Airworthiness Directives; Sikorsky Aircraft Corporation Model S-61A, S-61D, S-61E, and S-61V Helicopters

This amendment adopts a new airworthiness directive (AD) for the specified Sikorsky Aircraft Corporation (Sikorsky) model helicopters that requires installing an electric chip detector on each engine and an on-board chip detector annunciation system. The AD also requires revising the Rotorcraft Flight Manual (RFM) to add procedures for crew response to the illumination of an on-board chip detector warning light. This AD also requires testing the engine chip detector system at specified intervals. This amendment is prompted by reports of Number 5 engine bearing failures. Failure of the bearing resulted in erratic movement of the high-speed, engine-to-transmission shaft (shaft), an oil leak, an in-flight fire, and an emergency landing. The actions specified by this AD are intended to detect an impending bearing failure, which if undetected and not addressed by appropriate crew action may result in an oil leak, a severed shaft housing, an uncontained in-flight fire, and a subsequent emergency landing.