major failure conditions to all
airplanes certified for IFR operations. Furthermore, while the FAA is
not restricting the application of paragraph (b) to only level 3 and 4
airplanes, paragraph (b) allows for a
[[Page 96655]]
tiered means of compliance approach based on airworthiness level and
the associated risk. The FAA replaced the prescriptive requirements,
which were further defined in former appendix J to part 23, with the
wording ``exposed to the HIRF environment.'' The intent is to allow for
the exposure environment to match the risk associated with each
airplane level. Therefore, the threat will be appropriately scaled to
the airworthiness level as the data and risk supports.
Garmin suggested revising the proposed rule language of paragraph
(b) to require each electrical and electronic system to be designed and
installed, rather than requiring the applicant to design and install
each system.
The FAA adopts Garmin's recommendation, which makes the language of
paragraph (b) parallel the language of paragraph (a).
Embraer suggested the FAA adopt the same HIRF environments and test
levels that are described in former appendix J to part 23, which were
associated with former Sec. 23.1308.
The FAA finds the prescriptive environments and test levels found
in former appendix J to part 23 are more appropriately addressed as a
means of compliance to proposed Sec. 23.1325 (now Sec. 23.2520). This
allows the test levels to change as the environment changes without new
regulatory action. Additionally, one prescriptive level for all
airplanes does not allow for a tiered compliance approach, which was an
objective of this rule.
h. System Power Generation, Storage, and Distribution (Proposed Sec.
23.1330/Now Sec. 23.2525)
In the NPRM, proposed Sec. 23.1330 (now Sec. 23.2525) would have
required the power generation, storage, and distribution for any system
be designed and installed to supply the power required for operation of
connected loads during all likely operating conditions. Proposed Sec.
23.1330 would have required the design installation ensure no single
failure or malfunction would prevent the system from supplying the
essential loads required for continued safe flight and landing.
Finally, proposed Sec. 23.1330 would have required the design and
installation have enough capacity to supply essential loads, should the
primary power source fail, (for at least 30 minutes for airplanes
certificated with a maximum altitude of 25,000 feet or less and at
least 60 minutes for airplanes certificated with a maximum altitude
over 25,000 feet.
Textron requested the FAA make slight revisions to proposed Sec.
23.1330(a) to harmonize the wording with CS 23.630. Specifically,
Textron recommended requiring the power generation, storage, and
distribution for any system be designed and installed to supply the
power required for operation of connected loads during all intended
operating conditions rather than ``all likely operating conditions''
because it would provide a clear boundary for demonstration of
compliance. In the alternative, Textron suggested removing proposed
paragraph (a) because the requirement is already covered more broadly
in proposed Sec. 23.1300(a)(2).
The FAA agrees with Textron's recommendation to replace ``likely''
with ``intended'' to harmonize with EASA and make clear the boundary
for demonstration of compliance. Therefore, the FAA did not consider
Textron's alternative recommendation to remove paragraph (a). The FAA
notes that proposed Sec. 23.1330(a) (now Sec. 23.2525) is not
redundant with proposed Sec. 23.1300(a)(2) (now Sec. 23.2500).
Section 23.2500 is a rule of general applicability and does not
supersede more specific rules. It is appropriate for system power
generation, storage, and distribution to be addressed by a specific
rule.
Air Tractor noted that proposed Sec. 23.1330(b) appears more
restrictive than former Sec. 23.1310 in regards to single-point
failures. The commenter further noted this may require there be no
single failure points between the power supply and the essential load
bus.
The FAA did not intend for proposed Sec. 23.1330(b) (now Sec.
23.2525(b)) to be more restrictive than the requirements under former
part 23. The FAA revises proposed Sec. 23.1330(b) for clarity by
adding ``of any one power supply, distribution system, or other
utilization system.'' This sets limits as to what needs to be
considered when examining single-point failures.
Several commenters, including EASA, Kestrel, Daher, and the
Associations raised concerns about the minimum flight times (i.e., 30
minutes and 60 minutes) set forth in proposed Sec. 23.1330(c). The
commenters generally focused on allowing the means of compliance to
define the appropriate minimum flight times and basing the minimum
flight times on airplane performance. Daher suggested that ASTM
standards should provide minimum flight times for battery systems. The
Associations raised concerns the requirement in proposed Sec.
23.1330(c)(1) may be excessive for airplanes with a maximum ceiling
much lower than 25,000 feet. The Associations requested the FAA provide
a reasonable window of essential power required for these lower flying
airplanes for which electrical power will be controlled in a very
reliable but efficient manner due to the nature of their design.
Similarly, BendixKing noted that 25,000 feet and 30 minutes capacity
requirement to supply essential loads may be restrictive to newer
``simple'' airplanes, which operate only at 10,000 feet and require
only 10-15 minutes. Garmin noted the wording of the proposed rule would
require some new electrical-powered airplanes, which may have flight
durations of less than 30 or 60 minutes, to carry the power supply
regardless.
In response to numerous comments opposing the specific flights
times outlined in proposed Sec. 23.1330(c)(1) and (c)(2) (now Sec.
23.2525(c)), the FAA agrees the language would have been overly
prescriptive and incompatible with new technologies. The FAA revises
proposed Sec. 23.1330(c) to remove the specific time requirements and
add the safety intent requiring enough capacity for the time needed to
complete the functions required for continued safe flight and landing.
Kestrel questioned whether the language ``design and installation
have enough capacity to supply essential loads'' permitted use of both
the engine start battery and the emergency battery in combination to
supply essential loads in the event of loss of the primary electrical
power generating systems, without the need for an alternate means of
compliance. The commenter noted this is typically addressed using an
ELOS finding to former Sec. 23.1353(h).
Kestrel also raised concerns about the possible misinterpretation
of the phrase ``if the primary source fails'' in proposed Sec.
23.1330(c). Kestrel said it was aware of at least one such instance,
resulting in the issuance of an STC based on the understanding this
meant failure of the primary generator and proper operation of the
backup alternator. Kestrel asked FAA to revise the wording to prevent
this possible misinterpretation.
Both of Kestrel's comments relate to a specific design solution and
method of compliance that should be addressed with the use of industry
developed consensus standards or other accepted means of compliance. In
the past, the engine start battery could be used to meet the required
load capacity based on an ELOS finding (as pointed out be Kestrel). The
requirements found in this ELOS finding to former Sec. 23.1353(h)
could be documented in a consensus standard as an acceptable means of
compliance to the regulation. The same applies to the definition of the
``primary source.'' The intent is not to increase
[[Page 96656]]
design requirements, but to make showing of compliance more flexible.
Textron requested the FAA limit the applicability of proposed Sec.
23.1330(c) to electrical systems by changing the title proposed Sec.
23.1330 to ``Electrical system power generation, storage, and
distribution.''
The FAA disagrees with Textron's proposal as the Part 23 ARC
discussed this issue, with a consensus agreeing the rule should apply
to current technologies such as batteries and new technologies that may
apply in the future. The language proposed by the FAA would implement
the ARC's recommendation, and the FAA makes no changes to that language
in the final rule based on Textron's proposal.
i. External and Cockpit Lighting (Proposed Sec. 23.1335/Now Sec.
23.2530)
In the NPRM, proposed Sec. 23.1335 (now Sec. 23.2530) would have
required an applicant to design and install all lights to prevent
adverse effects on the performance of flightcrew duties. Proposed Sec.
23.1335 would have required position and anti-collision lights, if
installed, to have the intensities, flash rate, colors, fields of
coverage, and other characteristics to provide sufficient time for
another airplane to avoid a collision. Proposed Sec. 23.1335 would
have required position lights, if installed, to include a red light on
the left side of the airplane, a green light on the right side of the
airplane, spaced laterally as far apart as practicable, and a white
light facing aft, located on an aft portion of the airplane or on the
wing tips. Proposed Sec. 23.1335 would have required that an applicant
to design and install any taxi and landing lights, if required by
operational rules, so they provide sufficient light for night
operations. Finally, for seaplanes or amphibian airplanes, proposed
Sec. 23.1335 would have required riding lights to provide a white
light visible in clear atmospheric conditions.
Textron commented on proposed Sec. 23.1335(a), explaining it would
have been difficult to design and install lights to ``prevent adverse
effects'' on the performance of flightcrew duties in all cases.
Therefore, Textron recommended the FAA require lights to be installed
to ``minimize,'' rather than ``prevent,'' the possibility they will
adversely affect the satisfactory performance of the flightcrew's
duties.\53\
---------------------------------------------------------------------------
\53\ This wording was proposed in the ARC final report for Sec.
23.1383.
---------------------------------------------------------------------------
The FAA agrees the term ``prevent'' would be difficult to comply
with in all cases. The FAA also interprets the term ``prevent'' to be
more restrictive than the former requirements, which used descriptive
terms such as ``no dangerous glare'' in former Sec. 23.1383(a) and
``not seriously affected'' in former Sec. 23.1383(b). The term
``minimize'' more accurately reflects the former requirements of part
23. For these reasons, the FAA revises the proposed rule language to
require the applicant to design and install all lights to minimize any
adverse effects on the performance of flightcrew duties.
Kestrel commented that the proposed wording, ``as far as space
allows,'' in proposed Sec. 23.1335(c) could be interpreted to mean
that integrated wingtip navigation lights are no longer permitted, and
the only way to meet the requirement is to install external navigation
lights outboard of the wingtips. Kestrel recommended reverting to the
language used in former Sec. 23.1385, which stated that navigation
lights should be ``spaced laterally as far apart as practicable.''
The FAA agrees with the commenter. The FAA intended proposed Sec.
23.1335(c) (now Sec. 23.2530(c)) to capture the safety intent of
former Sec. 23.1385(c) without an increase in burden for
certification. Former Sec. 23.1385(c) required the left and right
position lights to consist of a red and a green light ``spaced
laterally as far apart as practicable.'' The FAA is reverting back to
this language for the reasons identified by the commenter. Accordingly,
Sec. 23.2530(c) now requires any position lights, if required by part
91, to include a red light on the left side of the airplane and a green
light on the right side of the airplane, spaced laterally as far apart
as practicable.
Kestrel and Air Tractor commented on proposed Sec. 23.1335(d),
which would have required the installation of taxi and landing lights.
Kestrel asked the FAA to align proposed paragraph (d) with former Sec.
23.1383, which did not require the installation of both taxi and
landing lights, but instead required ``sufficient light for each phase
of night operations.'' Air Tractor suggested the FAA add rule language
to paragraph (d) to make it applicable to taxi and landing lights, ``if
installed,'' because the regulations do not require night operations.
The FAA did not intend to require the design and installation of
taxi and landing lights in proposed Sec. 23.1335(d) (now Sec.
23.2530(d)). As explained in the NPRM, the FAA intended proposed Sec.
23.1335(d) to capture the safety intent of former Sec. 23.1383, which
required each taxi and landing light to be designed and installed so
that it provided enough light for night operations. The FAA revises the
proposed rule language to more clearly reflect its intent. Accordingly,
Sec. 23.2530(d) now requires any taxi and landing lights to be
designed and installed so they provide sufficient light for night
operations.
The Associations and ICON recommended the FAA not adopt proposed
Sec. 23.1335(e). The Associations noted that the requirement is
already addressed in regulations concerning maritime vessels, and could
create a conflict should those maritime regulations be changed. The
Associations also noted that there is no safety benefit in duplicate
coverage. ICON commented that the FAA proposed to add a requirement for
a riding light on seaplanes. ICON stated that the operational
requirement for a vehicle to display a white light on the water is not
an FAA requirement and should not be mandated as a vehicle design
requirement by the FAA. ICON recommended the FAA let the agency
controlling the body of water impose this operating rule on seaplanes.
ICON further noted it should not be a design requirement because a
pilot may choose to comply with the requirement by using a portable
light rather than an installed device on an airplane.
The FAA considered the commenters recommendations but notes
proposed Sec. 23.1335(e) (now Sec. 23.2530(e)) is not a new
requirement. As explained in the NPRM, proposed Sec. 23.1335(e)
captures the safety intent of former Sec. 23.1399. Former Sec.
23.1399 required each riding (anchor) light required for a seaplane or
amphibian, to be installed so it can show a white light for at least
two miles at night under clear atmospheric conditions; and show the
maximum unbroken light practicable when the airplane is moored or
drifting on the water. Former Sec. 23.1399 was adopted on February 1,
1965, as a recodification of CAR 3.704.\54\ The FAA's intent was to
remove the prescriptive requirements of former Sec. 23.1399 to means
of compliance and imposing the safety requirement as a performance-
based standard in paragraph (e). Therefore, the FAA adopts paragraph
(e) as proposed.
---------------------------------------------------------------------------
\54\ See 29 FR 17955 (1964).
---------------------------------------------------------------------------
While the commenters did not cite a specific regulation concerning
vessels, the FAA has determined the commenters are referring to Title
33 of the CFR (33 CFR), Navigation and Navigable Waters. 33 CFR part 83
contains rules applicable to all vessels upon the inland waters of the
United States,\55\ and defines a vessel as including every description
of water craft-- including seaplanes--used or
[[Page 96657]]
capable of being used as a means of transportation on the water.\56\
Thus, while a seaplane is anchored or afloat upon the inland waters of
the United States, it is subject to part 83. Although Sec. 83.30
contains light requirements for anchored vessels, the FAA finds it
necessary to require seaplanes to have a riding light that provides a
white light visible in clear atmospheric conditions. The objective of
Sec. 83.30 is to ensure vessels see other vessels. The objective of
Sec. 23.2530(e) is to ensure seaplanes are able to see other seaplanes
in the interest of safety, not to provide duplicate coverage. There is
no apparent conflict between part 83 and Sec. 23.2530(e), nor has
there been a known conflict in the last fifty years. Furthermore, Sec.
83.31 states that where it is impractical for a seaplane to exhibit
lights and shapes of the characteristics or in the positions prescribed
in subpart C of part 83, which contains Sec. 83.30, that seaplane
shall exhibit lights and shapes as closely similar in characteristics
and position as possible.
---------------------------------------------------------------------------
\55\ See 33 CFR 83.01.
\56\ See 33 CFR 83.03.
---------------------------------------------------------------------------
Also, former Sec. 23.1399(b) stated that externally-hung lights
may be used. While the FAA removed this prescriptive requirement from
the regulations, it may still be used as an acceptable means of
compliance to Sec. 23.2530(e).
Finally, Embraer suggested the FAA adopt guidance material and
standards, such as ACs and Agency Process Recommendations, as reference
to the certification project, provided these documents are compatible
with the former part 23 requirements.
The FAA notes that current published guidance, previously accepted
industry standards, and the prescriptive requirements found in former
part 23 will remain acceptable means of compliance for this final rule.
The FAA will continue to develop guidance as deemed necessary, but
intends to use industry-developed standards if they are found
acceptable. The FAA is actively engaged with industry consensus groups
developing suitable standards for this final rule.
j. Safety Equipment (Proposed Sec. 23.1400/Now Sec. 23.2535)
In the NPRM, proposed Sec. 23.1400 (now Sec. 23.2535) would have
required safety and survival equipment, required by the operating rules
of this chapter, to be reliable, readily accessible, easily
identifiable, and clearly marked to identify its method of operation.
Air Tractor noted that the requirement for safety and survival
equipment to be reliable may require some kind of testing or
certification of fire extinguishers. The commenter questioned whether
the current Underwriter's Laboratory (UL) rating of fire extinguishers
would be sufficient.
The FAA finds the UL rating for fire extinguishers will be an
acceptable means of compliance under Sec. 23.2535, as it was an
acceptable method of compliance under former Sec. 23.1411. As
explained in the NPRM, the FAA intended proposed Sec. 23.1400 (now
Sec. 23.2535) to capture the safety intent of former Sec. 23.1411.
While the FAA removed the prescriptive language from former Sec.
23.1411, it did not intend to change the current method of compliance
for the required safety and survival equipment.
k. Flight In Icing Conditions (Proposed Sec. 23.1405/Now Sec.
23.2540)
In the NPRM, proposed Sec. 23.1405 (now Sec. 23.2540) would have
required an applicant to demonstrate its ice protection system would
provide for safe operation, if certification for flight in icing
conditions is requested.\57\ Proposed Sec. 23.1405 would have required
these airplanes to be protected from stalling when the autopilot is
operating in a vertical mode. Proposed Sec. 23.1405 would have also
required this demonstration be conducted in atmospheric icing
conditions specified in part 1 of appendix C to part 25 of this
chapter, and any additional icing conditions for which certification is
requested.
---------------------------------------------------------------------------
\57\ Part 23 Icing ARC recommendations, including
recommendations on activation and operation of ice protection
systems, would have been used as a means of compliance to proposed
Sec. 23.1405(a)(1).
---------------------------------------------------------------------------
In light of comments received, the FAA revises Sec. 23.2540 to
move proposed paragraphs (a) and (b) to the introductory paragraph, and
renumber proposed paragraphs (a)(1) and (2) as new paragraphs (a) and
(b). This section discusses these changes in more detail.
The NTSB stated that adopting proposed Sec. Sec. 23.230 (now Sec.
23.2165) and 23.1405 will likely result in Safety Recommendation A-96-
54 being classified ``Closed--Acceptable Action.'' The NTSB agreed with
the FAA's statement in the NPRM that proposed Sec. 23.1405 would
address Safety Recommendations A-07-14 and-15.
The Associations suggested a better correlation between proposed
Sec. Sec. 23.230 and 23.1405 and added it may be appropriate to
combine these sections.
In light of this comment, the FAA is restructuring proposed Sec.
23.1405 to be consistent with Sec. 23.2165. Proposed Sec. 23.1405(a)
and Sec. 23.1405(b) were combined into the introductory sentence of
Sec. 23.2540 and modified to read similarly to Sec. 23.2165.
Accordingly, Sec. 23.2540 now requires an applicant who requests
certification for flight in icing conditions defined in part 1 of
appendix C to part 25, or an applicant who requests certification for
flight in these icing conditions and any additional atmospheric icing
conditions, to show compliance with paragraphs (a) and (b) in the icing
conditions for which certification is requested.\58\
---------------------------------------------------------------------------
\58\ See section III, B. Part 23, Airworthiness Standards,
Subpart B of this preamble (explaining the clarifying change made to
proposed Sec. 23.230(a)).
---------------------------------------------------------------------------
The FAA is not, however, combining proposed Sec. Sec. 23.230 and
23.1405. The FAA agrees with the Part 23 Icing ARC's and the Part 23
ARC's recommendations to separate the performance and flight
characteristics requirements for flight in icing conditions from the
system requirements for flight in icing conditions.\59\ The FAA notes
Sec. 23.2165 contains the requirement to safely avoid or exit icing
conditions for which certification is not requested, whereas Sec.
23.2540 does not contain such a requirement for systems. The FAA finds
it appropriate to keep these sections separate as the distinction
between the sections means that systems, such as the windshield or air
data, do not have to be evaluated in icing conditions for which the
airplane is not requesting certification.
---------------------------------------------------------------------------
\59\ See docket number FAA-2015-1621.
---------------------------------------------------------------------------
Textron and Kestrel commented on ice crystal conditions. Textron
noted that the proposed rule would not have defined ice crystal
conditions and asked the FAA where the term would be defined. Kestrel
asked if the requirements of TSO C16a, ``Electrically Heated Pitot and
Pitot-Static Tubes'', would be an acceptable means of compliance to the
ice crystal requirements of proposed Sec. 23.1405.
The FAA notes the phrase ``any additional atmospheric icing
conditions'' in proposed Sec. 23.1405 includes ``ice crystal
conditions''. However, the FAA is not defining ``ice crystal
conditions'' in the final rule because it is more appropriately
addressed in means of compliance.
The FAA finds TSO C16a will be an acceptable means of compliance
when it is revised to include SAE airworthiness standard AS 5562, ``Ice
and Rain Minimum Qualification Standards for Pitot and Pitot-static
Probes''. The FAA notes SAE AS 5562 is an acceptable means of
compliance to the ice crystal requirements for pitot and static
systems. The FAA points out, however, that SAE AS 5562 does not include
ice crystal requirements for certain angle-of-
[[Page 96658]]
attack instruments, such as sensors that utilize differential static
pressure.
Kestrel questioned if the FAA would permit ice protection systems
to be operational on an airplane not certified for Flight Into Known
Ice (FIKI), as it does today via the guidelines established in Appendix
4 of AC 23.1419-2D for ``non-hazard'' systems. Kestrel noted that it
was unclear whether the FAA intends to continue the use of the ``non-
hazard'' classification because the NPRM does not explicitly mention
``non-hazard'' systems. Kestrel believed that operational ice
protection systems on non-FIKI-certified airplane do not need a special
``non-hazard'' classification. Kestrel suggested ice protections
systems could be considered supplemental systems, which are addressed
by the installation and inadvertent operation requirements of proposed
Sec. Sec. 23.1300 and 23.1315.
Prior to this final rule, the FAA certified ``non-hazard'' systems
in accordance with former Sec. Sec. 23.1301 and 23.1309(a)(2), (b),
(c), and (d). As explained in the NPRM, the FAA intended proposed
Sec. Sec. 23.1300(b) (now Sec. 23.2500(b)), 23.1305 (now Sec.
23.2505), and 23.1315 (now Sec. 23.2510) to capture the safety intent
of the applicable portions of former Sec. 23.1301 and Sec. 23.1309.
Therefore, the FAA intends to certify these ``non-hazard'' systems in
accordance with Sec. Sec. 23.2500(b), 23.2505, and 23.2510.
The FAA received several comments on proposed Sec. 23.1405(a)(2).
Garmin stated that proposed Sec. 23.1405(a)(2) should apply regardless
of whether an airplane is certified for flight in icing conditions.
Garmin recommended the FAA either move the proposed requirement to
proposed Sec. 23.215 (now Sec. 23.2150) or delete it.
The FAA agrees that an airplane must be protected from stalling
when the autopilot is operating, regardless of whether the airplane is
certified for flight in icing conditions. However, proposed Sec.
23.1405(a)(2) (now Sec. 23.2540(b)) should not apply to airplanes
where the applicant is not requesting certification for flight in icing
conditions. The stall warning requirements of Sec. 23.2150 will
provide low-airspeed awareness, with or without the autopilot engaged,
for new airplanes not certified for icing. The FAA finds Sec.
23.2165(a) will provide stall warning for new airplanes where the
applicant is requesting certification for flight in icing conditions.
For new airplanes, the FAA acknowledges that a stall warning system
that complies with Sec. Sec. 23.2150 and 23.2165(a) will comply with
Sec. 23.2540(b). Section 23.2540(b) will also be added to the
certification basis of certain STCs and amended TCs on icing certified
airplanes, as discussed below in this section.
Textron and Rockwell Collins commented on the prescriptiveness of
proposed Sec. 23.1405(a)(2). Textron added that proposed Sec.
23.1405(a)(2), which was in place only for changed product rule
considerations, appeared to be a band-aid solution and not in line with
higher-level goals for the new rules. Textron suggested the FAA delete
proposed paragraph (a)(2).
The FAA finds that proposed Sec. 23.1405(a)(2), with the exception
of specifying ``vertical mode,'' is performance-based and consistent
with the higher-level goals of the proposal, because the standard does
not specify how to achieve protection from a stall. The FAA expects
means of compliance to include the Icing ARC's recommendations. The FAA
deletes the reference to ``vertical mode'' from Sec. 23.2540(b) to
make it less prescriptive, since it is expected the icing means of
compliance will recognize that only vertical modes may result in
airspeed loss. The FAA renumbers this section as part of the final
rule. Proposed Sec. 23.1405(a)(2) is now Sec. 23.2540(b).
Additionally, in response to Textron's comment, proposed Sec.
23.1405(a)(2) (now Sec. 23.2540(b)) is intended to increase the safety
of the existing fleet. While Sec. 23.2540(a) and (b) apply to new
airplanes, the FAA intends Sec. 23.2540(b) to specifically target
older airplanes adding an autopilot for the first time, modifying
certain autopilots on airplanes with a negative service history in
icing, or making significant changes that affect performance or flight
characteristics and affect the autopilot. As stated in the NPRM, under
the changed product rule, Sec. 23.2540(b) will be added to the
certification basis of these types of STCs and amended TCs for icing
certified airplanes. This will result in a targeted increase in safety
without requiring compliance to an entire later amendment, including
Sec. 23.2540(a). Compliance with Sec. 23.2540(a) would require the
applicant to address areas unaffected by an autopilot STC. The Part 23
Icing ARC Report (Icing ARC Report) provides examples of modifications
in which new Sec. 23.2540(b) will be applicable. Numerous icing
accidents have shown that unrecognized airspeed loss can occur with
autopilots in altitude hold or vertical speed modes. Means of
compliance other than modifications to the airplanes' stall warning
system may be acceptable under Sec. 23.2540(b) for these STCs and
amended TCs. The Task 9, ``Determine if implementation of NTSB Safety
Recommendation A-10-12 is feasible for part 23 airplanes for operations
in icing conditions,'' discussion in the Icing ARC Report provides
additional background.
Rockwell Collins stated that proposed Sec. 23.1405(a)(2) could be
interpreted as requiring the autopilot to protect the airplane from
stalling.
To address the commenter's concern, the FAA revises the proposed
rule language (now Sec. 23.2540(b)) to clarify that the airplane
design must provide protection from stalling when the autopilot is
operating.
The NTSB disagreed that proposed Sec. 23.1405(a)(2) would address
Safety Recommendation A-10-12, which concerns low-airspeed alerting
systems. The NTSB stated that this safety recommendation would be more
appropriately addressed in proposed Sec. 23.1500, ``Flightcrew
Interface.''
The FAA notes, as explained in the NPRM, proposed Sec.
23.1405(a)(2) was based on NTSB safety recommendation A-10-12. This
implied proposed Sec. 23.1405(a)(2) responded to recommendation A-10-
12. The FAA acknowledges Sec. 23.2540(b) is not the type of stall
protection the NTSB recommended because it does not require the
installation of low-airspeed alert systems. Instead, Sec. 23.2540(b)
addresses a different and more urgent safety problem by requiring
airplanes with autopilots to provide an adequate stall warning in icing
conditions. Furthermore, Sec. 23.2540(b) is an airworthiness standard
that establishes a minimum level of safety for all airplanes under part
23. If the FAA were to adopt a requirement in part 23 that required
applicants to install a low-speed alert system in their airplanes, that
requirement would apply to all airplanes. The FAA did not propose such
a requirement because safety recommendation A-10-12 applies only to
commercial airplanes under part 91 subpart K, and parts 121, and 135.
To properly respond to NTSB safety recommendation A-10-12, the FAA
would have to change the operating rules, which is outside the scope of
this rulemaking.
Embraer and Garmin both commented on the term ``demonstration.''
Embraer recommended the FAA change ``in atmospheric icing conditions''
in proposed paragraph (b) to ``considering atmospheric icing
conditions''. Embraer stated that its proposal aimed to make a broad
statement, implying that there may be several means of addressing the
icing conditions as shown in figures 1 through 6 of Appendix C to Part
25. The commenter asserted the original text in the NPRM might be
understood as
[[Page 96659]]
requiring only a flight test demonstration. Garmin commented on the
importance of clarifying this term because the FAA Aircraft
Certification Office has almost always insisted that ``demonstration''
means the applicant must perform it on an airplane.
In light of these comments, the FAA is using the phrase ``must
show'' rather than ``must demonstrate'' in the introductory sentence of
Sec. 23.2540, which is consistent with the changes made to Sec.
23.2165. This change is also consistent with the NPRM, which explained
that demonstration, as a means of compliance, may include design and/or
analysis and does not mean flight tests are required. However, for the
foreseeable future, the FAA does expect means of compliance to include
icing flight tests for applicants seeking icing certification for new
TCs.
l. Pressurized System Elements (Proposed Sec. 23.1410/Now Sec.
23.2545)
In the NPRM, proposed Sec. 23.1410(a), (c) and (d) (now Sec.
23.2545) would have required the minimum burst pressure of--
Hydraulic systems be at least 2.5 times the design
operating pressure with the proof pressure at least 1.5 times the
maximum operating pressure;
Pressurization system elements be at least 2.0 times, and
proof pressure be at least 1.5 times, the maximum normal operating
pressure; and
Pneumatic system elements be at least 3.0 times, and proof
pressure be at least 1.5 times, the maximum normal operating pressure.
Proposed Sec. 23.1410(e) would have required that other pressurized
system elements to have pressure margins that take into account system
design and operating conditions. Additionally, proposed Sec.
23.1410(b) would have required engine driven accessories essential to
safe operation to be distributed among multiple engines, on multiengine
airplanes.
In light of comments received, the FAA withdraws proposed Sec.
23.1410(a) through (e) and adopts new language for Sec. 23.2545. This
section discusses these changes in more detail.
Garmin commented that proposed Sec. 23.1410 was still extremely
prescriptive and suggested the FAA revise the rule to a higher safety
objective, and burst and proof pressures should be in a consensus
standard. Garmin proposed alternative, less prescriptive language. ANAC
similarly stated that parts of proposed Sec. 23.1410 were too
prescriptive and suggested that it might be more appropriate to set the
``minimum burst'' and ``proof pressure'' values for the hydraulic,
pressurization, and pneumatic systems using consensus standards. ANAC
also proposed alternative language.
The FAA agrees with ANAC's recommendation to set the proof and
burst factors for hydraulic, pneumatic and pressurization systems in
consensus standards or means of compliance. This is consistent with the
FAA's goal of moving from prescriptive regulations to performance-based
regulations. The FAA did not use Garmin's suggested language because it
did not clearly state that the requirement was for ``proof'' and
``burst'' pressure, and would have applied to ``pressurized system
elements''. This may be more limited than using the phrase
``pressurized system''. ANAC's suggested language was also not used
because it was not inclusive of all pressurized systems. Consensus
standards or means of compliance can be used to document the
appropriate proof and burst factors, the operating pressure to be
factored, pass/fail criteria for tests, and other information included
in former Sec. 23.1435(a)(4), (b), Sec. 23.1438, and AC 23-17C.
Textron noted it is unclear what the difference is between the
terminology used to describe the system pressures upon which the
factors in proposed Sec. 23.1410(a), (c), (d), and (e) are applied
(i.e., ``design operation pressure,'' ``maximum operating pressure,''
and ``maximum normal operating pressure.''). ANAC made a similar
observation, as it noted the phrase ``maximum operating pressure'' in
proposed Sec. 23.1410(a) and the phrase ``maximum normal operating
pressure'' in proposed Sec. 23.1410(b) and (c) might share the same
interpretation. ANAC recommended a harmonization between these
paragraphs in order to avoid misinterpretations for the consensus
standards, while Textron suggested that using the ASTM to identify
those differences would be more in keeping with the move from
prescriptive to performance-based standards. ANAC also recommended
merging proposed Sec. 23.1410(a), (c), and (d).
The FAA agrees with merging proposed Sec. 23.1410 (a), (c) and (d)
because they are similar and related. In addition, the FAA has decided
to merge proposed Sec. 23.1410(e) with these requirements to address
all systems containing fluids under pressure. Therefore, the FAA
withdraws proposed paragraphs (a), (c), (d), and (e) and adopts new
language in Sec. 23.2545 that requires pressurized systems to
withstand appropriate proof and burst pressures.
ANAC, Textron, and an individual commenter addressed proposed Sec.
