Published 2024-04-29 · Federal Register document 2024-09110
Airworthiness Directives; CFM International, S.A. Engines
Publication summary
The FAA is adopting a new airworthiness directive (AD) for certain CFM International, S.A. (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, and LEAP-1A35A engines. This AD was prompted by a report of multiple aborted takeoffs and air turn-backs (ATBs) caused by high-pressure compressor (HPC) stall, which was induced by high levels of non-synchronous vibration (NSV). Additional manufacturer investigation revealed that wear on the No. 3 bearing spring finger housing can lead to high levels of NSV. This AD requires initial and repetitive calculations of the levels of NSV, inspection of the stage 2 high-pressure turbine (HPT) nozzle assembly honeycomb and HPT stator stationary seal honeycomb and, depending on the results of the calculations and inspections, replacement of certain parts. This AD also requires replacement of certain No. 3 bearing spring finger housings at a certain time. The FAA is issuing this AD to address the unsafe condition on these products.
Why this record is shown
Source: Federal Register annual FAA metadata. Acquired 2026-09-03T22:24:17.530091+00:00. The title, summary and date are source facts.
- Source revision
- federal_register_ad_metadata_2024-766a4e72ab891edd
- Source row
- results[102]
- Raw source SHA-256
- 766a4e72ab891edde7194caaae181bc9ea3fd0d54e65313e290f97067e3b7c5a
Final-rule publication
Recorded publication clauses
- AD identifier printed in this edition
- 2024-07-06
- Effective date printed in this edition
- 2024-06-03
Read 12 complete recorded clauses
Effective Date
(a) Effective Date
This airworthiness directive (AD) is effective June 3, 2024.
Exact source excerpt. Text positions 22609–22695, end exclusive, in the original decoded publication. SHA-256: 911e825a773148c29cdc7d50981edb0b20189bf9f7d97b96766eeee4fadc620e
Affected ADs
(b) Affected ADs
None.
Exact source excerpt. Text positions 22695–22724, end exclusive, in the original decoded publication. SHA-256: 871a4afc60ceeae06e8010585055188633d616078500c45937092bfe892239c0
Applicability wording · Applicability
(c) Applicability
This AD applies to CFM International, S.A. (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, and LEAP-1A35A engines with an installed No. 3 bearing
spring finger housing having part number (P/N) 2629M62G01 and a
serial number identified in Table 1 or Table 2 of CFM Service
Bulletin (SB) LEAP-1A-72-00-0504-01A-930A-D, Issue 002, dated
October 17, 2023 (CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002).
Exact source excerpt. Text positions 22724–23263, end exclusive, in the original decoded publication. SHA-256: 5b45b6b5ef122717868c584deebf5b5355d9137d63da7ba0261e8f3a039b4b1a
Subject
(d) Subject
Joint Aircraft System Component (JASC) Code 7230, Turbine Engine
Compressor Section.
Exact source excerpt. Text positions 23263–23367, end exclusive, in the original decoded publication. SHA-256: 151db2778cdfea7f0edc36f3dc91c040e977d403cabb29f1bb70ebf8781db722
Unsafe Condition
(e) Unsafe Condition
This AD was prompted by a report of multiple aborted takeoffs
and air turn-backs caused by high-pressure compressor (HPC) stall,
which was induced by high levels of non-synchronous vibration (NSV),
and an additional manufacturer investigation that revealed wear on
the No. 3 bearing spring finger housing. The FAA is issuing this AD
to prevent HPC stall. The unsafe condition, if not addressed, could
result in engine power loss at a critical phase of flight such as
takeoff or climb, loss of engine thrust control, reduced
controllability of the airplane, and loss of the airplane.
[[Page 33215]]
Exact source excerpt. Text positions 23367–24001, end exclusive, in the original decoded publication. SHA-256: f4930f28174a44e962d23dba76ef770068e52052ea87362dbd320392b20c1d84
Compliance
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
Exact source excerpt. Text positions 24001–24103, end exclusive, in the original decoded publication. SHA-256: 00fbfa31932483f627d0ce0a11cbd2e35e15d9231842b91ac85623ce533912d3
Required Actions
(g) Required Actions
(1) Within 125 flight cycles (FCs) after the effective date of
this AD and thereafter at intervals not to exceed 125 FCs, calculate
the NSV data in accordance with the Accomplishment Instructions,
paragraphs 5.A.(1) and 5.A.(3), or 5.B.(1) and 5.B.(3) of CFM SB
LEAP-1A-72-00-0504-01A-930A-D, Issue 002.
