What happened
The aircraft was involved in a cross-country flight with a duration of two hours. During the approach phase, the pilot experienced a complete loss of power while being vectored through heavy turbulence. The pilot reported that the fuel gauges indicated zero fuel at this time. In an attempt to restore engine operation, the pilot switched fuel tanks and restarted the engine. However, the engine failed again shortly after and would not restart.
During the subsequent forced landing, the aircraft struck trees and electrical wires before crashing upside down. Three witnesses observed the aircraft being refueled prior to the flight. The refueler stated that he topped off all four tanks. Although the total fuel receipt was for 57 gallons covering two aircraft, only 30 gallons were actually pumped into this specific aircraft.
The investigation
Post-accident examination of the aircraft revealed no fuel remaining in any of the tanks. Investigators found no evidence of fuel spillage on the ground or around the wreckage. A thorough inspection of the fuel system showed no signs of leaks or mechanical failures that would account for the loss of fuel.
The pilot theorized that the fuel may have vented or siphoned out of the tanks prior to the flight. The discrepancy between the refueler's statement of topping off all tanks and the actual 30 gallons added, combined with the lack of leaks, points to fuel exhaustion as the primary factor.
Findings
The investigation determined that the aircraft landed short of the runway due to a forced landing. The root cause was the depletion of usable fuel. Despite the refueler's assertion that all tanks were topped off, the actual amount added was significantly less than required for the flight. The absence of leaks suggests the fuel was lost through venting or siphoning rather than a mechanical failure.
The pilot's decision to continue the flight with insufficient fuel, combined with the inability to restart the engine due to total fuel depletion, led to the crash. The heavy turbulence encountered during the final approach likely contributed to the difficulty in managing the aircraft during the emergency.