2024-05995. Airworthiness Directives; General Electric Company Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain General Electric Company (GE) Model GEnx–1B64/P1, GEnx–1B64/P2, GEnx–1B67, GEnx–1B67/P1, GEnx–1B67/P2, GEnx–1B70, GEnx–1B70/75/P1, GEnx–1B70/75/P2, GEnx–1B70/P1, GEnx–1B70/P2, GEnx–1B70C/P1, GEnx–1B70C/P2, GEnx–1B74/75/P1, GEnx–1B74/75/P2, GEnx–1B76/P2, GEnx–1B76A/P2, GEnx–2B67, GEnx–2B67B, and GEnx–2B67/P engines. This proposed AD was prompted by a manufacturer evaluation that determined a lower life limit is necessary for certain stages 6–10 compressor rotor spools (stages 6–10 spools) than allowed by the engine shop manual (ESM). This proposed AD would require a one-time inspection of the stages 6–10 spools for previously accomplished blend repairs, a one-time inspection of the blend repairs on the stages 6–10 spools for compliance with the updated allowable limits, and replacement if necessary. The FAA is proposing this AD to address the unsafe condition on these products.

DATES:

The FAA must receive comments on this proposed AD by May 9, 2024.

ADDRESSES:

You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:

• Federal eRulemaking Portal: Go to regulations.gov. Follow the instructions for submitting comments.

• Fax: [phone].

• Mail: U.S. Department of Transportation, Docket Operations, M–30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue SE, Washington, DC 20590.

• Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA–2024–0755; 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 NPRM, any comments received, and other information. The street address for Docket Operations is listed above.

Material Incorporated by Reference:

• For service information identified in this NPRM, contact GE, 1 Neumann Way, Cincinnati, OH 45215; phone: [phone]; email: [e-mail]; website: 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 (817) 222–5110.

FOR FURTHER INFORMATION CONTACT:

Alexei Marqueen, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under ADDRESSES . Include “Docket No. FAA–2024–0755; Project Identifier AD–2023–00521–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 amend 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 Alexei Marqueen, 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 was notified of a manufacturer evaluation, which consisted of a heat transfer analysis, that revealed significant changes in thermal gradients in certain areas of the high-pressure compressor rotor (HPCR) assembly on GE Model GEnx–1B64/P1, GEnx–1B64/P2, GEnx–1B67, GEnx–1B67/P1, GEnx–1B67/P2, GEnx–1B70, GEnx–1B70/75/P1, GEnx–1B70/75/P2, GEnx–1B70/P1, GEnx–1B70/P2, GEnx–1B70C/P1, GEnx–1B70C/P2, GEnx–1B74/75/P1, GEnx–1B74/75/P2, GEnx–1B76/P2, GEnx–1B76A/P2, GEnx–2B67, GEnx–2B67B, and GEnx–2B67/P engines. The results of the heat transfer analysis were used to determine that a lower life limit is required for certain areas of the HPCR. Consequently, the manufacturer re-checked the serviceable and repairable limits of the stages 6–10 spools to determine if they still maintained the threshold limit for serviceability, where it was discovered that two repair procedures listed in the ESM exceeded the updated repair limits at certain locations of the HPCR assembly.

Due to the findings of the previous evaluations, the manufacturer performed an updated analysis and determined that a new threshold for the repairable limits for blend-repaired stages 6–10 spools is necessary. The manufacturer also determined that certain areas of previous blend-repaired stages 6–10 spools may have a lower life limit than the ultimate life limit of the HPCR disks.

This condition, if not addressed, could result in fracture and potential uncontained failure of the stages 6–10 spools, with consequent uncontained debris release, damage to the engine, and damage to the aircraft.

FAA's Determination

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

Related Service Information Under 1 CFR Part 51

The FAA reviewed GE GEnx–1B Service Bulletin 72–0525, R00, dated October 4, 2023 (GEnx–1B SB 72–0525, R00), and GEnx–2B Service Bulletin 72–0460, R00, dated October 4, 2023 (GEnx–2B SB 72–0460, R00). This service information identifies the part numbers and serial numbers of affected stages 6–10 spools; and specifies instructions for a one-time inspection of the stages 6–10 spools for previously accomplished blend repairs, a one-time inspection of the blend repairs on the stages 6–10 spools for compliance with the updated allowable limits, and replacement if necessary. These documents are distinct since they apply to different engine models.

This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in ADDRESSES section.

Proposed AD Requirements in This NPRM

This NPRM would require accomplishing a one-time inspection of the stages 6–10 spools for previously accomplished blend repairs, a one-time inspection of the blend repairs on the stages 6–10 spools for compliance with the updated allowable limits, and replacement, if necessary, within compliance times specified in GE GEnx–1B SB 72–0525, R00 or GEnx–2B SB 72–0460, R00. Depending on the part numbers and serial numbers of the affected stages 6–10 spools, this NPRM proposes to require these actions to be accomplished at the next piece-part exposure after the effective date of this proposed AD, or before the affected stages 6–10 spool reaches the cyclic removal threshold of up to 11,894 cycles since new.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 6 engines installed on airplanes of U.S. registry.

