
[Federal Register Volume 88, Number 195 (Wednesday, October 11, 2023)]
[Proposed Rules]
[Pages 70409-70412]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-22373]


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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]
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-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 proposed 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 proposed AD would require 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 
proposed AD would also require replacement of the No. 3 bearing spring 
finger housing. 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 
27, 2023.

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 by 
searching for and locating 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 NPRM, any comments 
received, and other information. The street address for Docket 
Operations is listed above.
    Material Incorporated by Reference:
     For service information identified in this NPRM, 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].
     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:

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 ADDRESSES. Include ``Docket No. FAA-2023-1991; Project Identifier 
AD-2023-00700-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 amend 
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

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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

    The FAA was notified by the engine manufacturer 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. 
This 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.

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.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed CFM Service Bulletin (SB) LEAP-1A-72-00-0504-01A-
930A-D, Issue 001, dated June 14, 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 ADDRESSES.

Proposed AD Requirements in This NPRM

    This proposed AD would 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. This proposed 
AD would 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 proposed AD 
would also require replacement of the No. 3 bearing spring finger 
housing, regardless of calculated level of NSV, at a certain time.

Interim Action

    The FAA considers that this proposed AD would be an interim action. 
The design approval holder is currently developing a modification to 
address this issue. The FAA may consider additional rulemaking on this 
subject.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 48 engines installed on airplanes of U.S. registry. The FAA 
estimates that 33 engines installed on airplanes of U.S. registry would 
require replacement of the No. 3 bearing spring finger housing.
    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
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Calculate NSV data....................  1 work-hour 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.
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    The FAA estimates the following costs to do any necessary 
replacement and inspection that would be required based on the results 
of the proposed 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.
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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

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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-2023-1991; Project 
Identifier AD-2023-00700-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by November 27, 2023.

(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 001, dated June 
14, 2023 (CFM SB LEAP-1A-72-00-0504-01A-930A-D).

(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.

(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.
    (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, discontinue the calculations 
required by paragraph (g)(1) of this AD and within 150 FCs of 
performing the calculation:
    (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 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.
    (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.
    (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, 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, 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 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 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.

(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 the branch office, 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.

[[Page 70412]]

(k) Related 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 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 001, dated June 14, 2023.
    (ii) [Reserved]
    (3) For service information identified in this AD, 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 service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email: [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on October 3, 2023.
Ross Landes,
Deputy Director for Regulatory Operations, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2023-22373 Filed 10-10-23; 8:45 am]
BILLING CODE 4910-13-P


