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[Federal Register Volume 90, Number 5 (Wednesday, January 8, 2025)]
[Rules and Regulations]
[Pages 1365-1368]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-00207]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-1898; Project Identifier AD-2023-01013-E; 
Amendment 39-22904; AD 2024-25-02]
RIN 2120-AA64

Airworthiness Directives; CFM International, S.A. Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain CFM International, S.A. (CFM) Model LEAP-1B engines. This AD 
was prompted by a report of a quality escape involving certain high-
pressure compressor (HPC) stage 2 seals manufactured without detailed 
finish machining, which could result in deeper rubs and mechanical 
damage to the seal teeth of the stage 3-4 compressor rotor blisk (stage 
3-4 blisk) of the mating compressor rotor during initial operation. 
This AD requires a visual inspection of the HPC stage 2 seal, a visual 
inspection of the forward arm seal teeth of the stage 3-4 blisk, an 
eddy current inspection (ECI) of the forward arm seal teeth of the 
stage 3-4 blisk, and replacement of the HPC stage 2 seal and the stage 
3-4 blisk, if necessary. The FAA is issuing this AD to address the 
unsafe condition on these products.

DATES: This AD is effective February 12, 2025.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of February 12, 
2025.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2024-1898; 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:
     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].
     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. It is also available at 
regulations.gov under Docket No. FAA-2024-1898.

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-
1B engines. The NPRM published in the Federal Register on July 29, 2024 
(89 FR 60838). The NPRM was prompted by a report of a quality escape 
involving certain HPC stage 2 seals manufactured without detailed 
finish machining, which could result in deeper rubs and mechanical 
damage to the seal teeth of the stage 3-4 blisk of the mating 
compressor rotor during initial operation. In the NPRM, the FAA 
proposed to require a visual inspection of the HPC stage 2 seal, a 
visual inspection of the forward arm seal teeth of the stage 3-4 blisk, 
an ECI of the forward arm seal teeth of the stage 3-4 blisk, and 
replacement of the HPC stage 2 seal and the stage 3-4 blisk, if 
necessary. 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 six commenters. The commenters were 
The Boeing Company (Boeing), CFM, Ryanair, StandardAero, Southwest 
Airlines (SWA), and United Airlines (UAL). Boeing concurred with the 
contents of the NPRM and StandardAero expressed support for the NPRM. 
The following presents the comments received on the NPRM and the FAA's 
response to each comment.

Request To Remove Certain Engine Serial Numbers (ESNs) From the 
Applicability

    CFM and Ryanair requested that the FAA remove certain ESNs from the 
applicability of the proposed AD or include replacement of the HPC 
stage 2 seal and the stage 3-4 blisk with new parts as an option for 
complying with the proposed AD. Both commenters stated that certain 
ESNs had already replaced the HPC stage 2 seal and the stage 3-4 blisk 
with new parts. Both commenters also pointed out that by replacing the 
HPC stage 2 seal and the stage 3-4 blisk with new parts, the unsafe 
condition is mitigated for those engines, but not as specified in the 
required actions of the proposed AD.
    Since this is a quality escape issue and limited to the parts 
originally installed on the engine, the FAA agrees for the reasons 
provided and has removed ESNs 60A676 and 60A669 from the applicability 
of this AD.

Request for Clarification of Difference With the Service Information

    StandardAero and UAL requested that the FAA provide clarification 
regarding why the borescope inspection (BSI) specified in the required 
service information is not required by the NPRM. StandardAero pointed 
out that the NPRM does not address why the BSI is not required. 
StandardAero also mentioned that the European Union Aviation Safety 
Agency (EASA) has a corresponding proposed AD (EASA PAD 24-108), which 
discussed and inferred that the BSIs have already been completed on all 
affected engines. StandardAero specifically requested that the FAA 
confirm that the BSIs have been completed on all the ESNs that are 
specified in the service information, and that the ESNs specified in 
the NPRM are those that require additional action due to the BSI 
results. UAL pointed out that the service information contains Required 
for Compliance (RC) steps for a BSI. UAL requested clarification of 
whether those steps are required by the NPRM and whether the BSI is 
acceptable for verifying the condition of the HPC stage 2 seal and the 
stage 3-4 blisk.
    The FAA acknowledges the difference between the actions required by 
this AD and those specified in the service information. The engine 
manufacturer has provided the FAA with evidence

