On August 4, 1993, at approximately 1530 central daylight time, an Aero Commander S2R, N5570X, sustained substantial damage near England, Arkansas, following a partial loss of engine power during the initial takeoff climb. The main gear separated from the airframe as the airplane groundlooped during the forced landing. The commercial pilot did not receive injuries. Visual meteorological conditions prevailed for the planned local aerial application flight. During interviews, conducted by the investigator in charge, the pilot stated that the hopper contained approximately 20 pounds of chemical fertilizer and the fuel tanks were approximately half full for the spraying run. He further reported that during the initial climb, with an RPM decrease of approximately 150, the airplane could not sustain flight. As the load was being dumped, the airplane landed hard approximately 100 feet beyond the departure end of the runway. The pilot exited the airplane and returned to the hangar. Company personnel went to the airplane and initiated a recovery. Approximately two hours after the accident, the airplane was consumed by fire. The pilot reported in an enclosed statement that there had been previous discrepancies regarding propeller RPM control. Maintenance personnel had not been able to determine the cause for the malfunction. On September 14, 1993, the engine was tested. The engine test run was conducted with the carburetor, engine governor, and propeller intact. During an approximate 15 minute test run, there were no RPM fluctuations or engine anomalies. The airplane was released to the owner's representative following the investigation.