What happened
On 3 August 2003, a Scheibe SF25B, registration ZS-GXF, was conducting a private glider flight from Rustenburg Aerodrome toward Winterveld Aerodrome. During the approach to the airfield, the pilot operated the aircraft at a reduced throttle setting. Following a prolonged descent, the engine began to run roughly. In an attempt to restore power, the pilot increased the throttle, but the engine subsequently failed.
While the pilot attempted to use carburetor heat to address the rough running, the heat was closed shortly after application due to the smell of burning. The pilot was forced to perform an emergency landing near the Modikwe Mine. During the descent, the left wing collided with trees, causing the aircraft to swing left and impact the vegetation before coming to rest on the ground. Although the aircraft sustained substantial damage, the pilot escaped the crash without injury.
The investigation
Investigators examined the circumstances surrounding the engine's loss of power and the subsequent impact. The investigation noted that the aircraft had accumulated 4242.6 total airframe hours and had completed only 4.6 hours of flight since its last annual inspection. The inspection had been certified by an approved person rated for the aircraft type.
However, a significant complication arose regarding the physical evidence. Reports from the Soaring Society indicated that the carburetor had been stolen from the wreckage prior to its recovery. This loss of components prevented investigators from performing a definitive analysis of the engine's internal state.
Findings
- The engine failure occurred after the pilot increased throttle following a period of rough running.
- The pilot's use of carburetor heat was interrupted by the detection of a burning odor.
- The aircraft's left wing struck trees during the forced landing, leading to the final impact.
- The theft of the carburetor from the crash site made it impossible to determine the exact cause of the engine failure with certainty.