Summary
This proposal would require revisions to Chapter 5, Airworthiness Limitations section, of the AlliedSignal Inc. ALF502R and LF507 series Engine Manuals to include required enhanced inspection of selected critical life-limited parts at each piece-part exposure. This proposal would also require an air carrier's approved continuous airworthiness maintenance program to incorporate these inspection procedures. Air carriers with an approved continuous airworthiness maintenance program would be allowed to either maintain the records showing the current status of the inspections using the record keeping system specified in the air carrier's maintenance manual, or establish an acceptable alternate method of record keeping. This proposal is prompted by a Federal Aviation Administration (FAA) study of in-service events involving uncontained failures of critical rotating engine parts that indicated the need for improved inspections. The improved inspections are needed to identify those critical rotating parts with conditions, which if allowed to continue in service, could result in uncontained failures. The actions specified by this proposed AD are intended to prevent critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane.