AD 2025-10-11

This AD is effective June 24, 2025.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2024-2721; 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.

Alexei Marqueen, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: (781) 238-7178; email: alexei.t.marqueen@faa.gov.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain GE Model CF6-80E1A2, CF6-80E1A3, CF6-80E1A4, and CF6-80E1A4/B engines. The NPRM was published in the Federal Register on January 30, 2025 (90 FR 8505). The NPRM was prompted by a manufacturer investigation that revealed the detection of iron inclusion in an HPT stage 2 disk manufactured from the same powder metal material used to manufacture certain HPT stage 1 and HPT stage 2 disks for GE Model CF6-80E1A2, CF6- 80E1A3, CF6-80E1A4, and CF6-80E1A4/B engines. Further investigation by the manufacturer revealed that the iron inclusion is attributed to deficiencies in the manufacturing process and may cause reduced material properties and a lower fatigue life capability, which may result in premature fracture and uncontained failure. The manufacturer also informed the FAA that additional risk assessments showed that there were no failed events associated with the discovery of this iron inclusion material. However, it was concluded that replacement of the affected HPT stage 1 and HPT stage 2 disks is necessary to prevent any future failed events. In the NPRM, the FAA proposed to require replacement of affected HPT stage 1 and HPT stage 2 disks with parts eligible for installation. The FAA is issuing this AD to address the unsafe condition on these products.

The FAA received comments from three commenters. The commenters were Delta Air Lines, Inc. (DAL) and two individual commenters. The individual commenters supported the NPRM without change. DAL requested changes to the proposed AD. The following presents the comments received on the NPRM and the FAA's response to each comment.

DAL requested that the FAA revise the proposed AD to add certain engine variants to paragraph (c), Applicability, and to add a parts installation prohibition to paragraph (g), Required Actions, to prevent installation of the removed parts on non-CF6-80E1 engines. DAL noted that, according to the engine illustrated parts catalog, the HPT stage 1 and HPT stage 2 disks on the CF6-80E1 fleet of engines could be installed on the CF6-80C2 fleet of engines, specifically on the -B2F, -B4F, -B6F, -B7F, and -B8F variants. The commenter reasoned that without a parts installation prohibition in the proposed AD, the affected parts would be eligible for installation on the non-CF6-80E1 engines after the required removal action in the AD.

The FAA disagrees. This AD applies to engine models known to have affected parts installed. Paragraph (g) of this AD requires the removal of the affected parts from service. Since the FAA and the manufacturer know where these parts are, and parts removed from service by AD action are not serviceable and not eligible for reinstallation on any engine, it is not necessary to revise paragraph (c) of this AD to add engine variants and revise paragraph (g) of this AD to prohibit installation of the removed parts. The FAA did not change this AD as a result of these comments.

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, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.

The FAA estimates that this AD affects one engine installed on an airplane of U.S. registry.

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

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.

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.

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

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

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