SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under the ADDRESSES section. Include “Docket No. FAA-2026-8816; Project Identifier AD-2026-00605-E” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may revise this proposal because of those comments.

Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to regulations.gov, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.

Confidential Business Information

CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this NPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI should be sent to Carol Nguyen, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

Background

The FAA received six reports from the manufacturer of shop finds of clashing on either the HPC 2nd stage rotor or HPC 3rd stage rotor caused by wear on the HPC VSV bushing set. A manufacturer investigation revealed that the wear on the HPC VSV bushing set allowed the vane to rock forward, which caused the HPC variable vane inner locating ring to contact the HPC rotor rear rim. This contact can lead to failure of the HPC 1st stage, 2nd stage, and 3rd stage rotors. This condition, if not addressed, could result in uncontained part release, damage to the engine, damage to the airplane, and loss of control of the airplane.

FAA's Determination

The FAA is issuing this NPRM after determining that the unsafe condition ( printed page 58824) described previously is likely to exist or develop on other products of the same type design.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed PW Alert Service Bulletin (ASB) PW1000G-A-72-00-0200-00B-930A-D, Issue No: 001, dated July 13, 2026; and PW ASB PW1000G-A-72-00-0248-00A-930A-D, Issue No: 001, dated July 13, 2026. This material specifies procedures for performing initial and repetitive BSIs of the HPC 1st stage, 2nd stage, and 3rd stage rotor rear rim surfaces for signs of wear, scratching, or contact with the HPC VSV inner locating ring. This material also specifies the serial numbers for affected HPC modules. 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.

Proposed AD Requirements in This NPRM

This proposed AD would require performing initial and repetitive BSIs of the HPC 1st stage, 2nd stage, and 3rd stage rotor rear rim surfaces for evidence of wear, scratching, or contact with the corresponding HPC VSV inner locating ring and, depending on the results, removal from service and replacement. This proposed AD would also require replacement of the HPC VSV bushing set as terminating action to the initial and repetitive BSIs of the HPC 1st stage, 2nd stage, and 3rd stage rotor rear rim surfaces.

Interim Action

The FAA considers that this proposed AD would be an interim action. The manufacturer is currently developing additional mitigations that will address the unsafe condition identified in this AD. Once this is developed, approved, and available, the FAA might consider additional rulemaking.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 215 engines installed on airplanes of U.S. registry.

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

The FAA estimates the following costs to do any necessary replacements that would be required based on the results of the proposed inspection. 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

The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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:

Pratt & Whitney: Docket No. FAA-2026-8816; Project Identifier AD-2026-00605-E. ( printed page 58825)

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by October 19, 2026.

(b) Affected ADs

None.

(c) Applicability

(1) This AD applies to all Pratt & Whitney (PW) Model PW1519G, PW1521G, PW1521GA, PW1521G-3, PW1524G, PW1524G-3, PW1525G, PW1525G-3, PW1919G, PW1919G-RC, PW1921G, PW1921G-RC, PW1922G, PW1923G, and PW1923G-A engines that have a high-pressure compressor (HPC) module installed with a serial number listed in Table 1 of PW Alert Service Bulletin (ASB) PW1000G-A-72-00-0200-00B-930A-D, Issue No: 001, dated July 13, 2026 (PW1000G-A-72-00-0200-00B-930A-D, Issue No: 001); or Table 1 of PW1000G-A-72-00-0248-00A-930A-D, Issue No: 001, dated July 13, 2026 (PW ASB PW1000G-A-72-00-0248-00A-930A-D, Issue No: 001).

(2) This AD does not apply to engines that have incorporated PW Service Bulletin PW1000G-A-72-00-0224-00A-930A-D or PW Service Bulletin PW1000G-A-72-00-0170-00B-930A-D, as applicable.

(d) Subject

Joint Aircraft System Component (JASC) Code 7230, Turbine Engine Compressor Section.

(e) Unsafe Condition

This AD was prompted by six reports of clashing found on either the HPC 2nd stage rotor or 3rd stage rotor caused by contact with the HPC variable stator vanes (VSV). The FAA is issuing this AD to prevent failure of the HPC 1st stage, 2nd stage, and 3rd stage rotors. The unsafe condition, if not addressed, could result in uncontained part release, damage to the engine, damage to the airplane, and loss of control of the airplane.

