History of the Flight
On 31 October 2012, a Eurocopter AS350 B3 helicopter, registration ZS-HDI, departed from Grand Central Airport in South Africa at 06:00 hours with a pilot and one passenger aboard. It was part of a formation of three helicopters travelling to Jacks Camp in Botswana on a holiday trip. The other two helicopters were piston-engine Robinson R44s. After customs and immigration clearance at Pilanesburg, the aircraft departed at 07:00 hours and arrived at Francistown Airport at 09:30 hours.
Upon arrival, the three helicopters landed and parked at the fuel bay, but a distance from the fuel pumps due to windy conditions. The two R44s parked at the Avgas pump, while the accident aircraft was at the Jet A1 pump. Customs and immigration clearance was completed, and the helicopter was refuelled to full tank. A group flight plan was filed. At 11:15 hours, Francistown Air Traffic Control cleared the three helicopters for take-off under Visual Flight Rules. They took off within seconds of each other, with the accident helicopter being the last to lift off.
Accident Sequence
According to reports, after lifting off, a gust of wind suddenly pushed the helicopter, causing an apparent loss of tail rotor compensation effectiveness. The helicopter began to spin out of control, lost height, and struck a refuelling ladder stowed next to the fuel bay. It crashed beside the refuelling bay, sustaining substantial damage to the main rotor blades, main fuselage, boom, and tail rotor assembly. The two occupants were not injured.
Investigation Findings
Examination of the engine did not reveal any pre-impact failure. The Vehicle and Engine Multifunction Display (VEMD) and Digital Engine Control Unit (DECU) were sent to BEA in France for data download, which showed no engine failure prior to impact. The investigation revealed that the pilot had completed a type conversion only a day before the occurrence. A strong easterly wind was prevailing at the time. Additionally, wake turbulence from the other departing helicopters was considered a factor.
Probable Causes
The Directorate of Accident Investigation determined the following probable causes: 1. The pilot's lack of sufficient experience on the helicopter. 2. The prevailing wind that could have caused Loss of Tail Rotor Effectiveness (LTE). 3. Encounter with wake turbulence from departing helicopters.