AD 2022-25-20

This AD is effective January 26, 2023.

AD Docket: You may examine the AD docket at regulations.gov by searching for and locating Docket No. FAA-2022-0978; 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, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 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 GEnx-1B64, GEnx-1B64/P1, GEnx-1B64/P2, GEnx-1B67, GEnx-1B67/P1, GEnx-1B67/P2, GEnx-1B70, GEnx-1B70/75/P1, GEnx-1B70/75/P2, GEnx-1B70/P1, GEnx-1B70/P2, GEnx-1B70C/P1, GEnx-1B70C/P2, GEnx-1B74/75/P1, GEnx-1B74/75/P2, GEnx-1B76/P2, GEnx-1B76A/P2 (GEnx-1B), GEnx-2B67, GEnx-2B67B, and GEnx-2B67/P (GEnx-2B) model turbofan engines. The NPRM published in the Federal Register on September 9, 2022 (87 FR 55328). The NPRM was prompted by a manufacturer investigation that revealed that certain HPT stage 2 disks, forward seals, and stages 6-10 compressor rotor spools were manufactured from powder metal material suspected to contain iron inclusion. Further investigation by the manufacturer determined that the iron inclusion is attributed to deficiencies in the manufacturing process. The investigation by the manufacturer also determined that certain GEnx-1B and GEnx-2B HPT stage 2 disks, forward seals, and stages 6-10 compressor rotor spools made from billets manufactured using the same process may have reduced material properties and a lower fatigue life capability due to iron inclusion, which may cause premature fracture and uncontained failure. In the NPRM, the FAA proposed to require replacement of certain HPT stage 2 disks, forward seals, and stages 6-10 compressor rotor spools with parts eligible for installation. The FAA is issuing this AD to address the unsafe condition on these products.

The FAA received comments from four commenters. The commenters were Air Line Pilots Association, International (ALPA), American Airlines, GE Aviation, and The Boeing Company (Boeing). ALPA, American Airlines, and Boeing supported the proposed AD without change. GE Aviation requested a change to the proposed AD. The following presents the comments received on the NPRM and the FAA's response to each comment.

GE Aviation requested that the FAA add alternate part numbers (P/Ns) to Table 1 to paragraph (c) of this AD. GE Aviation explained that the forward seal and stages 6-10 compressor rotor spool may have reworked P/Ns that occur after entry into service. While the P/Ns provided in the NPRM are the best information available as to current P/Ns, GE requested that the FAA add certain alternate P/Ns to Table 1 to paragraph (c), Applicability, of this final rule to ensure compliance.

The FAA agrees for the reasons provided and has revised Table 1 to paragraph (c), Applicability, of this AD as requested by GE Aviation.

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.

The FAA reviewed GE GEnx-1B Service Bulletin 72-0505, Revision 02, dated April 5, 2022. The FAA also reviewed GE GEnx-2B Service Bulletin 72-0444, Revision 02, dated April 5, 2022. This service information describes procedures for removing the HPT stage 2 disk, forward seal, and stages 6-10 compressor rotor spool. These documents are distinct since they apply to different engine models.

The FAA estimates that this AD affects 3 engines installed on airplanes of U.S. registry. The FAA estimates that 0 engines installed on airplanes of U.S. registry require replacement of the forward seal or HPT stage 2 disk.

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: