Incident Overview
A certified flight instructor was conducting a training flight with a student pilot in a helicopter. The purpose of the flight was to demonstrate various maneuvers. Near the end of the flight, the instructor performed a demonstration of a power-on autorotation. During this maneuver, the instructor was late in rolling on the throttle. As a result, the helicopter did not have sufficient rotor RPM to recover before impacting the ground.
Damage Assessment
Upon ground impact, the helicopter sustained damage to its tail rotor drive shaft and main rotor blades. No other damage was reported.
Pilot Report
The instructor reported that there were no pre-impact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation. The helicopter was operating as expected prior to the incident.
Conclusion
The accident was attributed to the instructor's delayed throttle application during the autorotation demonstration, which prevented adequate rotor RPM recovery.