History of the Flight
On 23 October 2016, a Robinson R22 Beta II helicopter, registration B-HJU, owned and operated by the Hong Kong Aviation Club (HKAC), departed Shek Kong Airfield at approximately 1410 hours for a low-level navigation exercise. The flight was instructional, with an instructor as pilot-in-command and a student pilot on board. After returning, the student practiced two circuits on Runway 11. Subsequently, the instructor took control and began hover taxiing the helicopter over a grass strip parallel to and south of the runway, intending to return to the HKAC apron.
Noting three fixed-wing aircraft in the circuit practicing touch-and-go landings, the instructor decided to land the helicopter halfway down the grass strip to avoid downwash effects on a landing aircraft. During landing, he had difficulty judging height due to long grass. After the fixed-wing aircraft touched down, the instructor attempted to lift off to continue hover taxiing. He observed that the fronts of both skids were entangled with the grass. As he lifted, the student felt the helicopter rise slowly before beginning to roll forward and to the left. The instructor lowered the collective and applied cyclic control, but the forward rolling continued until the main rotor struck the ground. The engine stopped on impact. The helicopter came to rest on its left side.
Injuries and Damage
The instructor sustained minor injuries. The student was not injured. Both occupants exited through the right door without assistance. The helicopter suffered substantial damage.
Probable Cause
The investigation determined that the probable cause of the accident was a dynamic rollover resulting from an uncontrollable angular momentum created when the instructor attempted to lift off with the fronts of both skids entangled in long grass. The investigation also made two safety recommendations, though details were not provided in the source.