Background 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 GE90-90B, GE90-94B, GE90-110B1, and GE90-115B engines. The NPRM was published in the Federal Register on July 29, 2025 (90 FR 35642). The NPRM was prompted by the detection of iron inclusion in a turbine disk manufactured from the same powder metal material used to manufacture certain HPT stage 1 and HPT stage 2 disks for GE Model GE90-90B, GE90-94B, GE90-110B1, and GE90-115B 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 revealed that there were no incidents of premature fracture and uncontained failure associated with the discovery of this iron inclusion material on these engines but concluded that replacement of the affected HPT stage 1 and HPT stage 2 disks is necessary to prevent any future failure 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. Discussion of Final Airworthiness Directive Comments The FAA received comments from four commenters. The commenters were the Air Line Pilots Association, International (ALPA), The Boeing Company (Boeing), FedEx Express (FedEx), and GE Aerospace. The ALPA, Boeing, and FedEx supported the NPRM without change. The following presents the comment received on the NPRM and the FAA's response to the comment. Request To Correct Part Numbers GE Aerospace requested that the FAA revise the part number in Table 1 to Paragraph (c) of the proposed AD for serial numbers GWN0NJ92, GWN0NJ94, and GWN0NK87 from "1865M13G08" to "1865M13G07." GE Aerospace noted that GE GE90-100 Service Bulletin 72-0926, Revision 01, dated December 22, 2023, lists the current part numbers for affected disks, and they have been confirmed with product support engineering. The FAA agrees and has updated the part number in Table 1 to Paragraph (c) of this AD as requested. Conclusion 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. Material Incorporated by Reference Under 1 CFR Part 51 The FAA reviewed GE GE90-100 Service Bulletin 72-0926, Revision 01, dated December 22, 2023. This material specifies the affected part numbers, serial numbers, and cyclic removal thresholds for the HPT stage 1 and HPT stage 2 disks. 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. Costs of Compliance The FAA estimates that this AD affects two engines installed on airplanes of U.S. registry. The FAA estimates that one engine installed on an airplane of U.S. registry will require replacement of the HPT stage 1 disk, and one engine installed on an airplane of U.S. registry will require replacement of the HPT stage 2 disk. The FAA estimates the following costs to comply with this AD: Estimated Costs Action Labor cost Parts cost Cost per product Cost on U.S. operators Replace HPT stage 1 disk 8 work-hours × $85 per hour = $680 $932,136 (prorated) $932,816 $932,816 Replace HPT stage 2 disk 8 work-hours × $85 per hour = $680 $186,406 (prorated) 187,086 187,086 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 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. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. The Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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: 2025-25-07 General Electric Company: Amendment 39-23215; Docket No. FAA-2025-1364; Project Identifier AD-2024-00613-E. (a) Effective Date This airworthiness directive (AD) is effective February 6, 2026. (b) Affected ADs None. (c) Applicability This AD applies to the following General Electric Company (GE) Model engines: (1) GE90-90B and GE90-94B engines with a high pressure turbine (HPT) stage 1 disk having a part number and serial number identified in table 1 to paragraph (c) of this AD installed; and (2) GE90-110B1 and GE90-115B engines with an HPT stage 1 disk or HPT stage 2 disk having a part number and serial number identified in table 1 to paragraph (c) of this AD or Table 1 or Table 2 of GE GE90-100 Service Bulletin (SB) 72-0926, Revision 01, dated December 22, 2023 (GE GE90-100 SB 72-0926, Revision 01), installed. Table 1 to Paragraph ( c )-Affected HPT Stage 1 and 2 Disks Part name Part No. Serial No. HPT Stage 1 Disk 1847M95G01 GWN05K5J HPT Stage 1 Disk 1847M95G01 GWN05K5M HPT Stage 1 Disk 1847M95G01 GWN05NP6 HPT Stage 1 Disk 1865M13G08 GWN10N9A HPT Stage 1 Disk 1865M13G07 GWN0NJ92 HPT Stage 1 Disk 1865M13G07 GWN0NJ94 HPT Stage 1 Disk 1865M13G07 GWN0NK87 HPT Stage 1 Disk 1865M13G08 GWN0RJ4G HPT Stage 1 Disk 1865M13G08 GWN0WPEC HPT Stage 2 Disk 1865M14P04 TMT4RK67 HPT Stage 2 Disk 1865M14P04 TMT4RG10 HPT Stage 2 Disk 1865M14P04 TMT4RG11 (d) Subject Joint Aircraft System Component (JASC) Code 7250, Turbine Section. (e) Unsafe Condition This AD was prompted by a manufacturer investigation that revealed certain HPT stage 1 disks and HPT stage 2 disks were manufactured from powder metal material suspected to contain iron inclusion. The FAA is issuing this AD to prevent premature fracture and uncontained failure of the HPT stage 1 disks and HPT stage 2 disks. The unsafe condition, if not addressed, could result in uncontained debris release, damage to the engine, and damage to the airplane. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Required Actions At the applicable times specified in paragraphs (g)(1) through (3) of this AD, remove each affected HPT stage 1 disk and HPT stage 2 disk from service and replace with a part eligible for installation. (1) For HPT stage 1 disks and HPT stage 2 disks with a part number and serial number identified in table 1 to paragraph (c) of this AD, before further flight. (2) For HPT stage 1 disks with a part number and serial number identified in Table 1 of GE GE90-100 SB 72-0926, Revision 01, that are not identified in table 1 to paragraph (c) of this AD, at the next piece-part exposure or before exceeding 4,650 cycles since new (CSN), whichever occurs first. (3) For HPT stage 2 disks with a part number and serial number identified in Table 2 of GE GE90-100 SB 72-0926, Revision 01, that are not identified in table 1 to paragraph (c) of this AD, at the next piece-part exposure or before exceeding 11,300 CSN, whichever occurs first. (h) Grace Period for HPT Stage 1 Disk Replacement For affected HPT stage 1 disks having greater than 4,650 CSN on the effective date of this AD, the replacement required by paragraph (g)(2) of this AD may be deferred up to 50 flight cycles after the effective date of this AD. (i) Definitions (1) For the purpose of this AD, a "part eligible for installation" is any HPT stage 1 disk or HPT stage 2 disk having a part number and serial number that is not identified in table 1 to paragraph (c) of this AD or Table 1 or Table 2 of GE GE90-100 SB 72-0926, Revision 01. (2) For the purpose of this AD, a "piece-part exposure" is when the affected HPT stage 1 disk or HPT stage 2 disk is removed from the engine and completely disassembled. (j) Alternative Methods of Compliance (AMOCs) (1) The Manager, AIR-520 Continued Operational Safety Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of AIR-520 Continued Operational Safety Branch, send it to the attention of the person identified in paragraph (k) of this AD and email to: AMOC@faa.gov. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. (k) Additional Information For more information about this AD, contact Alexei Marqueen, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: (781) 238-7178; email: alexei.t.marqueen@faa.gov. (l) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference (IBR) of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this material as applicable to do the actions required by this AD, unless the AD specifies otherwise. (i) GE GE90-100 Service Bulletin 72-0926, Revision 01, dated December 22, 2023. (ii) [Reserved] (3) For GE material identified in this AD, contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: aviation.fleetsupport@ge.com; website: ge.com. (4) 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. (5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email fr.inspection@nara.gov. Issued on December 8, 2025. Peter A. White, Deputy Director, Integrated Certificate Management Division, Aircraft Certification Service.