Incident Overview
A pilot reported that while leveling off after departing from a private airport, the engine began to run rough. The pilot increased the mixture setting, which caused the engine rpm to rise and the engine to run smoothly before it again became rough. During a right descending turn, the engine quit completely. The pilot performed a forced landing into trees.
Pilot Report
The pilot stated that he was "99 percent sure" he had selected the left fuel tank during the flight. No other fuel tank selections or manipulations were mentioned.
Examination Findings
Post-incident examination of the fuel supply system revealed that the left wing aft fuel supply line was obstructed by insect larva. The engine was subsequently removed from the airframe and mounted on a test stand. When tested, the engine started, ran, and developed power normally, indicating that the obstruction in the fuel line was the likely cause of the power loss.
Conclusions
The investigation documented the presence of insect larva blocking the left wing fuel supply line. The engine itself was found to be functional when provided with an unobstructed fuel supply. No determination of probable cause was stated in the source.