What happened
On 12 July 2012, a private helicopter flight was traveling from a farm near Lephalale to the Africa Sand Safaris game farm in the Stockpoort district of Limpopo. The pilot, accompanied by his 14-year-old son, approached the intended landing site from the north. During the approach, the pilot attempted to assess the wind conditions by observing dust kicked up by a passing vehicle, as no windsock was available.
As the Robinson R44 Raven I, registration ZS-HIG, entered a hover at approximately 30 feet above the ground, the aircraft began a sudden and severe clockwise rotation. The pilot attempted to counteract this rightward yaw by applying left tail rotor pedal, and later right pedal, but the controls proved ineffective. The aircraft completed four full 360-degree rotations in a nose-down attitude before striking the ground. The impact caused the right aft skid gear to collapse and led the main rotor blades to strike both the tail boom and the terrain.
The investigation
The investigation examined the flight sequence, weather conditions, and the aircraft's mechanical state. While the pilot believed he was approaching into a north-easterly wind, the farm manager observed a south-westerly wind at approximately 20 knots. The investigation confirmed that the aircraft was within weight and balance limitations and that the engine and airframe were properly maintained. The pilot attempted several recovery maneuvers, including increasing the main rotor RPM and pushing the cyclic forward, but was unable to arrest the rotation.
Findings
- The primary cause of the accident was loss of tail rotor effectiveness (LTE), which rendered the pilot unable to maintain directional control.
- A discrepancy existed between the pilot's perceived wind direction and the actual wind direction, which likely contributed to the onset of LTE.
- The aircraft completed multiple rotations before ground impact, during which the pilot's control inputs were insufficient to stop the yaw.
- The impact resulted in two injuries, including a serious injury to the pilot's lower back and a minor injury to the passenger's elbow.