23.1410(b). ANAC recommended the provision be deleted. In addition to
being prescriptive, ANAC noted the provision is already addressed in
proposed Sec. 23.1315, which evaluates in a more systematic way the
design and installation of a system or component according to their
failure condition that is directly related to the airplane safe
operation. Additionally, Textron said the provision is misplaced and
should be moved to proposed subpart E, Sec. 23.900 or Sec. 23.910
(now Sec. 23.2410). An individual commenter also recommended moving
the provision to Sec. 23.900.
Based on the comments, the FAA has decided that the safety intent
of this requirement is adequately addressed in Sec. 23.2510 and Sec.
23.2410. Section 23.2510 requires equipment separation and redundancy
based on the severity of equipment failures. Section 23.2410 requires
powerplant failures, including engine driven accessory failures, to be
considered and mitigated--effectively requiring safety critical engine
driven accessories to be distributed on multiengine airplanes.
Therefore, the FAA withdraws proposed Sec. 23.1410(b) from the final
rule; hence, there is no reason to place it elsewhere.
m. Equipment Containing High-Energy Rotors (Sec. 23.2550)
The requirements of former Sec. 23.1461 were not fully
incorporated into proposed Sec. 23.755(a)(3), so the FAA creates a new
Sec. 23.2550 to correct this omission. The preamble section for Sec.
23.2320 discusses this change in more detail.
8. Subpart G--Flightcrew Interface and Other Information
a. General Discussion
In the NPRM, the FAA proposed substantial changes to former subpart
G based on its assessment that many of the regulations contained in
this subpart contain prescriptive requirements that are more
appropriate for inclusion as means of compliance to the new part 23
performance-based regulations. The FAA noted this approach would
provide at least the same level of safety as current prescriptive
requirements while providing greater flexibility for future designs.
The FAA also expanded the scope of the subpart to address flightcrew
interface requirements.
Zee agreed with the FAA's proposal to expand subpart G to address
not only current operating limitations and information, but also
flightcrew interface. Zee noted that, based on current technology, the
FAA anticipates new airplanes will heavily rely on
[[Page 96660]]
automation and systems that require new and novel pilot or flightcrew
interface methods and procedures. The commenter noted further that more
automated systems could dramatically reduce cockpit workload, which
would be a great boon for the public who has shied away from personal
aviation transportation due to increasing operational complexities of
traditional airplanes.
EASA commented that information from various other subparts in
proposed part 23 should be included in subpart G to provide
requirements on how the information should be provided. EASA noted that
proposed subpart G could include requirements for subjects such as
flightcrew interface; function and installation, flight, navigation,
powerplant instruments, cockpit controls, instrument markings, control
markings and placards, airplane flight manual, and instructions for
continued airworthiness. EASA also noted these subjects were under
consideration by EASA for inclusion as separate sections in a future
proposal to revise CS 23.
The FAA finds its proposed actions respond to the concerns of Zee,
EASA, and others within the industry to better address the issue of
flightcrew interface. The FAA recognizes that flightcrew interface
issues have become increasingly more important as a result of recent
technological developments in flight, navigation, surveillance, and
powerplant control systems. The FAA partially agrees with EASA's
comment that information from various other subparts in proposed part
23 should be included in subpart G. However, the FAA finds the full
extent of the material EASA proposes for inclusion would establish
requirements that would be too prescriptive in nature and therefore not
in accord with the overall objective of this rulemaking to replace the
detailed prescriptive requirements with more general performance-based
standards. The FAA does, however, acknowledge that certain sections of
EASA A-NPA 2015-06 and NPA 2016-05 may better address those
requirements where the FAA's proposed language may have been too
general in nature and not sufficiently detailed to permit adequate
means of compliance to be developed. In a number of instances, the FAA
has adopted either the specific regulatory language used by EASA or
similar equivalent language to better address those safety concerns and
achieve greater harmonization. The specific instances where the FAA has
adopted these revisions are discussed in the preamble to the sections
in which those changes have been made.
The FAA notes that EASA proposed the inclusion of three sections in
its revision of CS 23, subpart G, which added substantial detail to
that subpart. The FAA did not include corresponding sections within its
proposed subpart G. Proposed CS 23.2605, ``Installation and operation
information'', and proposed CS 23.2610, ``Flight, navigation, and
powerplant instruments'', however, did correspond to proposed Sec.
23.1305 and proposed Sec. 23.1310, respectively, in subpart F of the
NPRM. Proposed CS 23.2615, ``Cockpit controls,'' was also in EASA's
proposed subpart G, but did not have a corresponding section in the
NPRM.
The FAA agrees that placing the requirements contained in these
sections into subpart G is more appropriate than addressing those
requirements in subpart F, as these requirements more directly relate
to flightcrew interface issues. Accordingly, the FAA is relocating
proposed Sec. 23.1305 to subpart G, Sec. 23.2605, ``Installation and
operation,'' and proposed Sec. 23.1310 to Sec. 23.2615, ``Flight,
navigation, and powerplant instruments.'' While adopting the general
safety intent embodied in EASA's proposed regulations, the FAA is not
including the complete level of detail specified in those regulations
because the FAA considers the additional information more appropriate
as a means of compliance. While the FAA believes that cockpit controls
should be addressed under subpart G, the FAA did not include a separate
section in the final rule equivalent to proposed CS 23.2615 because the
FAA has determined these requirements are more appropriate as a means
of compliance to Sec. 23.2600.
b. Flightcrew Interface (Proposed Sec. 23.1500/Now Sec. 23.2600)
In the NPRM, proposed Sec. 23.1500 (now Sec. 23.2600) would have
required the pilot compartment and its equipment to allow each pilot to
perform their duties, including taxi, takeoff, climb, cruise, descent
approach and landing. The pilot compartment and its equipment would
also have to allow a pilot to perform any maneuvers within the
operating envelope of the airplane, without excessive concentration,
skill, alertness, or fatigue. Proposed Sec. 23.1500 would have
required an applicant to install flight, navigation, surveillance, and
powerplant controls and displays so qualified flightcrew could monitor
and perform all tasks associated with the intended functions of systems
and equipment so as to make the possibility that a flightcrew error
could result in a catastrophic event highly unlikely.
Textron noted that proposed Sec. 23.1500 has ``minimal wording''
as compared to CS 23.460 and recommended the FAA harmonize proposed
Sec. 23.1500 with EASA's proposed provisions.
Textron also specifically recommended the FAA add the requirement
in former Sec. 23.671(b) for controls to be arranged and identified to
provide convenience in operation and to prevent the possibility of
confusion and subsequent inadvertent operation, to proposed Sec.
23.1500.
The FAA has reviewed EASA A-NPA 2014-12 and NPA 2016-05 and finds
the level of detail included in the crew interface requirements in both
documents may be overly restrictive. The FAA finds Sec. 23.2600
adequately address pilot compartment requirements and the requirements
for the provision of necessary information and indications to the
flightcrew. The FAA is not revising Sec. 23.2600 as EASA recommended,
because the FAA is concerned that adding the extensive level of detail
that EASA is considering for inclusion in subpart G would neither
enhance the FAA's ability to respond to the introduction of new
technology nor foster future innovation. The FAA notes the adoption of
the EASA's recommended requirements would only serve to create issues
similar to those that the FAA is attempting to address with this
significant revision of part 23 airworthiness standards. However, the
FAA recognizes Textron's concerns and agrees that cockpit controls
should not only be convenient to operate, but also prevent the
possibility of confusion and subsequent inadvertent operation.
Nevertheless, the FAA finds the regulatory intent of former Sec.
23.671 will be achieved because Textron's concerns will be addressed in
any means of compliance developed and submitted for acceptance to
demonstrate compliance with Sec. 23.2600.
Air Tractor raised concerns that proposed Sec. 23.1500(b) added a
requirement that the flightcrew be able to monitor and perform ``all''
tasks associated with the intended functions of systems and equipment.
Air Tractor recommended the FAA insert the term ``required'' after
``all'' to ensure the proposal would not require the performance and
monitoring of non-required tasks. An individual commenter at the FAA's
public meeting also shared concerns regarding use of the term ``all''
and asked if its use would preclude systems from monitoring tasks the
flightcrew does not have to continuously monitor.
The FAA agrees that use of the term ``all'' is too encompassing in
this section
[[Page 96661]]
and could be misinterpreted to impose requirements that would exceed
the safety intent of the rule. However, the FAA finds adding the term
``required'' would make the rule's requirements narrower than the FAA
intended. The FAA notes that airplanes are currently equipped with
systems and equipment that are not necessarily required, yet the
flightcrew must be able have the ability to monitor and perform all
tasks associated with the intended functions of those systems and
equipment to operate the airplane safely. Accordingly, the FAA has
determined that including the term ``defined'' in Sec. 23.2600(b) will
address both the concerns of Air Tractor and the FAA, and also allow
for the installation of systems and equipment that can be used to
monitor a function or parameter for the flightcrew. The FAA notes this
term is currently used in Sec. 25.1302(a), which addresses flightcrew
interface with systems and equipment installed in transport category
airplanes. While the FAA recognizes that many of the requirements in
Sec. 25.1302 are inappropriate for the certification of airplanes
under part 23, the FAA finds its use of the concept of ``defined
tasks'' is appropriate for application to part 23 flightcrew interface
requirements.
An individual commenter asserted that proposed Sec. 23.1500(b) is
``convoluted and subject to varying interpretations.'' The commenter
noted that one such interpretation could be the flightcrew would not be
required to monitor and perform tasks and prevent errors that go beyond
the intended functions of the installed systems and equipment.
Accordingly, the commenter asserted that if there is no equipment
installed to prevent CFIT, such as TAWS, there would be no requirement
for monitoring and performing tasks and preventing errors associated
with terrain clearance. The commenter also stated the rule could be
interpreted to mean the tasks, monitoring, and error prevention
requirements are those associated with a particular flight phase and
flight conditions. For example, the commenter noted that there must be
equipment to prevent CFIT (e.g., TAWS or other), at least for IFR-
certified airplanes, and it must meet the stated requirements. The
commenter noted that many situations and types of equipment could be
affected by the proposal and maintained that if these interpretations
were accurate, there would be obvious cost, weight, practicability, and
other implications that were not adequately addressed in the preamble
or Regulatory Analysis.
In the NPRM, the FAA stated that it proposed to expand subpart G to
address not only current operating limitations and information, but
also the concept of flightcrew interface. The FAA further noted that it
was proposing to address the pilot interface issues found in subparts D
and F in proposed Sec. 23.1500. Otherwise, subpart G retained the
safety intent of the requirements in the former rules. This section
does not impose additional equipment requirements, as suggested by the
commenter's example, but it does require consideration of the
flightcrew interface and human factors in the design and installation
of equipment. The FAA notes the commenter's concern that the flightcrew
would not be required to monitor and perform tasks, such as terrain
avoidance, that are not directly addressed by installed systems and
equipment.
Several commenters raised concerns regarding the use of the term
``highly unlikely'' in proposed Sec. 23.1500(b) that addresses the
ability of the system and equipment design to avoid the possibility
that a flightcrew error could result in a catastrophic event. One
individual commenter specifically noted that ``highly unlikely'' is a
new and undefined term. The commenter recognized that prevention of
errors undoubtedly would increase safety, but noted there is a limit to
how much system and equipment design error prevention is justified and
practicable in any airplane, not just those certificated under the
provisions of part 23. This commenter also contended it would be
difficult to comply with a stringent reading of ``highly unlikely'' and
asserted a review of accident history would reveal this. Garmin, Air
Tractor, and BendixKing submitted similar comments regarding the
potential for this proposed requirement to increase the burden on
applicants. Each of these commenters proposed alternative regulatory
language addressing their concerns.
The Associations commented that the intent of this proposed
requirement is to prevent likely flightcrew errors with flight,
navigation, surveillance, and powerplant controls and displays and
proposed language to meet this intent. Textron also noted the proposed
requirement failed to exclude skill related errors, errors as a result
of malicious intent, recklessness, and actions taken under duress.
Textron contended that system designs should not be responsible for all
possible flightcrew errors, but only for reasonable errors. Textron
recommended proposed alternative regulatory language addressing its
concern.
Astronautics said the term ``highly unlikely,'' as it relates to
``catastrophic,'' would cause confusion in the context of failure
condition categorization and likelihood of occurrence. The commenter
suggested replacing the term ``highly unlikely'' with recognized terms
that categorize failure hazards and probabilities. Astronautics also
suggested recognizing a flightcrew error may have differing degrees of
severity by revising the proposed rule to include consideration of the
three different degrees of failure in proposed Sec. 23.1315(b).
The FAA agrees with many of the commenters concerns regarding the
use of the term ``highly unlikely'' in addressing the probability of
preventing flightcrew errors resulting from system and equipment
designs that could lead to catastrophic events. The FAA also recognizes
the difficulty in assessing complex flightcrew interface issues
associated with the approval of control and display designs. Prior to
the adoption of this rule, the FAA utilized very prescriptive
requirements with associated guidance material based on its need to
address traditional controls, displays, and flight operations in the
certification process. Although the FAA expects that this prescriptive
language for the evaluation of traditional controls and displays will
serve as a means of compliance with the new performance-based
requirements, the FAA determines the new performance-based requirements
will also allow for alternative approaches to meeting flightcrew
interface requirements for non-traditional airplanes, operations, and
non-traditional controls and displays.
As the FAA noted in the NPRM preamble, the smart use of automation
and phase-of-flight-based displays could reduce pilot workload and
increase pilot awareness. Accordingly, the FAA finds new technology can
help the pilot in numerous ways, all with the effect of reducing pilot
workload, which should help reduce accidents based on pilot error. The
FAA intended to remove many of the barriers to the introduction of new
technology while still retaining a clear performance-based requirement
to which an applicant could demonstrate compliance. The FAA recognizes
the potential for misinterpretation of the requirements with this new
approach; however, the FAA's intent is not to increase the requirements
set forth in former regulations, unless specifically stated in the
preamble. The FAA expects the use of performance-based requirements to
address flightcrew interface issues will result in the accelerated
development of industry standards that will be used to improve the
manner in which pilots
[[Page 96662]]
interface not only with information that has been traditionally
provided to them but also with new information. Section 23.2600 is not
intended to add any burden on the applicant and is expected to reduce
time to market for new system and equipment designs, thereby, resulting
in reduced costs.
As several commenters noted, the terms ``highly unlikely'' and
``catastrophic'' have specific meanings with respect to the
certification of systems that typically are not used when addressing
human interactions. Based on the commenters' recommendations, the FAA
finds the best approach to adequately address flightcrew interface
issues is to revise Sec. 23.2600 using language similar to that
contained in former Sec. 23.1309(d), which states that systems and
controls must be designed to minimize crew errors which could create
additional hazards. This avoids the problems associated with the use of
language more appropriate for evaluation of system and equipment
failures.
Shortly after the close of the comment period, EASA published NPA
2016-05, which proposed requirements to address an oversight in the
NPRM regarding the pilot visibility requirements originally contained
in subpart D. The FAA has adopted EASA's proposed language both in
paragraphs (a) and (c) to correct this oversight in the FAA's proposal,
to ensure that pilot compartment visibility requirements are addressed.
Adopting these requirements serves to ensure that pilot view
requirements, and particularly those requirements that could result
from the loss of vision through a windshield panel in a level 4
airplane, are addressed. The FAA finds that these revisions impose no
requirements in excess of those specified in the former Sec. 23.775
and will maintain the level of safety set forth in part 23, through
amendment 23-62, as originally intended in the proposal. As discussed
in the context of proposed Sec. 23.755, the requirement for level 4
airplanes that the flightcrew interface design must allow for continued
safe flight and landing after the loss of vision through any one of the
windshield panels has been moved to Sec. 23.2600(c).
c. Installation and Operation (Proposed Sec. 23.1305/Now Sec.
23.2605)
In the NPRM, proposed Sec. 23.1305 (now Sec. 23.2605) would have
required each item of installed equipment--
To perform its intended function;
Be installed according to limitations specified for that
equipment; and
The equipment be labeled, if applicable, due to the size,
location, or lack of clarity as to its intended function, as to its
identification, function, or operation limitations, or any combination
of these factors.
Proposed Sec. 23.1305 would have required a discernable means of
providing system operating parameters required to operate the airplane,
including warnings, cautions, and normal indications to the responsible
crewmember. Proposed Sec. 23.1305 would have also required information
concerning an unsafe operating condition be provided in a clear and
timely manner to the crewmember responsible for taking corrective
action.
In light of comments received, the FAA revises proposed Sec.
23.1305 by moving paragraphs (a)(2) through (c) to new Sec. 23.2605.
This section discusses these changes in more detail.
The function and installation rule language in proposed Sec.
23.1305 was originally located in subpart F, Equipment. The logic
behind the location of these requirements was that requirements for the
display and control of a specific function would be in subpart G, while
requirements for the hardware or software for the display or control
are would be in subpart F. For this reason, proposed Sec. 23.1305,
``Function and installation,'' included specific paragraphs from the
requirements of former Sec. Sec. 23.1301, 23.1303, 23.1305, 23.1309,
23.1322, 23.1323, 23.1326, 23.1327, 23.1329, 23.1331, 23.1335, 23.1337,
23.1351, 23.1353, 23.1357, 23.1361, 23.1365, 23.1367, and 23.1416.
The Associations recommended the FAA delete proposed Sec.
23.1305(a)(2) and (a)(3). The commenters also suggested the FAA delete
proposed Sec. 23.1305(b), as the flightcrew interface portion of the
proposed rules already addressed the same subject area. Furthermore,
EASA recommended moving the flightcrew interface requirements from
proposed Sec. 23.1305(a)(2) through (c) to subpart G.
The FAA agrees with the commenters that the paragraphs in proposed
Sec. 23.1305 that address display and control for the flightcrew is
better located in subpart G. Upon closer review, the FAA agrees with
EASA's recommendation as it is consistent with the FAA's intent behind
moving requirements from subpart F to subpart G. As proposed, subpart G
did not have any sections that directly address these specific
paragraphs. For that reason, the FAA adds new Sec. 23.2605,
``Installation and operation'', which contains the language from
proposed Sec. 23.1305(a)(2) through (c).
d. Instrument Markings, Control Markings, and Placards (Proposed Sec.
23.1505/Now Sec. 23.2610)
In the NPRM, proposed Sec. 23.1505 (new Sec. 23.2610) would have
required each airplane to display in a conspicuous manner any placard
and instrument marking necessary for operation. Proposed Sec. 23.2610
would also have required an applicant to clearly mark each cockpit
control, other than primary flight controls, as to its function and
method of operation and include instrument marking and placard
information in the AFM.
Astronautics agreed that an applicant should ensure markings are
adequate and meet the marking requirements specified in 14 CFR 45.11,
``Marking of products.'' However, they asserted that the requirement
for applicants to mark the controls and instruments themselves, as
required by proposed Sec. 23.1505(b), is ``overly broad.'' The
proposed requirement fails to account for existing markings such as
those required by Sec. 45.15, ``Marking requirements for PMA articles,
TSO articles, and critical parts.'' Astronautics noted that some
controls, such as knobs and push buttons, are typically integrated
parts of TSO articles. The commenter believed that proposed Sec.
23.1505 could be interpreted to require an applicant to add or replace
markings on instruments already marked pursuant to a TSO authorization
or PMA. Astronautics recommended the FAA revise proposed Sec. 23.1505
to specify that an applicant is not required to alter markings already
required under Sec. 45.15.
The FAA agrees with Astronautics that the proposal is overly
prescriptive as to how information regarding function and method of
operation is to be provided. Accordingly, the FAA removes the
requirement from proposed paragraph (b) specifically requiring an
applicant to mark cockpit controls and instruments and revises the
proposal to require the airplane design clearly indicate the function
of each cockpit control (other than primary flight controls). This
revision will permit an applicant to utilize markings made pursuant to
a TSO authorization or PMA without imposing a repetitive and
potentially conflicting requirement.
BendixKing requested the FAA delete the phrase ``. . . and method
of operation'' from proposed Sec. 23.1505(b). The commenter believed
that the marking of cockpit controls should be limited to labeling the
function of the control and that including its method of operation as a
marking requirement is neither bounded nor appropriate.
[[Page 96663]]
The FAA agrees in part with BendixKing's comment. The FAA concurs
that application of the proposed requirement to all cockpit controls
(other than primary flight controls) is overbroad and could lead to an
applicant including information on cockpit control markings that is
excessive, unnecessary, and contrary to the agency's original intent.
Accordingly, the FAA revises proposed paragraph (b) to eliminate the
proposed requirement that an applicant mark cockpit controls with their
method of operation. However, cockpit controls (other than primary
flight controls) would continue to be required to clearly indicate
their function. As under the former regulations, information on the
method of operation of equipment is provided in the airplane flight
manual and equipment manuals, which is sufficient to satisfy the
objective of the proposal.
Textron requested the FAA be more specific as to what placards
(i.e., emergency, passenger safety, or operational placards) need to be
included in the AFM pursuant to proposed Sec. 23.1505(c).
The FAA recognizes that information may be provided to pilots and
passengers using a variety of methods and considers it unnecessary to
specifically prescribe those placards that must be included in the AFM.
Additionally, a requirement to include specific placards would be
counter to this rule's intent to remove prescriptive requirements from
current regulatory text and replace those provisions with performance-
based regulations. The FAA finds that variations in airplane designs
and the methods of providing information to pilots and passengers may
necessitate the need for various types of placard information that
would be more appropriate for inclusion as a means of compliance to the
regulatory requirements, thereby providing applicants with more
flexibility in meeting the underlying safety intent of the rule.
e. Flight, Navigation, and Powerplant Instruments (Proposed Sec.
23.1310/Now Sec. 23.2615)
In the NPRM, proposed Sec. 23.1310 (now Sec. 23.2615) would have
required installed systems to provide the flightcrew member who sets or
monitors flight parameters for the flight, navigation, and powerplant
information necessary to do so during each phase of flight. Proposed
Sec. [thinsp]23.1310 would have required this information include
parameters and trends, as needed for normal, abnormal, and emergency
operation, and limitations, unless an applicant showed the limitation
would not be exceeded in all intended operations. Proposed Sec.
[thinsp]23.1310 would have prohibited indication systems that integrate
the display of flight or powerplant parameters to operate the airplane
or are required by the operating rules of this chapter, from inhibiting
the primary display of flight or powerplant parameters needed by any
flightcrew member in any normal mode of operation. Proposed Sec.
[thinsp]23.1310 would have required these indication systems be
designed and installed so information essential for continued safe
flight and landing would be available to the flightcrew in a timely
manner after any single failure or probable combination of failures.
Several commenters raised concerns with proposed Sec.
23.1310(a)(1), which would have required installed systems to provide
the flightcrew member with parameters and trends, as needed. Air
Tractor questioned whether round gauge instruments produce a trend and
whether the FAA would use paragraph (a)(1) to mandate electric gauges.
Similarly, Garmin contended that proposed Sec. 23.1310(a)(1) could be
interpreted as requiring more information than was formerly required.
Garmin noted the pilot often determines the trend by monitoring a
gauge, but the trend itself may not be displayed. Garmin asked the FAA
to clarify whether it intended paragraph (a)(1) to require trend
information to be displayed, or information to be presented in a manner
that enables the pilot to monitor the parameter and determine trends.
Genesys Aerosystems commented that requiring ``trends'' rather than
addressing ``trends'' in guidance materials would lead to more trends
being required than needed.
The FAA did not intend proposed Sec. 23.1310(a)(1) to require
electric gauges. Traditional analog indicators, such as airspeed
indicators or altimeters, have been shown to provide adequate trend
indications and will still be acceptable. It may also be possible to
have a system that automatically monitors the parameter of interest and
warns the pilot of any trend that could lead to a failure. Paragraph
(a)(1), however, does not allow a light that comes on at the same time
that the failure occurs to replace analog indicators because such a
light does not provide trend information prior to a failure. A warning
light system that would comply must be sophisticated enough to read
transients and trends, and give a useful warning to the pilot of a
potential condition.
The FAA agrees the proposed rule language could have been
misinterpreted as requiring more information than former part 23. The
FAA intended proposed Sec. 23.1310 to capture the safety intent of the
former requirements, which was to provide flightcrew members the
ability to obtain the information necessary to operate the airplane
safely in flight, but not to exceed the safety intent of former part
23. Therefore, proposed Sec. 23.1310(a)(1) was intended to require
installed systems to provide adequate information to the flightcrew
member to determine trends by monitoring a gauge or display. The FAA
did not intend to expressly require an installed system to display the
trend itself, because not all systems display trends. The FAA revises
the proposed rule language to clarify its intent. Accordingly, Sec.
23.2615(a)(1) now requires the information to be presented in a manner
that enables the flightcrew member to monitor parameters and determine
trends, as needed, to operate the airplane.
Former Sec. 23.1311(a)(6) required electronic display indicators
to incorporate, as appropriate, trend information to the parameter
being displayed to the pilot. Section 23.2615(a)(1) is not meant to be
an increase in burden from the former requirement and associated
guidance regarding when trends are needed.
Kestrel raised concerns that although proposed Sec. 23.1310 is
less prescriptive, it did not minimally require the pilot to have
available airspeed, altitude, direction, and attitude indicators as
former Sec. 23.1303 prescribed. The commenter asked if the FAA
envisions a scenario where this information would not be required.
Kestrel was also concerned that the phrase ``as needed'' would lead to
diverging FAA interpretations of proposed Sec. 23.1310(a)(1). The
commenter asked the FAA to clarify its intent regarding the requirement
to provide parameters and trends ``as needed.'' If this was not a fixed
set of parameters, Kestrel asked for details on how this list would be
determined.
As explained in the NPRM, the former regulations that required
airspeed, altimeter, and magnetic direction were redundant with the
operating rules, specifically Sec. Sec. 91.205 and 135.149.
Furthermore, they required prescriptive design solutions that were
assumed to achieve an acceptable level of safety. These prescriptive
solutions precluded finding more effective or more economical paths to
providing acceptable safety. One of the stated goals of the proposal
was to facilitate the introduction of new technologies into small
airplanes. Concepts already envisioned with fly-by-wire system may
[[Page 96664]]
render the instruments that were required by former Sec. 23.1303
irrelevant in the future. New Sec. 23.2615 reflects the intent to
allow new technologies in the future, while maintaining a minimum
safety requirement by capturing the safety intent of the former
regulations and by relying on the operating rules and accepted means of
compliance to prescribe the details. This philosophy also applies to
the comment on the phrase ``as needed.'' The accepted means of
compliance, which may include industry consensus standards, will define
which parameters need trends.
Astronautics asked the FAA to insert a comma after ``as needed'' in
paragraph (a)(1) to clarify that ``as needed'' is a parenthetical
phrase. The FAA agrees and corrects the grammar in the revised rule
language.
ANAC suggested the FAA not adopt proposed Sec. 23.1310(a) because
it is covered by proposed Sec. 23.1305(b) and (c), which are broader
in scope. In light of the performance-based context of the proposed
rule, ANAC reasoned that defining specific requirements only for
flight, navigation, and powerplant instruments was unnecessary. ANAC
also recommended the FAA not adopt proposed Sec. 23.1310(b), which
appeared to apply to specific technologies (integrated systems). ANAC
noted the intent of paragraph (b) was already addressed in proposed
Sec. 23.1305(b) and (c) (requiring timely information), and proposed
Sec. 23.1315 (now Sec. 25.2510, requiring the capacity to maintain
continued safety flight and landing after single or probable failures).
The FAA notes ANAC's comment on proposed Sec. 23.1310(a) and (b),
but paragraphs (a) and (b) are not redundant. Sections 23.2505 and
23.2510 apply generally to installed equipment and systems. However,
Sec. Sec. 23.2505 and 23.2510 do not apply if another section of part
23 imposes requirements for specific installed equipment or systems.
The FAA finds that flight, navigation, and powerplant instrumentation
are significant enough to warrant their own requirements. Therefore,
the FAA adopts Sec. 23.1310 (nowSec. 23.2615(a) and (b)) as proposed.
ANAC also raised concerns that the phrase ``normal, abnormal, and
emergency operation'' in paragraph (a) may be interpreted as a required
classification of types of operations, meaning a system safety type
analysis may be required for each indicator, classification of each
condition, and three separate indications for each condition, which it
deemed overly prescriptive. As an alternative to deleting proposed
Sec. 23.1310(a)(1), ANAC recommended the FAA revise paragraph (a)(1)
to require parameters and trends, as needed, ``to operate the
airplane.''
The FAA agrees with ANAC and revises paragraph (a)(1) accordingly.
Genesys Aerosystems commented on proposed Sec. 23.1310(b), which
was formerly covered only in guidance material. Genesys Aerosystems
contended that paragraph (b) is a bit prescriptive and including it in
the regulation could stifle future innovation.
The FAA notes Genesys Aerosystems concern, but this requirement was
previously covered under former Sec. 23.1311. Section 23.2615(b)
captures the safety intent of former Sec. 23.1311, but removes the
prescriptive requirements of former Sec. 23.1311(a)(5), which mandated
secondary instruments as the means to providing information to the
flightcrew essential for continued safe flight and landing. This would
allow future innovations in system architecture and design to provide
the flight parameters necessary to maintain safe flight.
EASA recommended moving the pilot interface issues of proposed
Sec. 23.1310 to subpart G.
The FAA agrees with this recommendation because flightcrew
interface issues are more appropriately addressed in subpart G, which
contains requirements on flightcrew interface and other information.
Therefore, the FAA moves the entire proposed Sec. 23.1310 to subpart G
as new Sec. 23.2615.
f. Airplane Flight Manual (Proposed Sec. 23.1510/Now Sec. 23.2620)
In the NPRM, proposed Sec. 23.1510 (now Sec. 23.2620) would have
required an applicant to furnish an AFM with each airplane that
contained the operating limitations and procedures, performance
information, loading information, and any other information necessary
for the operation of the airplane.\60\
---------------------------------------------------------------------------
\60\ The NPRM erroneously stated that proposed Sec. 23.1510 was
intended to consolidate current Sec. Sec. 23.1505 through 23.1527.
See 81 FR at 13495. However, Sec. 23.1510 was actually intended to
consolidate the AFM provisions in former Sec. Sec. 23.1581 through
23.1589.
---------------------------------------------------------------------------
Garmin noted that the purpose of the AFM is to provide the pilot
with basic information required to safely fly the airplane and stated
it appreciates and supports the FAA's proposal to remove the
prescriptive detail about the AFM content from Sec. 23.1510. However,
Garmin did express concern about use of the phrases ``[o]perating
limits and procedures'' in proposed Sec. 23.1510(a) and ``[a]ny other
information necessary for the operation of the airplane'' in proposed
Sec. 23.1510(d). Garmin noted the possibility for confusion arising
from the ambiguity of the terms ``operating'' and ``operation'' in
former Sec. Sec. 23.1581(a)(2), 23.1581(a)(3), 23.1583(k), and
23.1585(j). For example, Garmin pointed out that many current FAA 20-
series ACs specify that equipment operation limitations should be
included in an AFM.\61\ Garmin contended the AFM was never intended as
a catch-all for equipment or airspace operating limitations and that
equipment operating limitations are more appropriately included in the
equipment's pilot guide or operating manual provided by the equipment
manufacturer.
