[Federal Register Volume 80, Number 224 (Friday, November 20, 2015)]
[Rules and Regulations]
[Pages 72561-72563]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-29589]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Parts 33 and 35
[Docket No. FAA-2015-4220; Special Conditions No. 33-017-SC]
Special Conditions: CFM International, LEAP-1B Engine Models;
Incorporation of Woven Composite Fan Blades
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the CFM International
(CFM), LEAP-1B engine models. This engine model will have a novel or
unusual design feature associated with the engine: woven composite fan
blades. The applicable airworthiness regulations do not contain
adequate or appropriate safety standards for this design feature. 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 December 21,
2015.
We must receive your comments by December 7, 2015.
ADDRESSES: Send comments identified by docket number FAA-2015-4220
using any of the following methods:
Federal eRegulations Portal: Go to http://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 9 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://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 http://DocketsInfo.dot.gov.
Docket: Background documents or comments received may be read at
http://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: Alan Strom, Federal Aviation
Administration Engine and Propeller Directorate, Aircraft Certification
Service, ANE-112, 12 New England Executive Park, Burlington,
Massachusetts, 01803-5213; telephone (781) 238-7143; fax (781) 238-
7199; email [email protected].
SUPPLEMENTARY INFORMATION:
Comment History
The FAA has determined, in accordance with 5 U.S.C. 553(b)(3)(B)
and 553(d)(3), that notice and opportunity for prior public comment
heron are unnecessary because the substance of these special conditions
was subject to the public comment process in a prior instance, with no
substantive comments received. The FAA therefore finds that good cause
exists for making these special conditions effective upon issuance.
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Special condition No. Company/Airplane model
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33-14-02-SC............................... CFM/LEAP-1A
CFM/LEAP-1C
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[[Page 72562]]
Comments Invited
We invite interested people to participate in this rulemaking by
sending written comments, data, or views. The agency also invites
comments relating to the economic, environmental, energy, or federalism
impacts that might result from adopting the proposals in this document.
The most helpful comments reference a specific portion of the special
conditions, explain the reason for any recommended change, and include
supporting data. To ensure the docket does not contain duplicate
comments, commenters should send only one copy of written comments, or
if comments are filed electronically, commenters should submit only one
time.
We will file in the docket all comments we receive, as well as a
report summarizing each substantive public contact with FAA personnel
concerning this action. Before acting on this action, we will consider
all comments we receive on or before the closing date for comments. We
will consider comments filed after the comment period has closed if it
is possible to do so without incurring expense or delay. We may change
these special conditions based on the comments we receive.
Background
On May 9, 2013, CFM International (CFM) applied for a type
certificate for their new LEAP-1B engine model(s). The high-bypass-
ratio LEAP-1B engine models incorporate woven composite fan blades, a
novel or unusual design feature. These fan blades have:
Significant material property characteristic differences
from conventional, single-load path, metallic fan blades.
Multiple load path feature and/or crack arresting feature
capabilities that, during blade life, may prevent delamination, crack
propagation, and/or blade failure.
Because of their novel or unusual design, these fan blades:
Require additional airworthiness standards for LEAP-1B
engine type certification, to account for material property and failure
mode differences with conventional fan blades. The applicable
airworthiness regulations that exist do not contain appropriate safety
standards for these new blades.
May allow for application of different fan blade
containment requirements, if CFM demonstrates improved load path
features and/or crack arresting feature capabilities of the new blade
design, below the inner annulus flow path line.
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.17, CFM must show that the LEAP-1B engine models meet the
applicable provisions of the applicable regulations in effect on the
date of application, except as detailed in paragraph 21.101(b) and
paragraph 21.101(c).
The FAA has determined the following certification basis for the
LEAP-1B engine models: 14 CFR part 33, ``Airworthiness Standards:
Aircraft Engines,'' dated February 1, 1965, with Amendments 33-1
through 33-33, dated September 20, 2012.
If the FAA finds that the regulations in effect on the date of the
application for the change do not provide adequate or appropriate
safety standards for the LEAP-1B engine model(s) 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 engine model(s)
for which they are issued. Should the type certificate for that engine
model be amended later to include any other engine model(s) that
incorporates the same novel or unusual design feature, the special
conditions would also apply to the other engine model(s) under Sec.
21.101.
In addition to complying with the applicable product airworthiness
regulations and special conditions, the LEAP-1B engine model(s) must
comply with the fuel venting and exhaust emission requirements of 14
CFR part 34.
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. 21.17(a)(2).
