Background
The pilot, an airline transport pilot with 14,000 hours of flight experience, was hired to fly the aircraft owner and the owner's mother on a cross-country flight.
Flight and Emergency
Approximately 3 hours and 15 minutes into the flight, the pilot reported a rough running engine and declared an emergency. A review of air traffic control voice communications indicated the pilot changed his mind several times about diverting to a closer airport or continuing to the intended destination. Before his final communication, the pilot informed air traffic control that he "was not gonna make it."
The sole survivor reported the flight was normal until approaching the destination, at which point "all of a sudden the engines did not sound right." The right engine sounded as though power was fluctuating up and down, and the left engine was sputtering. The airplane descended, and the pilot performed a forced landing in a wooded area.
Post-impact Examination
The cockpit, fuselage, empennage, and right wing were consumed by post-impact fire. During the impact, the left wing separated at the wing root and sustained no fire damage. No fuel was found in the left fuel tank, and no discoloration of vegetation was observed along the left side of the wreckage path or around where the wing came to rest.
The left fuel selector was positioned to the LEFT MAIN tank, and the right fuel selector valve was found between the LEFT and RIGHT MAIN positions. This configuration would have allowed fuel to be supplied from each tank to the right engine.
A review of the airplane's information manual emergency procedures for engine failure during flight at speeds above minimum control speed instructed the pilot to restart the engine by placing both fuel selector handles to the MAIN tanks (feeling for detent). If the engine did not start, the pilot was to secure the engine by closing the throttle and feathering the propeller. Examination revealed the propellers were not feathered.
Inspection of the airplane and the engines uncovered no mechanical deficiencies.
Probable Cause
The official probable cause states that the pilot's improper positioning of the fuel selector valves resulted in a loss of power to the left engine due to fuel exhaustion. After the power loss, the pilot failed to follow checklist procedures and did not secure (feather) the left propeller, which led to a loss of altitude and the subsequent forced landing.