SUPPLEMENTARY INFORMATION:

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 PW Model F117-PW-100, PW2037, PW2037D, PW2037M, PW2040, PW2040D, PW2043, PW2143, and PW2643 engines. The NPRM was published in the Federal Register on June 2, 2025 (90 FR 23294). The NPRM was prompted by an updated analysis of an event involving an IAE LLC Model PW1127GA-JM engine, which experienced an HPC IBR-7 separation that resulted in an engine shutdown and aborted takeoff. The analysis revealed that the failure was caused by a nickel powdered metal anomaly and concluded that there is an increased risk of failure for additional nickel powdered metal parts in certain nickel powdered metal production campaigns, and these parts are susceptible to failure much earlier than previously determined. In the NPRM, the FAA proposed to require repetitive AUSIs of certain HPT 1st-stage disks and turbine hubs for any crack indications, and if necessary, removal from service and replacement, and removal from service of certain HPT lenticular seal assemblies. During the publication process of this AD, the type certificate data sheet (TCDS) was revised and PW Model PW2043, PW2143, and PW2643 engines were removed from the TCDS. Therefore, this final rule does not apply to those engine models. The FAA is issuing this AD to address the unsafe condition on these products. ( printed page 21946)

Discussion of Final Airworthiness Directive

Updated Material

Since the NPRM was published, the manufacturer has published PW Alert Service Bulletin (ASB) PW2000 A72-779, Revision No. 1, dated December 17, 2025. This material corrects an incorrect maintenance manual task reference for disassembly of components and all other information is the same as the material in the NPRM. The FAA has revised the final rule to reference PW ASB PW2000 A72-779, Revision No. 1, dated December 17, 2025, as the appropriate source of material for the AUSIs of the HPT 1st-stage disk.

Comments

The FAA received comments from five commenters. The commenters were The Boeing Company (Boeing), Delta Air Lines (DAL), FedEx, MTU Maintenance Hannover GmbH (MTU), and PW. Boeing concurred with the contents of the NPRM. The following presents the comments received on the NPRM and the FAA's response to each comment.

Discussion Regarding the Applicability of the NPRM

MTU stated that the applicability of certain cited material in the proposed AD does not match the applicability in the proposed AD. MTU indicated that the material applies to PW Model PW2037, PW2037(M), and PW2040 engines, while the proposed AD applies to several civil PW2000 engine models.

PW pointed out that the proposed AD would apply to PW Model PW2043, PW2143, and PW2643 engines, none of which are in service. PW indicated that a request has been submitted to the FAA for withdrawal of these models from the TCDS; however, the update was not yet published. PW stated that there are no necessary actions, or operator burden imposed by including these models in the AD.

The FAA acknowledges the observations from MTU and PW. The FAA is aware that certain PW Models are included in the applicability of this AD but are not listed in the material. During the publication process of this AD, the TCDS has been revised and PW Model PW2043, PW2143, and PW2643 engines have been removed. Therefore, those same model engines have been removed from this AD.

Request To Revise the Cost of Compliance

DAL and FedEx requested that the FAA revise the Cost of Compliance section of the proposed AD to reflect 14 HPT lenticular seal assemblies. Both commenters indicated that figure 1 to paragraph (g)(4) of the proposed AD lists 14 seal assemblies by part number and serial number, but the Estimated Costs table lists only 13 engines that require replacement. Additionally, DAL stated that the manufacturer has confirmed that 14 is the correct number of affected seals.

The FAA agrees for the reasons provided and has revised the Cost of Compliance section of this AD to indicate there are 14 affected HPT lenticular seal assemblies.

Request for Re-Inspection Procedure Guidance

DAL requested that the FAA revise paragraphs (g) and (h) of the proposed AD to specifically state whether HPT 1st-stage disks and turbine hubs are authorized to be re-inspected after initially failing an angled ultrasonic inspection (AUSI), and if so, whether the parts may be returned to service upon passing a re-inspection. DAL indicated that certain parts have failed initial AUSI but then passed re-inspection, however the parts were tagged as unserviceable. The commenter asserted that none of the IBR material provides disposition instructions for parts that pass a re-inspection.

The FAA disagrees with the request. The current revisions of Non-Destructive Inspection Procedure (NDIP)-1282 and NDIP-1283 contain procedures for the AUSI inspections and re-inspections, and are second-tier references in the IBR material that are necessary to complete the actions specified in this AD. The FAA did not change this AD as a result of this comment.