(2) If, during any calculation required by paragraph (g)(1) of
this AD, the NSV data exceeds the limits specified in the
Accomplishment Instructions, paragraph 5.A.(4)(a)1 or 5.B.(4)(a)1 of
CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002, discontinue the
calculations required by paragraph (g)(1) of this AD and within 150
FCs of the flight when these limits are exceeded:
(i) Remove from service the No. 3 bearing spring finger housing
having P/N 2629M62G01 and a serial number identified in Table 1 or
Table 2 of CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002, and
replace with a part eligible for installation.
(ii) Inspect the stage 2 high-pressure turbine (HPT) nozzle
assembly honeycomb for rubs in accordance with the Accomplishment
Instructions, paragraphs 5.A.(4)(a)3b1) or 5.B.(4)(a)3b1) of CFM SB
LEAP-1A-72-00-0504-01A-930A-D, Issue 002.
(iii) Inspect the HPT stator stationary seal honeycomb for rubs
in accordance with the Accomplishment Instructions, paragraphs
5.A.(4)(a)3b2) or 5.B.(4)(a)3b2) of CFM SB LEAP-1A-72-00-0504-01A-
930A-D, Issue 002.
(3) If, during the inspection required by paragraph (g)(2)(ii)
of this AD, the stage 2 HPT nozzle assembly honeycomb fails to meet
the serviceability criteria referenced in the Accomplishment
Instructions, paragraphs 5.A.(4)(a)3b1) or 5.B.(4)(a)3b1) of CFM SB
LEAP-1A-72-00-0504-01A-930A-D, Issue 002, before further flight,
replace the stage 2 HPT nozzle assembly honeycomb.
(4) If, during the inspection required by paragraph (g)(2)(iii)
of this AD, the HPT stator stationary seal honeycomb fails to meet
the serviceability criteria referenced in the Accomplishment
Instructions, paragraphs 5.A.(4)(a)3b2) or 5.B.(4)(a)3b2) of CFM SB
LEAP-1A-72-00-0504-01A-930A-D, Issue 002, before further flight,
replace the HPT stator stationary seal.
(5) At the next piece-part exposure after the effective date of
this AD, but before exceeding 9,900 cycles since new, replace the
No. 3 bearing spring finger housing having P/N 2629M62G01 and a
serial number identified in Table 1 of CFM SB LEAP-1A-72-00-0504-
01A-930A-D, Issue 002, with a part eligible for installation.
Exact source excerpt. Text positions 24103–26619, end exclusive, in the original decoded publication. SHA-256: 775e323239380cf75211ded17d4549649757473b454d2d60ff2da9829ab7428c
Terminating Action
(h) Terminating Action
Replacement of the No. 3 bearing spring finger housing having P/
N 2629M62G01 and a serial number identified in Table 1 or Table 2 of
CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002 with a part eligible
for installation, as specified in paragraphs (g)(2)(i) and (g)(5) of
this AD, constitutes terminating action for the calculations
required by paragraph (g)(1) of this AD.
Exact source excerpt. Text positions 26619–27026, end exclusive, in the original decoded publication. SHA-256: a787b00db1fe448b58f24f84a08e886ba2bbcf3659ba69d16504ca02e557c340
Definition
(i) Definition
For the purpose of this AD, a ``part eligible for installation''
is a No. 3 bearing spring finger housing that does not have P/N
2629M62G01 and a serial number identified in Table 1 or Table 2 of
CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002.
Exact source excerpt. Text positions 27026–27295, end exclusive, in the original decoded publication. SHA-256: a0f721e71e90c02a943309c94dfe76e14292601c05116d89c61933e37ea784d8
Alternative Methods of Compliance (AMOCs)
(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, AIR-520 Continued Operational
Safety Branch, send it to the attention of the person identified in
paragraph (k) of this AD and email it 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.
