Airworthiness Directive · Amendment 39-21865 · Turbine engine accessory drive
General Electric Company Turbofan Engines
This AD applies to General Electric Company (GE) GE90-76B, GE90-85B, GE90-90B, GE90-94B, GE90-110B1, and GE90-115B model turbofan engines with a transfer gearbox (TGB) radial bevel gear (TGB radial gearshaft) serial number listed in paragraph 4., APPENDIX—A, Table 1 of GE GE90 Service Bulletin (SB) 72-1201 R01, dated April 28, 2021 (GE90 SB 72-1201 R01) or paragraph 4., APPENDIX—A, Table 1 of GE GE90-100 SB 72-0857 R01, dated April 28, 2021 (GE90-100 SB 72-0857 R01).
The FAA is adopting a new airworthiness directive (AD) for certain General Electric Company (GE) GE90 model turbofan engines. This AD was prompted by two separate in-flight shutdowns (IFSDs) resulting from failure of the transfer gearbox (TGB) radial bevel gear (TGB radial gearshaft). This AD requires visual inspection of the TGB radial gearshaft and, depending on the results of the inspection, replacement of the TGB radial gearshaft. The FAA is issuing this AD to address the unsafe condition on these products.
(1) At the next engine shop visit after the effective date of this AD, perform a visual inspection of the affected TGB radial gearshaft using Figure 1 to paragraph (g)(1) of this AD.
(2) If, during the visual inspection required by paragraph (g)(1) of this AD, discrepancies are found that meet the criteria in the Accomplishment Instructions, paragraph 3.A.(4)(a) or 3.A.(4)(b), of GE90 SB 72-1201 R01 or GE90-100 SB 72-0857 R01, before further flight, replace the TGB radial gearshaft with a part eligible for installation.
(1) For the purpose of this AD, an “engine shop visit” is when the compressor discharge pressure seal joint is disassembled.
(2) For the purpose of this AD, a “part eligible for installation” is a TGB radial gearshaft that does not have raised material or rework on the teeth chamfers as described in the Accomplishment Instructions, paragraph 3.A.(4)(a) or 3.A.(4)(b), of GE90 SB 72-1201 R01 or GE90-100 SB 72-0857 R01.
