Incident Description
During a training flight, a certified flight instructor (CFI) was conducting a simulated autorotative landing. After lowering the collective control with full throttle applied, the CFI observed that the engine RPM dropped to zero and the manifold pressure gauge indicated 30 inches. The helicopter entered an emergency descent.
At an altitude of approximately 100 feet, the CFI observed power lines ahead. He pulled collective control to clear the lines. However, the helicopter landed hard with the right skid low. The right skid broke, and the helicopter rolled onto its right side before coming to rest.
Investigation
The helicopter was recovered and taken to the operator's facility for examination. The fuel system was checked for contaminants; none were found. The fuel quantity was sufficient to sustain engine operation. The engine was started and found to operate normally.
Findings
No determination could be made as to the reason for the reported loss of engine power. The investigation did not identify any mechanical fault or fuel issue.