2023-05-17: Turbine Section

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: 2023-05-17 General Electric Company: Amendment 39-22386; Docket No. FAA-2022-1240; Project Identifier AD-2022-00683-E. (a) Effective Date This airworthiness directive (AD) is effective May 10, 2023. (b) Affected ADs None. (c) Applicability This AD applies to General Electric Company (GE) GE90-76B, GE90-85B, GE90-90B, and GE90-94B model turbofan engines, excluding those engines with an installed full set of high-pressure turbine (HPT) stage 2 nozzles with part numbers 1847M47G23 and 1847M47G24. (d) Subject Joint Aircraft System Component (JASC) Code 7250, Turbine Section. (e) Unsafe Condition This AD was prompted by a commanded in-flight shutdown (IFSD) due to cracking and rockback of the HPT stage 2 nozzles resulting in blade liberation, severe rotor imbalance, and liberation of the exhaust centerbody. The FAA is issuing this AD to prevent failure of the HPT stage 2 nozzles, HPT stage 2 blades, and exhaust centerbody. The unsafe condition, if not addressed, could result in IFSD, failure of the engine and exhaust centerbody, and loss of the airplane. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Required Actions (1) Within the compliance times specified in paragraphs (g)(1)(i) and (ii) of this AD, perform an initial borescope inspection (BSI) of the forward platforms of the HPT stage 2 blades, or perform a 360 degree BSI of the leading edges of the HPT stage 2 nozzles (optional procedure) in accordance with the Accomplishment Instructions, paragraph 3.A.(3)(a) of GE GE90 SB 72-1166, Revision 3, dated February 14, 2019 (the SB): (i) For engines with HPT stage 2 nozzles that have accumulated 22,000 or more flight hours since new or since last overhaul as of the effective date of this AD, perform the initial BSI before accumulating 250 flight cycles (FCs) after the effective date of this AD. (ii) For engines with HPT stage 2 nozzles that have accumulated less than 22,000 flight hours since new or since last overhaul as of the effective date of this AD, perform the initial BSI before accumulating 22,000 flight hours since new or since last overhaul, or within 250 FCs after the effective date of this AD, whichever occurs later. (2) Thereafter, at intervals not to exceed 100 FCs from performance of the last BSI of the forward platforms of the HPT stage 2 blades, or at intervals not to exceed 500 FCs from the last BSI of the leading edges of the HPT stage 2 nozzles, as applicable, perform a repetitive BSI of the forward platforms of the HPT stage 2 blades or the leading edges of the HPT stage 2 nozzles in accordance with the Accomplishment Instructions, paragraph 3.A.(3)(a) of the SB. (3) If, during any inspection required by paragraphs (g)(1) or (g)(2) of this AD, rub marks, evidence of contact on the HPT stage 2 blade forward platform on three or more HPT stage 2 blades, or an unserviceable HPT stage 2 nozzle is found, before further flight, remove and replace the HPT stage 2 nozzles with parts eligible for installation. Note 1 to paragraph (g)(3): Serviceability criteria can be found in the GE90 Boeing 777 Aircraft Maintenance Manual, 72-00-00, INSPECTION/CHECK, Subtask 72-00-00-220-074-G00. (h) Mandatory Terminating Action As a mandatory terminating action to the repetitive inspections required by paragraph (g)(2) of this AD, at the next engine shop visit after reaching 22,000 flight hours since new or since last overhaul, replace the HPT stage 2 nozzles with parts eligible for installation. (i) Definitions (1) For the purpose of this AD, "parts eligible for installation" is a full set of HPT stage 2 nozzles with part numbers 1847M47G23 and 1847M47G24. (2) For the purpose of this AD, an "overhaul" is the complete refurbishment of the HPT stage 2 nozzle segments. (3) For the purpose of this AD, an "engine shop visit" is the induction of an engine into the shop for maintenance involving separation of pairs of major mating engine case flanges, except for the following situations, which do not constitute an engine shop visit: (i) Separation of engine flanges solely for the purposes of transportation of the engine without subsequent maintenance; or (ii) Separation of engine flanges solely for the purpose of replacing the fan or propulsor without subsequent maintenance. (j) Credit for Previous Actions You may take credit for the initial inspection required by paragraph (g)(1) of this AD if you performed the inspection before the effective date of this AD using GE GE90 SB 72-1166, Revision 2, dated October 13, 2017, or earlier revisions. (k) Alternative Methods of Compliance (AMOCs) (1) The Manager, ECO 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 certification office, send it to the attention of the person identified in paragraph (l) of this AD. Information may be emailed to: ANE-AD-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) Related Information For more information about this AD, contact Stephen Elwin, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: (781) 238-7236; email: Stephen.L.Elwin@faa.gov. (m) 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) GE GE90 Service Bulletin (SB) 72-1166, Revision 3, dated February 14, 2019. (ii) [Reserved] (3) For GE service information identified in this AD, contact General Electric Company, GE Aerospace, Room 285, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: aviation.fleetsupport@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: fr.inspection@nara.gov, or go to: www.archives.gov/federal-register/cfr/ibr-locations.html. Issued on March 9, 2023. Christina Underwood, Acting Director, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2023-07005 Filed 4-4-23; 8:45 am]BILLING CODE 4910-13-P