What happened
On 4 June 2001, a Robinson R22 Beta, registration ZS-HNT, was conducting a game capture mission involving net-gunning. The flight originated from Grand Central Airport with the intention of landing at a farm located between Grand Central and Lanseria. During the operation, the pilot attempted a turn while flying downwind. During this maneuver, the aircraft lost altitude and struck a wire from a boma fence. There were two people on board the aircraft, and both sustained injuries, though there were zero fatalities.
The investigation
The investigation into the incident focused on the flight maneuvers and the mechanical state of the aircraft. Records indicated that the helicopter was maintained according to all required prescriptions, and no mechanical defects or malfunctions had been reported prior to the flight. The pilot held a valid commercial license and possessed significant experience on this specific aircraft type, with 6/51 total hours on the model.
Findings
The primary factor in the accident was an error in flight control during the downwind turn. The pilot applied excessive collective input, which caused the main rotor RPM to decrease significantly, a condition known as overpitching. This decay in rotor RPM reached a critical point where the pilot could no longer maintain control of the aircraft, leading to the impact with the fence wire.