Rule2025-14711
Special Conditions: CFM International, LEAP-1A and -1C Engine Models; Incorporation of Woven Composite Fan Blades
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
August 4, 2025
Effective
August 4, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
This action amends Special Condition No. 33-015-SC for the CFM International (CFM) Model LEAP-1A and LEAP-1C engines. These engines have a novel or unusual design feature associated with the engine fan blades--incorporation of woven composite fan blades. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions, as amended, 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.
Full Text
<html>
<head>
<title>Federal Register, Volume 90 Issue 147 (Monday, August 4, 2025)</title>
</head>
<body><pre>
[Federal Register Volume 90, Number 147 (Monday, August 4, 2025)]
[Rules and Regulations]
[Pages 36375-36378]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-14711]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 33
[Docket No. FAA-2014-0637; Special Conditions No. 33-015-SC]
Special Conditions: CFM International, LEAP-1A and -1C Engine
Models; Incorporation of Woven Composite Fan Blades
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments; amendment.
-----------------------------------------------------------------------
SUMMARY: This action amends Special Condition No. 33-015-SC for the CFM
International (CFM) Model LEAP-1A and LEAP-1C engines. These engines
have a novel or unusual design feature associated with the engine fan
blades--incorporation of woven composite fan blades. The applicable
airworthiness regulations do not contain adequate or appropriate safety
standards for this design feature. These special conditions, as
amended, 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: This action is effective on CFM International on August 4, 2025.
Send comments on or before September 18, 2025.
ADDRESSES: Send comments identified by Docket No. FAA-2014-0637 using
any of the following methods:
<bullet> Federal eRegulations Portal: Go to <a href="http://www.regulations.gov">www.regulations.gov</a> and
follow the online instructions for sending your comments
electronically.
<bullet> 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.
[[Page 36376]]
<bullet> 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.
<bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
Docket: Background documents or comments received may be read at
<a href="http://www.regulations.gov">www.regulations.gov</a> at any time. Follow the online instructions for
accessing the docket or go 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.
FOR FURTHER INFORMATION CONTACT: Philip Haberlen, Engine and Propulsion
Section, AIR-625, Technical Policy Branch, Policy and Standards
Division, Federal Aviation Administration, FAA AIR Office, 1200
District Ave., Burlington, MA 01803; telephone (781) 238-7770; email
<a href="/cdn-cgi/l/email-protection#9ecef6f7f2f7eeb0f6fffcfbecf2fbf0def8ffffb0f9f1e8"><span class="__cf_email__" data-cfemail="2c7c444540455c02444d4e495e4049426c4a4d4d024b435a">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: The substance of these special conditions
has been published in the Federal Register for public comment in
several prior instances with no substantive comments received.
Therefore, the FAA finds, pursuant to 14 CFR 11.38(b), that new
comments are unlikely, and notice and comment prior to this publication
are unnecessary.
Privacy
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in title
14, Code of Federal Regulations (14 CFR) 11.35, the FAA will post all
comments received without change to <a href="http://www.regulations.gov">www.regulations.gov</a>, including any
personal information you provide. The FAA will also post a report
summarizing each substantive verbal contact received about these
special conditions.
Confidential Business Information
Confidential Business Information (CBI) is commercial or financial
information that is both customarily and actually treated as private by
its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552),
CBI is exempt from public disclosure. If your comments responsive to
these special conditions contain commercial or financial information
that is customarily treated as private, that you actually treat as
private, and that is relevant or responsive to these special
conditions, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as ``PROPIN.'' The FAA will treat such marked submissions as
confidential under the FOIA, and the indicated comments will not be
placed in the public docket of these special conditions. Send
submissions containing CBI to the individual listed in the For Further
Information Contact section above. Comments the FAA receives, which are
not specifically designated as CBI, will be placed in the public docket
for these special conditions.
Comments Invited
The FAA invites 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.
The FAA will consider all comments received by the closing date for
comments. The FAA may change these special conditions based on the
comments received.
Background
On June 27, 2012, CFM International (CFM) applied for a new type
certificate (TC) to include the LEAP-1A and -1C engine models. The LEAP
engine models are high-bypass-ratio engines that incorporate a novel
and unusual design feature--new woven composite fan blades. The woven
composite fan blades will have significant differences in material
property characteristics when compared to conventionally designed fan
blades using non-composite metallic materials.
The FAA issued Special Condition No. 33-015-SC for this design
feature on June 1, 2015. Special Condition No. 33-015-SC became
effective on July 9, 2015 (80 FR 32440, June 9, 2015). The FAA issued
TC E00089EN on November 20, 2015. Subsequently, CFM highlighted an
error in the similar Special Condition No. 33-017-SC for the LEAP-1B
engine models and submitted a type design change request on July 18,
2024. Upon review, the FAA determined that Special Condition No. 33-
015-SC, which applies to the LEAP-1A and -1C engine models, contained
the same error. The FAA is proposing changes to Special Condition No.
33-015-SC based on CFM's application.
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.17, CFM must show that the Model LEAP-1A and -1C engines meet
the applicable provisions of the applicable regulations in effect on
the date of application, except as detailed in paragraphs 21.101(b) and
(c). The FAA has determined the following certification basis for the
LEAP-1A and -1C engine models:
Title 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 Administrator finds that the applicable airworthiness
regulations do not contain adequate or appropriate safety standards for
the LEAP-1A and -1C engine models 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 TC for that model be amended later to
include any other model that incorporates the same novel or unusual
design feature, the special conditions would also apply to the other
model under Sec. 21.101.
