Accident Summary
A pilot flying a single-engine airplane on a morning flight experienced engine trouble approximately 15 minutes after deciding to return to the departure airport for a shift change. The engine began spitting and sputtering. The pilot attempted to resolve the issue by switching the fuel selector back and forth multiple times and toggling the electric fuel transfer switch, but neither action produced a response. He initiated emergency procedures and ditched the airplane, which inverted after touchdown. The pilot exited the aircraft and was not reported injured.
Pilot Report
The pilot reported that he had flown the accident airplane for about 4 hours two days before the accident, after which the airplane was serviced. The day before the accident, he flew another 5.5 hours, and after landing, 37 gallons of fuel were added. On the accident morning, he arrived at the departure airport around 0800 and departed at about 0905. Approximately 1 hour 25 minutes after takeoff (around 1030), he began transferring fuel from the auxiliary fuel tank. The flight continued until about 1140, when he decided to return to the departure airport. Roughly 15 minutes later, the engine problems began. The pilot noted that the fuel transfer switch had been on since 1030. He reported to FAA personnel that he believed the auxiliary fuel tank pump, which transfers fuel to the right main tank, had malfunctioned.
Examination Findings
An FAA airworthiness inspector examined the airplane the day after the accident. Both main fuel tanks contained approximately 1/4 quart of fuel. The fuel drained from the left tank was reported to be cloudy, while about 1/2 quart of water was drained from the right fuel tank. The gascolator had approximately a thimbleful of clean fuel. The auxiliary fuel tank, installed in December 1989 under a Supplemental Type Certificate, was noted to be nearly full of fuel.
Auxiliary Fuel Tank Testing
Operational testing of the auxiliary fuel tank pump was performed successfully. The pump transferred approximately 15 gallons of fuel into the right main tank over a period of about 3 hours. According to the STC holder, the pump is designed to transfer 8 gallons of fuel per hour into the right main tank, meaning the tested transfer rate was roughly within design specifications.