---------------------------------------------------------------------------
\61\ As an example, the commenter noted that: AC 20-138D
(including change 1 and 2) for positioning and navigation equipment
includes 77 instances of ``AFM,'' AC 20-165B for ADS-B Out equipment
includes 8 instances of ``AFM,'' AC 20-149B for non-required safety
enhancing FIS-B equipment includes 7 instances of ``A/RFM,'' and
even AC 20-153B for aeronautical database LOAs includes 2 paragraphs
requiring specific AFM content. The commenter noted that these
counts do not include instances of ``airplane flight manual'' or
other similar phrases.
---------------------------------------------------------------------------
Garmin also suggested using the terms ``operating'' and
``operation'' in proposed Sec. 23.1510(a) and (d) could be easily
confused with operating rule limitations (e.g., Sec. 91.225 for ADS-B
Out) or system-wide operating limitations (e.g., the displayed age of
FIS-B weather products), which are not necessary to safely fly the
airplane and would be more appropriately captured in the Aeronautical
Information Manual (AIM).
Therefore, Garmin recommended proposed Sec. 23.1510(a) state:
``Airplane operating limitations and procedures.'' The Associations
recommended the same revision. Garmin also suggested revising the NPRM
preamble to state that the AFM is not intended to be used as a catch-
all for equipment operating limitations, or to be used for operating
rule limitations or system-wide operating limitations, all of which are
more appropriately included in guides and manuals.
The FAA agrees with Garmin in that the AFM was never intended as a
catch-all for equipment or airspace operating limitations. The
requirement for ``operating limitations and procedures'' in the
proposed Sec. 23.1510(a) was intended to capture information required
to be included in the AFM by former Sec. Sec. 23.1583 and 23.1585.
The FAA did not intend to expand Sec. 23.2620(a) to encompass
information that is not required to be included in the AFM by former
Sec. Sec. 23.1583 and 23.1585. To further clarify its intent, the FAA
[[Page 96665]]
adopts the commenters' suggestion and amends Sec. 23.2620(a)(1) to
specify that this section requires ``airplane'' operating limitations
and procedures.
Proposed Sec. 23.1510(a)(4) would have required that ``any other
information necessary for the operation of the airplane'' must be
included in the AFM. The FAA agrees with the commenters' concern that
the proposed language was too broad and could be interpreted as
requiring information that has not traditionally been included in the
AFM. The intent of this proposed provision was to retain the
requirement of former Sec. 23.1581(a)(2), which require the AFM to
include other information that is necessary for safe operation because
of design, operating, or handling characteristics.'' Because the
proposed language was unclear, the final rule will simply codify,
without change, the language of former Sec. 23.1581(a)(2) into Sec.
23.2620(a)(4).
Garmin noted that while it was not specifically covered in the NPRM
preamble, it appreciated that proposed Sec. 23.2620 no longer appears
to require FAA approval of certain information contained in the AFM as
required by former Sec. 23.1581(b). Garmin said this would eliminate
delays associated with seeking an Aircraft Certification Office
engineer's approval of AFM content for the TC or STC process, typically
a one-time occurrence; or Flight Standards District Office inspector's
approval of AFM content for post-certification installations, which
occur frequently. Garmin explained that these approval delays translate
into loss of revenue for the applicants. Garmin recommended the
preamble specifically indicate there is no intent to require FAA
approval of AFM content during certification or for post-certification
installation.
NATCA asked the FAA to clarify the Airworthiness Limitations
Sections (ALS), as well as portions of the AFM, requiring FAA approval.
NATCA indicated this clarification was need as approval of ALS and AFM
content are ``inherently governmental functions.'' NATCA noted that all
other sections of the continuing operating instructions, maintenance,
and some flight manual sections are accepted.
The FAA notes the requirement for the AFM in former Sec. 23.1581
required each portion of the AFM containing information required by the
FAA must be approved by the FAA, segregated, identified, and clearly
distinguished from each unapproved portion of the AFM. The former
requirements also provided an exception for reciprocating-powered
airplanes that do not weigh more than 6,000 pounds if certain
requirements were met.\62\ It was not the FAA's intent to discontinue
the former requirement to approve select AFM information. The approval
process allows the FAA to review an AFM to ensure it satisfies the
applicable requirements; this rule will generally retain the existing
requirement that FAA-required information provided in the AFM must be
approved by the FAA. For this reason, the FAA has added paragraph (b)
to clarify that the FAA will retain our authority to approve specific
AFM information.
---------------------------------------------------------------------------
\62\ Id. Sec. 23.1581(b)(2). To qualify for this exception, the
following requirements must be satisfied: (1) Each part of the AFM
containing the Limitations information must be limited to such
information, and must be approved, identified, and clearly
distinguished from each other part of the AFM; and (2) the remaining
required information must be presented in its entirety in a manner
acceptable to the FAA.
---------------------------------------------------------------------------
E. Miscellaneous Amendments (Sec. Sec. 21.9, 21.17, 21.24, 21.35,
21.50, 21.101, SFAR 23, Appendix E to Part 43, and 91.323)
1. Production of Replacement and Modification Articles (Sec. 21.9)
In the NPRM, the FAA proposed revising Sec. 21.9 by adding a new
paragraph (a)(7) to provide applicants with an alternative method to
obtain FAA approval to produce replacement and modification articles
that are reasonably likely to be installed on type certificated
aircraft. The FAA also proposed revising paragraphs (b) and (c) to
specify that these articles would be suitable for use in a type
certificated product. Lastly, the FAA also proposed allowing an
applicant to submit production information for a specific article, but
would not require the producer of the article to apply for approval of
the article's design or obtain approval of its quality system. Under
the proposed changes, approval to produce a modification or replacement
article under proposed Sec. 21.9(a)(7) would not constitute a
production approval as defined in Sec. 21.1(b)(6). In the NPRM, the
FAA indicated it would limit use of this procedure to articles whose
improper operation or failure would not cause a hazard. Additionally,
the approval would be granted on a case-by-case basis, specific to the
installation proposed, accounting for potential risk and considering
the safety continuum.
The FAA specifically solicited comments regarding whether the
proposed change would safely facilitate retrofit of low risk articles
and whether there are alternative methods to address the perceived
retrofit barrier.
All commenters expressed some level of support for the proposed
changes to Sec. 21.9. Several commenters asked the FAA to provide
guidance to clarify how the proposed changes will work.
The FAA agrees with the commenters that additional details and
clarification are needed to further define the process for obtaining
approval under Sec. 21.9(a)(7) and will provide the necessary policy
and guidance material. Generally, the process for obtaining FAA
approval under Sec. 21.9(a)(7) is intended to be scalable in nature in
that different degrees of substantiation may be required, depending on
the complexity of the article for which approval is sought. For
example, a non-required, low-risk article could be simple enough that a
design approval and quality system might not be required; however, a
more complex article might also require a Sec. 21.8(d) design approval
and some form of quality system. Examples of the requirements for more
complex projects include FAA policy memorandum AIR100-14-110-PM01,
``Approval of Non-Required Angle-of-Attack (AOA) Indicator Systems, and
FAA policy statement PS-AIR-21.8-1602, Approval of Non-Required Safety
Enhancing Equipment (NORSEE).'' For simple articles, a reduction in
scale could be negotiated with the FAA to provide an appropriate level
of safety. Audits of the manufacturer's facility would be at the
discretion of the appropriate MIDO. Typically, a MIDO audit would not
be required unless there is evidence that indicates improper quality
control issues that require a MIDO's involvement, as described in the
FAA Policy Statement PS-AIR-21.8-1602.\63\
---------------------------------------------------------------------------
\63\ Policy No. PS-AIR-21.8-1602 has been placed in docket
number FAA-20150-1621.
---------------------------------------------------------------------------
Astronautics Corporation commented that whether an article is
``required'' or ``non-required'' depends on the kind of operation the
applicant requests for certification. Garmin also questioned why the
qualifying articles have to be non-required and asked the FAA to
consider expanding use of the proposed Sec. 21.9(a)(7) process to
include low-risk required articles when the applicant has an approved
quality system. Garmin contended that low risk to the aircraft or its
occupants should be sufficient criteria to allow application to both
required and non-required equipment.
Astronautics Corporation is correct in its observation that the
approval means for an article could potentially affect the ``kinds of
operation'' authorized for an aircraft. The FAA's intent is not to
bypass existing certification process for required equipment, but to
provide an alternative process for non-required, low-risk articles. For
example, a weather
[[Page 96666]]
display approved under Sec. 21.9(a)(7) may have extensive information
available, but this information would be considered supplemental and
could not be used to satisfy operational requirements. If the FAA
determines that certain equipment is required for safety, then existing
certification processes must be followed to ensure the required safety
equipment is functioning properly.
Garmin also asked what would be needed for approval of the
installation of articles produced under Sec. 21.9(a)(7) and whether
new FAA policy would be needed each time there is a new equipment
standard proposed to allow its installation.
Section 21.9(a)(7) concerns only the production of articles, not
their installation. The required process for obtaining installation
approval remains unchanged by this rule.
Garmin asserted that the term ``low risk'' is subjective and asked
the FAA to clarify the intent of this term. Specifically, Garmin asked
if a system with a minor failure condition would fall into the low-risk
category.
The FAA intends the term ``low risk,'' for the purposes of Sec.
21.9(a)(7), to apply to non-required articles with a hazard
classification no greater than minor. In this context, a ``minor''
failure condition would result in only a slight reduction in functional
capabilities or safety margins.
Air Tractor asked whether the changes to Sec. 21.9 will apply
equally to TC and STC holders and applicants for those certificates,
which the commenter said it believed the changes should.
It is the FAA's intent that an article approved under Sec.
21.9(a)(7) can be subsequently approved for installation by a TC or STC
holder based on the installation data provided by the TC or STC holder.
Additionally, the FAA has decided not to except articles approved
under Sec. 21.9(a)(7) from the prohibition on representing an article
as suitable for installation on a type-certificated product found in
Sec. 21.9(b) and Sec. 21.9(c); therefore, the FAA is not adopting the
NPRM's proposed changes to Sec. 21.9(b) and Sec. 21.9(c). The current
Sec. 21.9 creates an exception from this prohibition for articles
produced under a TC or an FAA production approval because these
articles have approved installation data that justify a representation
of suitability. The proposed changes in the NPRM would have allowed
articles that are not produced under a TC or production approval to be
sold or represented as suitable for installation on type-certificated
products without approved installation data. A representation that an
article is ``suitable for installation'' could be misinterpreted as
``approved for installation.'' The FAA notes that approval under Sec.
21.9(a)(7) does not constitute approval for installation of the
article; however, a person may state that an article approved under
Sec. 21.9(a)(7) may be installed in a type-certificated aircraft
provided it has been determined suitable for installation by an
appropriately-rated mechanic using appropriate means.
2. Designation of Applicable Regulations (Sec. 21.17)
In the NPRM, the FAA proposed amending Sec. 21.17(a) by removing
the reference to Sec. 23.2 because Sec. 23.2 would be deleted by this
rule.
NATCA commented that elimination of the reference to retroactive
rules, former Sec. 23.2, leaves holes in certification basis for the
existing fleet of airplanes. This commenter noted that while Sec. 23.2
is not listed as a basis for certification for many existing airplanes,
the provision nevertheless applies due to the date of manufacture of
some airplanes. NATCA also raised concerns it would be burdensome to
revise Type Certificate Data Sheets (TCDS) to reflect the change;
therefore, NATCA requested that this regulation address the addition of
seatbelts as a retroactive, date of manufacture, requirement.
The FAA notes NATCA's concern; however, the provisions of current
Sec. 23.2 are duplicated in Sec. 91.205 and therefore remain
applicable based on date of manufacture. The revision of TCDS will be
unnecessary because any reference to current Sec. 23.2 in an existing
TCDS will include reference to the applicable amendment and continue to
be enforceable.
The NTSB commented that the FAA should retain Sec. 23.2 because it
is a regulatory mechanism to apply special retroactive requirements to
newly-manufactured items after the item has been issued a TC.
The FAA notes the NTSB's comment, but this rule does not affect the
FAA's ability to promulgate other special retroactive requirements
using the normal rulemaking process.
The FAA removes Sec. 23.2 and revises Sec. 21.17(a) by removing
the reference to Sec. 23.2, as proposed.
Although the NPRM did not propose changes to Sec. 21.17(b), which
addresses the designation of applicable regulations to special classes
of airplane, NATCA asked whether the FAA would continue to accept
EASA's CS-VLA and CS 22 sailplanes and powered sailplanes, as special,
stand-alone classes of airplanes, or whether the intent was to include
these airplanes in part 23 as EASA proposed.
The FAA intends to continue to allow CS-VLA and CS 22 airplanes to
be approved as special, stand-alone classes of airplanes while also
allowing eligibility for certification in accordance with part 23 using
accepted means of compliance.
3. Issuance of Type Certificate: Primary Category Aircraft (Sec.
21.24)
In the NPRM, the FAA proposed amending Sec. 21.24 by revising
paragraph (a)(1)(i) to modify the phrase ``as defined by Sec. 23.49''
to include reference to amendment 23-62 (76 FR 75736, December 2,
2011), effective on January 31, 2012. The FAA explained that revision
would be necessary to maintain a complete definition of stall speed in
Sec. 21.24, as the former Sec. 23.49 is removed by this rule.
The Associations said it is unnecessary to amend Sec.
21.24(a)(1)(i) as proposed. These commenters noted there are many
references to items such as stall speed that do not need to reference a
previous amendment regulation for the steps to determine stall speed.
The commenters contended it would be sufficient to include the intent
in the preamble discussion.
The FAA agrees the reference to Sec. 23.49, amendment 23-62, in
Sec. 21.24 is unnecessary. VSO is defined in Sec. 1.2. The
conditions and techniques for determining stall speed have been
consistent for decades. Furthermore, AC 23-8C has a thorough discussion
on how to do stall testing. Rather than referencing a regulation from a
previous amendment, the FAA is revising Sec. 21.24 to refer to
VSO stall speed as determined under part 23.
The Associations also asked the FAA to include electric propulsion
in the primary category aircraft once the FAA determines acceptable
standards by inserting the phrase ``or with electric propulsion
systems'' after the phrase ``naturally aspired engine.''
The commenters' request to include electric propulsion systems in
the primary category is beyond the scope of this rulemaking. Therefore,
the FAA defers the request for consideration in future part 21
rulemaking activity.
NATCA argued the establishment of Primary Category Aircraft in
current Sec. 21.24 has been an almost useless addition to part 21,
resulting in problems without providing any benefit. As an example,
NATCA referenced without elaboration the Seabird Seeker.\64\ NATCA also
noted that very
[[Page 96667]]
few airplanes have been certified under existing Sec. 21.24, except
perhaps those seeking to obtain EASA approval for CS-LSA (Light Sport
Aeroplanes). The commenter said the proposed changes to part 23 support
the use of industry specifications as a certification basis within part
23, thereby eliminating the need to retain procedural regulations for
Primary Category Aircraft. NATCA recommended FAA focus on harmonizing
the standards for Very Light Aircraft and Light Sport Aircraft with
bilateral partners, particularly EASA. The commenter observed that
United States manufacturers are at a disadvantage to obtain CS-LSA
approval in Europe.
---------------------------------------------------------------------------
\64\ It appears the Seabird Seeker is a light utility airplane
built by Seabird Aviation Australia that was prohibited from being
sold in the United States until receiving part 23 TC in 2015.
---------------------------------------------------------------------------
NATCA maintained that these types of airplanes are meant to be
included in the part 23 rewrite and therefore recommended the FAA
remove new type certification under Sec. 21.24 once the part 23
revisions becomes final. Specifically, NATCA recommended the FAA
rewrite Sec. Sec. 21.24 and 21.184 to eliminate Primary Category
certifications, or keep with an effective date to account for existing
fleet, and create procedural requirements in part 21 and maybe part 23
to recognize something equivalent to EASA's CS-LSA.
The FAA considered NATCA's proposal to remove Sec. 21.24, in
effect, eliminating primary category certification. Although Very Light
Aircraft and Light Sport Aircraft could be certified under the new part
23, eliminating Sec. 21.24 is beyond the scope of this rulemaking
because it would also remove a means of certification for certain
rotorcraft that qualify for the primary category. These rotorcraft will
not be able to take advantage of the new part 23 because it applies
only to the certification of airplanes. Additionally, Sec. 21.24 and
the new part 23 do not conflict; they are alternative paths for
certification.
Additionally, proposed Sec. 21.24(i) abbreviated ``January'' as
``Jan''. This rule replaces ``Jan'' with ``January''.
4. Flight Tests (Sec. 21.35)
The NPRM proposed amending Sec. 21.35(b)(2) to delete reference to
reciprocating engines and expanding the exempted airplanes to include
all low-speed part 23 airplanes 6,000 pounds or less. This proposed
change would align the requirements for function and reliability
testing with the proposed changes in part 23 that do not distinguish
between propulsion types. This change would allow the FAA flexibility
to address new propulsion types.
All commenters objected to the use of a 6,000-pound weight limit as
a threshold for exemption from testing in proposed Sec. 21.35(b)(2).
Each commenter noted that the stated intent of the part 23 revision is,
in part, to move away from weight and propulsion type classifications.
Each commenter also requested the FAA remove the 6,000-pound weight
limit.
Air Tractor proposed eliminating the need for function and
reliability testing entirely and suggested the market will sort out
function and reliability issues by means of natural economic controls.
The Associations suggested the FAA use a parameter other than
maximum weight as a discriminator. Recognizing that the 6,000-pound
weight limit appears to be based on the airplane's complexity and
considering the acceptable level of risk, these commenters suggested
using a low[hyphen]speed airplane, which is a measure of complexity,
and airworthiness level 2 or less, which are newly accepted measures of
risk, to provide the same level of safety. The commenters noted this
discriminator would also better align with the part 23 design rules.
Therefore, the Associations recommended replacing the phrase ``of 6,000
pound or less maximum weight'' with ``meeting part 23 airworthiness
level 1 or 2.''
The FAA disagrees with Air Tractor's proposal to eliminate all
Function and Reliability (F&R) testing, because elimination of F&R
testing for high-speed, complex airplanes, carrying larger numbers of
passengers is not in keeping with the FAA's statutory mandate to
prescribe minimum standards in the interest of safety for the design
and performance of airplanes.
The FAA agrees with Textron and the Associations to remove the
6,000-pound discriminator in favor of values based on complexity and
risk. Accordingly, the FAA has decided to replace the exception from
F&R testing for airplanes weighing 6,000 pounds and below with an
exception for airplanes with performance level of low-speed and
certification level of 2 or less. The 6,000-pound discriminator was
based on the FAA's assumptions regarding the complexity and risk
associated with airplanes of that weight. However, as the commenters
point out, their recommended parameters reflect the same assumptions
regarding complexity and risk. Although this change may provide an
exception for airplanes of up to 19,000 pounds, these airplanes would
still be within the allowable risk and complexity parameters.
5. Instructions for Continued Airworthiness and Manufacturer's
Maintenance Manuals Having Airworthiness Limitations Sections (Sec.
21.50)
In the NPRM, proposed Sec. 21.50(b) would have replaced the
reference Sec. 23.1529 with Sec. 23.1515 to align with the proposed
part 23 numbering convention.
The FAA has decided not to renumber Sec. 23.1529, which requires
applicants for a TC or a change to a TC under part 23 to prepare
Instructions for Continued Airworthiness; therefore, this section
retains the reference to Sec. 23.1529 in this rule. However, the FAA
will keep the proposed addition of the phrase ``for Continued
Airworthiness'' in the second sentence of Sec. 21.50 to clarify that
the second sentence in paragraph (b) refers to Instructions for
Continued Airworthiness.
6. Designation of Applicable Regulations (Sec. 21.101)
The NPRM proposed amending Sec. 21.101(b) to remove reference to
Sec. 23.2 because Sec. 23.2 was proposed to be removed from part 23
and the requirements of former Sec. 23.2 are addressed in the
operating rules. The NPRM, in order to align Sec. 21.101 with the
proposed part 23 certification levels, proposed amending Sec.
21.101(c) to include simple airplanes, level 1, low-speed airplanes,
and level 2, low-speed airplanes. The NPRM did not propose to revise
Sec. 21.101 to address airplanes certified under former part 23,
amendment 23-62, or prior amendments. Section 21.101 will continue to
allow for compliance with the certification requirements at amendment
23-62 or earlier when compliance to the latest amendment of part 23 is
determined by the FAA to be impractical.
The Associations said the FAA should remove the phrase ``to a
simple'' from the first sentence of Sec. 21.101(c), regardless of the
later utilization of the term as these aircraft are completely
encompassed by low[hyphen]speed, level 1 airplanes. The FAA agrees and
revises the rule language to remove ``to a simple'' from Sec.
21.101(c).
Textron commented that the purpose of the part 23 rewrite is to
move away from prescriptive classifications like weight and propulsion
type, and therefore asked FAA to remove the 6,000-pound weight-based
division in proposed Sec. 21.101(c). Textron also noted the FAA
provided no justifications for retaining the 6,000-pound weight-based
division. Textron also suggested adding
[[Page 96668]]
the word ``airplane'' after ``simple'' and after ``level 1 low speed''
for clarity.
The FAA considered Textron's comment. However, the 6,000-pound
weight division cannot be removed because it continues to apply to
legacy airplanes and modifications to those airplanes. A legacy
airplane would only be identified by a certification level if it was
re-certified to be fully compliant with the new rule. Therefore, the
proposed wording is intended to capture both legacy airplanes and newly
type certified airplanes. The FAA agrees that adding the word
``airplane'' after ``level 1 low speed'' in paragraph (c) will improve
the sentence's clarity.
NATCA observed that there do not appear to be FAA directives or
guidance on how to apply the part 23 rewrite to existing airplanes. As
an example, NATCA asked how this rewrite would apply to a Piper Seneca
V, an amendment 23-6 airplane. The commenter contended the FAA already
struggles with the existing regulations and guidance. NATCA also asked
how the proposed changes will be implemented on existing TC and STC
products and how the certification basis will be captured. NATCA asked
FAA to issue new directives, orders, and ACs specifically addressing
application of part 23, relative to the Changed Product Rule, to
prevent a situation in which each ACO (and applicant) comes up with
their own creative interpretation of the regulation.
The FAA has developed internal training and guidance material to
assist FAA employees. Specific to the application of the Changed
Product Rule (Sec. 21.101), there should be minimal variation from
existing procedures and guidance material. The certification basis for
changed products will be captured by section and amendment in
accordance with existing procedures, and section-specific certification
levels identified for those amendments issued concurrent with, or
subsequent to, this rulemaking.
7. Special Federal Regulation 23 (SFAR No. 23)
This final rule removes SFAR No. 23 as unnecessary because an
applicant may no longer certify an airplane to SFAR No. 23. SFAR No. 23
was first superseded by SFAR 41 and then by commuter category in part
23, amendment 23-34. The FAA's intent to remove SFAR No. 23 was
reflected in the amendatory language in the NPRM.
8. Altimeter System Test and Inspection (Appendix E to Part 43)
In the NPRM, the FAA proposed to revise paragraph (a)(2) of
appendix E to part 43 by removing the reference to Sec. 23.1325,\65\
which would cease to exist in the proposed rule, and by requiring each
person performing the altimeter system tests and inspections required
by Sec. 91.411 to perform a proof test to demonstrate the integrity of
the static pressure system in a manner acceptable to the Administrator.
This proposed change would have affected owners and operators of part
23 certificated airplanes in controlled airspace under IFR, who must
comply with Sec. 91.411.
---------------------------------------------------------------------------
\65\ In the NPRM, the FAA proposed to capture the safety intent
of Sec. 23.1325 in proposed Sec. Sec. 23.1300, 23.1310, and
23.1315.
---------------------------------------------------------------------------
Kestrel noted that existing appendix E to part 43 references Sec.
23.1325 for leakage tolerances; however, the proposed rule would not
have included Sec. 23.1325 and the specified tolerances. Kestrel asked
if the FAA plans to address the specified tolerances in guidance, or if
it will permit the varying tolerances between similar airplane.
The FAA agrees and will address the leakage tolerances in guidance.
As explained in the NPRM, the FAA is revising AC 43-6, Altitude
Reporting Equipment and Transponder System Maintenance and Inspection
Practices, to include a static pressure system proof test acceptable to
the Administrator. The revised AC will incorporate the same static
leakage standards that were formerly prescribed in Sec. 23.1325.
However, as ACs are not the only means of compliance, it is possible
that someone could ultimately propose an alternative means that the FAA
could find acceptable, which would lead to a difference between similar
airplane. But no such methods have been proposed to date.
9. Increased Maximum Certification Weights for Certain Airplanes
Operated in Alaska (Sec. 91.323)
The NPRM proposed amendments to Sec. Sec. 91.205, 91.313, 91.323,
and 91.531. The only section that received comments was Sec. 91.323.
increased maximum certification weights for certain airplanes operated
in Alaska.
The FAA proposed to amend Sec. 91.323 by removing the reference to
Sec. 23.337 because the FAA proposed revising and consolidating Sec.
23.337 with other structural requirements. The FAA proposed adding the
relevant prescriptive requirement of Sec. 23.337 to Sec.
91.323(b)(3).
Air Tractor noted that the weight in Sec. 91.323(b)(3) has been
changed to reflect a maneuvering load factor that is now independent of
the load factor in part 23, but matches the previous Sec. 23.337
definition. The commenter contended that there is now an increased
likelihood that the load factor considered under this new rule will not
match the load factors that were used in the original certification of
the design, because it is possible that some consensus standard will
impose some other creative interpretation. The commenter suggested that
safety would be better preserved if Sec. 91.323 were required to
reference the load factors that were used in the original
certification.
Air Tractor's concern is based on an incorrect interpretation of
the FAA's proposed amendment to Sec. 91.323. Section 91.323 applies
only to aircraft that have been type certificated under Airworthiness
Bulletin 7A or under normal category of part 4a of the former Civil Air
Regulations (CAR). The FAA's proposed amendment to Sec. 91.323 would
not permit any additional aircraft to be operated in accordance with
Sec. 91.323. It would only preserve the approval of increased maximum
certification weights for airplanes that were designed and built to a
higher design requirement than CAR 3 and 14 CFR part 23. Approving an
increase in the maximum certificated weight of an airplane pursuant to
Sec. 91.323, based on the equation from former Sec. 23.337(a)(1),
allows operation at the same weights had the airplane been certificated
in accordance with CAR 3.
10. Additional Emergency Equipment (Sec. 121.310)
In the NPRM, the FAA proposed to amend Sec. 121.310(b)(2)(iii) by
updating the reference to Sec. 23.811(b). Current Sec.
121.130(b)(2)(iii) references Sec. 23.811(b) of part 23, amendment 23-
62. Because the FAA is replacing part 23, amendment 23-62 with new part
23, the FAA proposed to update the reference to Sec. 23.811(b) by
specifying that each passenger emergency exit marking and each locating
sign must be manufactured to meet the requirements of Sec. 23.811(b)
of this chapter in effect on June 16, 1994. However, upon further
reflection, the FAA has decided not to reference a section that will no
longer exist in the CFR on August 30, 2017. Instead, the FAA is
incorporating the requirements of Sec. 23.811(b) in Sec.
121.310(b)(2)(iii). Accordingly, Sec. 121.310(b)(2)(iii) now requires,
for a nontransport category turbopropeller powered airplane type
certificated after December 31, 1964, that each passenger emergency
exit marking and each locating sign be manufactured to have white
letters 1 inch high on a red background 2 inches high, be self-
illuminated or independently, internally electrically illuminated, and
have a
[[Page 96669]]
minimum brightness of at least 160 microlamberts. The color may be
reversed if the passenger compartment illumination is essentially the
same.
11. Additional Airworthiness Requirements (Sec. 135.169)
In the NPRM, the FAA proposed to allow a small airplane in the
normal category, in Sec. 135.169(b)(8), to operate within the rules
governing commuter and on demand operations. Proposed Sec.
135.169(b)(8) would have required the new normal category airplane to
use a means of compliance accepted by the Administrator equivalent to
the airworthiness standards applicable to the certification of
airplanes in the commuter category found in part 23, amendment 23-62.
Upon further reflection, the FAA has decided not to reference part
23, amendment 23-62 in Sec. 135.169(b)(8) because part 23, amendment
23-62 will not exist in the CFR when new normal category airplanes are
being type certificated under new part 23. The FAA intended proposed
Sec. 135.169(b)(8) to ensure a continued higher level of safety for
commercial operations by requiring a new normal category airplane under
part 23 to use a means of compliance equivalent to the airworthiness
standards that applied to airplanes certified in the commuter category.
As explained in the NPRM, this final rule sunsets the commuter category
for newly type certificated airplanes and creates a new normal
category, certification level 4 airplane as equivalent to the commenter
category by applying it to 10-19 passengers. In order to retain the
FAA's intent while omitting the reference to part 23 at amendment 23-
62, the FAA is revising the proposed rule language to clarify that
Sec. 135.169(b)(8) applies to a normal category airplane equivalent to
the commuter category. Accordingly, Sec. 135.169(b)(8) now allows
consideration of a small airplane that is type certificated in the
normal category, as a multi-engine certification level 4 airplane, to
operate within the rules governing commuter and on demand operations.
Because new part 23 maintains the level of safety associated with
current part 23, except for areas addressing loss of control and icing
where a higher level of safety is established, the FAA expects that any
multi-engine, level 4 airplane approved for commercial operations with
10 or more passengers will meet, at a minimum, the performance required
for airplanes type certificated in the commuter category.
IV. Regulatory Notices and Analyses
A. Regulatory Evaluation Summary
Changes to Federal regulations must undergo several economic
analyses. First, Executive Order 12866 and Executive Order 13563 direct
that each Federal agency shall propose or adopt a regulation only upon
a reasoned determination that the benefits of the intended regulation
justify its costs. Second, the Regulatory Flexibility Act of 1980 (Pub.
L. 96-354) requires agencies to analyze the economic impact of
regulatory changes on small entities. Third, the Trade Agreements Act
(Pub. L. 96-39) prohibits agencies from setting standards that create
unnecessary obstacles to the foreign commerce of the United States. In
developing U.S. standards, this Trade Act requires agencies to consider
international standards and, where appropriate, that they be the basis
of U.S. standards. Fourth, the Unfunded Mandates Reform Act of 1995
(Pub. L. 104-4) requires agencies to prepare a written assessment of
the costs, benefits, and other effects of proposed or final rules that
include a Federal mandate likely to result in the expenditure by State,
local, or tribal governments, in the aggregate, or by the private
sector, of $100 million or more annually (adjusted for inflation with
base year of 1995). This portion of the preamble summarizes the FAA's
analysis of the economic impacts of this final rule. We suggest readers
seeking greater detail read the full regulatory evaluation, a copy of
which we have placed in the docket for this rulemaking.
In conducting these analyses, FAA has determined that this final
rule: (1) Has benefits that justify its costs, (2) is not an
economically ``significant regulatory action'' as defined in section
3(f) of Executive Order 12866, (3) is not ``significant'' as defined in
DOT's Regulatory Policies and Procedures; (4) has a significant
positive economic impact on small entities; (5) will not create
unnecessary obstacles to the foreign commerce of the United States; and
(6) will not impose an unfunded mandate on state, local, or tribal
governments, or on the private sector by exceeding the threshold
identified above. These analyses are summarized below.
