Factual Information
On 27 May 2010, at approximately 15:20 local time, a Robinson R22 Beta II helicopter, registration HB-ZHB, operated by Heli Sitterdorf AG, was destroyed in an accident at "Auzelgli", municipality of Uzwil, about 12 km south-west of Sitterdorf aerodrome. The flight was a VFR training flight, and the phase was an autorotation exercise. The elevation at the site was about 500 m AMSL.
The crew consisted of flight instructor A, a Swiss citizen born 1972, holding a commercial pilot licence for helicopters (CPL(H)) with a flight instructor rating (FI(H)) restricted under JAR-FCL 2.320B, and type ratings for R22 and Bell206. He had a total of 2588:06 flight hours, with 308:03 on the R22 type and 338:47 as an instructor. His medical certificate was Class 1 without restrictions. The trainee pilot, a Swiss citizen born 1969, held a private pilot licence for helicopters (PPL(H)) issued by the FAA and a trainee pilot licence (Trainee(H)) issued by FOCA. He had approximately 186 total flight hours, with about 118 on the R22 type. His medical certificate was Class 1 without restrictions.
Accident Sequence
According to statements and FLARM data, the flight instructor and trainee met at Sitterdorf aerodrome around 13:00 for a planned training flight. They conducted a detailed pre-flight preparation and briefing, discussing airspace, weather, and performance calculations. The planned programme included off-airport landings, low RPM recovery, autorotations, and attitude flying. The trainee had previously trained with another instructor, but due to that instructor's absence, flight instructor A agreed to conduct this training flight.
During the autorotation exercise, the flight instructor did not intervene in a timely manner, and the trainee did not initiate a recovery. The helicopter subsequently struck the ground, resulting in minor injuries to both occupants and destroying the aircraft. Fuel and oil leakage caused slight damage to the field; the topsoil was removed and disposed of appropriately.
Cause
According to the aircraft accident investigation, the accident is due to the fact that during an autorotation exercise the flight instructor did not intervene in a timely manner and the helicopter subsequently struck the ground. Contributing factors were that the trainee did not initiate a recovery, and the flight instructor had an incorrect expectation of the trainee's flying abilities.