What happened
During the 15th flight of the day for the aircraft, the pilot took over duties following a briefing from the previous pilot. This briefing included information regarding airplane performance and the current fuel status, which indicated the left tank was 1/4 full and the right tank was full.
While departing with a glider in tow, the engine sputtered, briefly regained power, and then sputtered again. In response to the engine instability, the pilot released the glider and attempted to switch the fuel source to the right tank. During this sequence, the aircraft collided with a fence located at the end of the field. No fatalities or injuries were reported.
The investigation
The investigation examined the aircraft's engine configuration, noting that the original 150 horsepower engine had been replaced by a 180 horsepower engine under a Supplemental Type Certificate (STC).
According to the STC, the left tank serves as the main tank intended for use during takeoff and landings, while the right tank is an auxiliary tank to be used only during level flight. The investigation reviewed specific requirements from the STC and a supplement to the airplane flight manual, which included:
- A placard on the left fuel tank noting a capacity of 18 gallons with 9 gallons useable.
- An "EMPTY" placard placed on the left-hand fuel gauge at the original 1/2 full mark.
- A limitation stating that takeoff should not be attempted when the left-hand fuel tank gauge registers in the red area.