ERA12LA429 · Robinson Helicopter R44

The pilot was operating the helicopter in night visual meteorological conditions in the early morning hours, after having driven about 6 hours and then flown about 3.5 hours immediately before the accident flight. He stated that he was in cruise flight about 600-800 feet above ground level and had been flying less than 10 minutes when, while turning over a lake, the pilot saw the clutch actuator light illuminate. The pilot reached for the circuit breaker box under the passenger seat to pull the clutch circuit breaker, and then felt "light in the seat." He stated that the helicopter was rapidly descending, and he pulled up on the collective to arrest the descent. After pulling on the collective, he received a low rotor rpm horn and then observed the surface of the lake reflecting the moonlight about 50 feet below the helicopter, as it continued to descend. The pilot pulled on the collective to soften the impact, and the helicopter came to rest in the lake. The pilot then egressed and swam to shore. Postaccident examination revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Operational testing of the clutch actuator revealed no anomalies. The reason for the illumination of the clutch actuator light could not be determined. It is likely that, while reaching down in an attempt to pull the clutch circuit breaker, with a lack of outside visual references due to the night conditions and the helicopter’s location over a lake, the pilot made an inadvertent cyclic input that resulted in the helicopter’s nose-down attitude and subsequent descent. The pilot's lengthy time awake and the time of the accident suggest that he may have been fatigued at the time of the event.

Verbatim NTSB analysis and probable cause from the NTSB dataset