(3) For service information that contains steps that are labeled
as Required for Compliance (RC), the following provisions apply.
(i) The steps labeled as RC, including substeps under an RC step
and any figures identified in an RC step, that are required by
paragraph (g) of this AD must be done to comply with this AD. An
AMOC is required for any deviations to RC steps required by
paragraph (g) of this AD, including substeps and identified figures.
(ii) Steps not labeled as RC may be deviated from using accepted
methods in accordance with the operator's maintenance or inspection
program without obtaining approval of an AMOC, provided the RC
steps, including substeps and identified figures, can still be done
as specified, and the airplane can be put back in an airworthy
condition.
Exact source excerpt. Text positions 27295–28900, end exclusive, in the original decoded publication. SHA-256: 59094b4801951225272580b33b4ef295838f0301d0017cf81de4ee0b4e685d0f
Additional Information
(k) Additional Information
For more information about this AD, Mehdi Lamnyi, Aviation
Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198;
phone: (781) 238-7743; email: [email protected].
Exact source excerpt. Text positions 28900–29112, end exclusive, in the original decoded publication. SHA-256: 7159fe03dbefa5dade06c93286aaf245893495b5d416246f492f1830765560a9
Material Incorporated by Reference
(l) Material Incorporated by Reference
(1) The Director of the Federal Register approved the
incorporation by reference (IBR) of the service information listed
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this service information as applicable to do
the actions required by this AD, unless the AD specifies otherwise.
(i) CFM International, S.A. Service Bulletin LEAP-1A-72-00-0504-
01A-930A-D, Issue 002, dated October 17, 2023.
(ii) [Reserved]
(3) For service information, contact CFM International, S.A., 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 service information at 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/[email protected]">www.archives.gov/federal-register/cfr/[email protected].
Exact source excerpt. Text positions 29112–30330, end exclusive, in the original decoded publication. SHA-256: 733f563203f63cf2144e92f1b83b4344788f66612b0b367a3062c9b83f558ed0
No replacement link has been established from this edition. The complete historical rule chain and current legal effect remain unknown.
Find all recorded historical references to AD 2024-07-06 · 0 printed reference observations in this pinned collection.
These are observations from one dated publication. Current legal status is unknown; aircraft applicability, installed configuration, compliance and burden require separate evidence. Missing or unparsed conditions remain unknown.
Why these observations are shown
They were extracted offline from the same immutable official HTML source as the complete recorded text. The dated source wording, original text coordinates and exact quote digests are retained. PDF/text agreement and current regulatory effect have not been qualified.
Observation revision: whole-ad-publication-clause-observations-1.0.1. Text SHA-256: ae2c7bc9eea4f301897f9732472a629edcf41a375c6e3bc088d684b605e4d64f. Source manifest: a32b2b2db7744dfbb584f82407a24e76411cd7db0d147c3a83c574e50bd19ca1.
Official source · 2024-04-29
Publication text
This is the complete recorded text of this dated publication.
Current legal effect is unknown. Aircraft applicability, installed configuration and compliance require separate evidence. PDF/text agreement has not been evaluated.
Read the complete official publication text
[Federal Register Volume 89, Number 83 (Monday, April 29, 2024)]
[Rules and Regulations]
[Pages 33211-33215]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-09110]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2023-1991; Project Identifier AD-2023-00700-E;
Amendment 39-22727; AD 2024-07-06]
RIN 2120-AA64
Airworthiness Directives; CFM International, S.A. Engines
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain CFM International, S.A. (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, and LEAP-1A35A engines.
This AD was prompted by a report of multiple aborted takeoffs and air
turn-backs (ATBs) caused by high-pressure compressor (HPC) stall, which
was induced by high levels of non-synchronous vibration (NSV).
Additional manufacturer investigation revealed that wear on the No. 3
bearing spring finger housing can lead to high levels of NSV. This AD
requires initial and repetitive calculations of the levels of NSV,
inspection of the stage 2 high-pressure turbine (HPT) nozzle assembly
honeycomb and HPT stator stationary seal honeycomb and, depending on
the results of the calculations and inspections, replacement of certain
parts. This AD also requires replacement of certain No. 3 bearing
spring finger housings at a certain time. The FAA is issuing this AD to
address the unsafe condition on these products.
