Airworthiness Directives; Turbomeca Turmo IV A and Turmo IV C Series Turboshaft Engines

Résumé

The Federal Aviation Administration (FAA) proposes to adopt a new airworthiness directive (AD) that is applicable to Turbomeca Turmo IV A and IV C series turboshaft engines. This proposal would require initial and repetitive borescope and eddy current or ultrasonic inspections of centrifugal compressor intake wheel blades for cracks and evidence of corrosion pitting, and, if found cracked or if there is evidence of corrosion pitting, replacement with serviceable parts. This proposal is prompted by reports of cracked centrifugal compressor intake wheel blades, resulting in the release of one or more blade fragments. The actions specified by the proposed AD are intended to prevent centrifugal compressor intake wheel blade cracks, which can result in in-flight engine power loss or shutdown.