1. Total Benefits and Costs of This Rule
The following table shows the estimated benefits and costs of the
final rule. Another way to consider the expected net benefit to the
society is if the rule saves only one human life by improving stall
characteristics and stall warnings, this alone would result in benefits
which substantially outweigh the costs.
Estimated Benefits and Costs
[2015 $ Millions]
------------------------------------------------------------------------
Safety benefits +
Stall & spin + other cost savings = total
costs benefits
------------------------------------------------------------------------
Total....................... $0.8 + $3.1 = $3.9.. $17.9 + $9.9 = $27.8
Present value at 7%......... 0.8 + 3.1 = 3.9..... 6.1 + 4.9 = 11.0
Present value at 3%......... 0.8 + 3.1 = 3.9..... 11.1 + 7.1 = 18.3
------------------------------------------------------------------------
* These numbers are subject to rounding error.
2. Who is potentially affected by this rule?
The proposal will affect U.S. manufacturers and operators of new
part 23 type certificated airplanes.
3. Assumptions
The benefit and cost analysis for the regulatory evaluation is
based on the following factors/assumptions:
The analysis is conducted in constant dollars with 2015 as
the base year.
The final rule will be effective in 2017.
The primary analysis period for costs and benefits extends
for 20 years, from 2017 through 2036. This period was selected because
annual costs and benefits will have reached a steady state by 2036.
Future part 23 type certifications and deliveries are
estimated from historical part 23 type certifications and deliveries.
Costs for the new part 23 type certifications forecasted
in the ``Fleet Discussion'' section will all occur in year 1 of the
analysis interval.
[[Page 96670]]
Airplane deliveries from the forecasted part 23 type
certificates will start in year 5 of the analysis interval. Therefore,
accident reduction benefits will begin five years after the rule is in
effect.
The FAA uses a three and seven percent discount rate for
the benefits and costs as prescribed by OMB in Circular A-4.
The baseline for estimating the costs and benefits of the
rule will be part 23, through the current amendment level.
Based on FAA Small Airplane Directorate expert judgment,
the FAA estimates 335 FAA part 23 certification engineers will require
additional training as a result of this final rule. The FAA assumes
that the same number of industry part 23 certification engineers will
also require additional training as a result of this final rule.
The FAA estimates this rulemaking will add 16 hours of
training to FAA and industry part 23 certification engineers.
Since this training program will be on-line, we estimate
no travel costs for the engineers.
FAA pay-band tables and the Bureau of Labor Statistics
(BLS) determines the hourly wages used to estimate the costs to the FAA
and applicants.
Using the U.S. Department of Transportation guidance, the
wage multiplier for employee benefits is 1.17.
4. Benefits of This Rule
The major safety benefit of this rule is to add stall
characteristics and stall warnings that will result in airplane designs
that are more resistant to inadvertently departing controlled flight.
The largest number of accidents for small airplanes is a stall or
departure based loss of control (LOC) in flight. This rule will have
cost savings by streamlining the certification process and encouraging
new and innovative technology. Streamlining the certification process
will reduce the issuance of special conditions, exemptions, and
equivalent level of safety findings.
5. Costs of This Rule
The final rules major costs are the engineer training costs and the
certification database creation costs. Additional costs will also
accrue from the controllability and stall sections that will increase
scope over current requirements and manual upgrade costs.
In the following table, we summarize the total estimated compliance
costs by category. The FAA notes that since we assumed that all costs
occurred in Year 1 of the analysis interval, the 2015-dollar costs
equal the present value costs.
Total Cost Summary by Category
[In 2015 present value dollars]
------------------------------------------------------------------------
Total costs in
Type of cost present value
at 7 percent
------------------------------------------------------------------------
Sec. 23.2150(c) Controllability....................... $277,318
Sec. 23.2150(b) Stall characteristics, stall warning, 500,595
and spins..............................................
Engineer Training Costs................................. 1,167,379
Certification Database Costs............................ 1,295,290
Manual Upgrade Costs.................................... 700,833
---------------
Total Costs........................................... 3,941,414
------------------------------------------------------------------------
* These numbers are subject to rounding error.
B. Final Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA)
establishes ``as a principle of regulatory issuance that agencies shall
endeavor, consistent with the objectives of the rule and of applicable
statutes, to fit regulatory and informational requirements to the scale
of the businesses, organizations, and governmental jurisdictions
subject to regulation. To achieve this principle, agencies are required
to solicit and consider flexible regulatory proposals and to explain
the rationale for their actions to assure that such proposals are given
serious consideration.'' The RFA covers a wide-range of small entities,
including small businesses, not-for-profit organizations, and small
governmental jurisdictions.
Agencies must perform a review to determine whether a rule will
have a significant economic impact on a substantial number of small
entities. If the agency determines that it will, the agency must
prepare a regulatory flexibility analysis as described.
The FAA believes that this final rule could have a significant
positive economic impact on a substantial number of entities because we
believe this rule could enable the creation of new part 23 type
certificates and new manufacturers. The FAA has been working with U.S.
and foreign small aircraft manufacturers since 2007 to review the life
cycle of part 23 airplanes and determine what needed improvement.
The purpose of this analysis is to provide the reasoning underlying
the FAA determination.
Section 604(a) of the Act specifies the content of a FRFA.
Each FRFA must contain:
A statement of the need for, and objectives of, the rule;
a statement of the significant issues raised by the public
comments in response to the initial regulatory flexibility analysis, a
statement of the assessment of the agency of such issues, and a
statement of any changes made in the proposed rule as a result of such
comments;
the response of the agency to any comments filed by the
Chief Counsel for Advocacy of the Small Business Administration in
response to the proposed rule, and a detailed statement of any change
made to the proposed rule in the final rule as a result of the
comments;
a description of and an estimate of the number of small
entities to which the rule will apply or an explanation of why no such
estimate is available;
a description of the projected reporting, recordkeeping
and other compliance requirements of the rule, including an estimate of
the classes of small entities which will be subject to the requirement
and the type of professional skills necessary for preparation of the
report or record; and
a description of the steps the agency has taken to
minimize the significant economic impact on small entities consistent
with the stated objectives of applicable statutes, including a
statement of the factual, policy, and legal reasons for selecting the
alternative adopted in the final rule and why each one of the other
significant alternatives to the rule considered by the agency which
affect the impact on small entities was rejected.
1. Reasons Why the Rule Is Needed
The FAA promulgates this action to amend the airworthiness
standards for new part 23 type certificated airplanes to reflect the
current needs of the small airplane industry, accommodate future
trends, address emerging technologies, and enable the creation of new
part 23 manufacturers and new type certificated airplanes. The rule's
changes to part 23 are necessary to eliminate the current workload of
exemptions, special conditions, and equivalent levels of safety
findings necessary to certificate new part 23 airplanes. These part 23
changes will also promote safety by enacting new regulations for
controllability and stall standards and promote the introduction of new
technologies in part 23 airplanes.
2. Significant Issues Raised by the Public Comments in Response to the
Initial Regulatory Flexibility Analysis
With regard to assessing the impact on small, numerous firms were
left out
[[Page 96671]]
of the FAA's analysis. Analysis concerning the impact on small firms
ultimately included data from only 5 firms, one of which has not been
in operation for 8 years, and another that no longer exists, but is
struggling to set up business under new ownership. It would seem that
the FAA should have knowledge of every company that still has active
manufacturing activities (active production certificates), and that the
data that was included was exceptionally non-representative of the
overall industry. Further, by eliminating from consideration all firms
that are not US-owned a distorted view of the true impact on the
general aviation industry in our country is presented.
FAA Response: Under the Small Business Regulatory Flexibility Act,
for each initial regulatory flexibility analysis, agencies are required
to provide a description of and, where feasible, an estimate of the
number of small entities to which the proposed rule would apply. Many,
if not most, small entities do not provide public data such as
publically available employment data in order to determine if a
business is small under the SBA guidelines, or publically available
revenue data, in order to determine if a business is disproportionately
burdened by the proposed or final rulemaking. The FAA does not have the
means or authority to require small entities to report their employment
or revenue data and therefore we do not have knowledge of every company
that still has active manufacturing activities. The small business
entities that the FAA analyzed provided data on their employment and
revenue either through the U.S. DOT Form 41 rules, SEC rules, or
through news releases the companies made public.
The FAA conducted research and found that all five businesses' we
examined at the time of our analysis were small and either actively
manufacturing aircraft or they were under new ownership and had
publically announced they were in the process of working towards
setting up an aircraft manufacturing line. The FAA notes the rule also
reduces the certification time for small part 23 parts manufacturers.
The FAA conclusion that the proposed rule may have a significant
positive impact on small entities extends well beyond our sample.
Further, FAA regulations apply to US-owned business and to any
foreign owned business that manufactures a product in the U.S. or
markets their products/services in the U.S. Foreign owned business'
voluntarily complies with the rules and regulations promulgated by the
FAA. Thus the FAA expects that the final rule would impact a
substantial number of small entities.
The comment regarding numerous firms being left out of the FAA's
small business analysis was from a company who certificates most of
their aircraft with a restricted category special air worthiness
certificate. A restricted category special airworthiness certificate is
issued to operate aircraft that have been type certificated in the
restricted category. Operation of restricted category aircraft is
limited to special purposes identified in the applicable type design.
Restricted category aircraft manufacturers do not follow part 23 in its
entirety, rather they follow parts of part 21, part 21 subpart H, part
45, section 91.313, part 91 subpart D, section 91.715, and part 375 and
can choose whatever other certification bases requirements, based on
FAA approval, to certificate their aircraft for the aircraft's special
operations. Therefore, since restricted category aircraft manufacturers
do not comply part 23 in its entirety for their type certifications,
these manufacturers are not included in our analysis.
In addition, many part suppliers may benefit from this performance-
based rule through an expected quicker approval process. The objective
of this rule is to allow industry more flexibility and lower cost
methods to certify future part 23 airplanes at a sufficiently lower
certification cost which can be driven by industry innovation and more
small entities will have additional opportunities that do not exist
today.
3. FAA Response to Any Comments Filed by the Chief Counsel for Advocacy
of the Small Business Administration in Response to the Proposed Rule
The Chief Counsel for Advocacy did not file comments for the
proposed rule.
4. A Description of and an Estimate of the Number of Small Entities to
Which the Rule Will Apply or an Explanation of Why No Such Estimate Is
Available
For the initial regulatory flexibility analysis (IRFA), the FAA
conducted a review to determine whether a rule will have a significant
economic impact on a substantial number of small entities. The IRFA
concluded that the proposed rule could have a significant economic
impact on a substantial number of entities because we believe this rule
could enable the creation of new part 23 type certificates and new
manufacturers.
The FAA is unable to estimate the total number of small entities to
which the rule will apply because many, if not most, small part 23
aircraft manufacturing entities do not provide public data such as
publically available employment data in order to determine if a
business is small under the SBA guidelines, and publically available
revenue data, in order to determine if a business is disproportionately
burdened by the final rulemaking. The FAA also believes that the final
rule will enable new part 23 aircraft manufacturing industries, while
maintaining a safe operating environment. In addition, many part
suppliers may benefit from this performance-based rule through an
expected quicker approval process.
5. A Description of the Projected Reporting, Recordkeeping and Other
Compliance Requirements of the Rule, Including an Estimate of the
Classes of Small Entities Which Will Be Subject to the Requirement and
the Type of Professional Skills Necessary for Preparation of the Report
or Record
The final rule will reduce the number of special conditions,
equivalent level of safety (ELOS), and exemptions and therefore will
reduce paperwork and processing time for both the FAA and industry. The
rule would also maintain the fundamental safety requirements from the
current part 23 regulations but allow more flexibility in airplane
designs, faster adoption of safety enhancing technology, and reduce the
regulatory cost burden. To estimate savings driven by this change, the
FAA counted the special conditions, ELOS, and exemption applications
submitted to the FAA for part 23 aircraft between 2012 and 2014 and
divided the number by two years for an average of 37 applications per
year. The Aviation Rulemaking Committee (ARC) report offered a similar
average of 37 applications per year. Additionally, the FAA counted the
number of pages per application to obtain an average number of pages
per application. For special conditions, there were approximately 21
pages, 16 pages for an exemption, and 15 pages per ELOS application.
The FAA assumes that the applicant and each FAA office that reviews the
application spend 8 hours on research, coordination, and review per
page. The ARC also noted ``an ELOS finding or exemption can take the
FAA between 4 to 12 months to develop and approve. The applicant spends
roughly the same amount of time as the FAA in proposing what they need
and responding to FAA questions for SC, exemption, or ELOS. As
explained in number four above, the FAA is unable to estimate the total
number of small entities to which the rule will apply. The completion
of these reports will not require professional skills beyond basic
literacy and aviation
[[Page 96672]]
skills required to work for a part 23 aircraft manufacturer.
6. A Description of the Steps the Agency Has Taken To Minimize the
Significant Economic Impact on Small Entities Consistent With the
Stated Objectives of Applicable Statutes, Including a Statement of the
Factual, Policy, and Legal Reasons for Selecting the Alternative
Adopted in the Final Rule and Why Each One of the Other Significant
Alternatives to the Rule Considered by the Agency Which Affect the
Impact on Small Entities Was Rejected
The Federal Aviation Administration (FAA) is revising the
airworthiness standards for normal, utility, acrobatic, and commuter
category part 23 airplanes and believes this action will provide a set
of requirements that will allow more flexibility in part 23 airplane
designs and faster adoption of safety enhancing technology while
maintaining a higher level of safety. The current issue with part 23 is
the prescriptive regulatory framework does not readily allow the
adoption of new and innovative technology. This rulemaking will solve
this issue by putting in place a performance-based regulatory structure
that will result in the FAA accepting new means of compliance based
upon industry consensus standards.
This rulemaking project will comply with the Congressional mandated
Small Airplane Revitalization Act of 2013, which requires the FAA to
issue a final rule that revises the certification requirements for
small airplanes by creating a regulatory regime that will improve
safety and decrease certification costs. This action will increase the
FAA's ability to address future technology and be relieving for all
part 23 manufacturers regardless of their size and number of employees.
For the initial regulatory flexibility analysis, the FAA analyzed
two alternatives and solicited and received no comments on the
alternative analysis. The two alternatives the FAA analyzed follows.
Alternative 1
The FAA will continue to issue special conditions, exemptions, and
equivalent level of safety findings to certificate part 23 airplanes.
As this approach will not follow congressional direction, we choose not
to continue with the status quo.
Alternative 2
The FAA will continue to enforce the current regulations that
affect stall and controllability. The FAA rejected this alternative
because the accident rate for part 23 airplanes identified a safety
issue that had to be addressed.
Thus, this rule's benefits small entities by allowing new designs
and parts with lower certifications costs.
C. International Trade Impact Assessment
The Trade Agreements Act of 1979 (Pub. L. 96-39), as amended by the
Uruguay Round Agreements Act (Pub. L. 103-465), prohibits Federal
agencies from establishing standards or engaging in related activities
that create unnecessary obstacles to the foreign commerce of the United
States. Pursuant to these Acts, the establishment of standards is not
considered an unnecessary obstacle to the foreign commerce of the
United States, so long as the standard has a legitimate domestic
objective, such as the protection of safety, and does not operate in a
manner that excludes imports that meet this objective. The statute also
requires consideration of international standards and, where
appropriate, that they be the basis for U.S. standards. The FAA has
assessed the potential effect of this final rule and determined that
the standards are necessary for aviation safety and will not create
unnecessary obstacles to the foreign commerce of the United States.
D. Unfunded Mandates Assessment
Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement
assessing the effects of any Federal mandate in a proposed or final
agency rule that may result in an expenditure of $100 million or more
(in 1995 dollars) in any one year by State, local, and tribal
governments, in the aggregate, or by the private sector; such a mandate
is deemed to be a ``significant regulatory action.'' The FAA currently
uses an inflation-adjusted value of $155.0 million in lieu of $100
million. This final rule does not contain such a mandate; therefore,
the requirements of Title II of the Act do not apply.
E. Paperwork Reduction Act
The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires
that the FAA consider the impact of paperwork and other information
collection burdens imposed on the public. The information requirements
for aircraft certification are covered by existing OMB No. 2120-0018.
Burdens associated with special conditions, ELOS, and exemptions are
not quantified in this collection because the need to seek relief under
one of these options is dependent on each applicant and is difficult to
quantify. It is expected that this rulemaking will reduce the number of
special conditions, ELOS, and exemptions filed, thus reducing paperwork
and processing time for both the FAA and industry. It would also
maintain the fundamental safety requirements from the current part 23
regulations but allow more flexibility in airplane designs, faster
adoption of safety enhancing technology, and reduce the regulatory cost
burden.
To estimate savings driven by this change, the FAA counted the
special conditions, ELOS, and exemption applications submitted to the
FAA for part 23 aircraft between 2012 and 2014 and divided the number
by three years for an average of 37 applications per year.\66\
Additionally, the FAA counted the number of pages per application to
obtain an average number of pages per application. For special
conditions, there were approximately 21 pages, 16 pages for an
exemption, and 15 pages per ELOS application. The FAA assumes that the
applicant and each FAA office that reviews the application spend 8
hours on research, coordination, and review per page. The ARC also
noted ``an ELOS finding or exemption can take the FAA between 4 to 12
months to develop and approve. The applicant spends roughly the same
amount of time as the FAA in proposing what they need and responding to
FAA questions for SC, exemption, or ELOS.'' \67\
---------------------------------------------------------------------------
\66\ https://my.faa.gov/org/linebusiness/avs/offices/air/tools/cert.html.
\67\ Ibid., 54.
---------------------------------------------------------------------------
The number of applications is multiplied by the number of pages and
by the hourly wage for the applicant and different FAA offices to
account for the cost to the FAA and the applicant. The following table
shows annual hours and cost by special condition, exemption, and ELOS.
[[Page 96673]]
------------------------------------------------------------------------
Annual total
-------------------------------
Man hours Cost
------------------------------------------------------------------------
Savings from Special Conditions (SC).... 8,826 $553,962
Savings from Exemptions................. 1,620 101,596
Savings from Equivalent Level of Safety 5,268 330,691
(ELOS).................................
------------------------------------------------------------------------
Using these yearly cost estimates in the table above, over 20 years
$6.6 million in man-hours will be spent on applying for and processing
special conditions, exemptions, and ELOS. However under the rule, the
need to demonstrate compliance through special conditions, exemptions,
or ELOS will largely be eliminated. Instead new products will simply
need to demonstrate compliance by following consensus standards
acceptable to the Administrator, or by submitting their own proposed
means of compliance using the process outlined in AC 23.10.\68\ As a
conservative estimate, the FAA estimates that special conditions,
exemptions, and ELOS will be reduced by half for a savings to the FAA
and applicant of roughly $3.3 million ($1.6 million present value). The
total cost and hour savings by year is shown in the table below.
---------------------------------------------------------------------------
\68\ See Section VI. Discussion of the Regulatory Amendments of
the preamble for a discussion of how this might be accomplished.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
FAA SAD FAA ACO Applicant Total
-------------------------------------------------------------------------------------------------------------------------------
Man-hours Savings Man-hours Savings Man-hours Savings Man-hours Savings
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total........................................................... 34,920 $2,613,227 34,920 $1,789,953 34,920 $2,171,813 104,760 $6,574,993
0.5*Total....................................................... 17,460 1,306,613 17,460 904,977 17,460 1,085,907 52,380 3,287,497
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
These numbers are subject to rounding error.
In addition to this savings, there would also be additional
paperwork burden associated with Sec. 23.2150(c). This rulemaking will
not require a new control number, but does need an update to the
control number that currently covers part 23. A PRA questionnaire has
been updated with new requirements from this rule, and submitted to our
PRA officer. This provision could result in a change to a limitation or
a performance number in the flight manual, which will require an update
to the training courseware or flight manual. Industry ARC members
believe that this change could cost from $100,119 to $150,179 in 2015
dollars. Therefore, the FAA uses $125,149 (($100,119 + $150,179)/2) as
an average cost for this change. This will be a one-time cost per new
type certification.
There will also be additional paperwork associated with this
requirement that is not part of the costs discussed above. The FAA
estimates the paperwork costs for these provisions by multiplying the
number of hours the FAA estimates for each page of paperwork, by the
number of pages for the training courseware, or flight manual, by the
hourly rate of the person responsible for the update. The FAA estimates
that this section will add a total of four pages to the training
courseware and flight manual. The FAA also estimates that it will take
a part 23 certification engineer eight hours to complete the one page
required for each new type certification. The eight hours to complete a
page includes the research, coordination, and review each document
requires. Therefore, the FAA estimates the total paperwork costs for
Sec. 23.2150(c) will be about $1,990 in 2015 dollars. The FAA assumes
that this section will add costs to only one of the new part 23
turbojet airplane type certificates estimated in the Fleet Discussion
section of the regulatory evaluation. The following table shows the
total paperwork costs for the changes to Sec. 23.2150(c).
----------------------------------------------------------------------------------------------------------------
Changes to
Airplane type Hours flight manual Paper work Total
----------------------------------------------------------------------------------------------------------------
Turbojet.................................... 2,044 $125,149 $1,990 $127,139
----------------------------------------------------------------------------------------------------------------
Conversations with the industry ARC members indicate that there may
need to be some changes to the engineering manuals to describe how the
accepted means of compliance must be related to the regulations.
Depending on the complexity of each company's manual, industry
estimates that these changes could run from about $50,060 up to
$200,238 in 2015 dollars. This will be a one-time cost per new type
certification.
As we received no comments to the paperwork analysis in the NPRM,
we use the same assumptions in the final rule regarding manual
complexity. The manufacturers of the two new part 23 reciprocating
engine airplane type certifications, discussed in the Fleet Discussion
section of the regulatory evaluation, will spend $50,060 to make the
changes to the engineering manual. We also assume that the one new part
23 turboprop airplane certification and the two new part 23 turbojet
airplane certifications, discussed in the Fleet Discussion section of
the regulatory evaluation, will use the more complex and costly
approach of $200,238.
The FAA notes that either the simple approach or the more complex
approach to updating the manuals could also either take place in-house
or could be contracted out to a consultant. The following table shows
the total paperwork costs for the changes to the engineering manuals in
2015 dollars.
[[Page 96674]]
----------------------------------------------------------------------------------------------------------------
Number of
estimated new Simple Complex
Airplane type type approach approach Hours Total
certificates
----------------------------------------------------------------------------------------------------------------
Recip........................... 2 $50,060 $0 1,610 $100,119
Turboprop....................... 1 0 200,238 3,219 200,238
Turbojet........................ 2 0 200,238 6,439 400,476
-------------------------------------------------------------------------------
Total....................... .............. .............. .............. 11,268 700,833
----------------------------------------------------------------------------------------------------------------
These numbers are subject to rounding error.
F. International Compatibility and Cooperation
In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA policy to conform to
International Civil Aviation Organization (ICAO) Standards and
Recommended Practices to the maximum extent practicable. The FAA has
reviewed the corresponding ICAO Standards and Recommended Practices and
has identified the following differences with these proposed
regulations. The ICAO Standards for small airplanes use weight and
propulsion to differentiate between some requirements. The proposed
regulations use certification levels and performance to differentiate
between some requirements. Furthermore, part 23 will still allow the
certification of airplanes up to 19,000 pounds. If this proposal is
adopted, the FAA intends to file these differences with ICAO. Executive
Order (EO) 13609, Promoting International Regulatory Cooperation, (77
FR 26413, May 4, 2012) promotes international regulatory cooperation to
meet shared challenges involving health, safety, labor, security,
environmental, and other issues and reduce, eliminate, or prevent
unnecessary differences in regulatory requirements. The FAA has
analyzed this action under the policy and agency responsibilities of
Executive Order 13609, Promoting International Regulatory Cooperation.
The agency has determined that this action would eliminate differences
between U.S. aviation standards and those of other CAAs by aligning the
revised part 23 standards with the new CS 23 standards that are being
developed concurrently by EASA. Several other CAAs are participating in
this effort and intend to either adopt the new part 23 or CS 23
regulations or revise their airworthiness standards to align with these
new regulations.
The Part 23 ARC included participants from several foreign CAAs and
international members from almost every GA manufacturer of both
airplanes and avionics. It also included several Light-Sport Aircraft
manufacturers who are interested in certificating their products using
the airworthiness standards contained in part 23. The rulemaking and
means of compliance are international efforts. Authorities from Europe,
Canada, Brazil, China, and New Zealand all are working to produce
similar rules. These rules, while not identical, are intended to allow
the use of the same set of industry developed means of compliance.
Industry has told that FAA that it is very costly to address the
differences that some contrived means of compliance imposes. If there
is substantial agreement between the major CAAs to use the same
industry means of compliance, then U.S. manufactures expect a
significant saving for exporting their products.
Furthermore, this project is a harmonization project between the
FAA and EASA.
EASA has worked a parallel rulemaking program for CS 23. The FAA
provided comments to the EASA A-NPA. EASA and other authorities will
have an opportunity to comment on this NPRM when it is published. These
efforts will allow the FAA, EASA and other authorities to work toward a
harmonized set of regulations when the final rules are published.
G. Environmental Analysis
FAA Order 1050.1F identifies FAA actions that are categorically
excluded from preparation of an environmental assessment or
environmental impact statement under the National Environmental Policy
Act in the absence of extraordinary circumstances. The FAA has
determined this rulemaking action qualifies for the categorical
exclusion identified in paragraph 5-6.6 and involves no extraordinary
circumstances.
H. Regulations Affecting Intrastate Aviation in Alaska
Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat.
3213) requires the Administrator, when modifying 14 CFR regulations in
a manner affecting intrastate aviation in Alaska, to consider the
extent to which Alaska is not served by transportation modes other than
aviation, and to establish appropriate regulatory distinctions. Because
this rule would apply to GA airworthiness standards, it could, if
adopted, affect intrastate aviation in Alaska. The FAA, therefore,
specifically requests comments on whether there is justification for
applying the proposed rule differently in intrastate operations in
Alaska.
V. Executive Order Determination
A. Executive Order 13132, Federalism
The FAA has analyzed this rule under the principles and criteria of
Executive Order 13132, Federalism. The agency has determined that this
action would not have a substantial direct effect on the States, or the
relationship between the Federal Government and the States, or on the
distribution of power and responsibilities among the various levels of
government, and, therefore, would not have Federalism implications.
B. Executive Order 13211, Regulations That Significantly Affect Energy
Supply, Distribution, or Use
The FAA analyzed this rule under Executive Order 13211, Actions
Concerning Regulations that Significantly Affect Energy Supply,
Distribution, or Use (May 18, 2001). The agency has determined that it
would not be a ``significant energy'' action under the executive order
and would not be likely to have a significant adverse effect on the
supply, distribution, or use of energy.
VI. How To Obtain Additional Information
A. Rulemaking Documents
An electronic copy of rulemaking documents may be obtained from the
Internet by--
1. Searching the Federal eRulemaking Portal (http://www.regulations.gov) for Docket FAA-2015-1621;
2. Visiting the FAA's Regulations and Policies Web page at http://www.faa.gov/regulations_policies/; or
3. Accessing the Government Printing Office's Web page at http://www.gpo.gov/fdsys/.
[[Page 96675]]
Copies may also be obtained by sending a request to the Federal
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence
Avenue SW., Washington, DC 20591, or by calling (202) 267-9680.
B. Comments Submitted to the Docket
Comments received may be viewed by going to http://www.regulations.gov and following the online instructions to search the
docket number (FAA-2015-1621) for this action. Anyone is able to search
the electronic form of all comments received into any of the FAA's
dockets by the name of the individual submitting the comment (or
signing the comment, if submitted on behalf of an association,
business, labor union, etc.).
C. Small Business Regulatory Enforcement Fairness Act
The Small Business Regulatory Enforcement Fairness Act (SBREFA) of
1996 requires FAA to comply with small entity requests for information
or advice about compliance with statutes and regulations within its
jurisdiction. A small entity with questions regarding this document,
may contact its local FAA official, or the person listed under the FOR
FURTHER INFORMATION CONTACT heading at the beginning of the preamble.
To find out more about SBREFA on the Internet, visit http://www.faa.gov/regulations_policies/rulemaking/sbre_act/.
Appendix 1 to the Preamble--Former to New Regulations Cross-Reference
Table
The below cross-reference table is intended to permit easy
access from former to new regulations. The preamble is organized
topical, section-by-section, former to new regulations. This table
should assist the reader in following the section discussions
contained in the preamble. If the intent of a former regulation was
incorporated into multiple new regulations, only the most pertinent
new regulations were listed.
----------------------------------------------------------------------------------------------------------------
Former section Former title New section New title
----------------------------------------------------------------------------------------------------------------
Subpart A--General
----------------------------------------------------------------------------------------------------------------
23.1................................. Applicability.......... 23.2000................ Applicability.
23.2................................. Special retroactive 23.2................... Interim Airworthiness
requirements. Requirements.
23.3................................. Airplane categories.... 23.2005................ Certification of normal
category airplanes
23.2010................ Accepted means of
compliance.
----------------------------------------------------------------------------------------------------------------
Subpart B--Flight
----------------------------------------------------------------------------------------------------------------
23.21................................ Proof of compliance.... 23.2100................ Weight and center of
gravity.
23.23................................ Load distribution 23.2100................ Weight and center of
limits. gravity.
23.25................................ Weight limits.......... 23.2100................ Weight and center of
gravity.
23.29................................ Empty weight and 23.2100................ Weight and center of
corresponding center gravity.
of gravity.
23.31................................ Removable ballast...... 23.2100................ Weight and center of
gravity.
23.33................................ Propeller speed and 23.2400................ Powerplant
pitch limits. installation.
23.45................................ Performance--General... 23.2105................ Performance data.
23.49................................ Stalling speed......... 23.2110................ Stall Speed.
23.51................................ Takeoff speeds......... 23.2115................ Takeoff performance.
23.53................................ Takeoff performance.... 23.2115................ Takeoff performance.
23.55................................ Accelerate-stop 23.2115................ Takeoff performance.
distance.
23.57................................ Takeoff path........... 23.2115................ Takeoff performance.
23.59................................ Takeoff distance and 23.2115................ Takeoff performance.
takeoff run.
23.61................................ Takeoff flight path.... 23.2115................ Takeoff performance.
23.63................................ Climb: General......... 23.2120................ Climb requirements.
23.65................................ Climb: All engines 23.2120................ Climb requirements.
operating.
23.66................................ Takeoff climb: one 23.2125................ Climb information.
engine inoperative.
23.67................................ Climb: One engine 23.2120................ Climb requirements.
inoperative.
23.69................................ Enroute climb/descent.. 23.2125................ Climb information.
23.71................................ Glide: single engine 23.2125................ Climb information.
airplanes.
23.73................................ Reference landing 23.2130................ Landing.
approach speed.
23.75................................ Landing distance....... 23.2130................ Landing.
23.77................................ Balked landing......... 23.2120................ Climb requirements.
23.141............................... Flight Characteristics- 23.2135................ Controllability.
General.
23.143............................... Controllability and 23.2135................ Controllability.
Maneuverability--Gener
al.
23.145............................... Longitudinal control... 23.2135................ Controllability.
23.147............................... Directional and lateral 23.2135................ Controllability.
control.
23.149............................... Minimum control speed.. 23.2135................ Controllability.
23.151............................... Acrobatic maneuvers.... 23.2135................ Controllability.
23.153............................... Control during landings 23.2135................ Controllability.
