On May 3, 1987, a Bell 47G-3B1 (registration N43CD) operated by Whirleybird Helicopters was involved in an aviation accident near Panama City Bch, FL. Investigators recorded the probable cause as: The clutch drum ring failed due to fatigue. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced engine power loss shortly after takeoff; the pilot autorotated and landed about 6 feet offshore. Investigation revealed a clutch drum ring failure due to fatigue and an overdue inspection.
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.