2023-18858. 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 GE90–90B, GE90–94B, GE90–110B1, and GE90–115B engines. This proposed AD was prompted by a manufacturer investigation that revealed certain high-pressure turbine (HPT) stage 1 disks, HPT stage 2 disks, forward HPT rotor seals, interstage HPT seals, and stages 7–9 compressor rotor spools were manufactured from powder metal material suspected to contain iron inclusion. This proposed AD would require replacement of affected HPT stage 1 disks, HPT stage 2 disks, forward HPT rotor seals, interstage HPT seals, and stages 7–9 compressor rotor spools. 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 October 20, 2023.

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 by searching for and locating Docket No. FAA–2023–1647; 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 incorporated by reference in this NPRM, contact General Electric Company, 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–2023–1647; Project Identifier AD–2023–00487–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 by the manufacturer of the detection of iron inclusion in a turbine disk manufactured from the same powder metal material used to manufacture certain HPT stage 1 disks, HPT stage 2 disks, forward HPT rotor seals, interstage HPT seals, and stages 7–9 compressor rotor spools for GE90–90B, GE90–94B, GE90–110B1, and GE90–115B engines. Further investigation by the manufacturer determined 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 subsequent uncontained failure. The FAA has been informed that GE has communicated with affected operators with affected HPT stage 1 and stage 2 disks regarding the proposed corrective action for this unsafe condition. As a result, affected operators are already aware of the proposed corrective action and have already performed the actions proposed in this AD. Therefore, the FAA has determined that the compliance time to replace the affected HPT stage 1 and stage 2 disks before further flight is appropriate. This condition, if not addressed, could result in uncontained debris release, damage to the engine, and damage to the airplane. The FAA is proposing this AD to address the unsafe condition on these products.

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 GE90–100 Service Bulletin (SB) 72–0914, dated January 25, 2023 (GE GE90–100 SB 72–0914); which provides the affected part and serial numbers of the HPT stage 2 disks, forward HPT rotor seals, and stages 7–9 compressor rotor spools; and specifies replacement instructions for the HPT stage 2 disks, forward HPT rotor seals, and stages 7–9 compressor rotor spools. 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 .

Proposed AD Requirements in This NPRM

This proposed AD would require replacement of certain HPT stage 1 disks, HPT stage 2 disks, forward HPT rotor seals, interstage HPT seals, and stages 7–9 compressor rotor spools with parts eligible for installation.

Differences Between This Proposed AD and the Service Information

GE GE90–100 SB 72–0914, uses the term “HPT rotor stage 2 disk,” while this proposed AD uses the term “HPT stage 2 disk.”

GE GE90–100 SB 72–0914, Effectivity, identifies GE Model GE–90–110B1 and GE–90–115B engines. The GE Model GE90–90B and GE90–94B engines are also affected by the unsafe condition, however, the FAA is not incorporating service information that is specific to GE Model GE90–90B and GE90–94B engines.

Interim Action

The FAA considers that this proposed AD would be an interim action. This unsafe condition is still under investigation by the manufacturer and, depending on the results of that investigation, the FAA may consider further rulemaking action.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 9 engines installed on airplanes of U.S. registry. The FAA estimates that 0 engines installed on airplanes of U.S. registry would require replacement of the interstage HPT seal. 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
Replace HPT stage 1 disk	8 work-hours × $85 per hour = $680	$1,116,300	$1,116,980	$2,233,960
Replace HPT stage 2 disk	8 work-hours × $85 per hour = $680	531,578	532,258	532,258
Replace stages 7–9 compressor rotor spool	8 work-hours × $85 per hour = $680	493,588	494,268	1,977,072
Replace forward HPT rotor seal	8 work-hours × $85 per hour = $680	25,093	25,773	51,546
Replace interstage HPT seal	8 work-hours × $85 per hour = $680	108,256	108,936	0

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–2023–1647; Project Identifier AD–2023–00487–E.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by October 20, 2023.

