Incident
Approximately three and a half hours after takeoff, the engine of the aircraft ceased operating while fuel was being drawn from the left main tank. The pilot, believing that the left main tank contained five gallons and the right main tank fifteen gallons, moved the fuel selector to the right main tank. He then pushed the mixture control forward, activated the primer system, and cycled the magnetos off and on, but the engine did not restart. A forced landing was subsequently executed. During the landing, the aircraft broke through a fence and struck two cows.
Investigation
Post-incident examination revealed that the right main fuel tank, with a capacity of twenty gallons, was approximately three-quarters full. All other tanks were empty. The aircraft had been fueled to its total capacity of seventy-two gallons prior to departure.
Fuel Calculations
The pilot reported that the aircraft consumed an average of fourteen gallons per hour. Based on this rate, the aircraft would have used forty-nine gallons of the sixty-four gallons of usable fuel during the three-and-a-half-hour flight. This consumption would account for the fifteen gallons remaining in the right main tank, consistent with the pilot's initial estimate. However, the actual fuel distribution indicated that the left main tank was empty earlier than anticipated, leading to the engine failure.
Primer Usage
To prevent flooding during an engine start, the fuel boost pump (primer) must be turned off immediately after fuel pressure is restored. The duration of primer usage during the attempted restart was not verified.