AD 2020-20-11

This AD is effective November 3, 2020.

For service information identified in this final rule, contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: aviation.fleetsupport@ae.ge.com; website: www.ge.com. You may view this service information 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 781-238-7759. It is also available on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-0555.

Mehdi Lamnyi, Aerospace Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: 781-238-7743; fax: 781-238-7199; email: Mehdi.Lamnyi@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 GEnx-1B64/P2, -1B67/P2, -1B70/P2, -1B70C/P2, -1B70/75/P2, -1B74/75/P2, -1B76/P2, -1B76A/P2, and GEnx-2B67/P model turbofan engines. The NPRM published in the Federal Register on June 8, 2020 (85 FR 35021). The NPRM was prompted by the detection of melt-related freckles in the billet, which may reduce the life limits of certain HPT rotor stage 2 disks and a certain stages 6-10 compressor rotor spool. The NPRM proposed to require the removal of certain HPT rotor stage 2 disk and the removal of a certain stages 6-10 compressor rotor spool before reaching their new life limits. The FAA is issuing this AD to address the unsafe condition on these products.

The FAA gave the public the opportunity to participate in developing this final rule. The following presents the comments received on the NPRM and the FAA's response to each comment.

GE requested that both the affected part and serial numbers be listed in the Applicability section of this AD instead of the affected engine serial numbers.

The FAA agrees. The FAA recognizes that affected HPT rotor stage 2 disks could be moved from one engine to another engine. The intent of this AD is to mandate the removal of the affected parts from service, regardless of the engine on which they are installed. The FAA is revising the Applicability section of this AD as suggested by the commenter. This change does not expand the scope of this AD because the number of affected engines installed on airplanes of U.S. registry remains the same in this final rule compared to what was published in the NPRM.

The Air Line Pilots Association, International; the Boeing Company; and United Airlines Engineering expressed support for the AD as written.

The FAA reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this final rule with the changes described previously and minor editorial changes. The FAA has determined that these minor changes:

• Are consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and

• Do not add any additional burden upon the public than was already proposed in the NPRM.

The FAA also determined that these changes will not increase the economic burden on any operator or increase the scope of this final rule.

The FAA reviewed GE GEnx-1B Service Bulletin (SB) 72-0473 R00, dated April 14, 2020; GE GEnx-1B SB 72-0474 R00, dated April 14, 2020; and GE GEnx-2B SB 72-0416 R00, dated April 14, 2020. GE GEnx-1B SB 72-0473 R00 describes procedures for removing and replacing the HPT rotor stage 2 disks on GE GEnx-1B model engines. GE GEnx-1B SB 72-0474 R00 describes procedures for removing and replacing the stages 6-10 compressor rotor spool on GE GEnx-1B model engines. GE GEnx-2B SB 72-0416 R00 describes procedures for removing and replacing the HPT rotor stage 2 disks on GE GEnx-2B model engines.

The FAA estimates that this AD affects two engines installed on airplanes of U.S. registry; one engine requires the HPT rotor stage 2 disk replacement and one engine requires the stages 6-10 compressor rotor spool replacement.

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 (AD):