(f) Compliance

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

(g) Definitions

For the purpose of this AD:

(1) Model “PW1500G” engines are PW Model PW1519G, PW1521G, PW1521GA, PW1521G-3, PW1524G, PW1524G-3, PW1525G, and PW1525G-3 engines.

(2) Model “PW1900G” engines are PW Model PW1919G, PW1919G-RC, PW1921G, PW1921G-RC, PW1922G, PW1923G, and PW1923G-A engines.

(3) An “HPC front case split flange separation” is when the HPC front case horizontal flange is separated.

(4) An “HPC VSV bushing set” is comprised of sleeve bearings having part numbers (P/Ns) 30G1934, 30G1935, and 30G1936; and thrust washer bearings having P/Ns 30G1938, 30G1939, and 30G1940.

(5) “Parts eligible for installation” are comprised of sleeve bearings having P/Ns 30G6496, 30G6497, and 30G6498; and thrust washer bearings having P/Ns 30G6499, 30G6500, and 30G6503; or later approved P/Ns.

Note 1 to paragraph (g)(5): An HPC case with P/N 30G6509 has installed sleeve bearings with P/Ns 30G6496, 30G6497, and 30G6498.

(6) An “HPC 1st stage, 2nd stage, or 3rd stage rotor eligible for installation” is any HPC 1st stage, 2nd stage, or 3rd stage rotor that was not removed from service in accordance with the requirements of this AD.

(h) Required Actions

(1) Before accumulating 8,000 flight hours (FH) or within 1,000 FH after the effective date of this AD, whichever occurs later, perform an initial borescope inspection (BSI) of the HPC 1st stage, 2nd stage, and 3rd stage rotor rear rim surfaces for evidence of circumferential wear, scratching, or damage that shows previous contact with the corresponding HPC VSV inner locating ring in accordance with the applicable ASB listed in table 1 to paragraph (h)(1) of this AD, as applicable to engine model.

(2) Thereafter, at intervals not to exceed 1,000 FH since the last BSI, perform repetitive BSIs of the HPC 1st stage, 2nd stage, and 3rd stage rotor rear rim surfaces for circumferential wear, scratching, or damage that shows previous contact with the corresponding HPC VSV inner locating ring in accordance with the applicable ASB listed in table 1 to paragraph (h)(1) of this AD, as applicable to the engine model.

(3) If, during any BSI required by paragraph (h)(1) or (2) of this AD, evidence of circumferential wear, scratching, or damage that shows previous contact with the corresponding HPC VSV inner locating ring is discovered on the HPC 1st stage, 2nd stage, or 3rd stage rotor rear rim surface, before further flight, remove each damaged part from service and replace with an HPC 1st stage, 2nd stage, or 3rd stage rotor eligible for installation.

(4) At the next HPC front case split flange separation after the effective date of this AD, replace the HPC VSV bushing set with parts eligible for installation.

Note 2 to paragraph (h)(4): Guidance for performing the replacement of the HPC VSV bushing set may be found in PW Service Bulletin PW1000G-A-72-00-0224-00A-930A-D, Issue No: 003, dated April 25, 2025, for PW Model PW1500G engines; and PW Service Bulletin PW1000G-A-72-00-0170-00B-930A-D, Issue No: 004, dated July 25, 2025, for PW Model PW1900G engines.

(i) Terminating Action

Replacing the HPC VSV bushing set in accordance with paragraph (h)(4) of this AD constitutes terminating action for the initial and repetitive BSIs of the HPC 1st stage, 2nd stage, and 3rd stage rotor rear rim surface required by paragraphs (h)(1) and (2) of this AD.

(j) No Reporting Requirement

Although PW1000G-A-72-00-0200-00B-930A-D, Issue No: 001, and PW ASB PW1000G-A-72-00-0248-00A-930A-D, Issue No: 001, specify to submit certain ( printed page 58826) information to the manufacturer, including capturing photos and videos, this AD does not require those actions.

(k) Alternative Methods of Compliance (AMOCs)

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)(1) 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.

(l) Additional Information

(1) For more information about this AD, contact Carol Nguyen, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: (781) 238-7655; email: carol.nguyen@faa.gov.

(2) Material identified in this AD that is not incorporated by reference is available at the address specified in paragraph (m)(4) of this AD.

(m) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference 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) PW1000G-A-72-00-0200-00B-930A-D, Issue No: 001, dated July 13, 2026.

(ii) PW ASB PW1000G-A-72-00-0248-00A-930A-D, Issue No: 001, dated July 13, 2026.

(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 58823