23.155............................... Elevator control force 23.2135................ Controllability.
in maneuvers.
23.157............................... Rate of roll........... 23.2135................ Controllability.
23.161............................... Trim................... 23.2140................ Trim.
23.171............................... Stability--General..... 23.2145................ Stability.
23.173............................... Static longitudinal 23.2145................ Stability.
stability.
23.175............................... Demonstration of static 23.2145................ Stability.
longitudinal stability.
23.177............................... Static directional and 23.2145................ Stability.
lateral stability.
[[Page 96676]]
23.179............................... Instrument stick force 23.2145................ Stability.
measurements.
23.181............................... Dynamic stability...... 23.2145................ Stability.
23.201............................... Wings level stall...... 23.2150................ Stall characteristics,
stall warning, and
spins.
23.203............................... Turning Flight and 23.2150................ Stall characteristics,
accelerated turning stall warning, and
stalls. spins.
23.207............................... Stall Warning.......... 23.2150................ Stall characteristics,
stall warning, and
spins.
23.221............................... Spinning............... 23.2150................ Stall characteristics,
stall warning, and
spins.
23.231............................... Longitudinal stability 23.2155................ Ground and water
and control. handling
characteristics.
23.233............................... Directional stability 23.2155................ Ground and water
and control. handling
characteristics.
23.235............................... Operation on unpaved 23.2155................ Ground and water
surfaces. handling
characteristics.
23.237............................... Operation on water..... 23.2155................ Ground and water
handling
characteristics.
23.239............................... Spray characteristics.. 23.2155................ Ground and water
handling
characteristics.
23.251............................... Vibration and buffeting 23.2160................ Vibration, buffeting,
and high-speed
characteristics.
23.253............................... High-speed 23.2160................ Vibration, buffeting,
characteristics. and high-speed
characteristics.
23.255............................... Out of trim 23.2160................ Vibration, buffeting,
characteristics. and high-speed
characteristics.
23.2165................ Performance and flight
characteristics
requirements for
flight in icing
conditions.
----------------------------------------------------------------------------------------------------------------
Subpart C--Structure
----------------------------------------------------------------------------------------------------------------
23.301............................... Loads.................. 23.2210, 23.2230....... Structural design
loads, Limit and
ultimate loads.
(a).................................. ....................... 23.2230................ Limit and ultimate
loads.
(b).................................. ....................... 23.2210................ Structural design
loads.
(c).................................. ....................... 23.2210................ Structural design
loads.
(d).................................. ....................... 23.2210................ Structural design
loads.
23.302............................... Canard or tandem wing 23.2210................ Structural design
configurations. loads.
23.303............................... Factors of safety...... 23.2230................ Limit and ultimate
loads.
23.305............................... Strength and 23.2235................ Structural strength.
deformation.
23.2205................ Interaction of systems
and structures.
23.307............................... Proof of structure..... 23.2235................ Structure strength.
23.321............................... Flight Loads--General.. 23.2210................ Structural design
loads.
(a).................................. ....................... 23.2210................ Structural design
loads.
(b).................................. ....................... 23.2200................ Structural design
envelope.
(c).................................. ....................... 23.2200................ Structural design
envelope.
23.331............................... Symmetrical flight 23.2210................ Structural design
conditions. loads.
23.333............................... Flight envelope........ 23.2200................ Structural design
envelope.
(a).................................. ....................... 23.2200................ Structural design
envelope.
(b).................................. ....................... 23.2200................ Structural design
envelope.
(c).................................. ....................... 23.2215................ Flight load conditions.
(d).................................. ....................... 23.2200................ Structural design
envelope.
23.335............................... Design airspeeds....... 23.2200................ Structural design
envelope.
23.337............................... Limit maneuvering load 23.2200................ Flight load conditions.
factors.
(a).................................. ....................... 23.2200................ Structural design
envelope.
(b).................................. ....................... 23.2200................ Structural design
envelope.
(c).................................. ....................... Means of Compliance....
23.341............................... Gust load factors...... 23.2215................ Flight load conditions.
23.343............................... Design fuel loads...... 23.2200................ Structural design
envelope.
(a).................................. ....................... 23.2200................ Structural design
envelope.
(b).................................. ....................... 23.2200................ Structural design
envelope.
(c).................................. ....................... Means of Compliance....
23.345............................... High lift devices...... 23.2225................ Component loading
conditions.
23.347............................... Unsymmetrical flight 23.2215................ Flight load conditions.
loads.
23.349............................... Rolling conditions..... 23.2215................ Flight load conditions.
23.351............................... Yawing conditions...... 23. 215................ Flight load conditions.
23.361............................... Engine torque.......... 23.2225................ Component loading
conditions.
23.363............................... Side load on engine 23.2225................ Component loading
mount. conditions.
23.365............................... Pressurized cabin loads 23.2225................ Flight load conditions.
(e).................................. ....................... 23.2240................ Structural durability.
[[Page 96677]]
23.367............................... Unsymmetrical loads due 23.2215................ Flight load conditions.
to engine failure.
23.369............................... Rear lift truss........ Means of Compliance....
23.371............................... Gyroscopic and 23.2225................ Component loading
aerodynamic loads. conditions.
23.373............................... Speed control devices.. 23.2225................ Component loading
conditions.
23.391............................... Control surface loads.. 23.2225................ Component loading
conditions.
23.393............................... Loads parallel to hinge 23.2225................ Component loading
line. conditions.
23.395............................... Control system loads... 23.2225................ Component loading
conditions.
23.397............................... Limit control forces 23.2225................ Component loading
and torques. conditions.
23.399............................... Dual control system.... 23.2225................ Component loading
conditions.
23.405............................... Secondary control 23.2225................ Component loading
system. conditions.
23.407............................... Trim tab effects....... 23.2225................ Component loading
conditions.
23.409............................... Tabs................... 23.2225................ Component loading
conditions.
23.415............................... Ground gust conditions. 23.2225................ Component loading
conditions.
23.421............................... Balancing loads........ Means of Compliance....
23.423............................... Maneuvering loads...... 23.2215................ Flight load conditions.
23.425............................... Gust loads............. 23.2215................ Flight load conditions.
23.427............................... Unsymmetrical loads due 23.2215................ Flight load conditions.
to engine failure.
23.441............................... Maneuvering loads...... 23.2215................ Flight load conditions.
23.443............................... Gust loads............. 23.2215................ Flight load conditions.
23.445............................... Outboard fins or Means of Compliance....
winglets.
23.455............................... Ailerons............... 23.2225................ Component loading
conditions.
23.459............................... Special devices........ 23.2225................ Component loading
conditions.
23.471............................... Ground Loads--General.. 23.2220................ Ground and water load
conditions.
23.473............................... Ground load conditions 23.2220................ Ground and water load
and assumptions. conditions.
23.477............................... Landing gear 23.2220................ Ground and water load
arrangement. conditions.
23.479............................... Level landing 23.2220................ Ground and water load
conditions. conditions.
23.481............................... Tail down landing 23.2220................ Ground and water load
conditions. conditions.
23.483............................... One-wheel landing 23.2220................ Ground and water load
conditions. conditions.
23.485............................... Side load conditions... 23.2220................ Ground and water load
conditions.
23.493............................... Braked roll conditions. 23.2220................ Ground and water load
conditions.
23.497............................... Supplementary 23.2220................ Ground and water load
conditions for tail conditions.
wheels.
23.499............................... Supplementary 23.2220................ Ground and water load
conditions for nose conditions.
wheels.
23.505............................... Supplementary 23.2220................ Ground and water load
conditions for conditions.
skiplanes.
23.507............................... Jacking loads.......... 23.2220................ Ground and water load
conditions.
23.509............................... Towing loads........... 23.2220................ Ground and water load
conditions.
23.511............................... Ground load: 23.2220................ Ground and water load
Unsymmetrical loads on conditions.
multiple-wheel units.
23.521............................... Water load conditions.. 23.2220................ Ground and water load
conditions.
23.523............................... Design weights and 23.2220................ Ground and water load
center of gravity conditions.
positions.
23.525............................... Application of loads... 23.2220................ Ground and water load
conditions.
23.527............................... Hull and main float 23.2220................ Ground and water load
load factors. conditions.
23.529............................... Hull and main float 23.2220................ Ground and water load
landing conditions. conditions.
23.531............................... Hull and main float 23.2220................ Ground and water load
takeoff conditions. conditions.
23.533............................... Hull and main float 23.2220................ Ground and water load
bottom pressures. conditions.
23.535............................... Auxiliary float loads.. 23.2220................ Ground and water load
conditions.
23.537............................... Seawing loads.......... 23.2220................ Ground and water load
conditions.
23.561............................... Emergency Landing 23.2270................ Emergency conditions.
Conditions--General.
[[Page 96678]]
23.562............................... Emergency landing 23.2270................ Emergency conditions.
dynamic conditions.
23.571............................... Metallic pressurized 23.2240................ Structural durability.
cabin structures.
23.572............................... Metallic wing, 23.2240................ Structural durability.
empennage, and
associated structures.
23.573............................... Damage tolerance and 23.2240................ Structural durability.
fatigue evaluation of
structure.
23.574............................... Metallic damage 23.2240................ Structural durability.
tolerance and fatigue
evaluation of commuter
category airplanes.
23.575............................... Inspections and other 23.2240................ Structural durability.
procedures.
----------------------------------------------------------------------------------------------------------------
Subpart D--Design and Construction
----------------------------------------------------------------------------------------------------------------
23.601............................... General................ 23.2250................ Design and construction
principles.
23.603............................... Materials and 23.2250, 23.2260....... Design and construction
workmanship. principles, Materials
and processes.
23.605............................... Fabrication methods.... 23.2260................ Materials and
processes.
23.607............................... Fasteners.............. 23.2250, 23.2255....... Design and construction
principles, Protection
of structure.
23.609............................... Protection of Structure 23.2255................ Protection of
structure.
23.611............................... Accessibility.......... 23.2255................ Protection of
structure.
23.613............................... Material strength 23.2260................ Materials and
properties and design processes.
values.
23.619............................... Special factors........ 23.2265................ Special factors of
safety.
23.621............................... Casting factors........ 23.2265................ Special factors of
safety.
23.623............................... Bearing factors........ 23.2265................ Special factors of
safety.
23.625............................... Fitting factors........ 23.2265................ Special factors of
safety.
23.627............................... Fatigue strength....... 23.2240................ Structural durability.
23.629............................... Flutter................ 23.2245................ Aeroelasticity.
23.641............................... Proof of strength...... Means of Compliance....
23.651............................... Proof of strength...... Means of Compliance....
23.655............................... Installation........... 23.2300(a)(2).......... Flight control systems.
23.657............................... Hinges................. 23.2265................ Special factors of
safety.
23.659............................... Mass balance........... 23.2215, 23.2335....... Flight load conditions,
Structural strength.
23.671............................... Control systems--
General.
(a).................................. ....................... 23.2300(a)(1) & Flight control systems
23.2600(a). & Flightcrew
interface.
(b).................................. ....................... 23.2600, 23.2605....... Flightcrew interface,
Installation and
operation.
23.672............................... Stability augmentation
and automatic and
power-operated systems.
(a).................................. ....................... 23.2605(c)............. Installation and
operation.
(b).................................. ....................... 23.2300(a)(2).......... Flight control systems.
(c).................................. ....................... 23.2510, 23.2300(a)(2). Installation and
operation, Flight
control systems.
23.673............................... Primary flight controls ....................... Definition.
23.675............................... Stops.................. 23.2300(a)(2).......... Flight control systems.
23.677............................... Trim systems...........
(a).................................. ....................... 23.2300(b) & 23.2600... Flight control systems
& Flightcrew
interface.
(b).................................. ....................... 23.2300(a)(2).......... Flight control systems.
(c).................................. ....................... 23.2245................ Aeroelasticity.
(d).................................. ....................... 23.2515................ Equipment, systems and
installations.
23.679............................... Control system locks...
(a), (b)............................. ....................... 23.2605(c)............. Installation and
operation.
(c).................................. ....................... 23.2300(a)(2).......... Flight control systems.
23.681............................... Limit load static tests
(a).................................. ....................... 23.2225(b), 23.2235.... Component loading
conditions, Structural
strength.
(b).................................. ....................... 23.2265................ Special factors of
safety.
23.683............................... Operation tests........ 23.2250(d), Design and construction
23.2300(a)(2). principles, Flight
control systems.
23.685............................... Control system details. 23.2300(a)(2).......... Flight control systems.
23.687............................... Spring devices......... 23.2245, 23.2250 & Aeroelasticity.
23.2300(a)(2). Structural design &
Flight control
systems.
23.689............................... Cable systems.......... 23.2250(c)............. Design and construction
principles.
(a)(3)............................... ....................... 23.2255(c)............. Protection of
structure.
[[Page 96679]]
23.691............................... Artificial stall
barrier system.
(a), (b)............................. ....................... 23.2250................ Design and construction
principles.
(c).................................. ....................... 23.2605(c)............. Installation and
operation.
(d), (e), (f)........................ ....................... 23.2300(a)(2).......... Flight control systems.
(g).................................. ....................... 23.2510................ Equipment, systems, and
installations.
23.693............................... Joints................. 23.2265................ Special factors of
safety.
23.697............................... Wing flap controls..... 23.2300(a)............. Flight control systems.
23.699............................... Wing flap position 23.2600(b)............. Flightcrew interface.
indicator.
23.701............................... Flap interconnection... 23.2300(a)(2), 23.2510. Flight control systems
& Equipment, systems,
and installations.
23.703............................... Takeoff warning system. 23.2605(c)............. Installation and
operation.
23.721............................... General................ 23.2305(a)(2), Landing gear systems,
23.2430(a)(6). Fuel systems.
23.723............................... Shock absorption tests. 23.2235, 23.2250(c).... Structural strength,
Design and
construction
principles.
23.725............................... Limit drop tests....... 23.2235................ Structural strength.
23.726............................... Ground load dynamic 23.2235................ Structural strength.
tests.
23.727............................... Reserve energy 23.2235, 23.2250(c).... Structural strength,
absorption drop tests. Design and
construction
principles.
23.729............................... Landing gear extension
and retraction system.
(a).................................. ....................... 23.2235................ Structural strength.
(b).................................. ....................... 23.2305(c)(1).......... Landing gear systems.
(c).................................. ....................... 23.2305(c)(2).......... Landing gear systems.
(d).................................. ....................... 23.2505................ Function and
installation.
(e).................................. ....................... 23.2600................ Flightcrew interface.
(f).................................. ....................... 23.2605(c)............. Installation and
operation.
(g).................................. ....................... 23.2305(a)(2).......... .......................
23.731............................... Wheels................. 23.2220, 23.2250(c).... Ground and water load
conditions, Design and
construction
principles.
23.733............................... Tires..................
(a).................................. ....................... 23.2250(c)............. Design and construction
principles.
(b).................................. ....................... 23.2610................ Instrument markings,
control markings, and
placards.
(c).................................. ....................... 23.2250(c)............. Design and construction
principles.
23.735............................... Brakes.................
(a), (b), (c), (e)................... ....................... 23.2305(b)............. Landing gear systems.
(b).................................. ....................... 23.2250(c)............. Design and construction
principles.
(d).................................. ....................... 23.2510................ Equipment, systems, and
installations.
23.737............................... Skis................... 23.2235................ Structural strength.
23.745............................... Nose/Tail wheel 23.2305 & 23.2600(a)... Landing gear systems &
steering. Flightcrew interface.
23.751............................... Main float buoyancy.... 23.2310................ Buoyancy for seaplanes
and amphibians.
23.753............................... Main float design...... 23.2220................ Ground and water load
conditions.
23.755............................... Hulls.................. 23.2310................ Buoyancy for seaplanes
and amphibians.
23.757............................... Auxiliary floats....... 23.2310................ Buoyancy for seaplanes
and amphibians.
23.771............................... Pilot compartment......
(a).................................. ....................... 23.2600................ Flightcrew interface.
(b).................................. ....................... 23.2320(a)(1).......... Occupant physical
environment.
(c).................................. ....................... 23.2320(a)(2).......... Occupant physical
environment.
23.773............................... Pilot compartment view. 23.2600(a)............. Flightcrew interface.
23.775............................... Windshields and windows
(a).................................. ....................... 23.2320(a)(3).......... Occupant physical
environment.
(b), (c), (d)........................ ....................... 23.2250................ Design and construction
principles.
(e).................................. ....................... 23.2600(a)............. Flightcrew interface.
(f).................................. ....................... 23.2540................ Flight in icing
conditions.
(g).................................. ....................... 23.2510................ Equipment, systems and
installations.
(h)(1)............................... ....................... 23.2320(b)............. Occupant physical
environment.
(h)(2)............................... ....................... 23.2600(c)............. Flightcrew interface.
[[Page 96680]]
23.777............................... Cockpit controls....... 23.2600, 23.2610....... Flightcrew interface,
Instrument markings,
control markings and
placards.
23.779............................... Motion and effect of 23.2600................ Flightcrew interface.
cockpit controls.
23.781............................... Cockpit control knob 23.2600................ Flightcrew interface.
shape.
23.783............................... Doors..................
(a), (b), (c)(2), (c)(3), (c)(4), ....................... 23.2315(a)............. Means of egress and
(c)(5), (c)(6), (d), (f), (g). emergency exits.
(b).................................. ....................... 23.2250................ Design and construction
principles.
(c)(1), (e).......................... ....................... 23.2250(e)............. Design and construction
principles.
(e)(3)............................... ....................... 23.2605(c)............. Installation and
operation.
23.785............................... Seats, berths, litters, 23.2265 and 23.2270.... Special factors of
safety belts, and safety, Emergency
shoulder harnesses. conditions.
23.787............................... Baggage and cargo 23.2270(e) & 23.2315(a) Emergency conditions &
compartments. Means of egress and
emergency exits.
23.791............................... Passenger information 23.2320(a)(1).......... Occupant physical
signs. environment.
23.803............................... Emergency evacuation... 23.2315(a)............. Means of egress and
emergency exits.
23.805............................... Flightcrew emergency 23.2315(a)............. Means of egress and
exits. emergency exits.
23.807............................... Emergency exits........
(a), (b)(1), (b)(2), (b)(3), (b)(4), ....................... 23.2315(a)............. Means of egress and
(d)(1), (d)(3), (d)(4), (c), (e). emergency exits.
(b)(5), (b)(6)....................... ....................... 23.2315(b)............. Means of egress and
emergency exits.
(d)(2)............................... ....................... 23.2250(e)............. Design and construction
principles.
23.811............................... Emergency exit marking. 23.2315(a)............. Means of egress and
emergency exits.
23.812............................... Emergency lighting..... 23.2315(a)............. Means of egress and
emergency exits.
23.813............................... Emergency exit access.. 23.2315(a)............. Means of egress and
emergency exits.
23.815............................... Width of aisle......... 23.2315(a)............. Means of egress and
emergency exits.
23.831............................... Ventilation............
(a), (b), (c)........................ ....................... 23.2320(c)............. Occupant physical
environment.
(c).................................. ....................... 23.2600(a)............. Flightcrew interface.
(d).................................. ....................... 23.2510................ Equipment, systems and
installations.
23.841............................... Pressurized cabins.....
(a), (b)(4), (d)(1).................. ....................... 23.2320(c)............. Occupant physical
environment.
(b)(1), (b)(2), (b)(8), (c), (d)(2), ....................... 23.2320(d)............. Occupant physical
(d)(3). environment.
(b)(3)............................... ....................... 23.2320(c), (d)........ Occupant physical
environment.
(b)(5), (b)(6), (d)(4), (d)(5)....... ....................... 23.2605................ Installation and
operation.
(b)(7)............................... ....................... 23.2610................ Instrument markings,
control markings, and
placards.
(b)(8), (c), (d)(2), (d)(3).......... ....................... 23.2510................ Equipment, systems and
installations.
(d)(5)............................... ....................... 23.2505................ Function and
installation.
23.843............................... Pressurization tests...
(a).................................. ....................... 23.2225(c), 23.2236.... Component loading
conditions, Structural
strength.
(b).................................. ....................... 23.2320 & 23.2505...... Occupant physical
environment & Function
and installation.
23.851............................... Fire extinguishers.....
(a) and (b).......................... ....................... 23.2325................ Fire protection.
(c).................................. ....................... Means Of Compliance....
23.853............................... Passenger and crew ....................... .......................
compartment interiors.
(a), (d)(3)(i), (d)(3)(iii), ....................... 23.2325................ Fire protection.
(d)(3)(iv), (e), (f).
(b)(c) and (d)(1)(2)................. ....................... Means Of Compliance....
23.855............................... Cargo and baggage 23.2325................ Fire protection.
compartment fire
protection.
23.856............................... Thermal/acoustic 23.2325................ Fire protection.
insulation materials.
23.859............................... Combustion heater fire
protection.
(a).................................. ....................... 23.2325(h)............. Fire protection.
[[Page 96681]]
(b) thru (i)......................... ....................... 23.2250(c)............. Design and construction
principles.
23.863............................... Flammable fluid fire 23.2325(g)............. Fire protection.
protection.
23.865............................... Fire protection of 23.23330............... Fire protection in
flight controls, designated fire zones
engine mounts, and and adjacent areas.
other flight structure.
23.867............................... Electrical bonding and 23.2335................ Lightning protection.
protection against
lightning and static
electricity.
23.871............................... Leveling means......... Means Of Compliance....
----------------------------------------------------------------------------------------------------------------
Subpart E--Powerplant
----------------------------------------------------------------------------------------------------------------
23.901(a) and (f).................... Installation........... 23.2400(a)............. Powerplant
Installation.
(b), (c), and (d)(2)................. ....................... 23.2400(c)............. Powerplant
Installation.
(d)(1) and (e)....................... ....................... 23.2400(e)............. Powerplant
Installation.
23.903(a)(1)......................... Engines................ 23.2400(b)............. Powerplant
Installation.
(a)(2)............................... ....................... 23.2400(c)............. Powerplant
Installation.
(b).................................. ....................... 23.2400(c), 23.2410(a), Powerplant
(b) and 23.2425(a). installation,
Powerplant
installation hazard
assessment; Powerplant
operational
characteristics.
(c).................................. ....................... 23.2410(a) and (c)..... Powerplant installation
hazard assessment.
(d) thru (g)......................... ....................... 23.00(d), 23.2410(a) Powerplant
and 23.2425(b). installation,
Powerplant
installation hazards
assessment, Powerplant
operational
characteristics.
23.904............................... Automatic power reserve 23.2405................ Automatic power or
system. thrust control
systems.
23.905(a)............................ Propellers............. 23.2400(b)............. Powerplant
installation.
(b).................................. ....................... 23.2400(e)............. Powerplant
installation.
(c).................................. ....................... 23.2425(b)............. Powerplant operational
characteristics.
(d), (e) and (f)..................... ....................... 23.2400(c)............. Powerplant
installation.
(g).................................. ....................... 23.2400(c), (e)........ Powerplant
installation.
(h).................................. ....................... 23.2400(c)(3).......... Powerplant
installation.
23.907............................... Propeller vibration and 23.2400(c)(4), (e)..... Powerplant
fatigue. installation.
23.909(a)............................ Turbocharger systems... 23.2400(e) and Powerplant
23.2425(a). installation,
Powerplant operational
characteristics.
(b).................................. ....................... 23.2410(a)............. Powerplant installation
hazards assessment.
(c).................................. ....................... 23.2400(c)(3) and Powerplant
23.2410(a). installation,
Powerplant
installation hazards
assessment.
(d).................................. ....................... 23.2400(c)............. Powerplant
installation.
(e).................................. ....................... 23.2400(e), 23.2420 and Powerplant
23.2620. installation,
Powerplant operational
characteristics,
Airplane flight
manual.
23.925............................... Propeller clearance.... 23.2400(c)(2).......... Powerplant
installation.
23.929............................... Engine installation ice 23.2415(b)............. Powerplant ice
protection. protection.
23.933............................... Reversing systems...... 23.2420................ Reversing systems.
23.934............................... Turbojet and turbofan 23.2400(c), (e) and Powerplant
engine thrust reverser 23.2425(a). installation,
systems tests. Powerplant operational
characteristics.
23.937............................... Turbopropeller-drag 23.10(a)............... Powerplant installation
limiting systems. hazard assessment.
23.939............................... Powerplant operating 23.2400(c)(4), (e) and Powerplant
characteristics. 23.2425(a). installation,
Powerplant operational
characteristics.
23.943............................... Negative acceleration.. 23.2400(c)(1), (c)(3) Powerplant
and 23.2425(a). installation,
Powerplant operational
characteristics.
23.951 (a), (b) and (c).............. Fuel System--General... 23.2400(c)(1), (3) and Powerplant
23.2430(a)(3). installation, Fuel
systems.
(d).................................. ....................... ....................... Intent covered under
Part 34.
23.953............................... Fuel system 23.2410(a), (c), Powerplant installation
independence. 23.2430(a)(1) and hazards assessment,
23.2440(d). Fuel systems,
Powerplant fire
protection.
23.954............................... Fuel system lightning 23.2430(a)(2).......... Fuel systems.
protection.
23.955............................... Fuel flow.............. 23.2400(c)(1), (3), Powerplant
23.2410(a) and installation,
23.2430(a)(3), (4). Powerplant
installation hazard
assessment, Fuel
systems.
[[Page 96682]]
23.957(a)............................ Flow between 23.2430(a)(2), (b)(3).. Fuel systems.
interconnected tanks.
(b).................................. ....................... 23.2400(c)(1), (3), Powerplant
23.2430(b)(3). installation, Fuel
systems--.
23.959............................... Unusable fuel supply... 23.2430(a)(4) and Fuel systems and
23.2410(a). Powerplant
installation hazard
assessment.
23.961............................... Fuel system hot weather 23.2430(a)(3).......... Fuel systems.
operation.
23.963(a)............................ Fuel tank: general..... 23.2430(a)(1).......... Fuel systems.
(b) and (c).......................... ....................... 23.2400(c)............. Powerplant
installation.
(d).................................. ....................... 23.2430(b)(4).......... Fuel systems.
(e).................................. ....................... 23.2430(a)(4).......... Fuel systems.
23.965............................... Fuel tank tests........ 23.2430(b)(1).......... Fuel systems.
23.967............................... Fuel tank installation.
(a).................................. ....................... 23.2400(c) and Powerplant
23.2430(a), (b). installation, Fuel
systems.
(b).................................. ....................... 23.2400(d)............. Fuel systems.
(c) and (d).......................... ....................... 23.2430(b)(2).......... Fuel systems.
(e).................................. ....................... 23.2430(a)(6).......... Fuel systems.
23.969............................... Fuel tank expansion 23.2430(b)(3).......... Fuel systems.
space.
23.971............................... Fuel tank sump......... 23.2430(a)(7).......... Fuel systems.
23.973............................... Fuel tank filler 23.2430(c)............. Fuel systems.
connection.
23.975............................... Fuel tank vents and 23.2400(c)(1), (3), Powerplant
carburetor vapor vents. 23.2415 and installation,
23.2430(a)(3), (b)(3). Powerplant ice
protection, Fuel
systems.
23.977............................... Fuel tank outlet....... 23.2430(a)(7).......... Fuel systems.
23.979............................... Pressure fueling 23.2400(c) and Powerplant
systems. 23.2430(c). installation, Fuel
systems.
23.991(a), (b) and (d)............... Fuel pumps............. 23.2410(a) and Powerplant installation
23.2430(a)(1), (3). hazard assessment,
Fuel systems.
(a), (b), (c)........................ ....................... 23.2430(a)(1), (3) and Fuel systems.
23.2410(a).
(c).................................. ....................... 23.2605................ Installation and
operation.
23.993............................... Fuel system lines and 23.2430(a)(6).......... Fuel systems.
fittings.
23.994............................... Fuel system components. 23.2430(a)(6).......... Fuel systems.
23.995............................... Fuel valves and 23.2440(d)............. Powerplant fire
controls. protection.
23.997(a)............................ Fuel strainer or filter 23.2400(c)(3).......... Fuel systems.
(b).................................. ....................... 23.2430(a)(7).......... Fuel systems.
(c).................................. ....................... 23.2400(c)(1).......... Powerplant
installation.
(d).................................. ....................... 23.2400(e) and Powerplant
23.2430(a)(7). installation, Fuel
systems.
(e).................................. ....................... 23.2430(a)(3).......... Fuel systems.
23.999............................... Fuel system drains..... 23.2400(c)(3), Powerplant
23.2430(a)(5). installation, Fuel
systems.
23.1001(a) thru (f).................. Fuel jettisoning system 23.2400(c)(1), (3) and Powerplant
23.2430(b)(5). installation, Fuel
systems.
(g).................................. ....................... 23.2610................ Instrument markings,
controls markings, and
placards.
(h).................................. ....................... 23.2410(a)............. Powerplant installation
hazard assessment.
23.1011.............................. General................ 23.2400(c), (e) and Powerplant installation
23.2410(a). and Powerplant
installation hazard
assessment.
23.1013.............................. Oil tanks.............. 23.2400(c)............. Powerplant
installation.
23.1015.............................. Oil tank tests......... 23.2400(c)............. Powerplant
installation.
23.1017.............................. Oil lines and fittings. 23.2400(c)............. Powerplant
installation.
23.1019.............................. Oil strainer or filter. 23.2400(c), (e) and Powerplant
23.2600(b). installation.
23.1021.............................. Oil system drains...... 23.2400(c)............. Powerplant
installation.
23.1023.............................. Oil radiators.......... 23.2400(c)............. Powerplant
installation.
23.1027.............................. Propeller feathering 23.2400(c) and Powerplant installation
system. 23.2410(a). and Hazard assessment.
23.1041.............................. Cooling--General....... 23.2400(c) and (e)..... Powerplant
installation.
23.1043.............................. Cooling tests.......... 23.2400(c), (e)........ Powerplant
installation.
23.1045.............................. Cooling test procedures 23.2400(c), (e)........ Powerplant
for turbine engine installation.
powered airplanes.
23.1047.............................. Cooling test procedures 23.2400(c), (e)........ Powerplant
for reciprocating installation.
engine powered
airplanes.
23.1061.............................. Installation........... 23.2400(c)............. Powerplant
installation.
23.1063.............................. Coolant tank tests..... 23.2400(c)............. Powerplant
installation.
23.1091.............................. Air induction system... 23.2435(a)............. Powerplant induction
and exhaust systems.
23.1093.............................. Induction system icing 23.2415(a)............. Powerplant ice
protection. protection.
23.1095.............................. Carburetor deicing 23.2415(a)............. Powerplant ice
fluid flow rate. protection.
[[Page 96683]]
23.1097.............................. Carburetor deicing 23.2400(c) and Powerplant installation
fluid system capacity. 23.2415(a). and Powerplant ice
protection.
23.1099.............................. Carburetor deicing 23.2400(c) and Powerplant installation
fluid system detail 23.2415(a). and Powerplant ice
design. protection.
23.1101(a)........................... Induction air preheater 23.2400(c), 23.2435(b). Powerplant installation
design. and Powerplant
induction and exhaust
systems.
(b) and (c).......................... ....................... 23.2400(c)............. Powerplant
installation.
23.1103(a) thru (d).................. Induction system ducts. 23.2400(c) and Powerplant installation
23.2435(a). and Powerplant
induction and exhaust
systems.