DATES: This AD is effective June 3, 2024.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of June 3,
2024.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2023-1991; 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 final rule, any comments received, and other
information. The address for Docket Operations is U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
<bullet> For service information, contact CFM International, S.A.,
GE Aviation Fleet Support, 1 Neumann Way, M/D Room 285, Cincinnati, OH
45215; phone: (877) 432-3272; email: [email protected].
<bullet> You may view this service information 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:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain CFM Model LEAP-
1A23, LEAP-1A24, LEAP-1A24E1,
[[Page 33212]]
LEAP-1A26, LEAP-1A26CJ, LEAP-1A26E1, LEAP-1A29, LEAP-1A29CJ, LEAP-1A30,
LEAP-1A32, LEAP-1A33, LEAP-1A33B2, and LEAP-1A35A engines. The NPRM
published in the Federal Register on October 11, 2023 (88 FR 70409).
The NPRM was prompted by a manufacturer's report of three aborted
takeoffs and two ATBs caused by HPC stall. Additional manufacturer
investigation revealed that wear on the No. 3 bearing spring finger
housing can lead to high levels of NSV, which could induce HPC stall.
As a result of its investigation, the manufacturer published service
information that specifies procedures for addressing this situation. In
the NPRM, the FAA proposed to require repetitive calculations of the
levels of NSV and, depending on the results of the calculations,
replacement of the No. 3 bearing spring finger housing. The FAA also
proposed to require, following the removal and replacement of the No. 3
bearing spring finger housing, inspection of the stage 2 HPT nozzle
assembly honeycomb and HPT stator stationary seal honeycomb for rubs
and, depending on findings, replacement of the stage 2 HPT nozzle
assembly honeycomb and HPT stator stationary seal. This FAA also
proposed to require replacement of the No. 3 bearing spring finger
housing regardless of calculated level of NSV at a certain time. The
FAA is issuing this AD to address the unsafe condition on these
products.
Discussion of Final Airworthiness Directive
Comments
The FAA received comments from four commenters. Commenters included
the Air Line Pilots Association, International (ALPA), American
Airlines (AA), Avianca Airlines (AVA), and CFM International (CFM).
ALPA supported the NPRM without change. The following presents the
comments received from AA, AVA, and CFM on the NPRM and the FAA's
response to each comment.
Request To Allow Automated Monitoring
AA requested that the FAA allow for the use of automated condition
monitoring solutions as an alternative to the accomplishment of the
manual review every 125 cycles required by paragraph (g)(1) of the
proposed AD. AA noted that automated monitoring solutions have already
been accepted to replace previously FAA required MRB tasks, and
allowing automated condition monitoring will provide a safer, more
robust solution that exceeds the minimum requirements outlined in CFM
Service Bulletin (SB) LEAP-1A-72-00-0504-01A-930A-D, Issue 001, dated
June 14, 2023, and the NPRM.
The FAA disagrees with the commenter's request to add automated
monitoring solutions as an alternative in the final rule. However, if
any operator prefers to address the unsafe condition by means other
than those specified in the referenced service information, they may
request approval for an alternative method of compliance (AMOC) in
accordance with paragraph (j) of this AD and, if approved, may use it
instead of the procedures specified in the service information and the
final rule. The FAA did not change this AD as a result of this comment.
Request To Include Customer Notification Report (CNR) in AD
Avianca requested that the CNR for exceedance of NSV thresholds be
included in the NPRM as an additional method of compliance for all
operators who have active CFM Diagnostics Monitoring. Avianca noted
that under the CFM Diagnostics Program, the parameter NSV TCF Max Vibe
Fleeting Event is actively monitored and if any exceedance is detected,
a CNR is triggered for NSV exceedance.
The FAA disagrees with the commenter's request to add CNR for NSV
thresholds exceedance as an additional method of compliance in the
final rule. However, if any operator prefers to address the unsafe
condition by means other than those specified in the referenced service
information, they may request approval for an AMOC in accordance with
paragraph (j) of this AD and, if approved, may use it instead of the
procedures specified in the service information and the final rule. The
FAA did not change this AD as a result of this comment.
