Circumstances:
During the flight the engine surged without warning and the pilot elected to land in a cleared area, to investigate the engine problem. The engine failed completely during the latter stage of the approach resulting in a heavy landing short of the cleared area. Subsequent investigation by the pilot revealed that the auxiliary fuel tank was completely empty. The main fuel gauge indicated that the main fuel tank was full of fuel. The two fuel tanks cannot be selected individually and fuel from both is supplied simultaneously. On this occasion it appears that only fuel from the auxiliary fuel tank reached the carburettor. The duration of the flight is consistent with this assumption. Examination by the company maintenance organisation revealed that a plastic hose in the main fuel tank vent line was pinched, possibly during the accident. Maintenance had been carried out before the previous flight, which had lasted 40 minutes. However, the work entailed the removal of the auxiliary fuel tank during which the main fuel vent line was not moved. No other fault was found.
