Airworthiness Directives; Honeywell International, Inc., (Formerly AlliedSignal, Inc., Textron Lycoming, Avco Lycoming, and Lycoming) Former Military T53 Series Turboshaft Engines

This amendment adopts a new airworthiness directive (AD), that is applicable to Honeywell International, Inc., (formerly AlliedSignal, Inc., Textron Lycoming, Avco Lycoming, and Lycoming) former military T53 series turboshaft engines. This amendment requires conducting a revised operating cycle count (prorate) and initial and repetitive inspections for cracks of centrifugal compressor impellers. This amendment is prompted by a report of a military surplus helicopter that experienced low-cycle fatigue failure of the centrifugal compressor impeller, resulting in an uncontained engine failure. The actions specified by this AD are intended to prevent centrifugal compressor impeller failure, which can result in an uncontained engine failure, in-flight engine shutdown, or damage to the helicopter.