(b) Affected ADs

None.

(c) Applicability

This AD applies to General Electric Company (GE) Model GE90–90B and GE90–94B with interstage HPT seals listed in Table 1 to Paragraph (c) and GE90–110B1 and GE90–115B engines with an installed high-pressure turbine (HPT) stage 1 disk, HPT stage 2 disk, forward HPT rotor seal, or stages 7–9 compressor rotor spool part number (P/N) and serial number (S/N) identified in Table 1 to paragraph (c) of this AD or identified in Paragraph 4. APPENDIX—A, Tables 1, 2, or 3, of GE GE90–100 Service Bulletin (SB) 72–0914, dated January 25, 2023 (GE90–100 SB 72–0914).

Table 1 to Paragraph ( c )—Affected HPT Stage 1 and Stage 2 Disks, and Interstage HPT Seals

Part name	P/N	S/N
HPT stage 1 disk	1865M13G08	GWN11657
		GWN117GN
		GWN10NNW
		GWN10PGW
		GWN10T0A
		GWN10T0C
		GWN10THW
		GWN10TJ0
HPT stage 2 disk	1865M14P04	TMT4RN06 TMT4RN26
Interstage HPT seal	2453M60P01	NCU61528
		NCU61686
		NCU56200
		NCU61527
		NCU61687

(d) Subject

Joint Aircraft System Component (JASC) Code 7230, Turbine Engine Compressor Section; 7250, Turbine Section.

(e) Unsafe Condition

This AD was prompted by a manufacturer investigation that revealed certain HPT stage 1 disks, HPT stage 2 disks, forward HPT rotor seals, interstage HPT seals, and stages 7–9 compressor rotor spools were manufactured from powder metal material suspected to contain iron inclusion. The FAA is issuing this AD to prevent premature fracture and subsequent uncontained failure. 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 (6) of this AD, remove each affected HPT stage 1 disk, HPT stage 2 disk, forward HPT rotor seal, interstage HPT seal, and stages 7–9 compressor rotor spool from service and replace with a part eligible for installation.

(1) For HPT stage 1 disks, before further flight.

(2) For HPT stage 2 disks with a P/N and S/N identified in Paragraph 4. APPENDIX—A, Table 1 of GE90–100 SB 72–0914, at the next piece part exposure or before exceeding 3,500 cycles since new (CSN), whichever occurs first.

(3) For HPT stage 2 disks with a P/N and S/N identified in Table 1 to paragraph (c) of this AD, before further flight.

(4) For forward HPT rotor seals with a P/N and S/N identified in Paragraph 4. APPENDIX—A, Table 3 of GE90–100 SB 72–0914, at the next piece part exposure or before exceeding 14,200 CSN, whichever occurs first.

(5) For interstage HPT seals, at the next piece part exposure or before exceeding 12,600 CSN, whichever occurs first.

(6) For stages 7–9 compressor rotor spools, at the next piece part exposure or before exceeding the cyclic removal thresholds identified in Paragraph 4. APPENDIX—A, Table 2 of GE90–100 SB 72–0914, whichever occurs first.

(h) Definition

For the purpose of this AD, a “part eligible for installation” is any HPT stage 1 disk, HPT stage 2 disk, stages 7–9 compressor rotor spool, forward HPT rotor seal, or interstage HPT seal with a P/N and S/N that is not identified in paragraph (c) of this AD.

(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 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].

(k) 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 GE90–100 Service Bulletin 72–0914, dated January 25, 2023.

(ii) [Reserved]

(3) For service information incorporated by reference in this AD, contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: [phone]; email: [e-mail]; website: ge.com.

(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 service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, email: [e-mail], or go to: www.archives.gov/​federal-register/​cfr/​ibr-locations.html.

Issued on August 11, 2023.

Ross Landes,

Deputy Director for Regulatory Operations, Compliance & Airworthiness Division, Aircraft Certification Service.