The pilot had filled the aircraft tanks prior to flying from Rockhampton to Bowen. The stated endurance from Rockhampton was 430 minutes. During the return flight he amended the flight plan by radio and continued the flight towards Bundaberg. The pilot estimated that the aircraft contained about 100 litres of fuel at Bowen and said the gauges indicated that the tanks were about half full overhead Rockhampton. He said that they were indicating about a quarter and a third full over Gladstone. After passing Gladstone both gauge indications moved rapidly towards empty. A descent for a precautionary landing was commenced. The pilot found a suitable area for landing, and commenced an inspection at about 200 feet above ground level when the engine stopped. The aircraft was landed in tall grass and overturned at the end of the landing roll. The accident occurred after about 380 minutes of engine running time, which included 366 minutes of flight time. Investigation of the fuel system failed to disclose any evidence of fuel leaks. The pilot's fuel calculations were based on lower fuel consumption rates than would be expected, given the speed at which the aircraft cruised. This resulted in the planned endurance being greater than the actual endurance possible. In addition to this error, the pilot had planned a flight duration which would have resulted in the aircraft having less than the planned fixed reserve on board on arrival at Bundaberg. This accident was not the subject of an on-site investigation.
