Airworthiness Directives; CFM International CFM56-5 Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), applicable to CFM International CFM56-5 series turbofan engines, that reduces the low cycle fatigue (LCF) retirement lives for certain high pressure turbine rotor (HPTR) front air seals, and provides a drawdown schedule for those affected parts with reduced LCF retirement lives. This amendment is prompted by results of a refined life analysis performed by the manufacturer that revealed minimum calculated LCF lives significantly lower than the published LCF retirement lives. The actions specified by this AD are intended to prevent a LCF failure of the HPTR front air seal, which could result in an uncontained engine failure and damage to the aircraft.