Airworthiness Directive · Amendment 39-21765 · Engine controls
General Electric Company Turbofan Engines
This AD applies to General Electric Company (GE) GEnx-1B64, 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-2B67/P, and GEnx-2B67B model turbofan engines.
The FAA is adopting a new airworthiness directive (AD) for all General Electric Company (GE) GEnx-1B64, 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-2B67/P, and GEnx-2B67B model turbofan engines. This AD was prompted by an in-service occurrence of loss of engine thrust control resulting in uncommanded high thrust. This AD requires revising the operator's existing FAA-approved minimum equipment list (MEL) by incorporating into the MEL the dispatch restrictions listed in this AD. This AD also requires initial and repetitive replacement of the electronic engine control (EEC) MN4 microprocessor. The FAA is issuing this AD to address the unsafe condition on these products.
(1) For all affected GEnx-1B model turbofan engines, within 120 days of the effective date of this AD, revise the operator's existing FAA-approved minimum equipment list (MEL) by incorporating into the MEL the dispatch restriction specified in Figure 1 to paragraph (g)(1) of this AD, as a required operation or maintenance procedure.
Note 1 to paragraph (g)(1): Specific alternative MEL wording to accomplish the actions specified in Figure 1 can be approved by the operator's principal operations or maintenance inspector.
(2) For all affected GEnx-2B model turbofan engines, within 120 days of the effective date of this AD, revise the operator's existing FAA-approved MEL by incorporating into the MEL the dispatch restriction specified in Figure 2 to paragraph (g)(2) of this AD, as a required operation or maintenance procedure.
Note 2 to paragraph (g)(2): Specific alternative MEL wording to accomplish the actions specified in Figure 2 can be approved by the operator's principal operations or maintenance inspector.
(3) For all affected engines, before the EEC reaches 11,000 cycles since new, replace the EEC MN4 microprocessor using an approved overhaul procedure.
(i) If the number of accumulated cycles on the EEC MN4 microprocessor cannot be determined through operator maintenance logs or FADEC International shop visit reports, before the EEC exceeds 12 years since entry into service (EIS) for affected GEnx-1B model turbofan engines or 14 years since EIS for affected GEnx-2B model turbofan engines, replace the EEC MN4 microprocessor using an approved overhaul procedure.
(ii) [Reserved]
(4) Thereafter, replace the EEC MN4 microprocessor before accumulating 11,000 cycles since the last replacement.
For the purposes of this AD, an “approved overhaul procedure” is one of the following:
(1) Replacement of the EEC MN4 microprocessor using FADEC International-approved maintenance procedures; or
(2) Replacement of the EEC MN4 microprocessor using the Accomplishment Instructions, paragraph 3., as applicable, of:
(i) GE GEnx-1B Service Bulletin (SB) 73-0097 R00, dated December 17, 2020; R01, dated January 29, 2021; or R02, dated May 17, 2021; or
(ii) GE GEnx-2B SB 73-0090 R00, dated December 17, 2020; R01, dated January 28, 2021; R02, dated May 20, 2021; or R03, dated August 18, 2021.
