[Federal Register Volume 77, Number 202 (Thursday, October 18, 2012)]
[Rules and Regulations]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-25604]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2012-1118; Special Conditions No. 25-469-SC]
Special Conditions: Airbus Model A318, A319, A320, and A321
Series Airplanes; Interaction of Systems and Structures
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
SUMMARY: These special conditions are issued for the Airbus Model A318,
A319, and A320 series airplanes with modification 160500 and Model A321
series airplanes with modification 160023 (Sharklet). These airplanes
will have novel or unusual design features when compared to the state
of technology envisioned in the airworthiness standards for transport
category airplanes. The design features are associated with the systems
that affect the structural performance of the airplane. The applicable
airworthiness regulations do not contain adequate or appropriate safety
standards for these design features. These special conditions contain
the additional safety standards that the Administrator considers
necessary to establish a level of safety equivalent to that established
by the existing airworthiness standards.
DATES: The effective date of these special conditions is October 11,
2012. We must receive your comments by December 3, 2012.
ADDRESSES: Send comments identified by docket number FAA-2012-1118
using any of the following methods:
Federal eRegulations Portal: Go to
http:[sol][sol]www.regulations.gov/ and follow the online instructions
for sending your comments electronically.
Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE., Washington, DC, between 8 a.m. and 5 p.m.,
Monday through Friday, except federal holidays.
Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: The FAA will post all comments it receives, without
change, to http:[sol][sol]www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket Web site, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478), as well as at
Docket: Background documents or comments received may be read at
http:[sol][sol]www.regulations.gov/ at any time. Follow the online
instructions for accessing the docket or go to the Docket Operations in
Room W12-140 of the West Building Ground Floor at 1200 New Jersey
Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through
Friday, except federal holidays.
FOR FURTHER INFORMATION CONTACT: Todd Martin, FAA, Airframe/Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone 425-227-1178; facsimile 425-227-1232.
SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and
opportunity for prior public comment on, these special conditions are
impracticable because these procedures would significantly delay
issuance of the design approval and thus delivery of the affected
aircraft. In addition, the substance of these special conditions has
been subject to the public comment process in several prior instances
with no substantive comments received. The FAA therefore finds that
good cause exists for making these special conditions effective upon
We invite interested people to take part in this rulemaking by
sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data.
We will consider all comments we receive by the closing date for
comments. We may change these special conditions based on the comments
On April 8, 2010, Airbus applied for a change to Type Certificate
No. A28NM to include modification 160500 on Airbus Model A318, A319,
and A320 series airplanes and modification 160023 on Model A321 series
airplanes for the installation of a ``Sharklet,'' a large wingtip
device. The Model A318, A319, A320, and A321 series airplanes are short
to medium-range, twin turbofan, transport category airplanes with a
maximum seating capacity of 136 to 220 passengers, a maximum takeoff
weight of 130,071 to 205,027 pounds, and a maximum operating altitude
of 39,800 feet.
FAA issued special conditions 25-ANM-23, effective December 15,
1988, originally applicable to Airbus Model A320 series airplanes and
later to the Model A318, A319, and A321 series airplanes. Those special
conditions included requirements for interactions of systems and
structures. Airbus requested, and FAA agrees, that these special
conditions be updated for the Airbus Model A318, A319, and A320 series
airplanes with modification 160500 and Model A321 series airplanes with
modification 160023 (Sharklet) and later derivatives to be consistent
with the latest European Aviation Safety Standards (EASA) standards and
the latest versions of the FAA special conditions issued on this
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulation (14
CFR) 21.101, Airbus must show that the Model A318, A319, A320, and A321
series airplanes, as changed, continue to meet the applicable
provisions of the regulations incorporated by reference in Type
Certificate No. A28NM or the applicable regulations in effect on the
date of application for the change. The regulations incorporated by
reference in the type certificate are commonly referred to as the
``original type certification basis.'' The regulations incorporated by
reference in Type Certificate No. A28NM are 14 CFR part 25, as amended
by Amendments 25-1 through 25-56, and special conditions 25-ANM-23. In
addition, the certification basis includes certain special conditions,
exemptions, or later amended sections of the applicable part that are
not relevant to these special conditions.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Model A318, A319, A320, and A321
series airplanes because of a novel or unusual design feature, special
conditions are prescribed under the provisions of Sec. 21.16.
