Accident Overview
The helicopter was substantially damaged during a run-on landing that followed a practice autorotation. According to the flight instructor, as the helicopter touched down, it rotated forward, lifting the tailboom into the path of the main rotor, which then severed the tailboom. The aircraft subsequently turned left by approximately 90 degrees before coming to a stop.
Pilot Accounts
The instructor was demonstrating a full touchdown autorotation leading to a run-on landing on a grass area adjacent to a paved runway. The dual student reported that the initial touchdown was light and that the helicopter did not decelerate quickly until near the end of the ground run. Both pilots described the grass landing area as smooth, firm, and dry. Neither pilot reported any malfunctions with the helicopter or its engine prior to the accident.
Operational Guidance
The pilot's flight manual includes a caution: "Avoid rapid lowering of collective pitch control after ground contact." Additionally, the FAA Rotorcraft Flying Handbook notes that during a running landing, increased ground friction when lowering the collective can cause the helicopter's nose to pitch forward. It advises caution against correcting this pitch with aft cyclic, as such a movement could result in the rotor making contact with the tailboom.