Summary
A pilot preparing for a flight noted that the aircraft needed fuel and refueled it. After refueling, the pilot observed a considerable amount of water in fuel samples taken from the aircraft. The pilot, who also held an A&P mechanic certificate, attempted to clear the fuel system of trapped water. The engine runup, takeoff, and cruise flight proceeded without incident until approximately half an hour into the flight, when the engine began running rough and lost power. The pilot executed a forced landing in an area with high vegetation, which resulted in substantial damage to the aircraft.
Post-Accident Findings
During the post-accident inspection of the fuel system, investigators found a milky solution consisting of soap and water. Further investigation determined that the aircraft had been washed shortly before this flight. The presence of the soap and water mixture in the fuel system was consistent with residues from the washing process.
Conclusion
The engine power loss was attributed to fuel contamination introduced by residual soap and water from the aircraft's recent washing. No other causal factors were identified.