On April 4, 2005, about 1025 mountain daylight time, an Air Tractor AT-602, N5015K, piloted by a commercial pilot, was substantially damaged during a forced landing following a loss of engine power while on approach to runway 31 at the Imperial Municipal Airport (IML), Imperial, Nebraska. The 14 CFR Part 137 flight was operating in visual meteorological conditions without a flight plan. The pilot was not injured. The local flight originated about 0928. According to a report filed by the pilot, he had completed spray operations at a field located about 12 miles south of IML and was returning. He stated that according to the fuel flow meter he had about 40 minutes of fuel remaining when he exited the last field sprayed. He stated that when he was about 1 mile south of the airport, the engine lost power. He checked the fuel flow meter which "suggested" he had over 30 minutes of fuel remaining with 1/4 in one tank and 1/8 in the other tank. He stated that he executed a landing to a field and the main landing gear sunk into the soft dirt and the airplane nosed over. Post accident examination of the airplane by Federal Aviation Administration inspectors revealed that some fuel had drained from the right wing fuel vent due to the position of the airplane. No other evidence of fuel leakage was detected. When the airplane was righted, no useable quantity of fuel was noted in the fuel tanks. Subsequent to the accident, the airplane's engine was removed from the airplane and a functional test performed. The engine was run on a test stand and no anomalies were found with respect to the engine.