On September 5, 1996, about 1700 central daylight time, a Air Tractor AT-310, N8563S, registered to Davco Aviation, Inc., crashed near St. Clair, Alabama, while on a Title 14 CFR Part 137 aerial application flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was destroyed and the commercial-rated pilot received serious injuries. The flight originated from St. Clair, the same day, about 1610. Witnesses report to Lowndes County Sheriff Department officers that they observed the aircraft flying and the engine suddenly cut off. The aircraft crashed and about 15 seconds later they heard an explosion. Examination of the crash site by FAA inspectors showed the aircraft crashed in a nose-down attitude while at a slow speed. The leading edge of each wing was crushed aft. The propeller had damage consistent with a propeller being turned by engine power at the time of ground impact. A postcrash fire erupted in the nose and center wing areas. Examination of the engine by FAA inspectors showed no evidence of precrash mechanical failure or malfunction of the engine.