Introduction
On 29 September 2005, a Robinson R22 Beta II helicopter, registered HB-ZGS, was involved in an accident near the locality of "Burehöchi" in the municipality of Limpach, Canton Bern, Switzerland. The flight was conducted as part of a flight instructor skill test (FI(H) skilltest) organized by the Swiss Federal Office of Civil Aviation (OFAC).
Flight Details
The helicopter was operated by Heli Sitterdorf AG and was configured with dual controls. The crew consisted of an examiner (acting as a student pilot) and a candidate aspiring flight instructor (acting as the instructor). The examiner held a professional pilot license with instructor qualifications and had accumulated 3,782 total flight hours, including 1,972 on the type. The candidate had 290 total flight hours, with 83 on the Robinson R22.
Accident Sequence
The skill test flight departed from Bern-Belp Airport at approximately 14:16 local time. After completing various test maneuvers, the final exercise required the examiner (simulating a student) to bring the helicopter to a hover at one meter above ground in a field near Limpach, perform a 90-degree turn, and land. This sequence was to be repeated four times to return to the starting position.
During the hover, the examiner simulated an unstable hover and released the cyclic control, intending to provoke a corrective action from the candidate. However, the situation quickly became uncontrollable. The helicopter descended laterally, and a skid contacted the ground, causing the helicopter to tip over onto its left side—a phenomenon known as dynamic rollover.
Injuries and Damage
Both pilots sustained minor injuries and were able to exit the wreckage. The examiner was wearing a helmet; the candidate was not. The helicopter was destroyed. Minor ground damage occurred due to a fuel leak requiring removal of approximately two cubic meters of soil.
Probable Cause
The accident is due to the fact that the examiner created an uncontrollable situation during a hover exercise and the helicopter subsequently tipped left upon ground contact (dynamic rollover).