Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain AlliedSignal Inc. high pressure compressor (HPC) impellers installed on TFE731 series turbofan engines. This proposal would require replacing the HPC impeller with a serviceable impeller that has been eddy-current inspected. This proposal is prompted by an incident of an uncontained impeller failure due to cracking in the seal relief area of the HPC impeller. The actions specified by the proposed AD are intended to prevent fatigue cracking of the HPC impeller, which could result in an uncontained failure of the impeller, an in-flight engine shutdown, and damage to the airplane.