What happened
After arriving at his destination, the pilot refueled the Cessna (registration not provided) and prepared for a return flight. Due to inclement weather, the pilot chose to drive home, leaving the aircraft parked outside for approximately 10 days. Upon returning to the aircraft, the pilot performed a preflight inspection, which included draining all four fuel tank sumps; no contaminants were identified at that time.
Following the completion of engine start and runup checks, the pilot departed. While cruising at 7,500 feet MSL, approximately 20 to 25 minutes into the flight, the engine lost all power. The pilot attempted to switch fuel tanks and checked each magneto independently, but was unable to restart the engine. The pilot then attempted a forced landing at an airport but struck trees short of the runway. There were no fatalities reported in the accident.
The investigation
A post-accident examination of the engine showed no mechanical deficiencies. However, an inspection of the airframe revealed that the seals on all four fuel caps showed varying degrees of deterioration, and the left main fuel cap was found to be loose. An examination of the fuel system identified 1/4 cup of water in the main fuel strainer, with only a trace amount of fuel present between the strainer and the individual cylinders.