Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to CFM International (CFMI) CFM56-5B/ 2P series turbofan engines. This proposal would require a reduction of the low cycle fatigue (LCF) retirement life for certain low pressure turbine (LPT) cases. 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 the published LCF retirement life. The actions specified by the proposed AD are intended to prevent a LCF failure of the LPT case, which could result in damage to the aircraft.