Summary
This document proposes the adoption of a new airworthiness directive that would supersede two existing airworthiness directives (AD's), applicable to General Electric Company (GE) 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 proposal would require applying an additional multiplying factor to life-limited rotating parts when the engine is used in heavy lifting operations. This proposal is prompted by a review of the current AD's, 69-23-02 and 79-23-04, and a determination that the requirements of those AD's may conflict. This AD would prevent RHL and utility service multiplier factors from being applied incorrectly. The actions specified in the proposed AD are intended to prevent low-cycle fatigue failure of rotating parts that could result in uncontained engine failure and damage to the helicopter.