On June 11, 1995, at 0930 central daylight time (CDT), an Air Tractor AT-301, N23477, operated by Lemaster Aerial Spraying, Inc., Ottawa, Kansas, was substantially damaged following a loss of engine power and subsequent forced landing on a road in Hoxie, Kansas. The pilot reported no injuries. The 14 CFR Part 137 aerial application flight originated from the Hoxie-Sheridan County Airport, Hoxie, Kansas, without a flight plan at 0915 CDT. Visual meteorological conditions existed at the time of the accident. The pilot reported he was en route for an aerial application operation. Approximately four miles after departure, the pilot stated the engine began to sputter. He stated there was no abnormal indications on any of the engine instruments or throttle quadrant. The engine then lost all power and the pilot made a forced landing on a small road. While landing the airplane's landing gear struck a ditch and the airplane came to rest inverted. Postaccident examination revealed the nut (P/N 9294) on the adjusting screw for the number three cylinder was loose. Due to the excessive clearance, the exhaust valve was not able to open. The airplane logbook shows the last inspection was a 100 hour inspection performed on December 5, 1994. The airplane has logged 188.5 hours since the inspection.