Request To Include Engine Manual (EM) Tasks as Material

DAL and MTU requested that the FAA update paragraphs (g)(1) and (2) of the proposed AD to include certain PW2000 EM tasks as additional material for compliance for the HPT 1st-stage disk and turbine hub inspections in addition to the referenced Alert Service Bulletins (ASBs). DAL stated that the EM provides the same AUSI scan tasks as the ASBs, and that PW previously incorporated the NDIPs into the EM tasks. DAL also noted that adding this reference as an option will provide an acceptable level of safety.

The FAA disagrees with the request. In determining an appropriate set of required actions for this unsafe condition, the FAA considered the recommendations of the manufacturer, the urgency associated with the subject unsafe condition, and the practical aspect of accomplishing the required actions using the specified material for most affected operators. However, under the provisions specified in paragraph (j) of this AD, the FAA will consider requests for alternative methods of compliance (AMOCs). The FAA did not change this AD as a result of this comment.

Request To Include Certain Assembly Part Numbers

DAL requested that the FAA include the assembly part numbers of the HPT 1st-stage disk assembly and turbine hub assembly, and the detail part numbers of the HPT 1st-stage disks and turbine hubs in paragraphs (h) and (i) of the proposed AD. DAL stated that the Form 8130s, received with each of the parts, occasionally list the assembly level part number instead of the detail part number, and operators sometimes track the parts at the assembly level. DAL indicated that specifying both the detail and assembly part numbers would help to reduce confusion regarding which parts are affected by the NPRM.

The FAA disagrees with the request but agrees that clarification is necessary. The definitions specified in paragraphs (h)(2)(i) through (vi), and the prohibitions specified in paragraphs (j)(1) and (2) of this AD are dependent on the part having passed the AUSI requirements specified in paragraph (g) of this AD, which apply to the detail part number only. Additionally, an AUSI will be completed on a detail part number at new manufacture, but not on an assembly part number. The FAA did not change this AD as a result of this comment.

Request To Include Threshold Date for Parts Inspected at Manufacture

DAL requested that the FAA update paragraphs (h)(2)(iii) and (h)(2)(vi) of the proposed AD to provide an FAA Form 8130-3 date after which all new zero-time HPT 1st-stage disks and turbine hubs can be considered parts eligible for installation. MTU requested clarification of how to determine which new manufacture parts have passed an AUSI during production. PW requested that the FAA remove paragraphs (h)(2)(iii) and (vi) of the proposed AD and proposed that the FAA allow all new manufactured parts to be eligible for installation regardless of confirmation of receiving an AUSI. PW indicated its fleet management plan does not require confirmation that new affected parts have received an AUSI during manufacture to be eligible for installation. PW also stated that all new parts shipped to PW as of March 1, 2025, have received AUSIs during ( printed page 21947) manufacture, and that all commercial inventory available from PW commercial spares have received an AUSI. DAL indicated that the manufacturer should have the ability to provide proof that new parts have passed an AUSI and are eligible for installation, that operators do not have access to the data, and placing the burden of proof on operators is tedious and problematic. DAL also stated that if providing proof is not possible, then the manufacturer should have the ability to guarantee to the FAA and operators that all newly manufactured parts with an FAA Form 8130-3 dated after a certain date have passed an AUSI and are eligible for installation.

The FAA agrees with the requests. Since operators do not have access to the necessary data to determine whether zero-time components have passed an AUSI at new part manufacture, the FAA has determined that the responsible party may determine if the part is eligible for installation based on the date specified on the FAA Form 8130-3. The FAA has revised paragraphs (h)(2)(iii) and (h)(2)(vi) of this AD by removing the words “that has passed an AUSI at new part production” and replacing them with “that has an FAA Form 8130-3 from the original equipment manufacturer for new production dated March 1, 2025, or later.”

Request To Remove Certain Definitions

DAL requested that the FAA remove paragraphs (h)(2)(ii) and (v) of the proposed AD, eliminating the references to NDIP-1282 and NDIP-1283. DAL stated that those paragraphs do not provide a revision level or date for the NDIPs which could cause confusion regarding compliance or whether an AMOC might be required to allow use of future revisions of the NDIPs. DAL indicated that those paragraphs all appear to have the same intent; an AUSI performed on parts that are not new production, with a passing result that is documented.

The FAA disagrees with the request. The NDIPs referenced in paragraphs (h)(2)(ii) and (v) of this AD are necessary because some parts may have received an AUSI in compliance with NDIP-1282 or NDIP-1283 prior to publication of this AD. Additionally, the revision of the NDIP is not relevant, as all revisions are acceptable to the FAA for the purposes of this AD. The FAA did not change this AD as a result of this comment.

Request To Update Definition of “Piece-Part Exposure”

DAL requested that the FAA revise the definition of “piece-part exposure” in paragraph (h)(1)(i) and (ii) of the proposed AD (for the HPT 1st-stage disk and turbine hub) to include removal of all parts from the disk and hub and correspond with certain PW2000 EM disassembly tasks. DAL pointed out that the disk and hub can be removed from the engine as specified in the NPRM, with all the blades removed, but for the associated PW2000 EM disassembly tasks, removing the blades from the disk or hub is not the final step in the process and some parts remain installed on the disk or hub. DAL also stated certain workscope levels provided by the manufacturer to operators could be nullified by the definition provided in the NPRM.

The FAA agrees with the request for the reasons provided. The FAA has revised paragraph (h)(1)(i) of this AD to state: “. . . when the HPT 1st-stage disk is removed from the engine and all blades, all retaining plates, and all airseals are removed from the HPT 1st-stage disk.” The FAA has revised paragraph (h)(1)(ii) of this AD to state: “. . . when the turbine hub is removed from the engine and all blades and all retaining plates are removed from the turbine hub.”

Request To Remove Revision Date From Referenced Service Bulletins

FedEx requested that the FAA revise certain material citations specified in paragraphs (g)(1) and (2) of the proposed AD to read “dated May 2, 2024, or later,” or remove the revision date entirely. FedEx stated that if the material is revised in the future, an AMOC would be required for implementation. FedEx also stated that removing the date would minimize the effect on operator engineering orders and maintenance, repair, and overhaul (MRO) inspection provider procedures.

The FAA disagrees with the request. To IBR the material specified in this AD, the citation must refer to a specific document, including the specific revision date. Additionally, the FAA is unable to cite a future revision to a document which does not yet exist. The FAA also notes that, since the NPRM was published, PW has published PW ASB PW2000 A72-779, Revision No. 1, dated December 17, 2025. The FAA has revised this AD to reference PW ASB PW2000 A72-779, Revision No. 1, dated December 17, 2025 as the appropriate source of material for the AUSIs of the HPT 1st-stage disk. The FAA did not change this AD as a result of this comment.

Request To Standardize Compliance Documentation

FedEx requested that the FAA revise paragraph (h)(2)(i) of the proposed AD to state that for all affected parts, used or new production, compliance must be recorded on the associated FAA Form 8130-3, and delete paragraphs (h)(2)(ii), (h)(2)(iii), (h)(2)(v), and (h)(2)(vi). FedEx stated that the specific document type associated with the terms “certificate of conformance” and “passed an AUSI at new part production” is not defined in the NPRM, and that during records verification or audits, the document format or content may be considered invalid. FedEx indicated that a single compliance standard would help to clarify the definitions and the installation prohibition included in paragraphs (i)(1) and (2) of the proposed AD.

The FAA disagrees with the request. The proposed document (FAA Form 8130-3) does not contain the information necessary to show compliance. The FAA did not change this AD as a result of this comment.

Request To Mandate Airworthiness Limitation Section (ALS) Updates Instead of Service Material

PW requested that the FAA revise the NPRM to require updating the ALS instead of the actions specified in the service material. PW stated that the inspections specified in the service material for the HPT 1st-stage disks and 2nd-stage hubs have been included in the ALS/Enhanced Rotor Inspection (ERI) requirements of the EM as of February 2025 and are now duplicate requirements.

The FAA disagrees with the request. However, the FAA finds that updating the ALS provides acceptable mitigation of the unsafe condition. The FAA has added paragraph (i) of this AD to include optional terminating action for operators that update their ALS to include the inspections required by paragraphs (g)(1) through (3) of this AD.

Request To Allow Cycle Limit for a Certain HPT Lenticular Seal Assembly

PW requested that the FAA revise figure 1 to paragraph (g)(4) of the proposed AD to add a note to serial number DKLBG48292 stating “or 2,750 cycles since new, whichever occurs first.” PW stated that it has previously communicated to an operator a 2,750 cycle since new removal requirement for this serial number, while all other HPT lenticular seal assemblies identified in figure 1 to paragraph (g)(4) ( printed page 21948) of the proposed AD only require removal at the next piece-part exposure.

The FAA agrees with the request. The FAA has removed serial number DKLBG48292 from figure 1 to paragraph (g)(4) of this AD and moved that serial number to paragraph (g)(5) of this AD, which states “. . . or before exceeding 2,750 cycles since new, whichever occurs first. . .”

Request To Include Additional Serial Numbers

PW requested that the FAA add 25 HPT lenticular seal assembly serial numbers, which are installed on PW Model F117-PW-100 engines, to figure 1 to paragraph (g)(4) of the proposed AD. PW stated that the serial numbers were omitted from the NPRM.

The FAA agrees with the request. The FAA has added the missing serial numbers to figure 1 to paragraph (g)(4) of this AD. However, the Cost of Compliance section has not changed because the additional HPT lenticular seal assemblies are installed on F117 engines which are not installed on U.S. registered airplanes.

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 PW ASB PW2000 A72-779, Revision No. 1, dated December 17, 2025, and PW ASB PWF117 A72-434, dated May 1, 2024, which specify procedures for repetitive AUSIs of the HPT 1st-stage disk for crack indications. This material is distinct since each applies to different engine models.

The FAA also reviewed PW ASB PW2000 A72-780, dated May 2, 2024, and PW ASB PWF117 A72-433, dated May 1, 2024, which specify procedures for repetitive AUSIs of the turbine hub. This material is distinct since each applies to different engine models.

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 484 engines installed on airplanes of U.S. registry. The FAA estimates that 14 engines will require replacement of the HPT lenticular seal assembly. PW Model F117-PW-100 engines, which are not installed on U.S. registered airplanes, are not included in this cost estimate.

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

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

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.

( printed page 21949)

The Amendment

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:

Authority: 49 U.S.C. 106(g), 40113, 44701.

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

2026-07-06 Pratt & Whitney: Amendment 39-23301; Docket No. FAA-2025-0918; Project Identifier AD-2024-00526-E.

(a) Effective Date

This airworthiness directive (AD) is effective May 29, 2026.

(b) Affected ADs

None.

(c) Applicability

This AD applies to Pratt & Whitney (PW) Model F117-PW-100, PW2037, PW2037D, PW2037M, PW2040, and PW2040D engines.

(d) Subject

Joint Aircraft System Component (JASC) Code 7250, Turbine Section.

(e) Unsafe Condition

This AD was prompted by an updated analysis of an event involving an International Aero Engines, LLC Model PW1127GA-JM engine, which experienced a high-pressure compressor 7th-stage integrally bladed rotor separation that resulted in an engine shutdown and aborted takeoff. The FAA is issuing this AD to prevent failure of the high-pressure turbine (HPT) 1st-stage disk, and turbine hub. The unsafe condition, if not addressed, could result in uncontained disk failure, release of high-energy debris, damage to the engine, damage to the airplane, and possible loss of the airplane.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Required Actions

(1) At the next piece-part exposure after the effective date of this AD and thereafter at every piece-part exposure, do an angled ultrasonic inspection (AUSI) of the HPT 1st-stage disk for any crack indications in accordance with Paragraph 4. of the Accomplishment Instructions of PW Alert Service Bulletin (ASB) PW2000 A72-779, Revision No. 1, dated December 17, 2025, or Paragraph 4. of the Accomplishment Instructions of PW ASB PWF117 A72-434, dated May 1, 2024, as applicable to the engine model.

(2) At the next piece-part exposure after the effective date of this AD and thereafter at every piece-part exposure, do an AUSI of the turbine hub for any crack indications in accordance with Paragraph 4. of the Accomplishment Instructions of PW ASB PW2000 A72-780, dated May 2, 2024, or Paragraph 4. of the Accomplishment Instructions of PW ASB PWF117 A72-433, dated May 1, 2024, as applicable to the engine model.

(3) If, during any inspection required by paragraph (g)(1) or (2) of this AD, any crack indication is found, remove the affected part from service and replace with a part eligible for installation.

(4) For engines with an installed HPT lenticular seal assembly having a part number (P/N) and serial number (S/N) identified in figure 1 to paragraph (g)(4) of this AD: At the next piece-part exposure after the effective date of this AD, remove the HPT lenticular seal assembly from service and replace with a part eligible for installation.

(5) For an HPT lenticular seal assembly having P/N 1B8575 and S/N DKLBG48292: At the next piece-part exposure after the effective date of this AD or before exceeding 2,750 cycles since new, whichever occurs first, remove the HPT lenticular seal assembly from service and replace with a part eligible for installation.

(h) Definitions

(1) For the purpose of this AD, a “piece-part exposure” is:

(i) For paragraph (g)(1) of this AD, when the HPT 1st-stage disk is removed from the engine and all blades, all retaining plates, and all air seals are removed from the HPT 1st-stage disk.

(ii) For paragraph (g)(2) of this AD, when the turbine hub is removed from the engine and all blades and all retaining plates are removed from the turbine hub.

(iii) For paragraph (g)(4) of this AD, when the HPT lenticular seal assembly is removed from either the HPT 1st-stage disk or the HPT 2nd-stage hub.

(2) For the purpose of this AD, a “part eligible for installation” is:

(i) An HPT 1st-stage disk having P/N 1B7801, 1B3601, or 1B3601-001 that has passed the AUSI required by paragraph (g)(1) of this AD.

(ii) An HPT 1st-stage disk having P/N 1B7801, 1B3601, or 1B3601-001, that has a certificate of conformance that shows compliance with Non-Destructive Inspection Procedure (NDIP)-1282.

(iii) A new zero-time HPT 1st-stage disk having P/N 1B7801, 1B3601, or 1B3601-001 that has an FAA Form 8130-3 from the original equipment manufacturer for new production dated March 1, 2025, or later.

(iv) A turbine hub having P/N 1B4902, 1B6602, or 1B8002 that has passed the AUSI required by paragraph (g)(2) of this AD.

(v) A turbine hub having P/N 1B4902, 1B6602, or 1B8002 that has a certificate of conformance that shows compliance with NDIP-1283.

(vi) A new zero-time turbine hub having P/N 1B4902, 1B6602, or 1B8002 that has an FAA Form 8130-3 from the original equipment manufacturer for new production dated March 1, 2025, or later.

(vii) Any HPT lenticular seal assembly that does not have a part number and serial number identified in figure 1 to paragraph (g)(4) of this AD

(i) Optional Terminating Action

Revising the airworthiness limitations section (ALS) of the existing engine manual and the operator's existing approved maintenance program or inspection program, as applicable, by incorporating the information in figure 2 to paragraph (i) of this AD, constitutes terminating action for the inspections required by paragraphs (g)(1) through (3) of this AD. ( printed page 21950)

(j) Installation Prohibition

(1) As of the effective date of this AD, no person may install on any engine, an HPT 1st-stage disk having P/N 1B7801, 1B3601, or 1B3601-001, unless it is a part eligible for installation as defined in paragraph (h)(2) of this AD.

(2) As of the effective date of this AD, no person may install on any engine, a turbine hub having P/N 1B4902, 1B6602, or 1B8002, unless it is a part eligible for installation as defined in paragraph (h)(2) of this AD.

(3) As of the effective date of this AD, no person may install on any engine, an HPT lenticular seal assembly having a part number and serial number identified in figure 1 to paragraph (g)(4) of this AD.

(k) 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 the AIR-520 Continued Operational Safety Branch, send it to the attention of the person identified in paragraph (l) of this AD and email to: AMOC@faa.gov.

(2) 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.

(l) Additional Information

For more information about this AD, contact Molly Sturgis, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: (562) 627-5373; email: molly.a.sturgis@faa.gov.

(m) 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) Pratt & Whitney (PW) Alert Service Bulletin (ASB) PW2000 A72-779, Revision No. 1, dated December 17, 2025.

(ii) PW ASB PW2000 A72-780, dated May 2, 2024.

(iii) PW ASB PWF117 A72-433, dated May 1, 2024.

(iv) PW ASB PWF117 A72-434, dated May 1, 2024.

(3) For PW material identified in this AD, contact PW, 400 Main Street, East Hartford, CT 06118; phone: (860) 565-0140; email: help24@prattwhitney.com; website: connect.prattwhitney.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.

91 FR 21945