Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to CFM International (CFMI) CFM56-3C series turbofan engines. This proposal would require a reduction of the low cycle fatigue (LCF) retirement lives for certain fan disks. This proposal is prompted by the results of a refined life analysis performed by the manufacturer which revealed minimum calculated LCF lives significantly lower than published LCF retirement lives. The actions specified by the proposed AD are intended to prevent a LCF failure of the fan disk, which could result in an uncontained engine failure and damage to the aircraft.