Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Allison Engine Company AE 3007 series turbofan engines. This proposal would require removing from service certain cone shafts prior to them reaching new cyclic life limits, and replacing with serviceable parts. This proposal is prompted by additional testing and low cycle fatigue (LCF) life analysis that indicates lower cyclic lives than originally determined. The actions specified by the proposed AD are intended to prevent LCF failure of cone shafts, which could result in an uncontained engine failure and damage to the aircraft.