[[Page 1366]]

that all affected engines have completed the on-wing BSI, as well as 
the results of the on-wing BSI. Therefore, the FAA has determined that 
there is no need for the BSI to be completed as part of the actions 
required by this AD and that only the follow-on in-shop actions are 
necessary. The FAA has not changed this AD in this regard.

Request for Clarification of RC Steps

    StandardAero requested that the FAA provide clarification regarding 
the RC steps specified in the required service information but are not 
required by the NPRM. StandardAero pointed out that the service 
information states that certain paragraphs are labeled as ``RC,'' and 
that if the service information is mandated by an AD, then those steps 
must be done to comply with the AD. StandardAero requested that the FAA 
coordinate with the engine manufacturer to prevent differences between 
and confusion regarding the service information and the requirements of 
the AD. StandardAero also stated its preference that OEMs and type 
certificate holders do not attempt to highlight required actions in 
their service information for an AD, especially those that do not yet 
exist, and allow the FAA to specify the required actions in the AD.
    To clarify, the FAA does not make changes to the service 
information; such changes are implemented by the engine manufacturer. 
The FAA agrees with the concept of minimizing AD requirements when 
appropriate. The FAA worked in conjunction with industry, under the 
Airworthiness Directive Implementation Aviation Rulemaking Committee 
(AD ARC), to enhance the AD system. One enhancement is a process for 
annotating which steps in the service information are ``required for 
compliance'' (RC) with an AD. Differentiating these steps from other 
tasks in the service information improves an owner's/operator's 
understanding of AD requirements and helps provide consistent judgment 
in AD compliance. However, even though the on-wing BSI is labeled RC in 
the service information, the FAA has been given evidence that all 
affected engines have completed this inspection. The FAA has chosen to 
limit the applicability of this AD based on the results of those 
inspections. Therefore, since the on-wing BSI would not be mandated by 
this AD and the applicability adjusted accordingly, the FAA has 
determined that it would be less confusing to call out the specific 
steps from the service bulletin to complete this action rather than 
utilize the RC concept. The FAA has determined to include a 
``Differences Between this Final Rule and the Related Material'' 
section in the preamble of this final rule to discuss the difference; 
however, no changes were made to the regulatory text of the AD.

Request To Include Credit for Previous Actions

    SWA and UAL requested that the FAA include credit for previous 
actions accomplished using Issue 001-00 of the service information. SWA 
stated that the primary differences between Issue 001-00 and Issue 002-
00 are reidentifying steps as RC steps. SWA also pointed out that Issue 
001-00 was accomplished on SWA affected engines prior to publication of 
the NPRM.
    The FAA disagrees with the request. Issue 001-00 of the service 
information was revised to include a new ECI tool part number for the 
module level inspection required for the stage 3-4 blisk. Any ECI 
completed in accordance with Issue 001-00 of the service information, 
was done without this tool, rendering the results of the ECI 
unacceptable. Therefore, the FAA is unable to include credit for 
previous actions. However, if the affected parts were removed from 
service and replaced before the effective date of this AD without 
performing the inspections required by this AD, and substantiating 
information can be provided, the operator may request an alternative 
method of compliance (AMOC) under the provisions of paragraph (h) of 
this AD. Additionally, regarding the RC label, this AD does not require 
the on-wing BSI since the manufacturer has already provided the FAA 
with evidence that all the affected engines have complied with the on-
wing BSI, and the FAA has chosen to limit the applicability of this AD 
based on the results of those inspections. Therefore, since the on-wing 
BSI would not be mandated by this AD and the applicability adjusted 
accordingly, the FAA has determined that it would be less confusing to 
call out the specific steps from the service bulletin to complete this 
action rather than utilize the RC concept. Therefore, this AD only 
requires the subsequent in-shop inspections for those engines that 
failed the on-wing BSI, all of which are included in the applicability 
of this AD. The FAA has determined to include a ``Differences Between 
this Final Rule and the Referenced Material'' section in the preamble 
of this final rule to discuss this; however, no changes were made to 
the regulatory text.

