What happened
A commercial pilot departed from a private lake in a float equipped airplane to perform a flight over a 12-mile wide area of water. The mission was intended to pick up two friends staying at a cabin, whom the pilot had dropped off the previous day. The aircraft failed to arrive at the destination lake and was subsequently reported overdue.
Six days after the disappearance, the body of the pilot was discovered along the shoreline of the water area the pilot had intended to cross. At the time of discovery, the pilot was wearing a flotation cushion that was carried onboard the aircraft. The cause of death was determined to be hypothermia and drowning. The airplane remains missing.
The investigation
The investigation revealed that for several months prior to the accident, the engine had experienced recurring roughness, backfiring, and multiple engine fires during start-up procedures. One month before the accident, a mechanic had installed a six-point engine primer system during an annual inspection. Passengers traveling on flights within two days of the accident noted that the engine would backfiring when the throttle was reduced.
One day prior to the accident, the pilot purchased 20 gallons of automotive fuel and added it to the right wing fuel tank. During the taxi for departure on the day of the accident, the engine quit, and the pilot encountered difficulty restarting the engine. Automotive fuel is not approved or recommended for use in this engine.