(e) and (f).......................... ....................... 23.2400(c) and Powerplant installation
23.2440(c). and Powerplant fire
protection.
23.1105.............................. Induction system 23.2400(c) and Powerplant installation
screens. 23.2415(a). and Powerplant ice
protection.
23.1107.............................. Induction system 23.2400(c)............. Powerplant
filters. installation.
23.1109.............................. Turbocharger bleed air 23.2400(c)(1), (3) and Powerplant installation
system. 23.2410(a). and Powerplant
installation hazard
assessment.
23.1111(a) and (c)................... Turbine engine bleed 23.2400(c)(3).......... Powerplant
air system. installation.
(b).................................. ....................... 23.2400(c) and Powerplant installation
23.2435(a). and Powerplant
induction and exhaust
systems.
23.1121.............................. Exhaust System--General 23.2400(c), (d) and Powerplant installation
23.2435(b). and Powerplant
induction and exhaust
systems.
23.1123.............................. Exhaust system......... 23.2435(b)............. Powerplant induction
and exhaust systems.
23.1125.............................. Exhaust heat exchangers 23.2400(c) and Powerplant installation
23.2435(b). and Powerplant
induction and exhaust
systems.
23.1141(a)........................... Powerplant controls: 23.2600................ Flightcrew interface.
General.
(b), (c) and (d)..................... ....................... 23.2400(c) and 23.2500. Powerplant installation
and Airplane level
systems requirements.
(e).................................. ....................... 23.2410(a)............. Powerplant installation
hazard assessment.
(f).................................. ....................... 23.2440(c)(2).......... Powerplant fire
protection.
(g).................................. ....................... 23.2600 and 23.2615.... Flightcrew interface
and Flight, Navigation
and Powerplant
Instruments.
23.1142.............................. Auxiliary power unit 23.2425(b), 23.2600, Powerplant operational
controls. 23.2605 and 23.2615. characteristics,
Flightcrew interface,
Installation and
operation, and Flight,
Navigation and
Powerplant
Instruments.
23.1143(a) thru (f).................. Engine controls........ 23.2600................ Flightcrew interface.
(g).................................. ....................... 23.2410(a)............. Powerplant installation
hazard assessment.
23.1145.............................. Ignition switches...... 23.2425(a) and 23.2600. Powerplant operational
characteristics and
Flightcrew interface.
23.1147.............................. Mixture controls....... 23.2410(a) and 23.2600. Powerplant installation
hazard assessment and
Flightcrew interface.
23.1149.............................. Propeller speed and 23.2600................ Flightcrew interface.
pitch controls.
23.1153.............................. Propeller feathering 23.2600................ Flightcrew interface.
controls.
23.1155.............................. Turbine engine reverse 23.2600................ Flightcrew interface.
thrust and propeller
pitch settings below
the flight regime.
23.1157.............................. Carburetor air 23.2600................ Flightcrew interface.
temperature controls.
23.1163.............................. Powerplant accessories. 23.2400(c), (e) and Powerplant installation
23.2410(a). and Powerplant
installation hazard
assessment.
23.1165.............................. Engine ignition systems 23.2400(c), 23.2425(b) Powerplant
and 23.2605. installation,
Powerplant operational
characteristics, and
Installation and
operation.
23.1181.............................. Designated fire zones: 23.2440(a)............. Powerplant fire
Regions included. protection.
23.1182.............................. Nacelle areas behind 23.2440(c)............. Powerplant fire
firewalls. protection.
23.1183.............................. Lines, fittings, and 23.2440(c)............. Powerplant fire
components. protection.
23.1189.............................. Shutoff means.......... 23.2440(d)............. Powerplant fire
protection.
23.1191.............................. Firewalls.............. 23.2440(a), (b) and (c) Powerplant fire
protection.
[[Page 96684]]
23.1192.............................. Engine accessory 23.2440(a) and (b)..... Powerplant fire
compartment diaphragm. protection.
23.1193.............................. Cowling and nacelle.... 23.2400(c), 23.2440(a) Powerplant
and (b). installation,
Powerplant fire
protection.
23.1195.............................. Fire extinguishing 23.2440(f)............. Powerplant fire
systems. protection.
23.1197.............................. Fire extinguishing 23.2400(d) and Powerplant fire
agents. 23.2440(f). protection.
23.1199.............................. Extinguishing agent 23.2400(c)............. Powerplant
containers. installation.
23.1201.............................. Fire extinguishing 23.2400(c), 23.2440(c) Powerplant
system materials. and 23.2500. installation,
Powerplant fire
protection, and
Airplane systems level
requirements.
23.1203(a)........................... Fire detector system... 23.2440(e)............. Powerplant fire
protection.
(a).................................. ....................... 23.2440(e)............. Powerplant fire
protection.
(b) and (c).......................... ....................... 23.2400(c)............. Powerplant
installation.
(d).................................. ....................... 23.2600................ Flight crew interface.
(e).................................. ....................... 23.2440(c) and 23.2500. Powerplant fire
protection and
Airplane systems level
requirements.
----------------------------------------------------------------------------------------------------------------
Subpart F--Equipment
----------------------------------------------------------------------------------------------------------------
23.1301.............................. Function and
installation.
(a).................................. ....................... 23.2250(a), 23.2500(a), Design and construction
23.2505. principles, Airplane
level systems
requirements, Function
and installation.
(b).................................. ....................... 23.2605................ Installation and
operation.
(c).................................. ....................... 23.2505................ Function and
installation.
23.1303.............................. Flight and navigation 23.2500, 23.2615, 23.2 Airplane level systems
instruments. and 23.2525. requirements; Flight,
navigation, and
powerplant
instruments; Function
and installation;
System power
generation, storage,
and distribution.
23.1305.............................. Powerplant instruments. 23.2500, 23.2615 and Airplane level systems
23.2605. requirements; Flight,
navigation, and
powerplant
instruments;
Installation and
operation.
23.1306.............................. Electrical and 23.2515................ Electrical and
electronic system electronic system
lightning protection. lightning protection.
23.1307.............................. Miscellaneous equipment 23.2500 and 23.2610.... Airplane level systems
requirements; Flight,
navigation, and
powerplant
instruments.
23.1308.............................. High-Intensity Radiated 23.2520................ High-intensity Radiated
Fields (HIRF) Fields (HIRF)
protection. protection.
23.1309.............................. Equipment, systems, and 23.2510................ Equipment, systems, and
installations. installations.
(a)(1)............................... ....................... 23.2500(a)............. Airplane level systems
requirements.
(a)(2)............................... ....................... 23.2500(b)............. Airplane level systems
requirements.
(b).................................. ....................... ....................... --Deleted--.
(c).................................. ....................... 23.2510................ Equipment, systems, and
installations.
(d).................................. ....................... 23.2605................ Installation and
operation.
23.1310.............................. Power source capacity 23.2525................ System power
and distribution. generation, storage,
and distribution.
23.1311.............................. Electronic display 23.2500 and 23.2615.... Airplane level systems
instrument systems. requirements; Flight,
navigation, and
powerplant
instruments.
23.1321.............................. Arrangement and 23.2500 and 23.2610.... Airplane level systems
visibility. requirements; Flight,
navigation, and
powerplant
instruments.
23.1322.............................. Warning, caution, and 23.2605................ Flight, navigation, and
advisory lights. powerplant
instruments.
23.1323.............................. Airspeed indicating 23.2250, 23.2500, Design and construction
system. 23.2505, 23.2615, and principles; Airplane
23.2510. level systems
requirements; Function
and installation;
Flight, navigation,
and powerplant
instruments; and
Equipment, systems,
and installations.
(d).................................. ....................... 23.2250, 23.2540(a).... Design and construction
principles, Flight in
icing conditions.
[[Page 96685]]
23.1325.............................. Static pressure system. 23.2500, 23.2615, and Airplane level systems
23.2510. requirements; Flight,
navigation, and
powerplant
instruments; and
Equipment, systems,
and installations.
(a), (b), (c), (d), (e).............. ....................... 23.2250................ Design and construction
principles.
(b)(3) and (g)....................... ....................... 23.2540(a)............. Flight in icing
conditions.
23.1326.............................. Pitot heat indication 23.2605................ Installation and
systems. operation.
23.1327.............................. Magnetic direction 23.2500, 23.2505 and Airplane level systems
indicator. 23.2615. requirements; Function
and installation;
Flight, navigation,
and powerplant
instruments.
23.1329.............................. Automatic pilot system. 23.2500, 23.2505, Airplane level systems
232510, and 23.2605. requirements; Function
and installation;
Equipment, systems,
and installations;
Installation and
operation.
(a).................................. ....................... 23.2500 and 23.2510.... Airplane level systems
requirements;
Equipment, systems,
and installations.
(b).................................. ....................... 23.2300 and 23.2600.... Flight control systems;
Flightcrew interface.
(c).................................. ....................... 23.2605................ Installation and
operation.
(d).................................. ....................... 23.2300 and 23.2600.... Flight control systems;
Flightcrew interface.
(e), (f), (g)........................ ....................... 23.2500 and 23.2510.... Airplane level systems
requirements;
Equipment, systems,
and installations.
(h).................................. ....................... 23.2605................ Installation and
operation.
23.1331.............................. Instruments using a
power source.
(a).................................. ....................... 23.2605................ Installation and
operation.
(b) and (c).......................... ....................... 23.2510 and 23.2525.... Equipment, systems, and
installations; System
power generation,
storage, and
distribution.
23.1335.............................. Flight director systems 23.2500, 23.2505, Airplane level systems;
23.2510, 23.2600, and Function and
23.2605. installation;
Equipment systems and
installations;
Flightcrew interface;
and Installation and
operation.
23.1337.............................. Powerplant instruments
installation.
(a).................................. ....................... 23.2325................ Fire protection.
23.2430................ Fuel systems.
(b).................................. ....................... 23.2605................ Installation and
operation.
23.2610................ Flight, navigation, and
powerplant
instruments.
23.2510................ Equipment, systems, and
installations.
(c).................................. ....................... 23.2510................ Equipment, systems, and
installations.
(d).................................. ....................... 23.2605................ Installation and
operation.
23.2615................ Flight, navigation, and
powerplant
instruments.
23.1351.............................. Electrical Systems--
General.
(a).................................. ....................... 23.2525................ System power
generation, storage,
and distribution.
(b).................................. ....................... 23.2500, 23.2525....... Airplane level systems
requirements: System
power generation,
storage, and
distribution.
(c).................................. ....................... 23.2525, 23.2605....... System power
generation, storage,
and distribution;
Installation and
operation.
(d).................................. ....................... 23.2605................ Installation and
operation.
(e).................................. ....................... 23.2500, 23.2325....... Airplane level systems
requirements: Fire
protection.
(f), (g)............................. ....................... 23.2500................ Airplane level systems
requirements.
23.1353.............................. Storage battery design 23.2525................ System power
and installation. generation, storage,
and distribution.
[[Page 96686]]
23.1357.............................. Circuit protective 23.2500, 23.2505, Airplane level systems
devices. 23.2510, and 23.2525. requirements; Function
and installation;
Equipment, systems,
and installations; and
System power
generation, storage,
and distribution.
23.1359.............................. Electrical system fire
protection.
(a).................................. ....................... 23.2330, 23.2325....... Fire protection in
designated fire zones;
Fire protection.
(b).................................. ....................... 23.2330................ Fire protection in
designated fire zones.
(c).................................. ....................... 23.2325................ Fire protection.
23.1361.............................. Master switch 23.2500 and 23.2505.... Airplane level systems
arrangement. requirements; Function
and installation.
23.1365.............................. Electrical cables and 23.2505................ Function and
equipment. installation.
(b).................................. ....................... 23.2330................ Fire protection in
designated fire zones.
23.1367.............................. Switches...............
(a) and (b).......................... ....................... 23.2505................ Function and
installation.
(c) and (d).......................... ....................... 23.2600................ Flightcrew interface.
23.1381.............................. Instrument lights......
(a) and (b).......................... ....................... 23.2600................ Flightcrew interface.
(c).................................. ....................... 23.2500................ Airplane level systems
requirements.
23.1383(a), (b), (c)................. Taxi and landing lights 23.2530................ External and cockpit
lighting.
(d).................................. Taxi and landing lights 23.2325................ Fire protection.
23.1385(a), (b), (c)................. Position light system 23.2530................ External and cockpit
installation. lighting.
(d).................................. Position light system 23.2325................ Fire protection.
installation.
23.1387.............................. Position light system 23.2530................ External and cockpit
dihedral angles. lighting.
23.1389.............................. Position light 23.2530................ External and cockpit
distribution and lighting.
intensities.
23.1391.............................. Minimum intensities in 23.2530................ External and cockpit
the horizontal plane lighting.
of position lights.
23.1393.............................. Minimum intensities in 23.2530................ External and cockpit
any vertical plane of lighting.
position lights.
23.1395.............................. Maximum intensities in 23.2530................ External and cockpit
overlapping beams of lighting.
position lights.
23.1397.............................. Color specifications... 23.2530................ External and cockpit
lighting.
23.1399.............................. Riding light........... 23.2530................ External and cockpit
lighting.
23.1401.............................. Anticollision light
system.
(a), (a)(1).......................... ....................... 23.2530................ External and cockpit
lighting.
(a)(2)............................... ....................... Means Of Compliance....
(b) thru (f)......................... ....................... 23.2530................ External and cockpit
lighting.
23.1411.............................. Safety Equipment-
General.
(a), (b)(1).......................... ....................... 23.2535................ Safety equipment.
(b)(2)............................... ....................... 23.2270................ Emergency conditions.
23.1415.............................. Ditching equipment..... 23.2535................ Safety equipment.
(a), (c), (d)........................ ....................... 23.2535................ Safety equipment.
(b).................................. ....................... Means Of Compliance....
23.1416.............................. Pneumatic de-icer boot 23.2500................ Airplane level systems
system. requirements.
23.2505................ Function and
installation.
(c).................................. ....................... 23.2605(b)............. Installation and
operation.
23.1419.............................. Ice protection......... 23.2165(a)(1).......... Performance and flight
characteristics
requirements for
flight in icing
conditions.
23.2540(a)............. Flight in icing
conditions.
(d).................................. ....................... 23.2600(a)............. Flightcrew interface.
23.1431.............................. Electronic equipment... 23.2510................ Equipment, systems and
installations.
23.1435.............................. Hydraulic systems......
(a)(1)............................... ....................... 23.2235................ Structural strength.
(a)(2)............................... ....................... 23.2600................ Flightcrew interface.
(a)(3)(c)............................ ....................... 23.2250................ Design and construction
principles.
(a)(4), (b).......................... ....................... 23.2545................ Pressurized system
elements.
(c).................................. ....................... 23.2440(c)............. Powerplant fire
protection.
23.1437.............................. Accessories for 23.2410 & 23.2515...... Powerplant installation
multiengine airplanes. hazard assessment and
Equipment, systems and
installations.
23.1438.............................. Pressurization and 23.2545................ Pressurized system
pneumatic systems. elements.
[[Page 96687]]
23.1441.............................. Oxygen equipment and 23.2320(e)............. Occupant physical
supply. environment.
(c).................................. ....................... 23.2605(b)............. Installation and
operation.
23.1443.............................. Minimum mass flow of 23.2320(e)............. Occupant physical
supplemental oxygen. environment.
23.1445.............................. Oxygen distribution 23.2320(e)............. Occupant physical
system. environment.
(a), (b)............................. ....................... 23.2250(c)............. Design and construction
principles.
23.1447.............................. Equipment standards for 23.2320(e)............. Occupant physical
oxygen dispensing environment.
units.
23.1449.............................. Means for determining 23.2320(e)............. Occupant physical
use of oxygen. environment.
23.1450.............................. Chemical oxygen
generators.
(a)(b)............................... ....................... 23.2320(e)............. Occupant physical
environment.
(c).................................. ....................... 23.2610................ Instrument markings,
control markings, and
placards.
23.1451.............................. Fire protection for 23.2320(e)............. Occupant physical
oxygen equipment. environment.
23.1453.............................. Protection of oxygen 23.2320(e) & 23.2545... Occupant physical
equipment from rupture. environment &
Pressurized system
elements.
23.1457.............................. Cockpit voice recorders 23.1457................ No Change.
23.1459.............................. Flight recorders....... 23.1459................ No Change.
23.1461.............................. Equipment containing 23.2550................ Equipment containing
high-energy rotors. high-energy rotors.
----------------------------------------------------------------------------------------------------------------
Subpart G--Operating Limitations and Information
----------------------------------------------------------------------------------------------------------------
23.1501.............................. General................ 23.2610................ Instrument, control
markings, and
placards.
23.1505.............................. Airspeed limitations... 23.2610................ Instrument markings,
control markings, and
placards.
23.1507.............................. Operating maneuvering 23.2610................ Instrument markings,
speed. control markings, and
placards.
23.1511.............................. Flap extended speed.... 23.2610................ Instrument markings,
control markings, and
placards.
23.1513.............................. Minimum control speed.. 23.2610................ Instrument markings,
control markings, and
placards.
23.1519.............................. Weight and center of 23.2610................ Instrument markings,
gravity. control markings, and
placards.
23.1521.............................. Powerplant limitations. 23.2610................ Instrument markings,
control markings, and
placards.
23.1522.............................. Auxiliary power unit 23.2610................ Instrument markings,
limitations. control markings, and
placards.
23.1523.............................. Minimum flight crew.... 23.2610................ Instrument markings,
control markings, and
placards.
23.1524.............................. Maximum passenger 23.2610................ Instrument markings,
seating configuration. control markings, and
placards.
23.1525.............................. Kinds of operation..... 23.2610................ Airplane level system
requirements.
23.2610................ Instrument markings,
control markings, and
placards.
23.1527.............................. Maximum operating 23.2610................ Instrument markings,
altitude. control markings, and
placards.
23.1529.............................. Instructions for 23.1529................ Instructions for
continued continued
airworthiness. airworthiness.
23.1541.............................. Marking and Placards-- 23.2610................ Instrument markings,
General. control markings, and
placards.
23.1543.............................. Instrument marking: 23.2610................ Instrument markings,
General. control markings, and
placards.
23.1545.............................. Airspeed indicator..... 23.2610................ Instrument markings,
control markings, and
placards.
23.1547.............................. Magnetic direction 23.2610................ Instrument markings,
indicator. control markings, and
placards.
23.1549.............................. Powerplant and 23.2610................ Instrument markings,
auxiliary power unit control markings, and
instruments. placards.
23.1551.............................. Oil quantity indicator. 23.2610................ Instrument markings,
control markings, and
placards.
23.1553.............................. Fuel quantity indicator 23.2610................ Instrument markings,
control markings, and
placards.
23.1555.............................. Control markings....... 23.2610................ Instrument markings,
control markings, and
placards.
23.1557.............................. Miscellaneous marking 23.2610................ Instrument markings,
and placards. control markings, and
placards.
23.1559.............................. Operating limitations 23.2610................ Instrument markings,
placard. control markings, and
placards.
[[Page 96688]]
23.1561.............................. Safety equipment....... 23.2610................ Instrument markings,
control markings, and
placards.
23.1563.............................. Airspeed placards...... 23.2610................ Instrument markings,
control markings, and
placards.
23.1567.............................. Flight maneuver placard 23.2610................ Instrument markings,
control markings, and
placards.
23.1581.............................. Airplane Flight Manual 23.2620................ Airplane flight manual.
and Approved Manual
Material--General.
23.1583.............................. Operating limitations.. 23.2620................ Airplane flight manual.
23.1585.............................. Operating procedures... 23.2620................ Airplane flight manual.
23.1587.............................. Performance information 23.2620................ Airplane flight manual.
23.1589.............................. Loading information.... 23.2620................ Airplane flight manual.
Appendix A........................... Simplified Design Load Means Of Compliance....
Criteria.
Appendix B........................... [Reserved].............
Appendix C........................... Basic Landing Means Of Compliance....
Conditions.
Appendix D........................... Wheel Spin-Up and Means Of Compliance....
Spring-Back Loads.
Appendix E........................... [Reserved].............
Appendix F........................... Test Procedure......... Means Of Compliance....
Appendix G........................... Instructions for Appendix A............. Instructions for
Continued Continued
Airworthiness. Airworthiness.
Appendix H........................... Installation of An Means Of Compliance....
Automatic Power
Reserve (APR) System.
Appendix I........................... Seaplane Loads......... Means Of Compliance....
Appendix J........................... HIRF Environments and Means Of Compliance....
Equipment HIRF Test
Levels.
----------------------------------------------------------------------------------------------------------------
Appendix 2 to the Preamble--Abbreviations and Acronyms Frequently Used
in This Document
AC Advisory Circular
AD Airworthiness Directive
AFM Airplane Flight Manual
A-NPA Advance Notice of Proposed Amendment
ARC Aviation Rulemaking Committee
ASTM ASTM International
FCAA Foreign Civil Aviation Authority
CAR 3 Civil Aviation Regulations, Part 3
Cf Confer (to identify a source or a usage citation for a word or
phrase)
CPS Certification Process Study
CS Certification Specification
CS-VLA Certification Specification-Very Light Aeroplanes
DER Designated Engineering Representative
EASA European Aviation Safety Agency
ELOS Equivalent Level of Safety
FR Federal Register
GA General Aviation
HIRF High-Intensity Radiated Field
IFR Instrument Flight Rules
IMC Instrument Meteorological Conditions
KCAS Knots Calibrated Airspeeds
LOC Loss of Control
NATCA National Air Traffic Controllers Association
NPA Notice of Proposed Amendment
NPRM Notice of Proposed Rulemaking
NTSB National Transportation Safety Board
OMB Office of Management and Budget
SAE SAE International
SARA Small Airplane Revitalization Act of 2013
SLD Supercooled Large Droplet
STC Supplemental Type Certificate
TC Type Certificate
TCDS Type Certificate Data Sheet
VA Design Maneuvering Speed
VC Design Cruising Speed
VD Design Dive Speed
VMC Minimum Control Speed
VMO/MMO Maximum Operating Limit Speed
VNO Maximum Structural Cruising Speed
VFR Visual Flight Rules
VSO Stalling speed or the minimum steady flight speed in
the landing configuration
List of Subjects
14 CFR Part 21
Aircraft, Aviation safety, Recording and recordkeeping
requirements.
14 CFR Part 23
Aircraft, Aviation Safety, Signs and symbols.
14 CFR Part 35
Aircraft, Aviation safety.
14 CFR Part 43
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
14 CFR Part 91
Air traffic control, Aircraft, Airmen, Airports, Aviation safety,
Reporting and recordkeeping requirements.
14 CFR Part 121
Aircraft, Airmen, Aviation safety, Reporting and recordkeeping
requirements.
14 CFR Part 135
Aircraft, Airmen, Aviation safety, Reporting and recordkeeping
requirements.
The Amendment
In consideration of the foregoing, the Federal Aviation
Administration amends chapter I of title 14, Code of Federal
Regulations as follows:
PART 21--CERTIFICATION PROCEDURES FOR PRODUCTS AND ARTICLES
0
1. The authority citation for part 21 is revised to read as follows:
Authority: 42 U.S.C. 7572; 49 U.S.C. 106(f), 106(g), 40105,
40113, 44701-44702, 44704, 44707, 44709, 44711, 44713, 44715, 45303.
0
2. In Sec. 21.9, revise paragraphs (a)(5), (a)(6), and add paragraph
(a)(7) to read as follows:
Sec. 21.9 Replacement and modification articles.
(a) * * *
(5) Produced by an owner or operator for maintaining or altering
that owner or operator's product;
(6) Fabricated by an appropriately rated certificate holder with a
quality system, and consumed in the repair or alteration of a product
or article in accordance with part 43 of this chapter; or
(7) Produced in any other manner approved by the FAA.
* * * * *
0
3. In Sec. 21.17, revise paragraph (a) introductory text to read as
follows:
[[Page 96689]]
Sec. 21.17 Designation of applicable regulations.
(a) Except as provided in Sec. Sec. 25.2, 27.2, 29.2, and in parts
26, 34, and 36 of this subchapter, an applicant for a type certificate
must show that the aircraft, aircraft engine, or propeller concerned
meets--
* * * * *
0
4. In Sec. 21.24, revise paragraph (a)(1)(i) to read as follows:
Sec. 21.24 Issuance of type certificate: primary category aircraft.
(a) * * *
(1) * * *
(i) Is unpowered; is an airplane powered by a single, naturally
aspirated engine with a 61-knot or less Vso stall speed as
determined under part 23 of this chapter; or is a rotorcraft with a 6-
pound per square foot main rotor disc loading limitation, under sea
level standard day conditions;
* * * * *
0
5. In Sec. 21.35, revise paragraph (b)(2) to read as follows:
Sec. 21.35 Flight tests.
* * * * *
(b) * * *
(2) For aircraft to be certificated under this subchapter, except
gliders and low-speed, certification level 1 or 2 airplanes, as defined
in part 23 of this chapter, to determine whether there is reasonable
assurance that the aircraft, its components, and its equipment are
reliable and function properly.
* * * * *
0
6. In Sec. 21.50, revise paragraph (b) to read as follows:
Sec. 21.50 Instructions for continued airworthiness and
manufacturer's maintenance manuals having airworthiness limitations
sections.
* * * * *
(b) The holder of a design approval, including either a type
certificate or supplemental type certificate for an aircraft, aircraft
engine, or propeller for which application was made after January 28,
1981, must furnish at least one set of complete Instructions for
Continued Airworthiness to the owner of each type aircraft, aircraft
engine, or propeller upon its delivery, or upon issuance of the first
standard airworthiness certificate for the affected aircraft, whichever
occurs later. The Instructions for Continued Airworthiness must be
prepared in accordance with Sec. Sec. [thinsp]23.1529, 25.1529,
25.1729, 27.1529, 29.1529, 31.82, 33.4, 35.4, or part 26 of this
subchapter, or as specified in the applicable airworthiness criteria
for special classes of aircraft defined in Sec. [thinsp]21.17(b), as
applicable. If the holder of a design approval chooses to designate
parts as commercial, it must include in the Instructions for Continued
Airworthiness a list of commercial parts submitted in accordance with
the provisions of paragraph (c) of this section. Thereafter, the holder
of a design approval must make those instructions available to any
other person required by this chapter to comply with any of the terms
of those instructions. In addition, changes to the Instructions for
Continued Airworthiness shall be made available to any person required
by this chapter to comply with any of those instructions.
* * * * *
0
7. In Sec. 21.101 revise paragraphs (b) introductory text, and (c) to
read as follows:
Sec. 21.101 Designation of applicable regulations.
* * * * *
(b) Except as provided in paragraph (g) of this section, if
paragraphs (b)(1), (2), or (3) of this section apply, an applicant may
show that the change and areas affected by the change comply with an
earlier amendment of a regulation required by paragraph (a) of this
section, and of any other regulation the FAA finds is directly related.
However, the earlier amended regulation may not precede either the
corresponding regulation included by reference in the type certificate,
or any regulation in Sec. Sec. 25.2, 27.2, or 29.2 of this chapter
that is related to the change. The applicant may show compliance with
an earlier amendment of a regulation for any of the following:
* * * * *
(c) An applicant for a change to an aircraft (other than a
rotorcraft) of 6,000 pounds or less maximum weight, to a non-turbine
rotorcraft of 3,000 pounds or less maximum weight, to a level 1 low-
speed airplane, or to a level 2 low-speed airplane may show that the
change and areas affected by the change comply with the regulations
included in the type certificate. However, if the FAA finds that the
change is significant in an area, the FAA may designate compliance with
an amendment to the regulation incorporated by reference in the type
certificate that applies to the change and any regulation that the FAA
finds is directly related, unless the FAA also finds that compliance
with that amendment or regulation would not contribute materially to
the level of safety of the product or would be impractical.
* * * * *
0
8. Revise part 23 to read as follows:
PART 23--AIRWORTHINESS STANDARDS: NORMAL CATEGORY AIRPLANES
Sec.
23.1457 Cockpit voice recorders.
23.1459 Flight data recorders.
23.1529 Instructions for continued airworthiness.
Subpart A--General
23.2000 Applicability and definitions.
23.2005 Certification of normal category airplanes.
23.2010 Accepted means of compliance.
Subpart B--Flight
Performance
23.2100 Weight and center of gravity.
23.2105 Performance data.
23.2110 Stall speed.
23.2115 Takeoff performance.
23.2120 Climb requirements.
23.2125 Climb information.
23.2130 Landing.
Flight Characteristics
23.2135 Controllability.
23.2140 Trim.
23.2145 Stability.
23.2150 Stall characteristics, stall warning, and spins.
23.2155 Ground and water handling characteristics.
23.2160 Vibration, buffeting, and high-speed characteristics.
23.2165 Performance and flight characteristics requirements for
flight in icing conditions.
Subpart C--Structures
23.2200 Structural design envelope.
23.2205 Interaction of systems and structures.
Structural Loads
23.2210 Structural design loads.
23.2215 Flight load conditions.
23.2220 Ground and water load conditions.
23.2225 Component loading conditions.
23.2230 Limit and ultimate loads.
Structural Performance
23.2235 Structural strength.
23.2240 Structural durability.
23.2245 Aeroelasticity.
Design
23.2250 Design and construction principles.
23.2255 Protection of structure.
23.2260 Materials and processes.
23.2265 Special factors of safety.
Structural Occupant Protection
23.2270 Emergency conditions.
Subpart D--Design and Construction
23.2300 Flight control systems.
23.2305 Landing gear systems.
23.2310 Buoyancy for seaplanes and amphibians.
[[Page 96690]]
Occupant System Design Protection
23.2315 Means of egress and emergency exits.
23.2320 Occupant physical environment.
Fire and High Energy Protection
23.2325 Fire protection.
23.2330 Fire protection in designated fire zones and adjacent areas.
23.2335 Lightning protection.
Subpart E--Powerplant
23.2400 Powerplant installation.
23.2405 Automatic power or thrust control systems.
23.2410 Powerplant installation hazard assessment.
23.2415 Powerplant ice protection.
23.2420 Reversing systems.
23.2425 Powerplant operational characteristics.
23.2430 Fuel system.
23.2435 Powerplant induction and exhaust systems.
23.2440 Powerplant fire protection.
Subpart F--Equipment
23.2500 Airplane level systems requirements.
23.2505 Function and installation.
23.2510 Equipment, systems, and installations.
23.2515 Electrical and electronic system lightning protection.
23.2520 High-intensity Radiated Fields (HIRF) protection.
23.2525 System power generation, storage, and distribution.
23.2530 External and cockpit lighting.
23.2535 Safety equipment.
23.2540 Flight in icing conditions.
23.2545 Pressurized system elements.
23.2550 Equipment containing high-energy rotors.
Subpart G--Flightcrew Interface and Other Information
23.2600 Flightcrew interface.
23.2605 Installation and operation.
23.2610 Instrument markings, control markings, and placards.
23.2615 Flight, navigation, and powerplant instruments.
23.2620 Airplane flight manual.
Appendix A to Part 23--Instructions for Continued Airworthiness
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704,
Pub. L. 113-53, 127 Stat. 584 (49 U.S.C. 44704) note.
Sec. 23.1457 Cockpit voice recorders.
(a) Each cockpit voice recorder required by the operating rules of
this chapter must be approved and must be installed so that it will
record the following:
(1) Voice communications transmitted from or received in the
airplane by radio.
