What happened
While attempting to find a break in the cloud cover to land at Mildura Airport, the pilot of the aircraft performed several turns while switching between fuel tanks. During these maneuvers, the engine failed. At the time of the failure, the aircraft had approximately 10 minutes of flying time remaining based on the estimated fuel burn rate. The engine failure was the result of fuel starvation occurring as the fuel in the tanks became unusable during the turns.
The investigation
The investigation examined the refueling process and the pilot's method of monitoring fuel levels. Before the flight, the aircraft had been refueled on an incline, which caused the left wing to sit lower than the right. Because the refueling points are located at the wingtips, the left tank may have appeared full before it actually reached maximum capacity. While the aircraft was parked on level ground overnight to prevent leaks, the fuel level was only checked visually the following morning rather than with a dipstick, leaving the exact fuel volume uncertain.
Furthermore, the pilot relied on a fuel flow computer to monitor usage. This device calculates remaining fuel by subtracting consumed fuel from a manually entered starting value, rather than providing a direct reading of the tank contents. Because the pilot entered a full fuel capacity into the computer, the device displayed a higher fuel level than what was actually present in the tanks.
Findings
- The engine failed because the remaining fuel in one tank became inaccessible during maneuvering.
- The aircraft was likely not filled to its maximum capacity prior to departure.
- The pilot's reliance on the fuel flow computer provided an inaccurate indication of the actual fuel remaining, as the computer does not measure tank levels directly.