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

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Inspect stages 6–10 spools	8 work-hours × $85 per hour = $680	$0	$680	$4,080
Inspect previous blend repairs	1 work-hours × $85 per hour = $85	0	85	510

The FAA estimates the following costs to do any necessary 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 this replacement:

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Replace stages 6–10 spool	8 work-hours × $85 per hour = $680	$1,307,600	$1,308,280

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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Proposed Amendment

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

General Electric Company: Docket No. FAA–2024–0755; Project Identifier AD–2023–00521–E.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by May 9, 2024.

(b) Affected ADs

None.

(c) Applicability

This AD applies to General Electric Company (GE) Model GEnx–1B64/P1, GEnx–1B64/P2, GEnx–1B67, GEnx–1B67/P1, GEnx–1B67/P2, GEnx–1B70, GEnx–1B70/75/P1, GEnx–1B70/75/P2, GEnx–1B70/P1, GEnx–1B70/P2, GEnx–1B70C/P1, GEnx–1B70C/P2, GEnx–1B74/75/P1, GEnx–1B74/75/P2, GEnx–1B76/P2, GEnx–1B76A/P2, GEnx–2B67, GEnx–2B67B, and GEnx–2B67/P engines with an installed:

(1) Stages 6–10 compressor rotor spool (stages 6–10 spool) having a part number (P/N) and serial number (S/N) listed in paragraph 4, Appendix—A, Table 1 of GE GEnx–1B Service Bulletin 72–0525, R00, dated October 4, 2023 (GEnx–1B SB 72–0525, R00); or

(2) Stages 6–10 spool having a P/N and S/N listed in paragraph 4, Appendix—A, Table 1 of GE GEnx–2B Service Bulletin 72–0460, R00, dated October 4, 2023 (GEnx–2B SB 72–0460, R00).

(d) Subject

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

(e) Unsafe Condition

This AD was prompted by a manufacturer evaluation which determined that a lower life limit is necessary for certain stages 6–10 spools than that allowed in the engine shop manual. The FAA is issuing this AD to prevent fracture and potential uncontained failure of the stages 6–10 spools. The unsafe condition, if not addressed, could result in uncontained debris release, damage to the engine, and damage to the aircraft.

(f) Compliance

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

(g) Required Actions

At the next piece-part exposure after the effective date of this AD or before the affected stages 6–10 spool reaches the cyclic removal threshold specified in paragraph 4., Appendix—A, Table 1 of GEnx–1B 72–0525, R00 or GEnx–2B SB 72–0460, R00, as applicable, do the following actions:

(1) Inspect the stages 6–10 spool for previously accomplished blend repairs in accordance with the Accomplishment Instructions, paragraph 3.B.(1) of GEnx–1B SB 72–0525, R00 or GEnx–2B SB 72–0460, R00, as applicable.

(2) If during any inspection required by paragraph (g)(1) of this AD, any stages 6–10 spool is found to have a previously accomplished blend repair, before further flight, inspect the blend repair for compliance with the allowable limits in accordance with the Accomplishment Instructions, paragraph 3.B.(2) of GEnx–1B SB 72–0525, R00 or GEnx–2B SB 72–0460, R00, as applicable.

(3) If during any inspection required by paragraph (g)(2) of this AD, any stages 6–10 spool is found to have a previously accomplished blend repair that is not within the allowable limits, before further flight, remove the stages 6–10 spool from service and replace with a part eligible for installation in accordance with the Accomplishment Instructions, paragraph 3.B.(2)(a)1 or 3.B.(2)(b)1 of GEnx–1B SB 72–0525, R00 or GEnx–2B SB 72–0460, R00, as applicable.

(h) Definition

(1) For the purpose of this AD, a “piece-part exposure” is when the stages 6–10 spool is disassembled from the high-pressure compressor rotor assembly.

(2) For the purpose of this AD, a “part eligible for installation” is a stages 6–10 spool that does not have a P/N and S/N identified in paragraph 4, Appendix—A, Table 1 of GEnx–1B 72–0525, R00 or GEnx–2B 72–0460, R00.

(i) 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 (j) of this AD and email to: [e-mail].

(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.

(j) Related Information

For more information about this AD, contact Alexei Marqueen, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: [phone]; email: [e-mail].

(l) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise.

(i) General Electric Company (GE) GEnx–1B Service Bulletin 72–0525, R00, dated October 4, 2023.

(ii) GE GEnx–2B Service Bulletin 72–0460, R00, dated October 4, 2023.

(4) You may view this service information at 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 [e-mail].

Issued on March 15, 2024.

Victor Wicklund,

Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.