Airworthiness Directive · Amendment 39-21122 · Turbine section
General Electric Company Turbofan Engines
This AD applies to all General Electric Company (GE) GE90-110B1 and GE90-115B model turbofan engines with an interstage high-pressure turbine (HPT) rotor seal with a part number and serial number listed in Table 1 of GE GE90-100 Alert Service Bulletin (ASB) 72-A0841 R00, dated February 26, 2020 (“the ASB”).
The FAA is adopting a new airworthiness directive (AD) for all General Electric Company (GE) GE90-110B1 and GE90-115B model turbofan engines with a certain interstage high-pressure turbine (HPT) rotor seal installed. This AD requires initial and repetitive ultrasonic inspections (USIs) of the interstage HPT rotor seal and, depending on the results of the inspection, replacement of the interstage HPT rotor seal with a part eligible for installation. This AD also requires the removal of the interstage HPT rotor seal at the next engine shop visit. This AD was prompted by investigative findings from an event involving an uncontained interstage HPT rotor seal failure that resulted in debris penetrating the fuselage and the other engine. The FAA is issuing this AD to address the unsafe condition on these products.
(1) Perform an ultrasonic inspection (USI) of the interstage HPT rotor seal in accordance with the Accomplishment Instructions, paragraph 3.B.(1), of the ASB, as follows:
(i) After the effective date of this AD, perform an initial USI of the interstage HPT rotor seal before reaching the additional cycles listed in Table 1 of the ASB. When computing the additional cycles, use the effective date of this AD instead of the issue date of the ASB.
(ii) Thereafter, repeat the USI of the interstage HPT rotor seal required by paragraph (g)(1)(i) within every 100 cycles since the last inspection.
(2) If, during any USI required by paragraph (g)(1)(i) or (ii) of this AD, a non-serviceable indication is found, as defined in paragraph 3.B.(2)(b) of the ASB, before further flight, remove the interstage HPT rotor seal from service.
As a terminating action to the repetitive USI required by paragraph (g)(1)(ii) of this AD, at the next engine shop visit after the effective date of this AD, remove the affected interstage HPT rotor seal from service and replace with a part eligible for installation.
For the purpose of this AD, an “engine shop visit” is the induction of an engine into the shop for maintenance involving the separation of pairs of major mating engine case flanges, except separation of engine flanges solely for the purposes of transportation of the engine without subsequent maintenance does not constitute an engine shop visit.
