Accident Overview
A training flight encountered an unexpected event during landing at an airport in dark night visual meteorological conditions with calm winds. The flight instructor and trainee reported that while on downwind, a light helicopter, believed to be a Robinson R22, entered final approach and subsequently cleared the active runway about one-half to one-quarter mile before the aircraft's touchdown point. After clearing the runway, the helicopter moved right to the parallel taxiway, approximately 180 feet from the runway.
Sequence of Events
Approximately 200 to 300 feet past the runway threshold, the aircraft suddenly rolled right, yawed right, and sank. The pilots applied control inputs to counter these motions, but the aircraft touched down right-wing-low in the grass adjacent to the runway. The pilots elected to continue the landing rollout in the grass. During the landing rollout, the aircraft's nose gear failed.
Pilot Reports
The flight instructor indicated that no mechanical malfunction or failure was involved in the accident. The instructor noted that the helicopter was on the parallel taxiway at the north end of the airport, approximately seven main rotor diameters from the runway, which is outside the three main rotor diameters specified by the FAA Aeronautical Information Manual for rotor wash avoidance from a helicopter in a slow hover taxi or stationary hover. The accident aircraft's maximum gross weight was approximately twice that of the R22.
Conclusion
The event occurred under dark night visual meteorological conditions with calm winds. No probable cause was stated in the source material.