What happened
On the morning of 17 September 2022, an Aerospatiale AS350B3e Ecureuil (H125), registration ZT-RFG, was conducting a private flight from De Oudekraal Farm to Karoo Gateway Aerodrome (FABW) in the Western Cape. The flight, which was not accompanied by a filed flight plan, intended to stop at the aerodrome to refuel before continuing to Cape Town.
As the crew approached the airfield, they performed a hover-taxi along the runway centerline toward the Jet A-1 fuel bay. During this low-altitude maneuver, the aircraft experienced a sudden loss of control. The helicopter touched the ground twice before yawing sharply to the left and spinning 180 degrees. The momentum of the spin caused the tail boom to strike nearby equipment, resulting in the tail cone separating from the airframe. The aircraft then flipped onto its right side, with the main rotor blades striking the ground while the engine was still producing power. Despite the substantial damage to the airframe, both occupants escaped the wreckage without injury.
The investigation
An investigation by the SACAA AIID examined the wreckage, engine data recorder, and onboard video footage captured by the co-pilot. Investigators confirmed that the engine and flight controls were fully functional prior to the impact and that the aircraft had been properly maintained. The investigation also clarified that the engine shutdown was triggered by overspeed protection following the impact, rather than manual intervention as initially reported. Furthermore, while the crew believed ground resonance had occurred, investigators determined the aircraft was actually hover-taxiing in ground effect when the sequence began.
Findings
- The primary cause of the accident was a vertical descent and rightward drift caused by a light crosswind component from the left.
- As the pilot attempted to correct this drift, the aircraft made contact with the ground, leading to an uncontrollable leftward yaw and subsequent flip.
- A significant contributing factor was that the pilot was operating the aircraft from the left seat, which deviated from the flight manual's prescription for that specific configuration.
- The aircraft's mass and center of gravity were within approved limits, and no mechanical failures were identified.