Request To Clarify Replacement Language in Summary
CFM requested that the FAA update the Summary section of the
proposed AD to read: ``This proposed AD would also require replacement
of the No. 3 bearing spring finger housing having P/N 2629M62G01 and a
serial number identified in Table 1 of CFM SB LEAP-1A-72-00-0504-01A-93
0A-D.'' CFM noted that the focus of the proposed AD should be on NSV
monitoring and the actions required when NSV is present. CFM also noted
that service bulletins LEAP-1A-72-00-0505-01A-93 0A-D, Issue 001, dated
June 05, 2023, and LEAP-1A-72-00-0498-01A-93 0A-D, Issue 001, dated
June 05, 2023, include the shop visit workscope recommendations for
engines with potential No. 3 bearing spring finger housing wear,
regardless of the signs of NSV vibrations.
The FAA partially agrees with the request. The FAA agrees to edit
the Summary section of this AD to clarify that only certain No. 3
bearing spring finger housings require replacement. The FAA disagrees
with the request to specify the part number and serial number of the
affected parts in the Summary section of this AD because that level of
specificity is not appropriate for the Summary section. The FAA
acknowledges the presence of service bulletins LEAP-1A-72-00-0505-01A-
93 0A-D, Issue 001, dated June 05, 2023, and LEAP-1A-72-00-0498-01A-93
0A-D, Issue 001, dated June 05, 2023, and notes that neither of those
SBs are incorporated by reference in this AD.
Request To Update Proposed AD Requirements
CFM requested that the FAA update the Proposed AD Requirements in
This NPRM section to read: ``This proposed AD would also require
replacement of the No. 3 bearing spring finger housing having P/N
2629M62G01 and a serial number identified in Table 1 of CFM SB LEAP-1A-
72-00-0504-01A-930A-D, regardless of calculated level of NSV, at a
certain time.''
The FAA agrees with the requested language. However, this section
is not included in the final rule. Therefore, the FAA did not change
this AD as a result of this comment.
Request To Update Background and Unsafe Condition
CFM requested that the FAA update the Background and Unsafe
Condition sections of the proposed AD to include that CFM experience to
date has shown that NSV has led to self-recovering HPC stalls. CFM also
requested to remove the following portion from paragraph (e): ``The FAA
is issuing this AD to prevent HPC stall.'' CFM acknowledged that the
manufacturer investigation revealed that wear on the No. 3 bearing
spring finger housing can lead to high levels of NSV, which could
induce HPC stall.
The FAA disagrees with the request to include information regarding
self-recovering HPC stalls in this AD. The FAA also disagrees with the
requested change to paragraph (e) of this AD. The FAA notes that the
field experience to date does not provide conclusive evidence that NSV-
induced HPC stalls will always be self-recovering. The FAA did not
change this AD as a result of this comment.
[[Page 33213]]
Request To Update Interim Action
CFM requested that the FAA update the Interim Action section of the
proposed AD to reflect that this AD is the closing action of paragraph
(e) Unsafe Condition of the proposed AD and although there are
additional hardware modifications that are being developed by the
design approval holder, those modifications are not necessary to
address the unsafe condition.
The FAA disagrees with this request. Although at this time the
required actions of this AD address the unsafe condition, additional
hardware modifications, when developed and FAA-approved, could also
address the unsafe condition for the long-term. Therefore, the FAA
considers that the monitoring and corresponding actions required by
this AD would be an interim action to address the unsafe condition, and
the FAA may consider additional rulemaking on this subject. The FAA did
not change this AD as a result of this comment.
Request To Update Service Information Incorporated by Reference
CFM requested that the FAA change the SB referenced in the NPRM
from ``LEAP-1A-72-00-0504-01A-930A-D, Issue 001, dated June 14, 2023''
to ``LEAP-1A-72-00-0504-01A-930A-D, Issue 002, dated October 17,
2023.'' CFM noted that SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002,
dated October 17, 2023, contains the following revisions that are
pertinent to the NPRM;
(1) A note that NSV monitoring can be performed on-wing.
(2) Correction to data labels used in the alternative procedure for
NSV Monitoring with ACMS Takeoff Reports.
