What happened
On June 4, 2007, a Kolb Twinstar Mk. IIIA, registration G-BUZT, was conducting a private local flight near Taghmon, Co. Wexford. After climbing to approximately 1,000 feet, the aircraft's engine suddenly lost power while flying near Killoughrum. The pilot, the sole occupant, attempted to restart the engine by switching fuel tanks, but was unable to restore power before a forced landing became necessary.
The pilot selected a large field covered in barley for the landing. While the aircraft cleared a boundary hedge, it struck the left main wheel and impacted the ground with significant force. The impact caused severe damage to the cockpit area and the aircraft's structure was deemed beyond economic repair. The pilot sustained serious injuries during the deceleration.
The investigation
Investigators from the AAIU examined the wreckage and the fuel system. They found that while the engine and propeller were in good working condition, the fuel selector lever was significantly misaligned. Specifically, the handle was positioned 180 degrees away from the correct pointer, aligned instead with the 'OFF' position. This error was possible because a collar stop adjustment screw was loose, allowing the lever to rotate past its intended limit.
Analysis of the fuel tanks revealed that the left tank still contained approximately 4.5 US gallons of fuel, whereas the right tank contained only a small amount of unusable fuel. GPS data from the cockpit indicated that the aircraft's airspeed dropped significantly following the engine stoppage, entering a stalled condition prior to the impact. The investigation also noted that the pilot's flying experience on this specific aircraft type was very limited.
Findings
- The engine stopped because the usable fuel in the right tank had been exhausted.
- The fuel selector lever was 180 degrees out of its proper alignment, causing the pilot to believe fuel was being drawn from the left tank when it was actually being drawn from the depleted right tank.
- The pilot's low level of experience on the Twinstar type contributed to the aircraft flying in a stalled state during the descent, which prevented a proper flare before touchdown.