On June 5, 1998, at 0730 central daylight time, an Ayres S2R agricultural airplane, N4007Y, registered to and operated by P & D Flying Service of Watson, Arkansas, sustained substantial damage during a forced landing following a partial loss of engine power while maneuvering near Watson. The commercial pilot, the sole occupant, was not injured. No flight plan was filed and visual meteorological conditions prevailed for the Title 14 CFR Part 137 local aerial application flight that departed from a private airstrip 15 minutes before the accident. According to information provided by the operator to an FAA inspector, the purpose of the flight was to apply herbicide to a rice field. After completion of several spray passes, during the pull up at the end of a pass, the engine lost power. During the ensuing forced landing, the airplane touched down in a field and rolled into a hedgerow of trees. The FAA inspector examined the airplane and reported that the aft section of the fuselage was bowed and twisted, and the right wing incurred structural damage. The operator removed the engine from the airframe and transported it to Airmotive, Inc., an engine maintenance facility in Clinton, Arkansas. According to an Airmotive mechanic, upon examination of the engine, he found a discontinuity in the propeller governor control. The threads on the push-pull rod which retain the rod end that bolts to the propeller governor were stripped, and the rod end had separated from the rod. According to the mechanic, the separation of the rod end probably resulted in the reported loss of engine power, since the governor is "spring loaded" to a high pitch (low rpm) setting. No other discrepancies with the engine were noted, and it was placed on a test stand and ran "with no problems."