(3) Correction to vibration units used in the alternative procedure
for NSV Monitoring with ACMS Takeoff Reports.
The FAA agrees and has updated the service information incorporated
by reference from ``LEAP-1A-72-00-0504-01A-930A-D, Issue 001, dated
June 14, 2023'' to ``LEAP-1A-72-00-0504-01A-930A-D, Issue 002, dated
October 17, 2023.'' Requiring this updated service bulletin does not
increase the scope of the AD or increase the burden on any operator
over that already proposed in the NPRM.
Request To Remove ``At the Next Piece-part Exposure'' From Required
Actions
CFM requested that the FAA remove the reference to ``At the next
piece-part exposure'' in paragraph (g)(5) of the proposed AD. CFM
stated that NSV monitoring and actions required when NSV is present are
the focus of the proposed AD. CFM noted that the statement related to
``At the next piece-part exposure'' was taken from SB LEAP-1A-72-00-
0498-01A-930A-D, Issue 001, dated June 05, 2023, for shop visit work
scope recommendations for engines with potential No. 3 bearing spring
finger housing wear. CFM also noted that this is already referenced in
Chapter 05 of the LEAP-1A Engine Shop Manual LEAP-1A-05-11-03-01A-0B1B-
C.
The FAA disagrees with the request because the commenter did not
provide an adequate justification for changing the compliance time. The
FAA notes that decision to include a mandatory action to remove all
affected parts at the next piece-part exposure was not taken from SB
LEAP-1A-72-00-0498-01A-930A-D, Issue 001, dated June 05, 2023. The FAA
did not change this AD as a result of this comment.
Request To Add Credit for Previous Actions
CFM requested that the FAA add the following language to the NPRM
to allow customers to take credit for NSV monitoring that was performed
prior to the effective date of the proposed AD, in accordance with
section 5.A of SB LEAP-1A-72-00-0504-01A-930A-D, Issue 001, dated June
14, 2023; ``Evaluation of the NSV of an engine, accomplished before the
effective date of this AD in accordance with the instructions of
section 5.A of SB LEAP-1A-72-00-0504-01A-930A-D original issue (Issue
001) and, as applicable, accomplishment of corrective actions in
accordance with the instructions of SB LEAP-1A-72-00-0504-01A-930A-D
original issue (Issue 001) are acceptable to comply with the
requirements of paragraphs (1) and (2), as applicable, of this AD for
that engine (see Note 1 of this AD). Note 1: Evaluation of the NSV of
an engine, accomplished in accordance with the instructions of section
5.B (`Alternative Procedure--NSV Monitoring with ACMS Takeoff Reports')
of SB LEAP-1A-72-00-0504-01A-930A-D original issue (Issue 001) is not
acceptable to comply with the requirements of paragraphs (1) of this
AD.''
The FAA disagrees with the request because the FAA does not believe
it is necessary to provide such credit because NSV monitoring is
required initially at 125 flight cycles after the effective date of the
AD and repetitively at intervals of 125 flight cycles. Therefore, there
would be no advantage of taking credit for NSV monitoring done before
the effective date of this AD. Once the NSV data calculation exceeds
the specified limits, then the affected No. 3 bearing spring finger
housing must be removed from the engine and replaced with a part
eligible for installation, and the AD applicability no longer applies
to that engine. The FAA did not change this AD as a result of this
comment.
Request To Update Compliance Time for Removal From Service
CFM requested that the FAA change compliance time language in
paragraph (g)(2) of the proposed AD from, ``within 150 FCs of
performing the calculation'' to ``within 150 FCs of the flight when
this threshold is exceeded.'' CFM noted that there is a discrepancy in
the removal compliance time language between the NPRM and CFM SB LEAP-
1A-72-00-0504-01A-930A-D if NSV data exceeds the limits listed in CFM
SB LEAP-1A-72-00-0504-01A-930A-D.
The FAA agrees to update the language in paragraph (g)(2) of this
AD from, ``within 150 FCs of performing the calculation'' to ``within
150 FCs of the flight when these limits are exceeded.''
Conclusion
The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, and
any other changes described previously, this AD is adopted as proposed
in the NPRM. None of the changes will increase the economic burden on
any operator.