Novel or Unusual Design Features
The LEAP-1B engine models incorporate a novel or unusual design
feature: Woven composite fan blades.
Discussion
As discussed in the summary section, the LEAP-1B engine model(s)
incorporate woven composite fan blades instead of conventional, single-
load path, metallic fan blades, which is a novel or unusual design
feature for aircraft engines. The applicable airworthiness regulations
do not contain adequate or appropriate safety standards for this design
feature.
Applicability
As discussed above, these special conditions are applicable to the
LEAP-1B engine model(s). Should CFM apply at a later date for a change
to the type certificate to include another model on the same type
certificate incorporating the same novel or unusual design feature, the
special conditions would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on LEAP-1B models of engine(s). It is not a rule of general
applicability and applies only to CFM, who requested FAA approval of
this engine feature.
List of Subjects in 14 CFR Parts 33 and 35
Aircraft, Engines, Aviation safety, Reporting and recordkeeping
requirements.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
0
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 CFM LEAP-1B engine model(s).
Special Conditions: CFM International LEAP-1B Model Turbofan
Engines
Accordingly, the Federal Aviation Administration (FAA) issues the
following special conditions as part of the type certification basis
for the CFM, LEAP-1B turbofan engines.
Part 33, Requirements. In addition to the airworthiness standards
in 14 CFR part 33, effective February 1, 1965, with Amendments 33-1
through 33-33 applicable to the CFM, LEAP-1B engine models:
(a) Conduct an engine fan blade containment test with the fan blade
failing at the inner annulus flow path line instead of at the outermost
retention groove.
(b) Substantiate by test and analysis, or other methods acceptable
to the FAA, that a fan disk and fan blade retention system with minimum
material properties can withstand, without failure, a centrifugal load
equal to two times the maximum load the retention system could
experience within approved engine operating limitations. The fan blade
retention system includes the portion of the fan blade from the inner
annulus flow path line inward to the blade dovetail, the blade
retention components, and the fan disk and fan blade attachment
features.
(c) Using a procedure approved by the FAA, establish an operating
limitation that specifies the maximum allowable
[[Page 72563]]
number of start-stop stress cycles for the fan blade retention system.
The life evaluation must include the combined effects of high-cycle and
low-cycle fatigue. If the operating limitation is less than 100,000
cycles, that limitation must be specified in Chapter 5 of the Engine
Manual Airworthiness Limitation Section. The procedure used to
establish the maximum allowable number of start-stop stress cycles for
the fan blade retention system will incorporate the integrity
requirements in paragraphs (c)(1), (c)(2), and (c)(3) of these special
conditions for the fan blade retention system.
(1) An engineering plan, which establishes and maintains that the
combinations of loads, material properties, environmental influences,
and operating conditions, including the effects of parts influencing
these parameters, are well known or predictable through validated
analysis, test, or service experience.
(2) A manufacturing plan that identifies the specific manufacturing
constraints necessary to consistently produce the fan blade retention
system with the attributes required by the engineering plan.
(3) A service management plan that defines in-service processes for
maintenance and repair of the fan blade retention system, which will
maintain attributes consistent with those required by the engineering
plan.
(d) Substantiate by test and analysis, or other methods acceptable
to the FAA, that the blade design below the inner annulus flow path
line provides multiple load paths and/or crack arresting features that
prevent delamination or crack propagation to blade failure during the
life of the blade.
(e) Substantiate that during the service life of the engine, the
total probability of an individual blade retention system failure
resulting from all possible causes, as defined in Sec. 33.75, will be
extremely improbable with a cumulative calculated probability of
failure of less than 10E-9 per engine flight hour.
(f) Substantiate by test or analysis that not only will the engine
continue to meet the requirements of Sec. 33.75 following a lightning
strike on the composite fan blade structure, but that the lightning
strike will not cause damage to the fan blades that would prevent
continued safe operation of the affected engine.
(g) Account for the effects of in-service deterioration,
manufacturing variations, minimum material properties, and
environmental effects during the tests and analyses required by
paragraphs (a), (b), (c), (d), (e), and (f) of these special
conditions.
(h) Propose fleet leader monitoring and field sampling programs
that will monitor the effects of engine fan blade usage and fan blade
retention system integrity.
(i) Mark each fan blade legibly and permanently with a part number
and a serial number.
Issued in Burlington, Massachusetts, on October 30, 2015.
Colleen D'Alessandro,
Manager, Engine & Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 2015-29589 Filed 11-19-15; 8:45 am]
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