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[Federal Register Volume 89, Number 191 (Wednesday, October 2, 2024)]
[Proposed Rules]
[Pages 80155-80157]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-22600]

[[Page 80155]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2325; Project Identifier AD-2024-00412-E]
RIN 2120-AA64

Airworthiness Directives; CFM International, S.A. Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain CFM International, S.A. (CFM) Model LEAP-1A and LEAP-1C 
engines. This proposed AD was prompted by an investigation of an in-
flight shut down event that determined the aft arm of the high-pressure 
turbine (HPT) rotor interstage seal had failed. This proposed AD would 
require removal from service and replacement of the HPT rotor 
interstage seal for LEAP-1A engines. Since the HPT rotor interstage 
seal part number is interchangeable between LEAP-1A and LEAP-1C, this 
proposed AD will also prohibit installation of these affected parts 
onto any LEAP-1A or LEAP-1C engine. The FAA is proposing this AD to 
address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by November 
18, 2024.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to regulations.gov. Follow 
the instructions for submitting comments.
     Fax: (202) 493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2024-2325; or in person at Docket Operations between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD 
docket contains this NPRM, any comments received, and other 
information. The street address for Docket Operations is listed above.
    Material Incorporated by Reference:
     For CFM material identified in this proposed AD, contact 
CFM, GE Aviation Fleet Support, 1 Neumann Way, M/D Room 285, 
Cincinnati, OH 45215; phone: (877) 432-3272; email: 
[email protected].
     You may view this material at the FAA, Airworthiness 
Products Section, Operational Safety Branch, 1200 District Avenue, 
Burlington, MA 01803. For information on the availability of this 
material at the FAA, call (817) 222-5110.

FOR FURTHER INFORMATION CONTACT: Mehdi Lamnyi, Aviation Safety 
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: 
(781) 238-7743; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2024-2325; 
Project Identifier AD-2024-00412-E'' at the beginning of your comments. 
The most helpful comments reference a specific portion of the proposal, 
explain the reason for any recommended change, and include supporting 
data. The FAA will consider all comments received by the closing date 
and may revise this proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
regulations.gov, including any personal information you provide. The 
agency will also post a report summarizing each substantive verbal 
contact received about this NPRM.

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 this NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, 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 they will not be placed in the public 
docket of this NPRM. Submissions containing CBI should be sent to Mehdi 
Lamnyi, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des 
Moines, WA 98198. Any commentary that the FAA receives which is not 
specifically designated as CBI will be placed in the public docket for 
this rulemaking.

Background

    On May 19, 2022, an Airbus Model A320neo airplane powered by CFM 
Model LEAP-1A26 engines experienced an in-flight shutdown. Ground 
inspection following the event found that several low-pressure turbine 
blades had broken and metal had entered the exhaust. A manufacturer 
investigation later determined that the aft arm of the HPT rotor 
interstage seal had failed due to a non-conforming surface condition in 
the fillet area coupled with higher-than-expected operating stress due 
to friction. Three additional engines have been reported with shop 
finds or failure of the aft arm of the HPT rotor interstage seal. This 
condition, if not addressed, could result in failure of one or more 
engines, loss of thrust control, and loss of the airplane.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed the following CFM material:
     CFM Service Bulletin (SB) LEAP-1A-72-00-0525-01A-930A-D, 
Issue 002-00, dated June 28, 2024, which provides the serial numbers 
(S/Ns) of the affected HPT rotor interstage seals for LEAP-1A engines.
     CFM SB LEAP-1C-72-00-0124-01A-930A-D, Issue 001, dated 
September 5, 2024, which provides the S/Ns of the affected HPT rotor 
interstage seals that are excluded from installation onto LEAP-1C 
engines.
    This material also includes instructions for removal and 
installation of the HPT rotor interstage seal. This material is 
reasonably available because the interested parties have access to it 
through their normal course of business or by the means identified in 
the ADDRESSES section.

Proposed AD Requirements in This NPRM

    This proposed AD would require removal from service and replacement 
of the HPT rotor interstage seal.

[[Page 80156]]

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 56 engines installed on airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                  Cost per        Cost on U.S.
               Action                        Labor cost          Parts cost        product         operators
----------------------------------------------------------------------------------------------------------------
Replace HPT rotor interstage seal...  12 work-hours x $85 per        $195,000        $196,020        $10,977,120
                                       hour = $1,020.
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Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. 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.
    The FAA is issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: General requirements. 
Under that section, Congress charges the FAA with promoting safe flight 
of civil aircraft in air commerce by prescribing regulations for 
practices, methods, and procedures the Administrator finds necessary 
for safety in air commerce. This regulation is within the scope of that 
authority because it addresses an unsafe condition that is likely to 
exist or develop on products identified in this rulemaking action.

Regulatory Findings

    The FAA determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national government and the States, or on the distribution 
of power and responsibilities among the various levels of government.
    For the reasons discussed above, I certify this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and
    (3) Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

CFM International, S.A.: Docket No. FAA-2024-2325; Project 
Identifier AD-2024-00412-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by November 18, 2024.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to the following CFM International, S.A. (CFM) 
engines:
    (1) Model LEAP-1A23, LEAP-1A24, LEAP-1A24E1, LEAP-1A26, LEAP-
1A26CJ, LEAP-1A26E1, LEAP-1A29, LEAP-1A29CJ, LEAP-1A30, LEAP-1A32, 
LEAP-1A33, LEAP-1A33B2, and LEAP-1A35A engines.
    (2) Model LEAP-1C28, LEAP-1C30, and LEAP-1C30B1 engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7250, Turbine 
Section.

