2024-22600. Airworthiness Directives; CFM International, S.A. Engines

Estimated Costs

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

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.

§ 39.13

[Amended]

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

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

(a) Comments Due Date

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

(b) Affected ADs

None.

(c) Applicability

This AD applies to the following CFM International, S.A. (CFM) engines:

(1) Model LEAP-1A23, LEAP-1A24, LEAP-1A24E1, LEAP-1A26, LEAP-1A26CJ, LEAP-1A26E1, LEAP-1A29, LEAP-1A29CJ, LEAP-1A30, LEAP-1A32, LEAP-1A33, LEAP-1A33B2, and LEAP-1A35A engines.

(2) Model LEAP-1C28, LEAP-1C30, and LEAP-1C30B1 engines.

(d) Subject

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

(e) Unsafe Condition

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

(f) Compliance

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

(g) Required Actions

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

Table 1 to Paragraph ( g )(1)—Removal Thresholds for Each Engine Model

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