(2) Voice communications of flightcrew members on the flight deck.
(3) Voice communications of flightcrew members on the flight deck,
using the airplane's interphone system.
(4) Voice or audio signals identifying navigation or approach aids
introduced into a headset or speaker.
(5) Voice communications of flightcrew members using the passenger
loudspeaker system, if there is such a system and if the fourth channel
is available in accordance with the requirements of paragraph
(c)(4)(ii) of this section.
(6) If datalink communication equipment is installed, all datalink
communications, using an approved data message set. Datalink messages
must be recorded as the output signal from the communications unit that
translates the signal into usable data.
(b) The recording requirements of paragraph (a)(2) of this section
must be met by installing a cockpit-mounted area microphone, located in
the best position for recording voice communications originating at the
first and second pilot stations and voice communications of other
crewmembers on the flight deck when directed to those stations. The
microphone must be so located and, if necessary, the preamplifiers and
filters of the recorder must be so adjusted or supplemented, so that
the intelligibility of the recorded communications is as high as
practicable when recorded under flight cockpit noise conditions and
played back. Repeated aural or visual playback of the record may be
used in evaluating intelligibility.
(c) Each cockpit voice recorder must be installed so that the part
of the communication or audio signals specified in paragraph (a) of
this section obtained from each of the following sources is recorded on
a separate channel:
(1) For the first channel, from each boom, mask, or handheld
microphone, headset, or speaker used at the first pilot station.
(2) For the second channel from each boom, mask, or handheld
microphone, headset, or speaker used at the second pilot station.
(3) For the third channel--from the cockpit-mounted area
microphone.
(4) For the fourth channel from:
(i) Each boom, mask, or handheld microphone, headset, or speaker
used at the station for the third and fourth crewmembers.
(ii) If the stations specified in paragraph (c)(4)(i) of this
section are not required or if the signal at such a station is picked
up by another channel, each microphone on the flight deck that is used
with the passenger loudspeaker system, if its signals are not picked up
by another channel.
(5) And that as far as is practicable all sounds received by the
microphone listed in paragraphs (c)(1), (2), and (4) of this section
must be recorded without interruption irrespective of the position of
the interphone-transmitter key switch. The design shall ensure that
sidetone for the flightcrew is produced only when the interphone,
public address system, or radio transmitters are in use.
(d) Each cockpit voice recorder must be installed so that:
(1)(i) It receives its electrical power from the bus that provides
the maximum reliability for operation of the cockpit voice recorder
without jeopardizing service to essential or emergency loads.
(ii) It remains powered for as long as possible without
jeopardizing emergency operation of the airplane.
(2) There is an automatic means to simultaneously stop the recorder
and prevent each erasure feature from functioning, within 10 minutes
after crash impact.
(3) There is an aural or visual means for preflight checking of the
recorder for proper operation.
(4) Any single electrical failure external to the recorder does not
disable both the cockpit voice recorder and the flight data recorder.
(5) It has an independent power source--
(i) That provides 10 1 minutes of electrical power to
operate both the cockpit voice recorder and cockpit-mounted area
microphone;
(ii) That is located as close as practicable to the cockpit voice
recorder; and
(iii) To which the cockpit voice recorder and cockpit-mounted area
microphone are switched automatically in the event that all other power
to the cockpit voice recorder is interrupted either by normal shutdown
or by any other loss of power to the electrical power bus.
(6) It is in a separate container from the flight data recorder
when both are required. If used to comply with only the cockpit voice
recorder requirements, a combination unit may be installed.
(e) The recorder container must be located and mounted to minimize
the probability of rupture of the container as a result of crash impact
and consequent heat damage to the recorder from fire.
(1) Except as provided in paragraph (e)(2) of this section, the
recorder container must be located as far aft as practicable, but need
not be outside of the pressurized compartment, and may not be located
where aft-mounted engines may crush the container during impact.
(2) If two separate combination digital flight data recorder and
cockpit voice
[[Page 96691]]
recorder units are installed instead of one cockpit voice recorder and
one digital flight data recorder, the combination unit that is
installed to comply with the cockpit voice recorder requirements may be
located near the cockpit.
(f) If the cockpit voice recorder has a bulk erasure device, the
installation must be designed to minimize the probability of
inadvertent operation and actuation of the device during crash impact.
(g) Each recorder container must--
(1) Be either bright orange or bright yellow;
(2) Have reflective tape affixed to its external surface to
facilitate its location under water; and
(3) Have an underwater locating device, when required by the
operating rules of this chapter, on or adjacent to the container, which
is secured in such manner that they are not likely to be separated
during crash impact.
Sec. 23.1459 Flight data recorders.
(a) Each flight recorder required by the operating rules of this
chapter must be installed so that--
(1) It is supplied with airspeed, altitude, and directional data
obtained from sources that meet the aircraft level system requirements
and the functionality specified in Sec. 23.2500;
(2) The vertical acceleration sensor is rigidly attached, and
located longitudinally either within the approved center of gravity
limits of the airplane, or at a distance forward or aft of these limits
that does not exceed 25 percent of the airplane's mean aerodynamic
chord;
(3)(i) It receives its electrical power from the bus that provides
the maximum reliability for operation of the flight data recorder
without jeopardizing service to essential or emergency loads;
(ii) It remains powered for as long as possible without
jeopardizing emergency operation of the airplane;
(4) There is an aural or visual means for preflight checking of the
recorder for proper recording of data in the storage medium;
(5) Except for recorders powered solely by the engine-driven
electrical generator system, there is an automatic means to
simultaneously stop a recorder that has a data erasure feature and
prevent each erasure feature from functioning, within 10 minutes after
crash impact;
(6) Any single electrical failure external to the recorder does not
disable both the cockpit voice recorder and the flight data recorder;
and
(7) It is in a separate container from the cockpit voice recorder
when both are required. If used to comply with only the flight data
recorder requirements, a combination unit may be installed. If a
combination unit is installed as a cockpit voice recorder to comply
with Sec. 23.1457(e)(2), a combination unit must be used to comply
with this flight data recorder requirement.
(b) Each non-ejectable record container must be located and mounted
so as to minimize the probability of container rupture resulting from
crash impact and subsequent damage to the record from fire. In meeting
this requirement, the record container must be located as far aft as
practicable, but need not be aft of the pressurized compartment, and
may not be where aft-mounted engines may crush the container upon
impact.
(c) A correlation must be established between the flight recorder
readings of airspeed, altitude, and heading and the corresponding
readings (taking into account correction factors) of the first pilot's
instruments. The correlation must cover the airspeed range over which
the airplane is to be operated, the range of altitude to which the
airplane is limited, and 360 degrees of heading. Correlation may be
established on the ground as appropriate.
(d) Each recorder container must--
(1) Be either bright orange or bright yellow;
(2) Have reflective tape affixed to its external surface to
facilitate its location under water; and
(3) Have an underwater locating device, when required by the
operating rules of this chapter, on or adjacent to the container, which
is secured in such a manner that they are not likely to be separated
during crash impact.
(e) Any novel or unique design or operational characteristics of
the aircraft shall be evaluated to determine if any dedicated
parameters must be recorded on flight recorders in addition to or in
place of existing requirements.
Sec. 23.1529 Instructions for continued airworthiness.
The applicant must prepare Instructions for Continued
Airworthiness, in accordance with appendix A of this part, that are
acceptable to the Administrator. The instructions may be incomplete at
type certification if a program exists to ensure their completion prior
to delivery of the first airplane or issuance of a standard certificate
of airworthiness, whichever occurs later.
Subpart A--General
Sec. 23.2000 Applicability and definitions.
(a) This part prescribes airworthiness standards for the issuance
of type certificates, and changes to those certificates, for airplanes
in the normal category.
(b) For the purposes of this part, the following definition
applies:
Continued safe flight and landing means an airplane is capable of
continued controlled flight and landing, possibly using emergency
procedures, without requiring exceptional pilot skill or strength. Upon
landing, some airplane damage may occur as a result of a failure
condition.
Sec. 23.2005 Certification of normal category airplanes.
(a) Certification in the normal category applies to airplanes with
a passenger-seating configuration of 19 or less and a maximum
certificated takeoff weight of 19,000 pounds or less.
(b) Airplane certification levels are:
(1) Level 1--for airplanes with a maximum seating configuration of
0 to 1 passengers.
(2) Level 2--for airplanes with a maximum seating configuration of
2 to 6 passengers.
(3) Level 3--for airplanes with a maximum seating configuration of
7 to 9 passengers.
(4) Level 4--for airplanes with a maximum seating configuration of
10 to 19 passengers.
(c) Airplane performance levels are:
(1) Low speed--for airplanes with a VNO and
VMO <= 250 Knots Calibrated Airspeed (KCAS) and a
MMO <= 0.6.
(2) High speed--for airplanes with a VNO or
VMO > 250 KCAS or a MMO > 0.6.
(d) Airplanes not certified for aerobatics may be used to perform
any maneuver incident to normal flying, including--
(1) Stalls (except whip stalls); and
(2) Lazy eights, chandelles, and steep turns, in which the angle of
bank is not more than 60 degrees.
(e) Airplanes certified for aerobatics may be used to perform
maneuvers without limitations, other than those limitations established
under subpart G of this part.
Sec. 23.2010 Accepted means of compliance.
(a) An applicant must comply with this part using a means of
compliance, which may include consensus standards, accepted by the
Administrator.
(b) An applicant requesting acceptance of a means of compliance
must provide the means of compliance to the FAA in a form and manner
acceptable to the Administrator.
[[Page 96692]]
Subpart B--Flight
Performance
Sec. 23.2100 Weight and center of gravity.
(a) The applicant must determine limits for weights and centers of
gravity that provide for the safe operation of the airplane.
(b) The applicant must comply with each requirement of this subpart
at critical combinations of weight and center of gravity within the
airplane's range of loading conditions using tolerances acceptable to
the Administrator.
(c) The condition of the airplane at the time of determining its
empty weight and center of gravity must be well defined and easily
repeatable.
Sec. 23.2105 Performance data.
(a) Unless otherwise prescribed, an airplane must meet the
performance requirements of this subpart in--
(1) Still air and standard atmospheric conditions at sea level for
all airplanes; and
(2) Ambient atmospheric conditions within the operating envelope
for levels 1 and 2 high-speed and levels 3 and 4 airplanes.
(b) Unless otherwise prescribed, the applicant must develop the
performance data required by this subpart for the following conditions:
(1) Airport altitudes from sea level to 10,000 feet (3,048 meters);
and
(2) Temperatures above and below standard day temperature that are
within the range of operating limitations, if those temperatures could
have a negative effect on performance.
(c) The procedures used for determining takeoff and landing
distances must be executable consistently by pilots of average skill in
atmospheric conditions expected to be encountered in service.
(d) Performance data determined in accordance with paragraph (b) of
this section must account for losses due to atmospheric conditions,
cooling needs, and other demands on power sources.
Sec. 23.2110 Stall speed.
The applicant must determine the airplane stall speed or the
minimum steady flight speed for each flight configuration used in
normal operations, including takeoff, climb, cruise, descent, approach,
and landing. The stall speed or minimum steady flight speed
determination must account for the most adverse conditions for each
flight configuration with power set at--
(a) Idle or zero thrust for propulsion systems that are used
primarily for thrust; and
(b) A nominal thrust for propulsion systems that are used for
thrust, flight control, and/or high-lift systems.
Sec. 23.2115 Takeoff performance.
(a) The applicant must determine airplane takeoff performance
accounting for--
(1) Stall speed safety margins;
(2) Minimum control speeds; and
(3) Climb gradients.
(b) For single engine airplanes and levels 1, 2, and 3 low-speed
multiengine airplanes, takeoff performance includes the determination
of ground roll and initial climb distance to 50 feet (15 meters) above
the takeoff surface.
(c) For levels 1, 2, and 3 high-speed multiengine airplanes, and
level 4 multiengine airplanes, takeoff performance includes a
determination the following distances after a sudden critical loss of
thrust--
(1) An aborted takeoff at critical speed;
(2) Ground roll and initial climb to 35 feet (11 meters) above the
takeoff surface; and
(3) Net takeoff flight path.
Sec. 23.2120 Climb requirements.
The design must comply with the following minimum climb performance
out of ground effect:
(a) With all engines operating and in the initial climb
configuration--
(1) For levels 1 and 2 low-speed airplanes, a climb gradient of 8.3
percent for landplanes and 6.7 percent for seaplanes and amphibians;
and
(2) For levels 1 and 2 high-speed airplanes, all level 3 airplanes,
and level 4 single-engines a climb gradient after takeoff of 4 percent.
(b) After a critical loss of thrust on multiengine airplanes--
(1) For levels 1 and 2 low-speed airplanes that do not meet single-
engine crashworthiness requirements, a climb gradient of 1.5 percent at
a pressure altitude of 5,000 feet (1,524 meters) in the cruise
configuration(s);
(2) For levels 1 and 2 high-speed airplanes, and level 3 low-speed
airplanes, a 1 percent climb gradient at 400 feet (122 meters) above
the takeoff surface with the landing gear retracted and flaps in the
takeoff configuration(s); and
(3) For level 3 high-speed airplanes and all level 4 airplanes, a 2
percent climb gradient at 400 feet (122 meters) above the takeoff
surface with the landing gear retracted and flaps in the approach
configuration(s).
(c) For a balked landing, a climb gradient of 3 percent without
creating undue pilot workload with the landing gear extended and flaps
in the landing configuration(s).
Sec. 23.2125 Climb information.
(a) The applicant must determine climb performance at each weight,
altitude, and ambient temperature within the operating limitations--
(1) For all single-engine airplanes;
(2) For levels 1 and 2 high-speed multiengine airplanes and level 3
multiengine airplanes, following a critical loss of thrust on takeoff
in the initial climb configuration; and
(3) For all multiengine airplanes, during the enroute phase of
flight with all engines operating and after a critical loss of thrust
in the cruise configuration.
(b) The applicant must determine the glide performance for single-
engine airplanes after a complete loss of thrust.
Sec. 23.2130 Landing.
The applicant must determine the following, for standard
temperatures at critical combinations of weight and altitude within the
operational limits:
(a) The distance, starting from a height of 50 feet (15 meters)
above the landing surface, required to land and come to a stop.
(b) The approach and landing speeds, configurations, and
procedures, which allow a pilot of average skill to land within the
published landing distance consistently and without causing damage or
injury, and which allow for a safe transition to the balked landing
conditions of this part accounting for:
(1) Stall speed safety margin; and
(2) Minimum control speeds.
Flight Characteristics
Sec. 23.2135 Controllability.
(a) The airplane must be controllable and maneuverable, without
requiring exceptional piloting skill, alertness, or strength, within
the operating envelope--
(1) At all loading conditions for which certification is requested;
(2) During all phases of flight;
(3) With likely reversible flight control or propulsion system
failure; and
(4) During configuration changes.
(b) The airplane must be able to complete a landing without causing
substantial damage or serious injury using the steepest approved
approach gradient procedures and providing a reasonable margin below
Vref or above approach angle of attack.
(c) VMC is the calibrated airspeed at which, following
the sudden critical loss of thrust, it is possible to maintain control
of the airplane. For multiengine airplanes, the applicant must
determine VMC, if applicable, for the most critical
configurations used in takeoff and landing operations.
[[Page 96693]]
(d) If the applicant requests certification of an airplane for
aerobatics, the applicant must demonstrate those aerobatic maneuvers
for which certification is requested and determine entry speeds.
Sec. 23.2140 Trim.
(a) The airplane must maintain lateral and directional trim without
further force upon, or movement of, the primary flight controls or
corresponding trim controls by the pilot, or the flight control system,
under the following conditions:
(1) For levels 1, 2, and 3 airplanes in cruise.
(2) For level 4 airplanes in normal operations.
(b) The airplane must maintain longitudinal trim without further
force upon, or movement of, the primary flight controls or
corresponding trim controls by the pilot, or the flight control system,
under the following conditions:
(1) Climb.
(2) Level flight.
(3) Descent.
(4) Approach.
(c) Residual control forces must not fatigue or distract the pilot
during normal operations of the airplane and likely abnormal or
emergency operations, including a critical loss of thrust on
multiengine airplanes.
Sec. 23.2145 Stability.
(a) Airplanes not certified for aerobatics must--
(1) Have static longitudinal, lateral, and directional stability in
normal operations;
(2) Have dynamic short period and Dutch roll stability in normal
operations; and
(3) Provide stable control force feedback throughout the operating
envelope.
(b) No airplane may exhibit any divergent longitudinal stability
characteristic so unstable as to increase the pilot's workload or
otherwise endanger the airplane and its occupants.
Sec. 23.2150 Stall characteristics, stall warning, and spins.
(a) The airplane must have controllable stall characteristics in
straight flight, turning flight, and accelerated turning flight with a
clear and distinctive stall warning that provides sufficient margin to
prevent inadvertent stalling.
(b) Single-engine airplanes, not certified for aerobatics, must not
have a tendency to inadvertently depart controlled flight.
(c) Levels 1 and 2 multiengine airplanes, not certified for
aerobatics, must not have a tendency to inadvertently depart controlled
flight from thrust asymmetry after a critical loss of thrust.
(d) Airplanes certified for aerobatics that include spins must have
controllable stall characteristics and the ability to recover within
one and one-half additional turns after initiation of the first control
action from any point in a spin, not exceeding six turns or any greater
number of turns for which certification is requested, while remaining
within the operating limitations of the airplane.
(e) Spin characteristics in airplanes certified for aerobatics that
includes spins must recover without exceeding limitations and may not
result in unrecoverable spins--
(1) With any typical use of the flight or engine power controls; or
(2) Due to pilot disorientation or incapacitation.
Sec. 23.2155 Ground and water handling characteristics.
For airplanes intended for operation on land or water, the airplane
must have controllable longitudinal and directional handling
characteristics during taxi, takeoff, and landing operations.
Sec. 23.2160 Vibration, buffeting, and high-speed characteristics.
(a) Vibration and buffeting, for operations up to VD/
MD, must not interfere with the control of the airplane or
cause excessive fatigue to the flightcrew. Stall warning buffet within
these limits is allowable.
(b) For high-speed airplanes and all airplanes with a maximum
operating altitude greater than 25,000 feet (7,620 meters) pressure
altitude, there must be no perceptible buffeting in cruise
configuration at 1g and at any speed up to VMO/
MMO, except stall buffeting.
(c) For high-speed airplanes, the applicant must determine the
positive maneuvering load factors at which the onset of perceptible
buffet occurs in the cruise configuration within the operational
envelope. Likely inadvertent excursions beyond this boundary must not
result in structural damage.
(d) High-speed airplanes must have recovery characteristics that do
not result in structural damage or loss of control, beginning at any
likely speed up to VMO/MMO, following--
(1) An inadvertent speed increase; and
(2) A high-speed trim upset for airplanes where dynamic pressure
can impair the longitudinal trim system operation.
Sec. 23.2165 Performance and flight characteristics requirements for
flight in icing conditions.
(a) An applicant who requests certification for flight in icing
conditions defined in part 1 of appendix C to part 25 of this chapter,
or an applicant who requests certification for flight in these icing
conditions and any additional atmospheric icing conditions, must show
the following in the icing conditions for which certification is
requested under normal operation of the ice protection system(s):
(1) Compliance with each requirement of this subpart, except those
applicable to spins and any that must be demonstrated at speeds in
excess of--
(i) 250 knots CAS;
(ii) VMO/MMO or VNE; or
(iii) A speed at which the applicant demonstrates the airframe will
be free of ice accretion.
(2) The means by which stall warning is provided to the pilot for
flight in icing conditions and non-icing conditions is the same.
(b) If an applicant requests certification for flight in icing
conditions, the applicant must provide a means to detect any icing
conditions for which certification is not requested and show the
airplane's ability to avoid or exit those conditions.
(c) The applicant must develop an operating limitation to prohibit
intentional flight, including takeoff and landing, into icing
conditions for which the airplane is not certified to operate.
Subpart C--Structures
Sec. 23.2200 Structural design envelope.
The applicant must determine the structural design envelope, which
describes the range and limits of airplane design and operational
parameters for which the applicant will show compliance with the
requirements of this subpart. The applicant must account for all
airplane design and operational parameters that affect structural
loads, strength, durability, and aeroelasticity, including:
(a) Structural design airspeeds, landing descent speeds, and any
other airspeed limitation at which the applicant must show compliance
to the requirements of this subpart. The structural design airspeeds
must--
(1) Be sufficiently greater than the stalling speed of the airplane
to safeguard against loss of control in turbulent air; and
(2) Provide sufficient margin for the establishment of practical
operational limiting airspeeds.
(b) Design maneuvering load factors not less than those, which
service
[[Page 96694]]
history shows, may occur within the structural design envelope.
(c) Inertial properties including weight, center of gravity, and
mass moments of inertia, accounting for--
(1) Each critical weight from the airplane empty weight to the
maximum weight; and
(2) The weight and distribution of occupants, payload, and fuel.
(d) Characteristics of airplane control systems, including range of
motion and tolerances for control surfaces, high lift devices, or other
moveable surfaces.
(e) Each critical altitude up to the maximum altitude.
Sec. 23.2205 Interaction of systems and structures.
For airplanes equipped with systems that modify structural
performance, alleviate the impact of this subpart's requirements, or
provide a means of compliance with this subpart, the applicant must
account for the influence and failure of these systems when showing
compliance with the requirements of this subpart.
Structural Loads
Sec. 23.2210 Structural design loads.
(a) The applicant must:
(1) Determine the applicable structural design loads resulting from
likely externally or internally applied pressures, forces, or moments
that may occur in flight, ground and water operations, ground and water
handling, and while the airplane is parked or moored.
(2) Determine the loads required by paragraph (a)(1) of this
section at all critical combinations of parameters, on and within the
boundaries of the structural design envelope.
(b) The magnitude and distribution of the applicable structural
design loads required by this section must be based on physical
principles.
Sec. 23.2215 Flight load conditions.
The applicant must determine the structural design loads resulting
from the following flight conditions:
(a) Atmospheric gusts where the magnitude and gradient of these
gusts are based on measured gust statistics.
(b) Symmetric and asymmetric maneuvers.
(c) Asymmetric thrust resulting from the failure of a powerplant
unit.
Sec. 23.2220 Ground and water load conditions.
The applicant must determine the structural design loads resulting
from taxi, takeoff, landing, and handling conditions on the applicable
surface in normal and adverse attitudes and configurations.
Sec. 23.2225 Component loading conditions.
The applicant must determine the structural design loads acting on:
(a) Each engine mount and its supporting structure such that both
are designed to withstand loads resulting from--
(1) Powerplant operation combined with flight gust and maneuver
loads; and
(2) For non-reciprocating powerplants, sudden powerplant stoppage.
(b) Each flight control and high-lift surface, their associated
system and supporting structure resulting from--
(1) The inertia of each surface and mass balance attachment;
(2) Flight gusts and maneuvers;
(3) Pilot or automated system inputs;
(4) System induced conditions, including jamming and friction; and
(5) Taxi, takeoff, and landing operations on the applicable
surface, including downwind taxi and gusts occurring on the applicable
surface.
(c) A pressurized cabin resulting from the pressurization
differential--
(1) From zero up to the maximum relief pressure combined with gust
and maneuver loads;
(2) From zero up to the maximum relief pressure combined with
ground and water loads if the airplane may land with the cabin
pressurized; and
(3) At the maximum relief pressure multiplied by 1.33, omitting all
other loads.
Sec. 23.2230 Limit and ultimate loads.
The applicant must determine--
(a) The limit loads, which are equal to the structural design loads
unless otherwise specified elsewhere in this part; and
(b) The ultimate loads, which are equal to the limit loads
multiplied by a 1.5 factor of safety unless otherwise specified
elsewhere in this part.
Structural Performance
Sec. 23.2235 Structural strength.
The structure must support:
(a) Limit loads without--
(1) Interference with the safe operation of the airplane; and
(2) Detrimental permanent deformation.
(b) Ultimate loads.
Sec. 23.2240 Structural durability.
(a) The applicant must develop and implement inspections or other
procedures to prevent structural failures due to foreseeable causes of
strength degradation, which could result in serious or fatal injuries,
or extended periods of operation with reduced safety margins. Each of
the inspections or other procedures developed under this section must
be included in the Airworthiness Limitations Section of the
Instructions for Continued Airworthiness required by Sec. 23.1529.
(b) For Level 4 airplanes, the procedures developed for compliance
with paragraph (a) of this section must be capable of detecting
structural damage before the damage could result in structural failure.
(c) For pressurized airplanes:
(1) The airplane must be capable of continued safe flight and
landing following a sudden release of cabin pressure, including sudden
releases caused by door and window failures.
(2) For airplanes with maximum operating altitude greater than
41,000 feet, the procedures developed for compliance with paragraph (a)
of this section must be capable of detecting damage to the pressurized
cabin structure before the damage could result in rapid decompression
that would result in serious or fatal injuries.
(d) The airplane must be designed to minimize hazards to the
airplane due to structural damage caused by high-energy fragments from
an uncontained engine or rotating machinery failure.
Sec. 23.2245 Aeroelasticity.
(a) The airplane must be free from flutter, control reversal, and
divergence--
(1) At all speeds within and sufficiently beyond the structural
design envelope;
(2) For any configuration and condition of operation;
(3) Accounting for critical degrees of freedom; and
(4) Accounting for any critical failures or malfunctions.
(b) The applicant must establish tolerances for all quantities that
affect flutter.
Design
Sec. 23.2250 Design and construction principles.
(a) The applicant must design each part, article, and assembly for
the expected operating conditions of the airplane.
(b) Design data must adequately define the part, article, or
assembly configuration, its design features, and any materials and
processes used.
(c) The applicant must determine the suitability of each design
detail and part having an important bearing on safety in operations.
(d) The control system must be free from jamming, excessive
friction, and excessive deflection when the airplane is subjected to
expected limit airloads.
(e) Doors, canopies, and exits must be protected against
inadvertent opening in
[[Page 96695]]
flight, unless shown to create no hazard when opened in flight.
Sec. 23.2255 Protection of structure.
(a) The applicant must protect each part of the airplane, including
small parts such as fasteners, against deterioration or loss of
strength due to any cause likely to occur in the expected operational
environment.
(b) Each part of the airplane must have adequate provisions for
ventilation and drainage.
(c) For each part that requires maintenance, preventive
maintenance, or servicing, the applicant must incorporate a means into
the aircraft design to allow such actions to be accomplished.
Sec. 23.2260 Materials and processes.
(a) The applicant must determine the suitability and durability of
materials used for parts, articles, and assemblies, accounting for the
effects of likely environmental conditions expected in service, the
failure of which could prevent continued safe flight and landing.
(b) The methods and processes of fabrication and assembly used must
produce consistently sound structures. If a fabrication process
requires close control to reach this objective, the applicant must
perform the process under an approved process specification.
(c) Except as provided in paragraphs (f) and (g) of this section,
the applicant must select design values that ensure material strength
with probabilities that account for the criticality of the structural
element. Design values must account for the probability of structural
failure due to material variability.
(d) If material strength properties are required, a determination
of those properties must be based on sufficient tests of material
meeting specifications to establish design values on a statistical
basis.
(e) If thermal effects are significant on a critical component or
structure under normal operating conditions, the applicant must
determine those effects on allowable stresses used for design.
(f) Design values, greater than the minimums specified by this
section, may be used, where only guaranteed minimum values are normally
allowed, if a specimen of each individual item is tested before use to
determine that the actual strength properties of that particular item
will equal or exceed those used in the design.
(g) An applicant may use other material design values if approved
by the Administrator.
Sec. 23.2265 Special factors of safety.
(a) The applicant must determine a special factor of safety for
each critical design value for each part, article, or assembly for
which that critical design value is uncertain, and for each part,
article, or assembly that is--
(1) Likely to deteriorate in service before normal replacement; or
(2) Subject to appreciable variability because of uncertainties in
manufacturing processes or inspection methods.
(b) The applicant must determine a special factor of safety using
quality controls and specifications that account for each--
(1) Type of application;
(2) Inspection method;
(3) Structural test requirement;
(4) Sampling percentage; and
(5) Process and material control.
(c) The applicant must multiply the highest pertinent special
factor of safety in the design for each part of the structure by each
limit and ultimate load, or ultimate load only, if there is no
corresponding limit load, such as occurs with emergency condition
loading.
Structural Occupant Protection
Sec. 23.2270 Emergency conditions.
(a) The airplane, even when damaged in an emergency landing, must
protect each occupant against injury that would preclude egress when--
(1) Properly using safety equipment and features provided for in
the design;
(2) The occupant experiences ultimate static inertia loads likely
to occur in an emergency landing; and
(3) Items of mass, including engines or auxiliary power units
(APUs), within or aft of the cabin, that could injure an occupant,
experience ultimate static inertia loads likely to occur in an
emergency landing.
(b) The emergency landing conditions specified in paragraph (a)(1)
and (a)(2) of this section, must--
(1) Include dynamic conditions that are likely to occur in an
emergency landing; and
(2) Not generate loads experienced by the occupants, which exceed
established human injury criteria for human tolerance due to restraint
or contact with objects in the airplane.
(c) The airplane must provide protection for all occupants,
accounting for likely flight, ground, and emergency landing conditions.
(d) Each occupant protection system must perform its intended
function and not create a hazard that could cause a secondary injury to
an occupant. The occupant protection system must not prevent occupant
egress or interfere with the operation of the airplane when not in use.
(e) Each baggage and cargo compartment must--
(1) Be designed for its maximum weight of contents and for the
critical load distributions at the maximum load factors corresponding
to the flight and ground load conditions determined under this part;
(2) Have a means to prevent the contents of the compartment from
becoming a hazard by impacting occupants or shifting; and
(3) Protect any controls, wiring, lines, equipment, or accessories
whose damage or failure would affect safe operations.
Subpart D--Design and Construction
Sec. 23.2300 Flight control systems.
(a) The applicant must design airplane flight control systems to:
(1) Operate easily, smoothly, and positively enough to allow proper
performance of their functions.
(2) Protect against likely hazards.
(b) The applicant must design trim systems, if installed, to:
(1) Protect against inadvertent, incorrect, or abrupt trim
operation.
(2) Provide a means to indicate--
(i) The direction of trim control movement relative to airplane
motion;
(ii) The trim position with respect to the trim range;
(iii) The neutral position for lateral and directional trim; and
(iv) The range for takeoff for all applicant requested center of
gravity ranges and configurations.
Sec. 23.2305 Landing gear systems.
(a) The landing gear must be designed to--
(1) Provide stable support and control to the airplane during
surface operation; and
(2) Account for likely system failures and likely operation
environments (including anticipated limitation exceedances and
emergency procedures).
(b) All airplanes must have a reliable means of stopping the
airplane with sufficient kinetic energy absorption to account for
landing. Airplanes that are required to demonstrate aborted takeoff
capability must account for this additional kinetic energy.
(c) For airplanes that have a system that actuates the landing
gear, there is--
(1) A positive means to keep the landing gear in the landing
position; and
(2) An alternative means available to bring the landing gear in the
landing position when a non-deployed system position would be a hazard.
[[Page 96696]]
Sec. 23.2310 Buoyancy for seaplanes and amphibians.
Airplanes intended for operations on water, must--
(a) Provide buoyancy of 80 percent in excess of the buoyancy
required to support the maximum weight of the airplane in fresh water;
and
(b) Have sufficient margin so the airplane will stay afloat at rest
in calm water without capsizing in case of a likely float or hull
flooding.
