Accident Overview
On 26 July 2002, a Robinson R-22 Beta helicopter, registered ZS-RGI, was involved in an accident on a farm near Rietfontein, approximately 27 nautical miles northeast of Wonderboom Aerodrome. The aircraft was being operated under private category. There was one person on board, the pilot. No fatalities occurred.
Flight Details
The pilot, aged 42, held a valid private pilot license with a total flying experience of 1066.9 hours, including 490 hours on type. The helicopter had just undergone a mandatory periodic inspection and a test flight by a test pilot, with no defects reported. After a pre-flight inspection, the pilot started the helicopter and air taxied to the refuelling bays, where both the main and auxiliary fuel tanks were filled to capacity with 76 litres of fuel. The pilot received lift-off clearance, proceeded to the main windsock, and took off, routing towards a farm in the Gravelotte area, located 165 nautical miles northeast of Wonderboom Aerodrome.
Accident Sequence
After approximately 30 minutes of flight, while cruising at an altitude of about 4000 feet (±500 feet AGL) at an indicated airspeed of 85 knots, the helicopter suddenly yawed violently to the right. The pilot was able to regain only partial directional control, and the helicopter continued yawing alternately left and right, accompanied by severe vibration felt in the anti-torque pedals. The pilot then lowered the collective lever and entered an autorotational landing. During the autorotation, the helicopter became more controllable with less vibration but continued to "fish-tail." On flaring for landing, the helicopter yawed violently to the right and landed hard with a forward speed of between 20 and 30 knots. The right-hand skid gear collapsed, and the helicopter came to rest on its right-hand side approximately 35 meters further.
Injuries and Damage
The pilot sustained injuries to his right shoulder and a cut to his face. The helicopter was extensively damaged.
Probable Cause
According to the investigation, one of the tail rotor pitch link bolts came adrift during flight, resulting in a loss of tail rotor control and subsequent autorotational landing during which the helicopter was extensively damaged. The remaining three bolts were metallurgically analyzed and found serviceable with no signs of impending failure.