In addition to complying with the applicable airworthiness
regulations and special conditions, the CFM LEAP-1A and -1C engine
models must also 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-1A and -1C engine models will incorporate the following
novel or unusual design feature:
The LEAP-1A and -1C engine models will incorporate woven composite
fan blades. The woven composite fan blades will have significant
differences in material property characteristics when compared to
conventionally designed fan blades using non-composite metallic
materials. Composite material design provides the capability to
incorporate multiple load paths and crack arresting features that
prevent delamination or crack propagation to blade failure during the
life of the blade.
Discussion
The woven composite fan blades are a novel and unusual design
feature that require additional airworthiness standards for type
certification of the LEAP-1A and -1C engine models. The current
requirements of Sec. 33.94 are based on single-load path metallic fan
blade characteristics and service history
[[Page 36377]]
and are not appropriate for the unusual design features of the woven
composite fan blade found on the CFM LEAP series turbofan engines.
The properties of a composite blade are highly dependent of the
composite ply configuration, matrix material, and manufacturing
methods. The CFM LEAP engine incorporates 3-D woven resin transfer
molding (RTM) technology in the design and manufacture of the blade.
FAA requires that CFM conduct the required material testing per
Sec. 33.15 to determine material characteristics that include the
effects of defects, manufacturing variations, contamination,
environmental effect, and service damage on the material capability and
blade life.
Composite material design provides the capability to incorporate
multiple load paths and crack arresting features that prevent
delamination or crack propagation to blade failure during the life of
the blade. The probability of failure that an appropriately designed
composite fan blade will fail below the inner annulus flow path line
may be highly improbable. The airworthiness regulations of 14 CFR part
33 do not contain adequate or appropriate safety standards for an
aircraft engine incorporating these novel or unusual design features
i.e., woven composite fan blades, including release of the fan blade
under Sec. 33.94(a)(1) at the inner annulus flow path line (only the
airfoil) instead of the outermost retention feature.
Instead of blade failure at the outermost retention groove
currently required by Sec. 33.94(a)(1), the FAA has determined that a
more realistic blade-out test can be achieved with a fan blade failure
at the inner annulus flow path line i.e., releasing only the airfoil.
Additionally, the FAA considers any change to the design,
manufacturing, materials, or service management to the blade below the
inner annulus flow path to be a change that could affect the blade
integrity. Therefore, the FAA has determined that the blade must be
marked with a part and serial number, and that additional integrity
requirements must be applied to the blade below the inner annulus flow
path line.
Special conditions are necessary to ensure that the LEAP-1A and -1C
woven composite design fan blades account for the differences in
material properties and failure modes relative to conventional single-
load path metallic blades. In addition, different containment
requirements may be applied provided CFM shows 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.
The FAA, GE, and CFM recently found that the LEAP-1B proposed
special conditions as they appeared in the applicable certification
issue paper and the published special conditions do not accurately
reflect one of the agreed-upon criterion for the proposed woven fan
blade composite design. The FAA and CFM intended, as reflected in the
compliance data for the LEAP-1B TC and certification issue paper, that
the total probability of hazardous engine effects should be accounted
for rather than the probability of an individual blade retention system
failure as stated in paragraph (e), of the original special conditions.
The design similarity of the fan blade between the CFM LEAP-1B and the
CFM LEAP-1A and -1C prompted the need to correct paragraph (e) within
both sets of special conditions to ensure proper design. These amended
special conditions correct this error in the published special
conditions for the CFM LEAP-1A and -1C engines and are in line with CFM
and FAA's intention.
Paragraph (e) as originally issued for Special Condition No. 33-
015-SC reads as follows:
(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 10<SUP>-9</SUP> per engine flight hour.
The new paragraph will now read, (consistent with the TC compliance
data and Special Condition Nos. 33-007-SC, published April 24, 2009,
and 33-018-SC, published March 30, 2017):
(e) Substantiate that, during the service life of the engine, the
total probability of the occurrence of a hazardous engine effect
defined in Sec. 33.75 due to an individual blade retention system
failure resulting from all possible causes will be extremely
improbable, with a cumulative calculated probability of failure of less
than 10<SUP>-9</SUP> per engine flight hour.
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.
Applicability
As discussed above, these special conditions, as amended, are
applicable to the model for which they are issued. Should the TC for
that model be amended later to include any other model that
incorporates the same novel or unusual design feature, or should any
other model already included on the same TC be modified to incorporate
the same novel or unusual design feature, these special conditions
would apply to the other model as well.
Conclusion
This action affects only a certain novel or unusual design feature
on the LEAP-1A and -1C engine models.
List of Subjects in 14 CFR Part 33
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
Authority Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702, and
44704.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following amended special conditions are issued as
part of the type certification basis for CFM International (CFM) LEAP-
1A and -1C engine models.
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-1A and -1C 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 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
[[Page 36378]]
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), (2), and (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 the occurrence of a hazardous engine effect
defined in Sec. 33.75 due to an individual blade retention system
failure resulting from all possible causes will be extremely
improbable, with a cumulative calculated probability of failure of less
than 10<SUP>-9</SUP> 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 in Des Moines, Washington, on July 30, 2025.
Michael T. Thompson,
Acting Manager, Technical Policy Branch, Policy and Standards Division,
Aircraft Certification Service.
[FR Doc. 2025-14711 Filed 8-1-25; 8:45 am]
BILLING CODE 4910-13-P
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>Indexed from Federal Register on August 4, 2025.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.