Airworthiness Directive · Amendment 39-10831 · CFM International, S.A. CFM56-7B Series Turbofan Engines
CFM International, S.A. CFM56-7B Series Turbofan Engines
CFM International, S.A. (CFMI) CFM56-7B series turbofan engines, with electronic engine control (EEC) software, part numbers (P/Ns) 1853M78P07, 1853M78P08, 1853M78P10, or 1853M78P11 installed. These engines are installed on, but not limited to Boeing 737-600, 737-700, and 737-800 series aircraft.
This amendment adopts a new airworthiness directive (AD) that is applicable to CFM International, S.A. (CFMI) CFM56-7B series turbofan engines. This action supersedes telegraphic AD T98-18-51 that currently requires an inspection of electronic engine control (EEC) fault messages on both engines for the presence of any of the hydromechanical unit (HMU) fuel metering valve (FMV) signal faults identified in the All Operators Wire every 20 flight cycles or 3 calendar days, whichever occurs first, and, if necessary, removing the HMU and replacing it with a serviceable HMU. This action also requires installation of improved EEC software that constitutes terminating action to the repetitive fault message inspections. This amendment is prompted by development of improved EEC software that obviates the need for the repetitive fault message inspections. The actions specified by this AD are intended to prevent an uncommanded engine acceleration event, or inflight engine shutdown.
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.
