Airworthiness Directives: Sikorsky Aircraft Model S-58T Series Helicopters

摘要

This amendment supersedes an existing airworthiness directive (AD), applicable to Sikorsky Aircraft Model S-58T series helicopters, that currently requires a one-time inspection of the engine drive shaft assembly (drive shaft assembly) for cracks and loose balance weights. This amendment requires initial and repetitive visual and florescent penetrant inspections of the drive shaft assembly for cracks and improperly installed rivets. This amendment is prompted by three reported incidents of loose or missing drive shaft assembly balance weights and two reported incidents of fatigue cracks on the drive shaft assembly near the balance weight rivet hole. The actions specified by this AD are intended to prevent failure of the drive shaft assembly, loss of power to the rotor system, and a subsequent forced landing of the helicopter.