Incident Overview
A pilot with 10,100 hours of flight time reported an unusual event during a flight. The pilot heard a loud bang, followed by a decrease in both engine and rotor revolutions per minute (rpm). In response, the pilot increased the throttle, which successfully restored engine and rotor rpm. Subsequently, the pilot initiated a precautionary landing. During the landing, the engine lost power, and the helicopter made a hard landing in an open field.
Witness Account
A witness located near the accident site reported observing the helicopter strike a power line just prior to the landing. This contact occurred as the helicopter was descending for the precautionary landing.
Examination Findings
A thorough examination of both the airframe and the engine was conducted following the incident. The inspection revealed no anomalies or mechanical issues that could explain the loss of engine power. All components appeared to be functioning normally.
Determination of Cause
Despite the investigation, the reason for the loss of engine power during the precautionary landing could not be determined. The sequence of events—starting with the loud bang and rpm fluctuation, followed by the power line strike and subsequent hard landing—did not yield a definitive causal factor. No evidence of pre-existing mechanical failure or system malfunction was found.
Conclusion
The incident involved a hard landing after a power line strike during a precautionary landing. The pilot's actions in increasing throttle temporarily resolved an earlier rpm loss, but the final power loss remained unexplained. The investigation concluded that the reason for the loss of engine power was undetermined.