Airworthiness Directive · Amendment 39-18104 · CFM International S.A. Turbofan Engines
CFM International S.A. Turbofan Engines
This AD applies to all CFM International S.A. (CFM) CFM56-7B series turbofan engines.
We are adopting a new airworthiness directive (AD) for all CFM International S.A. (CFM) CFM56-7B series turbofan engines. This AD was prompted by a dual engine thrust instability event that resulted in the overspeed and in-flight shutdown (IFSD) of one engine. This AD requires modification of the engine by removing full authority digital engine control (FADEC) software, version 7.B.V4 or earlier, installed in the electronic engine controls (EECs) on CFM56-7B engines. We are issuing this AD to prevent a thrust instability event, which could lead to overspeed and IFSD of one or more engines, loss of thrust control, damage to the engine, and damage to the airplane.
(1) Comply with this AD within the compliance times specified, unless already done.
(2) Within 6 months after the effective date of this AD, modify the engine by removing full authority digital engine control (FADEC) software, version 7.B.V4 or earlier, installed in the electronic engine control (EEC).
(3) Do not return to service any aircraft configured with one engine with FADEC software, version 7.B.V4 or earlier, installed, and the other engine with an eligible FADEC software version, installed.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
