Airworthiness Directives; CFM International, S.A. Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain CFM International, S.A. (CFM) Model LEAP-1B engines. This proposed 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 proposed AD would 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 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 proposing this AD to address the unsafe condition on these products.

DATES:

The FAA must receive comments on this proposed AD by September 12, 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-2024-1898; 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 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 International, S.A., GE Aviation Fleet Support, 1 Neumann Way, M/D Room 285, Cincinnati, OH 45215; phone: (877) 432-3272; email:aviation.fleetsupport@ge.com.
• 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: mehdi.lamnyi@faa.gov.

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-2024-1898; Project Identifier AD-2023-01013-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

The FAA was notified by the manufacturer of a quality escape involving certain HPC stage 2 seals installed on certain 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 (LEAP-1B) engines. The suspect HPC stage 2 seals were 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, which could lead to failure of the stage 3-4 blisk. This condition, if not addressed, could result in uncontained part release, damage to the engine, and damage to the aircraft.

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 Material Under 1 CFR Part 51

The FAA reviewed CFM International, S.A. Service Bulletin LEAP-1B-72-00-0394-01A-930A-D, Issue 002-00, dated January 23, 2024, which specifies procedures for an on-wing borescope inspection (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.

Proposed AD Requirements in This NPRM

This proposed AD would require a 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, if necessary.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 31 engines installed on airplanes of U.S. registry.

The FAA estimates the following costs to comply with this proposed AD:

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

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

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

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

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

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

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by September 12, 2024.

(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.

(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 (SB) 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: AMOC@faa.gov.

(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: mehdi.lamnyi@faa.gov.

(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. 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 International, S.A., GE Aviation Fleet Support, 1 Neumann Way, M/D Room 285, Cincinnati, OH 45215; phone: (877) 432-3272; email: aviation.fleetsupport@ge.com.

(4) You may view this material 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/ibr-locations or email fr.inspection@nara.gov.