Accident Narrative
The pilot reported that shortly after takeoff, the engine began to lose power and then failed. The pilot performed an autorotation and set the helicopter down approximately 6 feet offshore.
Investigation Findings
Examination of the engine logbooks by FAA personnel revealed that airworthiness directive (AD) 62-23-02, which requires inspection of the oil filter every 25 hours, had been overdue by 20.9 hours.
Inspection of the transmission found that a 5.5-inch piece from the clutch drum ring had separated. This separation disengaged the main rotor from the engine, resulting in a loss of main rotor RPM.
Examination of the failed clutch drum ring revealed evidence suggesting that it failed due to fatigue.