Airworthiness Directives; CFM International CFM56-5C Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), applicable to CFM International CFM56-5C series turbofan engines, that requires a reduction of the low cycle fatigue (LCF) retirement lives for certain high pressure turbine rotor (HPTR) front shafts, HPTR front air seals, HPTR disks, booster spools, and low pressure turbine rotor (LPTR) stage 3 disks. This amendment is prompted by results of a refined life analysis performed by the manufacturer which revealed minimum calculated LCF lives lower than published LCF retirement lives. The actions specified by this AD are intended to prevent an LCF failure of the HPTR front shaft, HPTR front air seal, HPTR disk, booster spool, and LPTR stage 3 disk, which could result in an uncontained engine failure and damage to the aircraft.