What happened
The flight departed with full fuel tanks. Approximately one hour after takeoff, the pilot moved the fuel selector from the right tank to the left tank. The flight proceeded normally until the aircraft entered the traffic pattern for landing. Due to existing traffic, the pilot extended the downwind leg. As the aircraft turned left base, the engine failed to respond to throttle inputs. This led to a forced landing during which the airplane collided with trees.
The investigation
Upon recovery of the aircraft, investigators found that both fuel tanks had been ruptured. The fuel selector was positioned to the right fuel tank at the time of the accident. When the fuel line to the carburetor inlet and the carburetor bowl were drained, they each contained approximately 1-2 ounces of fuel. The investigation found no evidence of fuel contamination or obstructions within the fuel supply system. Testing was conducted with an undamaged propeller and an auxiliary fuel tank installed; during this test, the engine was started and functioned normally.