Occupant System Design Protection
Sec. 23.2315 Means of egress and emergency exits.
(a) With the cabin configured for takeoff or landing, the airplane
is designed to:
(1) Facilitate rapid and safe evacuation of the airplane in
conditions likely to occur following an emergency landing, excluding
ditching for level 1, level 2 and single engine level 3 airplanes.
(2) Have means of egress (openings, exits or emergency exits), that
can be readily located and opened from the inside and outside. The
means of opening must be simple and obvious and marked inside and
outside the airplane.
(3) Have easy access to emergency exits when present.
(b) Airplanes approved for aerobatics must have a means to egress
the airplane in flight.
Sec. 23.2320 Occupant physical environment.
(a) The applicant must design the airplane to--
(1) Allow clear communication between the flightcrew and
passengers;
(2) Protect the pilot and flight controls from propellers; and
(3) Protect the occupants from serious injury due to damage to
windshields, windows, and canopies.
(b) For level 4 airplanes, each windshield and its supporting
structure directly in front of the pilot must withstand, without
penetration, the impact equivalent to a two-pound bird when the
velocity of the airplane is equal to the airplane's maximum approach
flap speed.
(c) The airplane must provide each occupant with air at a
breathable pressure, free of hazardous concentrations of gases, vapors,
and smoke during normal operations and likely failures.
(d) If a pressurization system is installed in the airplane, it
must be designed to protect against--
(1) Decompression to an unsafe level; and
(2) Excessive differential pressure.
(e) If an oxygen system is installed in the airplane, it must--
(1) Effectively provide oxygen to each user to prevent the effects
of hypoxia; and
(2) Be free from hazards in itself, in its method of operation, and
its effect upon other components.
Fire and High Energy Protection
Sec. 23.2325 Fire protection.
(a) The following materials must be self-extinguishing--
(1) Insulation on electrical wire and electrical cable;
(2) For levels 1, 2, and 3 airplanes, materials in the baggage and
cargo compartments inaccessible in flight; and
(3) For level 4 airplanes, materials in the cockpit, cabin,
baggage, and cargo compartments.
(b) The following materials must be flame resistant--
(1) For levels 1, 2 and 3 airplanes, materials in each compartment
accessible in flight; and
(2) Any equipment associated with any electrical cable installation
and that would overheat in the event of circuit overload or fault.
(c) Thermal/acoustic materials in the fuselage, if installed, must
not be a flame propagation hazard.
(d) Sources of heat within each baggage and cargo compartment that
are capable of igniting adjacent objects must be shielded and insulated
to prevent such ignition.
(e) For level 4 airplanes, each baggage and cargo compartment
must--
(1) Be located where a fire would be visible to the pilots, or
equipped with a fire detection system and warning system; and
(2) Be accessible for the manual extinguishing of a fire, have a
built-in fire extinguishing system, or be constructed and sealed to
contain any fire within the compartment.
(f) There must be a means to extinguish any fire in the cabin such
that--
(1) The pilot, while seated, can easily access the fire
extinguishing means; and
(2) For levels 3 and 4 airplanes, passengers have a fire
extinguishing means available within the passenger compartment.
(g) Each area where flammable fluids or vapors might escape by
leakage of a fluid system must--
(1) Be defined; and
(2) Have a means to minimize the probability of fluid and vapor
ignition, and the resultant hazard, if ignition occurs.
(h) Combustion heater installations must be protected from
uncontained fire.
Sec. 23.2330 Fire protection in designated fire zones and adjacent
areas.
(a) Flight controls, engine mounts, and other flight structures
within or adjacent to designated fire zones must be capable of
withstanding the effects of a fire.
(b) Engines in a designated fire zone must remain attached to the
airplane in the event of a fire.
(c) In designated fire zones, terminals, equipment, and electrical
cables used during emergency procedures must be fire-resistant.
Sec. 23.2335 Lightning protection.
The airplane must be protected against catastrophic effects from
lightning.
Subpart E--Powerplant
Sec. 23.2400 Powerplant installation.
(a) For the purpose of this subpart, the airplane powerplant
installation must include each component necessary for propulsion,
which affects propulsion safety, or provides auxiliary power to the
airplane.
(b) Each airplane engine and propeller must be type certificated,
except for engines and propellers installed on level 1 low-speed
airplanes, which may be approved under the airplane type certificate in
accordance with a standard accepted by the FAA that contains
airworthiness criteria the Administrator has found appropriate and
applicable to the specific design and intended use of the engine or
propeller and provides a level of safety acceptable to the FAA.
(c) The applicant must construct and arrange each powerplant
installation to account for--
(1) Likely operating conditions, including foreign object threats;
(2) Sufficient clearance of moving parts to other airplane parts
and their surroundings;
(3) Likely hazards in operation including hazards to ground
personnel; and
(4) Vibration and fatigue.
(d) Hazardous accumulations of fluids, vapors, or gases must be
isolated from the airplane and personnel compartments, and be safely
contained or discharged.
(e) Powerplant components must comply with their component
limitations and installation instructions or be shown not to create a
hazard.
Sec. 23.2405 Automatic power or thrust control systems.
(a) An automatic power or thrust control system intended for in-
flight use must be designed so no unsafe condition will result during
normal operation of the system.
[[Page 96697]]
(b) Any single failure or likely combination of failures of an
automatic power or thrust control system must not prevent continued
safe flight and landing of the airplane.
(c) Inadvertent operation of an automatic power or thrust control
system by the flightcrew must be prevented, or if not prevented, must
not result in an unsafe condition.
(d) Unless the failure of an automatic power or thrust control
system is extremely remote, the system must--
(1) Provide a means for the flightcrew to verify the system is in
an operating condition;
(2) Provide a means for the flightcrew to override the automatic
function; and
(3) Prevent inadvertent deactivation of the system.
Sec. 23.2410 Powerplant installation hazard assessment.
The applicant must assess each powerplant separately and in
relation to other airplane systems and installations to show that any
hazard resulting from the likely failure of any powerplant system,
component, or accessory will not--
(a) Prevent continued safe flight and landing or, if continued safe
flight and landing cannot be ensured, the hazard has been minimized;
(b) Cause serious injury that may be avoided; and
(c) Require immediate action by any crewmember for continued
operation of any remaining powerplant system.
Sec. 23.2415 Powerplant ice protection.
(a) The airplane design, including the induction and inlet system,
must prevent foreseeable accumulation of ice or snow that adversely
affects powerplant operation.
(b) The powerplant installation design must prevent any
accumulation of ice or snow that adversely affects powerplant
operation, in those icing conditions for which certification is
requested.
Sec. 23.2420 Reversing systems.
Each reversing system must be designed so that--
(a) No unsafe condition will result during normal operation of the
system; and
(b) The airplane is capable of continued safe flight and landing
after any single failure, likely combination of failures, or
malfunction of the reversing system.
Sec. 23.2425 Powerplant operational characteristics.
(a) The installed powerplant must operate without any hazardous
characteristics during normal and emergency operation within the range
of operating limitations for the airplane and the engine.
(b) The pilot must have the capability to stop the powerplant in
flight and restart the powerplant within an established operational
envelope.
Sec. 23.2430 Fuel systems.
(a) Each fuel system must--
(1) Be designed and arranged to provide independence between
multiple fuel storage and supply systems so that failure of any one
component in one system will not result in loss of fuel storage or
supply of another system;
(2) Be designed and arranged to prevent ignition of the fuel within
the system by direct lightning strikes or swept lightning strokes to
areas where such occurrences are highly probable, or by corona or
streamering at fuel vent outlets;
(3) Provide the fuel necessary to ensure each powerplant and
auxiliary power unit functions properly in all likely operating
conditions;
(4) Provide the flightcrew with a means to determine the total
useable fuel available and provide uninterrupted supply of that fuel
when the system is correctly operated, accounting for likely fuel
fluctuations;
(5) Provide a means to safely remove or isolate the fuel stored in
the system from the airplane;
(6) Be designed to retain fuel under all likely operating
conditions and minimize hazards to the occupants during any survivable
emergency landing. For level 4 airplanes, failure due to overload of
the landing system must be taken into account; and
(7) Prevent hazardous contamination of the fuel supplied to each
powerplant and auxiliary power unit.
(b) Each fuel storage system must--
(1) Withstand the loads under likely operating conditions without
failure;
(2) Be isolated from personnel compartments and protected from
hazards due to unintended temperature influences;
(3) Be designed to prevent significant loss of stored fuel from any
vent system due to fuel transfer between fuel storage or supply
systems, or under likely operating conditions;
(4) Provide fuel for at least one-half hour of operation at maximum
continuous power or thrust; and
(5) Be capable of jettisoning fuel safely if required for landing.
(c) Each fuel storage refilling or recharging system must be
designed to--
(1) Prevent improper refilling or recharging;
(2) Prevent contamination of the fuel stored during likely
operating conditions; and
(3) Prevent the occurrence of any hazard to the airplane or to
persons during refilling or recharging.
Sec. 23.2435 Powerplant induction and exhaust systems.
(a) The air induction system for each powerplant or auxiliary power
unit and their accessories must--
(1) Supply the air required by that powerplant or auxiliary power
unit and its accessories under likely operating conditions;
(2) Be designed to prevent likely hazards in the event of fire or
backfire;
(3) Minimize the ingestion of foreign matter; and
(4) Provide an alternate intake if blockage of the primary intake
is likely.
(b) The exhaust system, including exhaust heat exchangers for each
powerplant or auxiliary power unit, must--
(1) Provide a means to safely discharge potential harmful material;
and
(2) Be designed to prevent likely hazards from heat, corrosion, or
blockage.
Sec. 23.2440 Powerplant fire protection.
(a) A powerplant, auxiliary power unit, or combustion heater that
includes a flammable fluid and an ignition source for that fluid must
be installed in a designated fire zone.
(b) Each designated fire zone must provide a means to isolate and
mitigate hazards to the airplane in the event of fire or overheat
within the zone.
(c) Each component, line, fitting, and control subject to fire
conditions must--
(1) Be designed and located to prevent hazards resulting from a
fire, including any located adjacent to a designated fire zone that may
be affected by fire within that zone;
(2) Be fire resistant if carrying flammable fluids, gas, or air or
required to operate in event of a fire; and
(3) Be fireproof or enclosed by a fire proof shield if storing
concentrated flammable fluids.
(d) The applicant must provide a means to prevent hazardous
quantities of flammable fluids from flowing into, within or through
each designated fire zone. This means must--
(1) Not restrict flow or limit operation of any remaining
powerplant or auxiliary power unit, or equipment necessary for safety;
(2) Prevent inadvertent operation; and
(3) Be located outside the fire zone unless an equal degree of
safety is provided with a means inside the fire zone.
(e) A means to ensure the prompt detection of fire must be provided
for each designated fire zone--
[[Page 96698]]
(1) On a multiengine airplane where detection will mitigate likely
hazards to the airplane; or
(2) That contains a fire extinguisher.
(f) A means to extinguish fire within a fire zone, except a
combustion heater fire zone, must be provided for--
(1) Any fire zone located outside the pilot's view;
(2) Any fire zone embedded within the fuselage, which must also
include a redundant means to extinguish fire; and
(3) Any fire zone on a level 4 airplane.
Subpart F--Equipment
Sec. 23.2500 Airplane level systems requirements.
This section applies generally to installed equipment and systems
unless a section of this part imposes requirements for a specific piece
of equipment, system, or systems.
(a) The equipment and systems required for an airplane to operate
safely in the kinds of operations for which certification is requested
(Day VFR, Night VFR, IFR) must be designed and installed to--
(1) Meet the level of safety applicable to the certification and
performance level of the airplane; and
(2) Perform their intended function throughout the operating and
environmental limits for which the airplane is certificated.
(b) The systems and equipment not covered by paragraph (a),
considered separately and in relation to other systems, must be
designed and installed so their operation does not have an adverse
effect on the airplane or its occupants.
Sec. 23.2505 Function and installation.
When installed, each item of equipment must function as intended.
Sec. 23.2510 Equipment, systems, and installations.
For any airplane system or equipment whose failure or abnormal
operation has not been specifically addressed by another requirement in
this part, the applicant must design and install each system and
equipment, such that there is a logical and acceptable inverse
relationship between the average probability and the severity of
failure conditions to the extent that:
(a) Each catastrophic failure condition is extremely improbable;
(b) Each hazardous failure condition is extremely remote; and
(c) Each major failure condition is remote.
Sec. 23.2515 Electrical and electronic system lightning protection.
An airplane approved for IFR operations must meet the following
requirements, unless an applicant shows that exposure to lightning is
unlikely:
(a) Each electrical or electronic system that performs a function,
the failure of which would prevent the continued safe flight and
landing of the airplane, must be designed and installed such that--
(1) The function at the airplane level is not adversely affected
during and after the time the airplane is exposed to lightning; and
(2) The system recovers normal operation of that function in a
timely manner after the airplane is exposed to lightning unless the
system's recovery conflicts with other operational or functional
requirements of the system.
(b) Each electrical and electronic system that performs a function,
the failure of which would significantly reduce the capability of the
airplane or the ability of the flightcrew to respond to an adverse
operating condition, must be designed and installed such that the
system recovers normal operation of that function in a timely manner
after the airplane is exposed to lightning.
Sec. 23.2520 High-intensity Radiated Fields (HIRF) protection.
(a) Each electrical and electronic systems that perform a function,
the failure of which would prevent the continued safe flight and
landing of the airplane, must be designed and installed such that--
(1) The function at the airplane level is not adversely affected
during and after the time the airplane is exposed to the HIRF
environment; and
(2) The system recovers normal operation of that function in a
timely manner after the airplane is exposed to the HIRF environment,
unless the system's recovery conflicts with other operational or
functional requirements of the system.
(b) For airplanes approved for IFR operations, each electrical and
electronic system that performs a function, the failure of which would
significantly reduce the capability of the airplane or the ability of
the flightcrew to respond to an adverse operating condition, must be
designed and installed such that the system recovers normal operation
of that function in a timely manner after the airplane is exposed to
the HIRF environment.
Sec. 23.2525 System power generation, storage, and distribution.
The power generation, storage, and distribution for any system must
be designed and installed to--
(a) Supply the power required for operation of connected loads
during all intended operating conditions;
(b) Ensure no single failure or malfunction of any one power
supply, distribution system, or other utilization system will prevent
the system from supplying the essential loads required for continued
safe flight and landing; and
(c) Have enough capacity, if the primary source fails, to supply
essential loads, including non-continuous essential loads for the time
needed to complete the function required for continued safe flight and
landing.
Sec. 23.2530 External and cockpit lighting.
(a) The applicant must design and install all lights to minimize
any adverse effects on the performance of flightcrew duties.
(b) Any position and anti-collision lights, if required by part 91
of this chapter, must have the intensities, flash rate, colors, fields
of coverage, and other characteristics to provide sufficient time for
another aircraft to avoid a collision.
(c) Any position lights, if required by part 91 of this chapter,
must include a red light on the left side of the airplane, a green
light on the right side of the airplane, spaced laterally as far apart
as practicable, and a white light facing aft, located on an aft portion
of the airplane or on the wing tips.
(d) Any taxi and landing lights must be designed and installed so
they provide sufficient light for night operations.
(e) For seaplanes or amphibian airplanes, riding lights must
provide a white light visible in clear atmospheric conditions.
Sec. 23.2535 Safety equipment.
Safety and survival equipment, required by the operating rules of
this chapter, must be reliable, readily accessible, easily
identifiable, and clearly marked to identify its method of operation.
Sec. 23.2540 Flight in icing conditions.
An applicant who requests certification for flight in icing
conditions defined in part 1 of appendix C to part 25 of this chapter,
or an applicant who requests certification for flight in these icing
conditions and any additional atmospheric icing conditions, must show
the following in the icing conditions for which certification is
requested:
(a) The ice protection system provides for safe operation.
(b) The airplane design must provide protection from stalling when
the autopilot is operating.
Sec. 23.2545 Pressurized systems elements.
Pressurized systems must withstand appropriate proof and burst
pressures.
[[Page 96699]]
Sec. 23.2550 Equipment containing high-energy rotors.
Equipment containing high-energy rotors must be designed or
installed to protect the occupants and airplane from uncontained
fragments.
Subpart G--Flightcrew Interface and Other Information
Sec. 23.2600 Flightcrew interface.
(a) The pilot compartment, its equipment, and its arrangement to
include pilot view, must allow each pilot to perform his or her duties,
including taxi, takeoff, climb, cruise, descent, approach, landing, and
perform any maneuvers within the operating envelope of the airplane,
without excessive concentration, skill, alertness, or fatigue.
(b) The applicant must install flight, navigation, surveillance,
and powerplant controls and displays so qualified flightcrew can
monitor and perform defined tasks associated with the intended
functions of systems and equipment. The system and equipment design
must minimize flightcrew errors, which could result in additional
hazards.
(c) For level 4 airplanes, the flightcrew interface design must
allow for continued safe flight and landing after the loss of vision
through any one of the windshield panels.
Sec. 23.2605 Installation and operation.
(a) Each item of installed equipment related to the flightcrew
interface must be labelled, if applicable, as to it identification,
function, or operating limitations, or any combination of these
factors.
(b) There must be a discernible means of providing system operating
parameters required to operate the airplane, including warnings,
cautions, and normal indications to the responsible crewmember.
(c) Information concerning an unsafe system operating condition
must be provided in a timely manner to the crewmember responsible for
taking corrective action. The information must be clear enough to avoid
likely crewmember errors.
Sec. 23.2610 Instrument markings, control markings, and placards.
(a) Each airplane must display in a conspicuous manner any placard
and instrument marking necessary for operation.
(b) The design must clearly indicate the function of each cockpit
control, other than primary flight controls.
(c) The applicant must include instrument marking and placard
information in the Airplane Flight Manual.
Sec. 23.2615 Flight, navigation, and powerplant instruments.
(a) Installed systems must provide the flightcrew member who sets
or monitors parameters for the flight, navigation, and powerplant, the
information necessary to do so during each phase of flight. This
information must--
(1) Be presented in a manner that the crewmember can monitor the
parameter and determine trends, as needed, to operate the airplane; and
(2) Include limitations, unless the limitation cannot be exceeded
in all intended operations.
(b) Indication systems that integrate the display of flight or
powerplant parameters to operate the airplane or are required by the
operating rules of this chapter must--
(1) Not inhibit the primary display of flight or powerplant
parameters needed by any flightcrew member in any normal mode of
operation; and
(2) In combination with other systems, be designed and installed so
information essential for continued safe flight and landing will be
available to the flightcrew in a timely manner after any single failure
or probable combination of failures.
Sec. 23.2620 Airplane flight manual.
The applicant must provide an Airplane Flight Manual that must be
delivered with each airplane.
(a) The Airplane Flight Manual must contain the following
information--
(1) Airplane operating limitations;
(2) Airplane operating procedures;
(3) Performance information;
(4) Loading information; and
(5) Other information that is necessary for safe operation because
of design, operating, or handling characteristics.
(b) The following sections of the Airplane Flight Manual must be
approved by the FAA in a manner specified by the administrator--
(1) For low-speed, level 1 and 2 airplanes, those portions of the
Airplane Flight Manual containing the information specified in
paragraph (a)(1) of this section; and
(2) For high-speed level 1 and 2 airplanes and all level 3 and 4
airplanes, those portions of the Airplane Flight Manual containing the
information specified in paragraphs (a)(1) thru (a)(4) of this section.
Appendix A to Part 23--Instructions for Continued Airworthiness
A23.1 General
(a) This appendix specifies requirements for the preparation of
Instructions for Continued Airworthiness as required by this part.
(b) The Instructions for Continued Airworthiness for each
airplane must include the Instructions for Continued Airworthiness
for each engine and propeller (hereinafter designated ``products''),
for each appliance required by this chapter, and any required
information relating to the interface of those appliances and
products with the airplane. If Instructions for Continued
Airworthiness are not supplied by the manufacturer of an appliance
or product installed in the airplane, the Instructions for Continued
Airworthiness for the airplane must include the information
essential to the continued airworthiness of the airplane.
(c) The applicant must submit to the FAA a program to show how
changes to the Instructions for Continued Airworthiness made by the
applicant or by the manufacturers of products and appliances
installed in the airplane will be distributed.
A23.2 Format
(a) The Instructions for Continued Airworthiness must be in the
form of a manual or manuals as appropriate for the quantity of data
to be provided.
(b) The format of the manual or manuals must provide for a
practical arrangement.
A23.3 Content
The contents of the manual or manuals must be prepared in the
English language. The Instructions for Continued Airworthiness must
contain the following manuals or sections and information:
(a) Airplane maintenance manual or section.
(1) Introduction information that includes an explanation of the
airplane's features and data to the extent necessary for maintenance
or preventive maintenance.
(2) A description of the airplane and its systems and
installations including its engines, propellers, and appliances.
(3) Basic control and operation information describing how the
airplane components and systems are controlled and how they operate,
including any special procedures and limitations that apply.
(4) Servicing information that covers details regarding
servicing points, capacities of tanks, reservoirs, types of fluids
to be used, pressures applicable to the various systems, location of
access panels for inspection and servicing, locations of lubrication
points, lubricants to be used, equipment required for servicing, tow
instructions and limitations, mooring, jacking, and leveling
information.
(b) Maintenance Instructions.
(1) Scheduling information for each part of the airplane and its
engines, auxiliary power units, propellers, accessories,
instruments, and equipment that provides the recommended periods at
which they should be cleaned, inspected, adjusted, tested, and
lubricated, and the degree of inspection, the applicable wear
tolerances, and work recommended at these periods. However, the
applicant may refer to an accessory, instrument, or equipment
manufacturer as the source of this information if the applicant
shows that the item has an exceptionally high degree of complexity
requiring specialized maintenance techniques, test
[[Page 96700]]
equipment, or expertise. The recommended overhaul periods and
necessary cross reference to the Airworthiness Limitations section
of the manual must also be included. In addition, the applicant must
include an inspection program that includes the frequency and extent
of the inspections necessary to provide for the continued
airworthiness of the airplane.
(2) Troubleshooting information describing probable
malfunctions, how to recognize those malfunctions, and the remedial
action for those malfunctions.
(3) Information describing the order and method of removing and
replacing products and parts with any necessary precautions to be
taken.
(4) Other general procedural instructions including procedures
for system testing during ground running, symmetry checks, weighing
and determining the center of gravity, lifting and shoring, and
storage limitations.
(c) Diagrams of structural access plates and information needed
to gain access for inspections when access plates are not provided.
(d) Details for the application of special inspection techniques
including radiographic and ultrasonic testing where such processes
are specified by the applicant.
(e) Information needed to apply protective treatments to the
structure after inspection.
(f) All data relative to structural fasteners such as
identification, discard recommendations, and torque values.
(g) A list of special tools needed.
(h) In addition, for level 4 airplanes, the following
information must be furnished--
(1) Electrical loads applicable to the various systems;
(2) Methods of balancing control surfaces;
(3) Identification of primary and secondary structures; and
(4) Special repair methods applicable to the airplane.
A23.4 Airworthiness limitations section.
The Instructions for Continued Airworthiness must contain a
section titled Airworthiness Limitations that is segregated and
clearly distinguishable from the rest of the document. This section
must set forth each mandatory replacement time, structural
inspection interval, and related structural inspection procedure
required for type certification. If the Instructions for Continued
Airworthiness consist of multiple documents, the section required by
this paragraph must be included in the principal manual. This
section must contain a legible statement in a prominent location
that reads ``The Airworthiness Limitations section is FAA approved
and specifies maintenance required under Sec. Sec. 43.16 and 91.403
of Title 14 of the Code of Federal Regulations unless an alternative
program has been FAA approved.''
PART 35--AIRWORTHINESS STANDARDS: PROPELLERS
0
9. The authority citation for part 35 is revised to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704.
0
10. In Sec. 35.1, revise paragraph (c) to read as follows:
Sec. 35.1 Applicability.
* * * * *
(c) An applicant is eligible for a propeller type certificate and
changes to those certificates after demonstrating compliance with
subparts A, B, and C of this part. However, the propeller may not be
installed on an airplane unless the applicant has shown compliance with
either Sec. 23.2400(c) or Sec. 25.907 of this chapter, as applicable,
or compliance is not required for installation on that airplane.
* * * * *
0
11. In Sec. 35.37, revise paragraph (c)(1) to read as follows:
Sec. 35.37 Fatigue limits and evaluation.
* * * * *
(c) * * *
(1) The intended airplane by complying with Sec. 23.2400(c) or
Sec. 25.907 of this chapter, as applicable; or
* * * * *
PART 43--MAINTENANCE, PREVENTIVE MAINTENANCE, REBUILDING, AND
ALTERATION
0
12. The authority citation for part 43 is revised to read as follows:
Authority: 42 U.S.C. 7572; 49 U.S.C. 106(f), 106(g), 40105,
40113, 44701-44702, 44704, 44707, 44709, 44711, 44713, 44715, 45303.
0
13. In part 43, appendix E, revise the introductory text and paragraph
(a)(2) to read as follows:
Appendix E to Part 43--Altimeter System Test and Inspection
Each person performing the altimeter system tests and
inspections required by Sec. 91.411 of this chapter must comply
with the following:
(a) * * *
(2) Perform a proof test to demonstrate the integrity of the
static pressure system in a manner acceptable to the Administrator.
For airplanes certificated under part 25 of this chapter, determine
that leakage is within the tolerances established by Sec. 25.1325.
* * * * *
PART 91--GENERAL OPERATING AND FLIGHT RULES
0
14. The authority citation for part 91 continues to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 1155, 40101, 40103, 40105,
40113, 40120, 44101, 44111, 44701, 44704, 44709, 44711, 44712,
44715, 44716, 44717, 44722, 46306, 46315, 46316, 46504, 46506-46507,
47122, 47508, 47528-47531, 47534, articles 12 and 29 of the
Convention on International Civil Aviation (61 Stat. 1180), (126
Stat. 11).
0
15. In Sec. 91.205, revise paragraphs (b)(13) and (b)(14), and remove
and reserve paragraph (b)(16) to read as follows:
Sec. 91.205 Powered civil aircraft with standard category U.S.
airworthiness certificates: Instrument and equipment requirements.
* * * * *
(b) * * *
(13) An approved safety belt with an approved metal-to-metal
latching device, or other approved restraint system for each occupant 2
years of age or older.
(14) For small civil airplanes manufactured after July 18, 1978, an
approved shoulder harness or restraint system for each front seat. For
small civil airplanes manufactured after December 12, 1986, an approved
shoulder harness or restraint system for all seats. Shoulder harnesses
installed at flightcrew stations must permit the flightcrew member,
when seated and with the safety belt and shoulder harness fastened, to
perform all functions necessary for flight operations. For purposes of
this paragraph--
(i) The date of manufacture of an airplane is the date the
inspection acceptance records reflect that the airplane is complete and
meets the FAA-approved type design data; and
(ii) A front seat is a seat located at a flightcrew member station
or any seat located alongside such a seat.
* * * * *
(16) [Reserved]
* * * * *
0
16. In Sec. 91.313, revise paragraph (g) introductory text to read as
follows:
Sec. 91.313 Restricted category civil aircraft: Operating
limitations.
* * * * *
(g) No person may operate a small restricted-category civil
airplane manufactured after July 18, 1978, unless an approved shoulder
harness or restraint system is installed for each front seat. The
shoulder harness or restraint system installation at each flightcrew
station must permit the flightcrew member, when seated and with the
safety belt and shoulder harness fastened or the restraint system
engaged, to perform all functions necessary for flight operation. For
purposes of this paragraph--
* * * * *
0
17. In Sec. 91.323, revise paragraph (b)(3) to read as follows:
[[Page 96701]]
Sec. 91.323 Increased maximum certificated weights for certain
airplanes operated in Alaska.
* * * * *
(b) * * *
(3) The weight at which the airplane meets the positive maneuvering
load factor n, where n=2.1+(24,000/(W+10,000)) and W=design maximum
takeoff weight, except that n need not be more than 3.8; or
* * * * *
0
18. In Sec. 91.531, revise paragraphs (a)(1) and (a)(3) to read as
follows:
Sec. 91.531 Second in command requirements.
(a) * * *
(1) A large airplane or normal category level 4 airplane, except
that a person may operate an airplane certificated under SFAR 41
without a pilot who is designated as second in command if that airplane
is certificated for operation with one pilot.
* * * * *
(3) A commuter category airplane or normal category level 3
airplane, except that a person may operate those airplanes
notwithstanding paragraph (a)(1) of this section, that have a passenger
seating configuration, excluding pilot seats, of nine or less without a
pilot who is designated as second in command if that airplane is type
certificated for operations with one pilot.
* * * * *
PART 121--OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL
OPERATIONS
0
19. The authority citation for part 121 continues to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40103, 40113, 40119, 41706,
42301 preceding note added by Pub. L. 112-95, Sec. 412, 126 Stat.
89, 44101, 44701-44702, 44705, 44709-44711, 44713, 44716-44717,
44722, 44729, 44732; 46105; Pub. L. 111-216, 124 Stat. 2348 (49
U.S.C. 44701 note); Pub. L. 112-95, 126 Stat. 62 (49 U.S.C. 44732
note).
0
20. In Sec. 121.310, revise paragraph (b)(2)(iii) to read as follows:
Sec. 121.310 Additional emergency equipment.
* * * * *
(b) * * *
(2) * * *
(iii) For a nontransport category turbopropeller powered airplane
type certificated after December 31, 1964, each passenger emergency
exit marking and each locating sign must be manufactured to have white
letters 1 inch high on a red background 2 inches high, be self-
illuminated or independently, internally electrically illuminated, and
have a minimum brightness of at least 160 microlamberts. The color may
be reversed if the passenger compartment illumination is essentially
the same. On these airplanes, no sign may continue to be used if its
luminescence (brightness) decreases to below 100 microlamberts.
* * * * *
PART 135--OPERATING REQUIREMENTS: COMMUTER AND ON DEMAND OPERATIONS
AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT
0
21. The authority citation for part 135 continues to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 41706, 40113, 44701-44702,
44705, 44709, 44711-44713, 44715-44717, 44722, 44730, 45101-45105;
Pub. L. 112-95, 126 Stat. 58 (49 U.S.C. 44730).
0
22. In Sec. 135.169, revise paragraphs (b) introductory text, (b)(6),
and (b)(7), and add paragraph (b)(8) to read as follows:
Sec. 135.169 Additional airworthiness requirements.
* * * * *
(b) No person may operate a small airplane that has a passenger-
seating configuration, excluding pilot seats, of 10 seats or more
unless it is type certificated--
* * * * *
(6) In the normal category and complies with section 1.(b) of
Special Federal Aviation Regulation No. 41;
(7) In the commuter category; or
(8) In the normal category, as a multi-engine certification level 4
airplane as defined in part 23 of this chapter.
* * * * *
Issued under authority provided by 49 U.S.C. 106(f), 44701(a),
44703 and Pub. L. 113-53 (127 Stat. 584; 49 U.S.C. 44704 note) in
Washington, DC, on December 12, 2016.
Michael P. Huerta,
Administrator.
[FR Doc. 2016-30246 Filed 12-21-16; 4:15 pm]
BILLING CODE 4910-13-P