History of Flight
On 13 December 2017 at approximately 0740Z, a Robinson R44 Raven II (registration ZS-ZZF) departed from Thaba Lesodi Farm, Vaalwater, Limpopo Province, for a private flight to a farm 32 km south. The pilot, the sole occupant, performed a preflight inspection and found a small amount of water in the fuel tanks, which he drained until no contaminant was apparent. After takeoff in a northerly direction, the pilot banked left to fly over a farmhouse to greet friends, as was his custom. Witnesses near the house reported hearing an unusual engine noise, then observed the helicopter yaw left and pitch nose-down. The engine sound ceased, replaced by rotor noise. The helicopter, at approximately 200 ft above the farmhouse, descended, struck trees 65 m south of the house, impacted the ground in a nose-down attitude, bounced, nosed over, and came to rest on its right side. The aircraft was destroyed. The pilot sustained serious injuries and was airlifted to hospital; he could not recall the accident due to head trauma. The accident occurred in daylight with CAVOK conditions, wind from 040° at 7 kts, temperature 26°C.
Investigation Findings
Examination of the wreckage revealed a substantial amount of water in the main fuel tank, auxiliary fuel tank, and gascolator – sufficient to cause fuel starvation and engine stoppage. The helicopter had been refueled from a bowser on the farm; the bowser had recently been cleaned, but water may have been present in the fuel pipes. The pilot had detected water during preflight and drained fuel until no water was visible, yet contamination remained. The alternator showed only minor impact damage to its lower half, with rotating aluminium blades undamaged, indicating the engine was not running at impact. Rotor blade damage suggested low rotor RPM at impact, consistent with an engine failure and failure to maintain autorotation. The pilot was flying at low altitude (approximately 200 ft) and likely low speed (probably under 60 kts) when the engine stopped, leaving insufficient time to execute a safe forced landing. Although a clear area existed to the left, the pilot likely chose to avoid the farmhouse, impacting trees 65 m ahead. The flight folio did not contain fuel records or flying hours for the period leading to the accident, a regulatory non-compliance.
Probable Cause
Unsuccessful forced landing following an engine stoppage caused by fuel contamination.