What happened
On 27 February 2006, a Robinson R22 Beta II helicopter, registration HB-ZGH, was conducting a scheduled annual check flight near Neumatt, Switzerland. The flight, supervised by a flying instructor, involved a series of maneuvers designed to verify both normal operations and emergency procedures.
During the training session, the crew attempted a simulated engine failure while hovering approximately one meter above a grass area. To simulate the loss of power, the instructor reduced the engine to idle. As the pilot attempted to manage the descent, the helicopter experienced a lateral shift to the left. Upon touchdown, the left skid caught in the grass, causing the aircraft to tip over. Both occupants sustained minor injuries, but the helicopter was considerably damaged.
The investigation
The investigation focused on the flight dynamics and the specific control inputs used during the simulated emergency. Investigators examined the manufacturer's Pilot Operating Handbook (POH) and compared it to the actions taken by the pilot. The investigation also reviewed the technical condition of the aircraft and the meteorological conditions, which included a north-easterly wind of 8 to 10 knots.
Findings
Technical analysis revealed that the Robinson R2-2 Beta II had no mechanical defects contributing to the accident. The investigation established that the pilot's specific handling of the collective pitch played a critical role. Specifically, the pilot lowered the collective pitch and then immediately pulled it up to cushion the landing. This sequence of events likely increased the rate of descent and contributed to the instability.
Furthermore, the investigation found that the lateral drift to the left was a result of the pilot applying right pedal to counteract yaw, which reduced tail rotor thrust and disturbed the lateral equilibrium. The primary cause of the accident was the loss of control during touchdown, exacerbated by the fact that the pilot's actions did not align with the manufacturer's recommended procedures.