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
include any other model that incorporates the same novel or unusual
design feature, or should any other model already included on the same
type certificate be modified to incorporate the same novel or unusual
design feature, the special conditions would also apply to the other
In addition to the applicable airworthiness regulations and special
conditions, the Model A318, A319, A320, and A321 series airplanes must
comply with the fuel vent and exhaust emission requirements of 14 CFR
part 34 and the noise certification requirements of 14 CFR part 36.
The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type-
certification basis under Sec. 21.101.
Novel or Unusual Design Features
The Airbus Model A318, A319, and A320 series airplanes with
modification 160500 and Model A321 series airplanes with modification
160023 (Sharklet) will incorporate the following novel or unusual
design features: Systems that, directly or as a result of failure or
malfunction, affect structural performance. These systems include
flight control systems, autopilots, stability augmentation systems,
load alleviation systems, fuel management systems, and other sytems.
These airplanes are equipped with systems that, directly or as a
result of failure or malfunction, affect its structural performance.
Current regulations do not take into account loads for the aircraft due
to the effects of systems on structural performance including normal
operation and failure conditions with strength levels related to
probability of occurrence. These special conditions define criteria to
be used in the assessment of the effects of these systems on
As discussed above, these special conditions are applicable to the
Airbus Model A318, A319, A320 series airplanes with modification 160500
and Model A321 series airplanes with modification 160023 (Sharklet).
Should Airbus apply at a later date for a change to the type
certificate to include another model incorporating the same novel or
unusual design features, the special conditions would apply to that
model as well.
This action affects only certain novel or unusual design features
on the model series of airplanes listed above. It is not a rule of
The substance of these special conditions has been subjected to the
notice and comment period in several prior instances and has been
derived without substantive change from those previously issued. It is
unlikely that prior public comment would result in a significant change
from the substance contained herein. Therefore, because a delay would
significantly affect the certification of the airplane, which is
imminent, the FAA has determined that prior public notice and comment
are unnecessary and impracticable, and good cause exists for adopting
these special conditions upon issuance. The FAA is requesting comments
to allow interested persons to submit views that may not have been
submitted in response to the prior opportunities for comment described
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for Airbus Model A318, A319, and A320
series airplanes with modification 160500 and Model A321 with
modification 160023 (Sharklet) series airplanes.
For airplanes equipped with systems that affect structural
performance, either directly or as a result of a failure or
malfunction, the influence of these systems and their failure
conditions must be taken into account when showing compliance with the
requirements of 14 CFR part 25 subparts C and D. The following criteria
must be used for showing compliance with these special conditions for
airplanes equipped with flight control systems, autopilots, stability
augmentation systems, load alleviation systems, fuel management
systems, and other systems that either directly or as a result of
failure or malfunction affect structural performance. If these special
conditions are used for other systems, it may be necessary to adapt the
criteria to the specific system.
(a) The criteria defined herein only address the direct structural
consequences of the system responses and performances and cannot be
considered in isolation but should be included in the overall safety
evaluation of the airplane. These criteria may in some instances
duplicate standards already established for this evaluation. These
criteria are only applicable to structure whose failure could prevent
continued safe flight and landing. Specific criteria that define
acceptable limits on handling characteristics or stability requirements
when operating in the system degraded or inoperative mode are not
provided in these special conditions.
(b) Depending upon the specific characteristics of the airplane,
additional studies may be required that go beyond the criteria provided
in these special conditions in order to demonstrate the capability of
the airplane in meeting other realistic conditions such as alternative
gust or maneuver descriptions for an airplane equipped with a load
(c) The following definitions are applicable to these special
Structural performance: Capability of the airplane to meet the
structural requirements of 14 CFR part 25.
