The improper shimmying of the tail rotor driveshaft by maintenance personnel which induced fatigue in the tail rotor driveshaft coupling causing it to fail, which resulted in a loss of tail rotor control. A factor is the failure of the pilot to recognize the warning vibrations indicating impending failure of the coupling.

A loss of engine power due to a deteriorated compressor air seal, which resulted from inadequate maintenance inspection of the helicopter to detect corrosion in the compressor case while being operated in a marine environment.