Airworthiness Directives; CFM International S.A. Turbofan Engines

We propose to adopt a new airworthiness directive (AD) for certain CFM International S.A. (CFM) CFM56-7B series turbofan engines. This proposed AD was prompted by reports of uncommanded in-flight shutdowns (IFSDs) on CFM CFM56-7B engines following rupture of the 73- tooth gearshaft located in the engine accessory gearbox (AGB). This proposed AD would require magnetic chip detector (MCD) inspection of the affected gearshafts until removal. We are proposing this AD to prevent failure of certain engine AGB gearshafts, which could lead to failure of one or more engines, loss of thrust control, and damage to the airplane.