Airworthiness Directives; General Electric Company T58 and CT58 Series Turboshaft Engines

This amendment surpersedes two existing airworthiness directives (AD's), applicable to General Electric Company (GE) T58 and CT58 series turboshaft engines. The current AD's revised the counting method for hours in repetitive heavy-lift (RHL) service and reduced the life limit for rotating components. Life-limited rotating components must be removed from service in accordance with the multiplying factors and retirement lives contained in General Electric Alert Service Bulletin (ASB) CT58 A72-162 (CEB-258), dated July 9, 1979. This amendment requires applying an additional multiplying factor to life- limited rotating parts when the engine is used in heavy lifting operations. This amendment is prompted by a review of the current AD's, AD-69-23-02 and AD-79-23-04, and a determination that the requirements of those AD's may conflict. This amendment will prevent RHL and utility service multiplier factors from being applied incorrectly. The actions specified in this AD are intended to prevent low-cycle fatigue failure of rotating parts that could result in uncontained engine failure and damage to the rotorcraft.