Flight limitations: Limitations that can be applied to the airplane
flight conditions following an in-flight occurrence and that are
included in the flight manual (e.g., speed limitations, avoidance of
severe weather conditions, etc.).
Operational limitations: Limitations, including flight limitations,
that can be applied to the airplane operating conditions before
dispatch (e.g., fuel, payload and Master Minimum Equipment List
Probabilistic terms: The probabilistic terms (probable, improbable,
extremely improbable) used in these special conditions are the same as
those used in Sec. 25.1309.
Failure condition: The term failure condition is the same as that
used in Sec. 25.1309, however, these special conditions apply only to
system failure conditions that affect the structural performance of the
airplane (e.g., system failure conditions that induce loads, change the
response of the airplane to inputs such as gusts or pilot actions, or
lower flutter margins).
2. Effects of Systems on Structures
The following criteria will be used in determining the influence of
a system and its failure conditions on the airplane structure.
(a) System fully operative. With the system fully operative, the
(1) Limit loads must be derived in all normal operating
configurations of the system from all the limit conditions
specified in Subpart C (or defined by special condition or equivalent
level of safety in lieu of those specified in Subpart C), taking into
account any special behavior of such a system or associated functions
or any effect on the structural performance of the airplane that may
occur up to the limit loads. In particular, any significant
nonlinearity (rate of displacement of control surface, thresholds, or
any other system nonlinearities) must be accounted for in a realistic
or conservative way when deriving limit loads from limit conditions.
(2) The airplane must meet the strength requirements of part 25
(static strength, residual strength), using the specified factors to
derive ultimate loads from the limit loads defined above. The effect of
nonlinearities must be investigated beyond limit conditions to ensure
the behavior of the system presents no anomaly compared to the behavior
below limit conditions. However, conditions beyond limit conditions
need not be considered when it can be shown that the airplane has
design features that will not allow it to exceed those limit
(3) The airplane must meet the aeroelastic stability requirements
of Sec. 25.629.
(b) System in the failure condition. For any system failure
condition not shown to be extremely improbable, the following apply:
(1) At the time of occurrence, starting from 1-g level flight
conditions, a realistic scenario, including pilot corrective actions,
must be established to determine the loads occurring at the time of
failure and immediately after failure.
(i) For static strength substantiation, these loads, multiplied by
an appropriate factor of safety that is related to the probability of
occurrence of the failure, are ultimate loads to be considered for
design. The factor of safety (FS) is defined in Figure 1.
[GRAPHIC] [TIFF OMITTED] TR18OC12.000
(ii) For residual strength substantiation, the airplane must be
able to withstand two thirds of the ultimate loads defined in
subparagraph 2(b)(1)(i). For pressurized cabins, these loads must be
combined with the normal operating differential pressure.
(iii) Freedom from aeroelastic instability must be shown up to the
speeds defined in Sec. 25.629(b)(2). For failure conditions that
result in speeds beyond VC/MC, freedom from
aeroelastic instability must be shown to increased speeds, so that the
margins intended by Sec. 25.629(b)(2) are maintained.
(iv) Failures of the system that result in forced structural
vibrations (oscillatory failures) must not produce loads that could
result in detrimental deformation of primary structure.
(2) For the continuation of the flight. For the airplane, in the
system failed state and considering any appropriate reconfiguration and
flight limitations, the following apply:
(i) The loads derived from the following conditions (or defined by
special condition or equivalent level of safety in lieu of the
following conditions) at speeds up to VC/MC, or
the speed limitation prescribed for the remainder of the flight, must
(A) The limit symmetrical maneuvering conditions specified in Sec.
25.331 and in Sec. 25.345.
(B) The limit gust and turbulence conditions specified in Sec.
25.341 and in Sec. 25.345.
(C) The limit rolling conditions specified in Sec. 25.349 and the
limit unsymmetrical conditions specified in Sec. 25.367 and Sec.
25.427(b) and (c).
(D) The limit yaw maneuvering conditions specified in Sec. 25.351.
(E) The limit ground loading conditions specified in Sec. Sec.
25.473 and 25.491.
(ii) For static strength substantiation, each part of the structure
must be able to withstand the loads in paragraph 2(b)(2)(i) of the
special conditions multiplied by a factor of safety depending on the
probability of being in this failure state. The factor of safety is
defined in Figure 2.
[GRAPHIC] [TIFF OMITTED] TR18OC12.001
Qj = (Tj)(Pj)
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per
Note: If Pj is greater than 10-3 per
flight hour, then a 1.5 factor of safety must be applied to all
limit load conditions specified in Subpart C.
(iii) For residual strength substantiation, the airplane must be
able to withstand two thirds of the ultimate loads defined in paragraph
2(b)(2)(ii) of the special conditions. For pressurized cabins, these
loads must be combined with the normal operating differential pressure.
(iv) If the loads induced by the failure condition have a
significant effect on fatigue or damage tolerance then their effects
must be taken into account.
(v) Freedom from aeroelastic instability must be shown up to a
speed determined from Figure 3. Flutter clearance speeds V' and V'' may
be based on the speed limitation specified for the remainder of the
flight using the margins defined by Sec. 25.629(b).
[GRAPHIC] [TIFF OMITTED] TR18OC12.002
V' = Clearance speed as defined by Sec. 25.629(b)(2).
V'' = Clearance speed as defined by Sec. 25.629(b)(1).
Qj = (Tj)(Pj) where:
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per
Note: If Pj is greater than 10-3 per
flight hour, then the flutter clearance speed must not be less than
(vi) Freedom from aeroelastic instability must also be shown up to
V' in Figure 3 above, for any probable system failure condition
combined with any damage required or selected for investigation by
(3) Consideration of certain failure conditions may be required by
other sections of 14 CFR part 25 regardless of calculated system
reliability. Where analysis shows the probability of these failure
conditions to be less than 10-9, criteria other than those
specified in this paragraph may be used for structural substantiation
to show continued safe flight and landing.
(c) Failure indications. For system failure detection and
indication, the following apply:
(1) The system must be checked for failure conditions, not
extremely improbable, that degrade the structural capability below the
level required by part 25 or significantly reduce the reliability of
the remaining system. As far as reasonably practicable, the flight crew
must be made aware of these failures before flight. Certain elements of
the control system, such as mechanical and hydraulic components, may
use special periodic inspections, and electronic components may use
daily checks, in lieu of detection and indication systems to achieve
the objective of this requirement. These certification maintenance
requirements must be limited to components that are not readily
detectable by normal detection and indication systems and where service
history shows that inspections will provide an adequate level of
(2) The existence of any failure condition, not extremely
improbable, during flight that could significantly affect the
structural capability of the airplane and for which the associated
reduction in airworthiness can be minimized by suitable flight
limitations, must be signaled to the flight crew. For example, failure
conditions that result in a factor of safety between the airplane
strength and the loads of subpart C below 1.25, or flutter margins
below V'', must be signaled to the crew during flight.
(d) Dispatch with known failure conditions. If the airplane is to
dispatched in a known system failure condition that affects structural
performance, or affects the reliability of the remaining system to
maintain structural performance, then the provisions of these special
conditions must be met, including the provisions of paragraph 2(a) for
the dispatched condition, and paragraph 2(b) for subsequent failures.
Expected operational limitations may be taken into account in
establishing Pj as the probability of failure occurrence for
determining the safety margin in Figure 1. Flight limitations and
expected operational limitations may be taken into account in
establishing Qj as the combined probability of being in the
dispatched failure condition and the subsequent failure condition for
the safety margins in Figures 2 and 3. These limitations must be such
that the probability of being in this combined failure state and then
subsequently encountering limit load conditions is extremely
improbable. No reduction in these safety margins is allowed if the
subsequent system failure rate is greater than 10-3 per
Issued in Renton, Washington, on October 11, 2012.
Manager, Transport Airplane Directorate, Aircraft Certification
[FR Doc. 2012-25604 Filed 10-17-12; 8:45 am]
BILLING CODE 4910-13-P