(e) Unsafe Condition

    This AD was prompted by an investigation of an in-flight shut 
down event that determined the aft arm of the high-pressure turbine 
(HPT) rotor interstage seal had failed. The FAA is issuing this AD 
to prevent failure of the HPT rotor interstage seal. The unsafe 
condition, if not addressed, could result in failure of one or more 
engines, loss of thrust control, and loss of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    (1) For LEAP-1A engines having an HPT rotor interstage seal 
installed with a part number (P/N) and serial number (S/N) listed in 
Table 1 of CFM Service Bulletin (SB) LEAP-1A-72-00-0525-01A-930A-D, 
Issue 002-00, dated June 28, 2024 (CFM SB LEAP-1A-72-00-0525-01A-
930A-D Issue 002-00), at the next engine shop visit or before 
exceeding the applicable cyclic threshold in Table 1 to paragraph 
(g)(1) of this AD, whichever occurs first after the effective date 
of this AD, remove the affected HPT rotor interstage seal from 
service and replace with a part eligible for installation.

  Table 1 to Paragraph (g)(1)--Removal Thresholds for Each Engine Model
------------------------------------------------------------------------
              Engine model                   Removal cyclic threshold
------------------------------------------------------------------------
LEAP-1A23, LEAP-1A24, LEAP-1A24E1, LEAP-  11,100 cycles since new (CSN)
 1A26, LEAP-1A26E1, LEAP-1A29, LEAP-       accumulated on the affected
 1A30, LEAP-1A32, LEAP-1A33, LEAP-         part.
 1A33B2, and LEAP-1A35A.
LEAP-1A26CJ and LEAP-1A29CJ.............  9,700 CSN accumulated on the
                                           affected part.
------------------------------------------------------------------------

    (2) For LEAP-1A engines having an HPT rotor interstage seal 
installed with a P/N and S/N listed in Table 2 of CFM SB LEAP-1A-72-
00-0525-01A-930A-D Issue 002-00, at the next piece part exposure or 
before exceeding the applicable cyclic threshold in Table 1 to 
paragraph (g)(1) of this AD, whichever occurs first after the 
effective date of this AD, remove the affected HPT rotor interstage 
seal from service and replace with a part eligible for installation.

(h) Installation Prohibition

    (1) After the effective date of this AD, do not install an HPT 
rotor interstage seal having a P/N and S/N listed in Table 1 or 
Table 2 of CFM SB LEAP-1A-72-00-0525-

[[Page 80157]]

01A-930A-D Issue 002-00, in any LEAP-1A engine.
    (2) After the effective date of this AD, do not install an HPT 
rotor interstage seal having a P/N and S/N listed in Table 1 of CFM 
SB LEAP-1C-72-00-0124-01A-930A-D, Issue 001, dated September 5, 
2024, in any LEAP-1C engine.

(i) Definitions

    For the purpose of this AD:
    (1) ``LEAP-1A engines'' are CFM Model LEAP-1A23, LEAP-1A24, 
LEAP-1A24E1, LEAP-1A26, LEAP-1A26CJ, LEAP-1A26E1, LEAP-1A29, LEAP-
1A29CJ, LEAP-1A30, LEAP-1A32, LEAP-1A33, LEAP-1A33B2, LEAP-1A35A 
engines.
    (2) ``LEAP-1C engines'' are CFM Model LEAP-1C28, LEAP-1C30, and 
LEAP-1C30B1 engines.
    (3) A ``part eligible for installation'' is any HPT rotor 
interstage seal having a P/N and S/N that is not listed in Table 1 
or Table 2 of CFM SB LEAP-1A-72-00-0525-01A-930A-D Issue 002-00.
    (4) An ``engine shop visit'' is the induction of an engine into 
the shop for maintenance involving the separation of major mating 
engine flanges, except for the separation of engine flanges solely 
for the purposes of transportation without subsequent engine 
maintenance.
    (5) A ``piece-part exposure'' is when the HPT rotor interstage 
seal is separated from the HPT rotor assembly.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, AIR-520 Continued Operational Safety Branch, 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. In accordance with 14 
CFR 39.19, send your request to your principal inspector or local 
Flight Standards District Office, as appropriate. If sending 
information directly to the manager of AIR-520 Continued Operational 
Safety Branch, send it to the attention of the person identified in 
paragraph (k)(1) of this AD and email to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(k) Additional Information

    For more information about this AD, contact Mehdi Lamnyi, 
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, 
WA 98198; phone: (781) 238-7743; email: [email protected].

(l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the material listed in this 
paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this material as applicable to do the actions 
required by this AD, unless the AD specifies otherwise.
    (i) CFM International, S.A. (CFM) Service Bulletin LEAP-1A-72-
00-0525-01A-930A-D, Issue 002-00, dated June 28, 2024.
    (ii) CFM Service Bulletin LEAP-1C-72-00-0124-01A-930A-D, Issue 
001, dated September 5, 2024.
    (3) For CFM material identified in this AD, contact CFM, GE 
Aviation Fleet Support, 1 Neumann Way, M/D Room 285, Cincinnati, OH 
45215; phone: (877) 432-3272; email: [email protected].
    (4) You may view this material at the FAA, Airworthiness 
Products Section, Operational Safety Branch, 1200 District Avenue, 
Burlington, MA 01803. For information on the availability of this 
material at the FAA, call (817) 222-5110.
    (5) You may view this material at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].

    Issued on September 27, 2024.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2024-22600 Filed 10-1-24; 8:45 am]
BILLING CODE 4910-13-P
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