Accident Overview
On 29 July 2010, a Robinson R22 Beta helicopter, registration ZS-RRM, sustained substantial damage during a dynamic rollover while in a hover approximately 10 ft above ground. The accident occurred in the general flying area of Rand Aerodrome (FAGM), Gauteng Province, South Africa. The pilot, the sole occupant, was not injured.
History of Flight
The pilot departed Rand Aerodrome on a private flight. While maintaining a stable hover, he decided out of curiosity to test the effect of changing rotor and engine RPM on helicopter performance. He closed the throttle fractionally and then immediately opened it, causing an immediate increase in rotor and engine RPM, with the tachometer reading rising rapidly above the green arc. Focused on the instrument panel, the pilot lost situational awareness and failed to notice the helicopter banking to the right in a nose-down attitude. The right skid struck the ground, leading to a dynamic rollover onto the helicopter's right side. The pilot reported that he had attempted to fly with the governor off. The investigation determined the governor system was not defective but had been switched off.
Damage and Injuries
The helicopter sustained extensive damage. The pilot, properly restrained by safety belt and harnesses, suffered no injuries. No other persons were on board.
Probable Cause
The probable cause of the accident was loss of control. A contributing factor was that the pilot's corrective action would have been to manually control RPM first and then engage the governor once stabilised. The onset of the uncontrolled RPM profile alarmed the pilot and led to the incident.