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.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed CFM Service Bulletin LEAP-1B-72-00-0394-01A-930A-
D, Issue 002-00, dated January 23, 2024, which specifies procedures for 
an on-wing BSI of the honeycomb structure of the affected stage 2 seals 
and rotating seal teeth coating condition and provides instructions for 
determining the serviceability of affected components that fail the 
BSI. This material also specifies procedures for an in-shop visual 
inspection of the HPC stage 2 seal and the forward arm seal teeth of 
the stage 3-4 blisk, an ECI of the forward arm seal teeth of the stage 
3-4 blisk, and replacement of the HPC stage 2 seal and the stage 3-4 
blisk. 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.

Differences Between This Final Rule and the Referenced Material

    Where CFM Service Bulletin LEAP-1B-72-00-0394-01A-930A-D, Issue 
002-00, dated January 23, 2024, includes RC steps that require a 360-
degree BSI of the trail edge area of the stage 2 seals, this AD does 
not require those steps. Additionally, this AD does not require any RC 
steps. Instead, the FAA has chosen to limit the applicability of this 
AD based on the results of those inspections. Therefore, since the on-
wing BSI would not be mandated by this AD and the applicability 
adjusted accordingly, the FAA has determined that it would be less 
confusing to call out the specific steps from the service bulletin to 
complete this action rather than utilize the RC concept.

Costs of Compliance

    The FAA estimates that this AD affects 31 engines installed on 
airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this AD:

[[Page 1367]]

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Visual inspection of HPC stage 2 seal.  1 work-hour x $85 per                 $0             $85          $2,635
                                         hour = $85.
Visual inspection of stage 3-4 blisk..  1 work-hour x $85 per                  0              85           2,635
                                         hour = $85.
ECI of stage 3-4 blisk................  4 work-hours x $85 per                 0             340          10,540
                                         hour = $340.
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do any necessary 
replacements that would be required based on the results of the 
inspection. The agency has no way of determining the number of engines 
that might need these replacements:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Replace HPC stage 2 seal......................  8 work-hours x $85 per hour =            $55,312         $55,992
                                                 $680.
Replace HPC stage 3-4 blisk...................  8 work-hours x $85 per hour =            518,500         519,180
                                                 $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 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:

2024-25-02 CFM International, S.A.: Amendment 39-22904; Docket No. 
FAA-2024-1898; Project Identifier AD-2023-01013-E.

(a) Effective Date

    This airworthiness directive (AD) is effective February 12, 
2025.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to CFM International, S.A. (CFM) Model LEAP-
1B21, LEAP-1B23, LEAP-1B25, LEAP-1B27, LEAP-1B28, LEAP-1B28B1, LEAP-
1B28B2, LEAP-1B28B2C, LEAP-1B28B3, LEAP-1B28BBJ1, and LEAP-1B28BBJ2 
engines having an engine serial number (ESN) identified in Table 1 
to paragraph (c) of this AD.

                                    Table 1 to Paragraph (c)--Applicable ESNs
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         ESN                    ESN                    ESN                    ESN                    ESN
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60A635                 60A647                 60A662                 60A682                 60A702
60A639                 60A650                 60A663                 60A686
60A642                 60A653                 60A670                 60A687
60A643                 60A655                 60A671                 60A689
60A644                 60A656                 60A673                 60A690
60A645                 60A660                 60A678                 60A691
60A646                 60A661                 60A679                 60A696
----------------------------------------------------------------------------------------------------------------

[[Page 1368]]

(d) Subject

    Joint Aircraft System Component (JASC) Code 7230, Turbine Engine 
Compressor Section.