Related Service Information Under 1 CFR Part 51
The FAA reviewed CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002,
dated October 17, 2023. This service information identifies affected
No. 3 bearing spring finger housings and specifies procedures for
monitoring NSV during engine operation. This service information also
specifies procedures for replacing the No. 3 bearing spring finger
housings, inspecting the stage 2 HPT nozzle assembly honeycomb and HPT
stator stationary seal honeycomb, and replacing the stage 2 HPT nozzle
assembly honeycomb and HPT stator stationary seal. This service
information 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.
[[Page 33214]]
Interim Action
The FAA considers this AD to be an interim action. This unsafe
condition is still under investigation by the manufacturer and,
depending on the results of that investigation, the FAA may consider
further rulemaking action.
Costs of Compliance
The FAA estimates that this AD affects 48 engines installed on
airplanes of U.S. registry. The FAA estimates that 33 engines installed
on airplanes of U.S. registry require replacement of the No. 3 bearing
spring finger housing.
The FAA estimates the following costs to comply with this AD:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
Calculate NSV data.................... 1 work-hours x $85 per $0 $85 $4,080
hour = $85.
Replace No. 3 bearing spring finger 17 work-hours x $85 per 64,590 66,035 2,179,155
housing. hour = $1,445.
----------------------------------------------------------------------------------------------------------------
The FAA estimates the following costs to do any necessary
replacement and inspection that would be required based on the results
of the calculation. The agency has no way of determining the number of
aircraft that might need these replacements and inspections:
On-Condition Costs
----------------------------------------------------------------------------------------------------------------
Cost per
Action Labor cost Parts cost product
----------------------------------------------------------------------------------------------------------------
Inspect stage 2 HPT nozzle assembly honeycomb 4 work-hours x $85 per hour = $0 $340
and HPT stator stationary seal honeycomb. $340.
Replace stage 2 HPT nozzle assembly honeycomb. 8 work-hours x $85 per hour = 58,536 59,216
$680.
Replace HPT stator stationary seal............ 8 work-hours x $85 per hour = 6,855 7,535
$680.
----------------------------------------------------------------------------------------------------------------
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
This AD will not have federalism implications under Executive Order
13132. This AD will 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 that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will 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 Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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:
2024-07-06 CFM International, S.A.: Amendment 39-22727; Docket No.
FAA-2023-1991; Project Identifier AD-2023-00700-E.
(a) Effective Date
This airworthiness directive (AD) is effective June 3, 2024.
(b) Affected ADs
None.
(c) Applicability
This AD applies to CFM International, S.A. (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, and LEAP-1A35A engines with an installed No. 3 bearing
spring finger housing having part number (P/N) 2629M62G01 and a
serial number identified in Table 1 or Table 2 of CFM Service
Bulletin (SB) LEAP-1A-72-00-0504-01A-930A-D, Issue 002, dated
October 17, 2023 (CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002).
(d) Subject
Joint Aircraft System Component (JASC) Code 7230, Turbine Engine
Compressor Section.
(e) Unsafe Condition
This AD was prompted by a report of multiple aborted takeoffs
and air turn-backs caused by high-pressure compressor (HPC) stall,
which was induced by high levels of non-synchronous vibration (NSV),
and an additional manufacturer investigation that revealed wear on
the No. 3 bearing spring finger housing. The FAA is issuing this AD
to prevent HPC stall. The unsafe condition, if not addressed, could
result in engine power loss at a critical phase of flight such as
takeoff or climb, loss of engine thrust control, reduced
controllability of the airplane, and loss of the airplane.
[[Page 33215]]
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) Within 125 flight cycles (FCs) after the effective date of
this AD and thereafter at intervals not to exceed 125 FCs, calculate
the NSV data in accordance with the Accomplishment Instructions,
paragraphs 5.A.(1) and 5.A.(3), or 5.B.(1) and 5.B.(3) of CFM SB
LEAP-1A-72-00-0504-01A-930A-D, Issue 002.
