What happened
During a training maneuver, a flight instructor was performing a simulated autorotative landing by lowering the collective control with full throttle applied. During this process, the instructor observed that the engine RPM dropped to zero while the manifold pressure gauge indicated 30 inches.
As the helicopter descended through an altitude of 100 feet, the pilot identified power lines directly ahead. The pilot responded by pulling the collective control, which successfully cleared the power lines. However, the helicopter struck the ground with significant force, landing hard on the right skid. The impact caused the right skid to break, and the aircraft rolled onto its right side before coming to a rest. There were no injuries reported.
The investigation
The aircraft was recovered and transported to the operator's facility for a mechanical examination. Investigators checked the fuel system for contaminants, but none were found. The fuel quantity on board was determined to be sufficient to sustain engine operation. Additionally, the engine was started during the investigation and was found to operate normally. Due to these findings, investigators could not determine the specific reason for the reported loss of engine power.