(e) Unsafe Condition

    This AD was prompted by a report of a quality escape involving 
certain high-pressure compressor (HPC) stage 2 seals manufactured 
without detailed finish machining, which could result in deeper rubs 
and mechanical damage to the seal teeth of the stage 3-4 compressor 
rotor blisk (stage 3-4 blisk) of the mating compressor rotor during 
initial operation. The FAA is issuing this AD to prevent uncontained 
failure of the stage 3-4 blisk. The unsafe condition, if not 
addressed, could result in uncontained part release, damage to the 
engine, and damage to the aircraft.

(f) Compliance

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

(g) Required Actions

    (1) Before accumulating 2,900 cycles since new (CSN) or within 
10 flight cycles after the effective date of this AD, whichever 
occurs later, perform the following:
    (i) A visual inspection of the HPC stage 2 seal in accordance 
with the Accomplishment Instructions, paragraph 5.B.(3) of CFM 
Service Bulletin LEAP-1B-72-00-0394-01A-930A-D, Issue 002-00, dated 
January 23, 2024 (CFM SB LEAP-1B-72-00-0394-01A-930A-D, Issue 002-
00).
    (ii) A visual inspection of the forward arm seal teeth of the 
stage 3-4 blisk in accordance with the Accomplishment Instructions, 
paragraph 5.B.(4) of CFM SB LEAP-1B-72-00-0394-01A-930A-D, Issue 
002-00.
    (iii) An eddy current inspection of the forward arm seal teeth 
of the stage 3-4 blisk in accordance with the Accomplishment 
Instructions, paragraph 5.B.(5) of CFM SB LEAP-1B-72-00-0394-01A-
930A-D, Issue 002-00.
    (2) If, during the inspection required by paragraph (g)(1)(i) of 
this AD, any of the HPC stage 2 seal segments fail to meet the 
serviceability criteria specified in the Accomplishment 
Instructions, paragraph 5.B.(3) of CFM SB LEAP-1B-72-00-0394-01A-
930A-D, Issue 002-00, before further flight, remove the 
unserviceable HPC stage 2 seal segments from service.
    (3) If, during the inspections required by paragraphs (g)(1)(ii) 
and (iii) of this AD, the stage 3-4 blisk fails to meet the 
serviceability criteria specified in the Accomplishment 
Instructions, paragraph 5.B.(6) of CFM SB LEAP-1B-72-00-0394-01A-
930A-D, Issue 002-00, before further flight:
    (i) Remove the stage 3-4 blisk from service;
    (ii) Remove all four HPC stage 2 seal segments from service; and
    (iii) Replace the stage 3-4 blisk in accordance with the 
Accomplishment Instructions, paragraph 5.B.(7)(a) of CFM SB LEAP-1B-
72-00-0394-01A-930A-D, Issue 002-00.
    (4) If, during the actions required by paragraphs (g)(2) and (3) 
of this AD, the HPC stage 2 seal is removed, before further flight, 
replace the HPC stage 2 seal in accordance with the Accomplishment 
Instructions, paragraph 5.B.(7)(b) of CFM SB LEAP-1B-72-00-0394-01A-
930A-D, Issue 002-00.

(h) 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 AIR-520 Continued 
Operational Safety Branch, send it to the attention of the person 
identified in paragraph (i) 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.

(i) 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].

(j) 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-1B-72-
00-0394-01A-930A-D, Issue 002-00, dated January 23, 2024.
    (ii) [Reserved]
    (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 December 3, 2024.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2025-00207 Filed 1-7-25; 8:45 am]
BILLING CODE 4910-13-P
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