(2) If, during any calculation required by paragraph (g)(1) of
this AD, the NSV data exceeds the limits specified in the
Accomplishment Instructions, paragraph 5.A.(4)(a)1 or 5.B.(4)(a)1 of
CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002, discontinue the
calculations required by paragraph (g)(1) of this AD and within 150
FCs of the flight when these limits are exceeded:
(i) Remove from service the No. 3 bearing spring finger housing
having P/N 2629M62G01 and a serial number identified in Table 1 or
Table 2 of CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002, and
replace with a part eligible for installation.
(ii) Inspect the stage 2 high-pressure turbine (HPT) nozzle
assembly honeycomb for rubs in accordance with the Accomplishment
Instructions, paragraphs 5.A.(4)(a)3b1) or 5.B.(4)(a)3b1) of CFM SB
LEAP-1A-72-00-0504-01A-930A-D, Issue 002.
(iii) Inspect the HPT stator stationary seal honeycomb for rubs
in accordance with the Accomplishment Instructions, paragraphs
5.A.(4)(a)3b2) or 5.B.(4)(a)3b2) of CFM SB LEAP-1A-72-00-0504-01A-
930A-D, Issue 002.
(3) If, during the inspection required by paragraph (g)(2)(ii)
of this AD, the stage 2 HPT nozzle assembly honeycomb fails to meet
the serviceability criteria referenced in the Accomplishment
Instructions, paragraphs 5.A.(4)(a)3b1) or 5.B.(4)(a)3b1) of CFM SB
LEAP-1A-72-00-0504-01A-930A-D, Issue 002, before further flight,
replace the stage 2 HPT nozzle assembly honeycomb.
(4) If, during the inspection required by paragraph (g)(2)(iii)
of this AD, the HPT stator stationary seal honeycomb fails to meet
the serviceability criteria referenced in the Accomplishment
Instructions, paragraphs 5.A.(4)(a)3b2) or 5.B.(4)(a)3b2) of CFM SB
LEAP-1A-72-00-0504-01A-930A-D, Issue 002, before further flight,
replace the HPT stator stationary seal.
(5) At the next piece-part exposure after the effective date of
this AD, but before exceeding 9,900 cycles since new, replace the
No. 3 bearing spring finger housing having P/N 2629M62G01 and a
serial number identified in Table 1 of CFM SB LEAP-1A-72-00-0504-
01A-930A-D, Issue 002, with a part eligible for installation.
(h) Terminating Action
Replacement of the No. 3 bearing spring finger housing having P/
N 2629M62G01 and a serial number identified in Table 1 or Table 2 of
CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002 with a part eligible
for installation, as specified in paragraphs (g)(2)(i) and (g)(5) of
this AD, constitutes terminating action for the calculations
required by paragraph (g)(1) of this AD.
(i) Definition
For the purpose of this AD, a ``part eligible for installation''
is a No. 3 bearing spring finger housing that does not have P/N
2629M62G01 and a serial number identified in Table 1 or Table 2 of
CFM SB LEAP-1A-72-00-0504-01A-930A-D, Issue 002.
(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, AIR-520 Continued Operational
Safety Branch, send it to the attention of the person identified in
paragraph (k) of this AD and email it 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.
(3) For service information that contains steps that are labeled
as Required for Compliance (RC), the following provisions apply.
(i) The steps labeled as RC, including substeps under an RC step
and any figures identified in an RC step, that are required by
paragraph (g) of this AD must be done to comply with this AD. An
AMOC is required for any deviations to RC steps required by
paragraph (g) of this AD, including substeps and identified figures.
(ii) Steps not labeled as RC may be deviated from using accepted
methods in accordance with the operator's maintenance or inspection
program without obtaining approval of an AMOC, provided the RC
steps, including substeps and identified figures, can still be done
as specified, and the airplane can be put back in an airworthy
condition.
(k) Additional Information
For more information about this AD, 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 service information listed
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this service information as applicable to do
the actions required by this AD, unless the AD specifies otherwise.
(i) CFM International, S.A. Service Bulletin LEAP-1A-72-00-0504-
01A-930A-D, Issue 002, dated October 17, 2023.
(ii) [Reserved]
(3) For service information, contact CFM International, S.A., 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 service information at 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/[email protected]">www.archives.gov/federal-register/cfr/[email protected].
Issued on March 29, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2024-09110 Filed 4-26-24; 8:45 am]
BILLING CODE 4910-13-P
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