Primary finding
Probable cause
An excessive descent rate during a simulated 180-degree power-off autorotation, and the flight instructor's failure to initiate corrective action in time to keep the helicopter from impacting the terrain.
Investigator assessment
Analysis narrative
While demonstrating a practice 180-degree autorotation to landing, the certified flight instructor allowed the helicopter to develop an excessive descent rate and low rotor rpm, which resulted in a hard landing. Although he attempted to take corrective action, he did not do so in time to keep the helicopter from contacting the asphalt surface with sufficient force to result in substantial damage to the helicopters airframe. Examination of the helicopter revealed no mechanical anomalies.
Source record
Factual narrative
While demonstrating a practice 180-degree autorotation to landing, the certified flight instructor allowed the helicopter to develop an excessive descent rate and low rotor rpm, which resulted in a hard landing. Although he attempted to take corrective action, he did not do so in time to keep the helicopter from contacting the asphalt surface with sufficient force to result in substantial damage to the helicopters airframe. Examination of the helicopter revealed no mechanical anomalies.