Incident Overview
Shortly after takeoff, the aircraft experienced a loss of power. During the subsequent forced landing, it struck trees in flight. The pilot sustained minor injuries.
Fuel System Examination
Investigation of the aircraft's fuel system revealed that less than half of the usable fuel was present in each of the three fuel tanks. The fuel selector valve was tested and found to have its selection plate indexed off center for all selectable positions due to wear. In the takeoff attitude, this misalignment caused unporting of the fuel pickup, allowing air to be drawn into the fuel system instead of fuel.
Probable Cause
The official findings determined that the partial loss of engine power was caused by a mechanical failure/malfunction in the fuel system: specifically, a worn fuel selector/valve that led to fuel starvation.