Summary
This document proposes to adopt a new airworthiness directive (AD), applicable to Rolls-Royce Corporation, (formerly Allison Engine Company), AE 2100 and AE 3007 series engines. This proposed AD would require a one-time acid etch inspection of the 2nd stage high pressure turbine (HPT) wheel for cracks. If the wheel is cracked, this proposed AD would require replacement of the turbine wheel with a serviceable part. This proposed AD is prompted by a report of a 2nd stage turbine wheel that was returned from the field with cracks in the aft bore face. The actions specified by this proposed AD are intended to detect and prevent early development of cracks due to low cycle fatigue of the HPT 2nd stage wheel in the aft bore face that can lead to wheel failure, power loss, and possible damage to the airplane.