Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to AlliedSignal Engines (formerly Textron Lycoming) Models LTS101-650B1, -750B1, -650C, and -750C turboshaft engines. This proposal would require installation of an improved power turbine (PT) rotor and electronic PT rotor overspeed controller as a terminating action to the currently required inspections of AD 88-14-01. This proposal is prompted by reports of additional bearing failures since publication of AD 88-14-01, including one additional uncontained PT disk failure. The actions specified by the proposed AD are intended to prevent PT overspeed and uncontained engine failure.