Incident Summary
The accident occurred on the airplane's 15th flight of the day, which was the pilot's first. Upon relieving the previous pilot, the tow pilot received a briefing that included information about previous flights, airplane performance, and fuel status. The left fuel tank was 1/4 full, and the right tank was full. While departing with a glider in tow, the engine sputtered, regained power, then sputtered again. The pilot released the glider and attempted to switch to the right tank. Subsequently, the airplane collided with a fence at the end of the field.
Aircraft Modifications
The airplane originally had a 150 horsepower engine, which was replaced by a 180 horsepower engine under a Supplemental Type Certificate (STC). According to the STC, the left tank was designated as the main tank and was to be used for takeoff and landings. The right tank was an auxiliary tank, intended for use only in level flight.
Fuel System Placards
The STC required specific placards to be installed. A placard on the left (main) fuel tank was to read: "capacity 18 gallons, 9 gallons useable." Another placard, reading "EMPTY," was to be placed on the left-hand fuel gauge at the original 1/2 full mark. These placards were noted in a supplement to the airplane flight manual. The supplement also included a limitation in the limitations section stating, "Do not take off when left hand fuel tank gauge registers in the red area."