What happened
During a flight training session, the pilot was demonstrating a full touchdown autorotation transitioning into a running landing on a grass area adjacent to a paved runway. The aircraft touched down lightly and continued along the ground. As the ground run progressed, the helicopter's nose pitched forward, causing the tailboom to rotate into the path of the main rotor.
The investigation
Investigators examined the aircraft and the flight conditions. The instructor reported that the forward pitch of the aircraft caused the main rotor to make contact with the tailboom, resulting in its severance. The students involved in the demonstration noted that the initial touchdown was light and that the helicopter did not experience rapid deceleration until the end of the ground run.
Findings
- The Robinson R22T10 sustained damage including a severed tailboom.
- There were no injuries reported among the crew members.
- The landing area was characterized as smooth, firm, and dry.
- No malfunctions of the engine or helicopter were reported prior to the accident.
- A critical factor in the accident was the pilot's movement of the collective pitch control; the aircraft's flight manual specifically cautions against the rapid lowering of the collective pitch after ground contact.