AD 2025-10-04

This AD is effective June 26, 2025.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of June 26, 2025.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2024-1883; 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.

Material Incorporated by Reference:

• For GE material identified in this AD, contact GE, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: aviation.fleetsupport@ge.com; website: 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. It is also available at regulations.gov under Docket No.FAA-2024-1883.

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 all GE Model CF34-10E2A1, CF34-10E6, CF34-10E6A1, CF34-10E7, and CF34-10E7-B engines with an installed HPT shroud/LPT nozzle assembly having part number (P/N) 2205M38G01, 2205M38G02, 2205M38G03, 2205M38G04, or 2205M38G05. The NPRM was published in the Federal Register on July 10, 2024 (89 FR 56674). The NPRM was prompted by a report from the manufacturer that during disassembly, the retention features of the inner and outer support air ducts on GE Model CF34-10E series engines were found to have failed. The retention features include a retaining ring, which becomes plastically deformed during installation. Vibrations loosen the retaining ring until it disengages. With the retaining ring disengaged, the outer support air duct has no radial constraint, and releases and migrates due to gravity, impacting the inner wall of the combustion case causing case wall damage. If this damage has been repaired in the past and after the repair the support air duct liberates and causes more damage, then the remaining wall thickness is not sufficient to sustain the loading from a fan-blade-out or other extreme event. In the NPRM, the FAA proposed to require a visual inspection of the combustion case for wear and gouges, repair if necessary, and rework of the affected HPT shroud/LPT nozzle assemblies to add a positive retention of the support air duct.

The FAA issued a supplemental notice of proposed rulemaking (SNPRM) to amend 14 CFR part 39 by adding an AD that would apply to all GE Model CF34-10E2A1, CF34-10E5, CF34-10E5A1, CF34-10E6, CF34-10E6A1, CF34-10E7, and CF34-10E7-B engines with an installed HPT shroud/LPT nozzle assembly having P/N 2205M38G01, 2205M38G02, 2205M38G03, 2205M38G04, or 2205M38G05. The SNPRM was published in the Federal Register on January 23, 2025 (90 FR 7998). The SNPRM was prompted by comments received on the NPRM from GE and Japan Airlines requesting the addition of GE Model CF34-10E5 and CF34-10E5A1 engines to the applicability of the NPRM. In response to these comments, the FAA determined that additional model engines are affected by the unsafe condition and, as a result, should be added to the applicability paragraph of this AD. The SNPRM proposed to require a visual inspection of the combustion case for wear and gouges, repair if necessary, and rework of the affected HPT shroud/LPT nozzle assemblies to add a positive retention of the support air duct. The FAA is issuing this AD to address the unsafe condition on these products.

The FAA received comments from one individual commenter. The following presents the comments received on the SNPRM and the FAA's response to the comments.

An individual commenter requested that the FAA evaluate the economic impact of compliance with the proposed AD, particularly on smaller operators, and explore cost-effective solutions like alternative repair procedures or extended compliance windows where safety permits. The commenter also recommended that the FAA consider additional guidance on streamlined approval processes for alternative methods of compliance (AMOCs) in order to allow for flexibility in addressing wear and damage while maintaining rigorous safety standards. The commenter noted that the estimated cost of compliance, particularly in cases requiring full combustion case replacement, could impose a financial burden on affected carriers.

The FAA acknowledges the commenter's concerns and notes that flexibility in compliance with an AD is allowed through a request for an AMOC, allowed through the procedures in paragraph (i) of this AD. The unsafe condition addressed in this AD includes failure of the combustion case, which could result in possible engine separation and loss of the airplane. Inspections and repairs are therefore necessary to detect and repair any wear and gouges on the combustion case before they lead to structural failure. The FAA did not change this AD as a result of this comment.

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 SNPRM. None of the changes will increase the economic burden on any operator.

The FAA reviewed GE CF34-10E Service Bulletin 72-0351 R01, dated July 17, 2019, which specifies procedures for a visual inspection of the combustion case for wear and gouges, repair if necessary, and rework of the affected HPT shroud/LPT nozzle assemblies. This material also introduces a new HPT shroud/LPT nozzle assembly P/N 2205M38G07 with welded retaining rings. 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.

The FAA estimates that this AD affects 221 engines installed on airplanes of U.S. registry.

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

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

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: