On May 12, 1993, at 0900 central daylight time (CDT), a Grumman G 164B, N6639Q, was substantially damaged during the landing roll following a forced landing to unsuitable terrain. The commercial pilot, owner and operator, was not injured during the visual flight rules (VFR) flight. The pilot reported to a Federal Aviation Administration (FAA) inspector that following agriculture operations he was enroute to his private airstrip, when the engine began to run rough and would not sustain flight, so he elected to land in the only available area. His touchdown was made to rice paddy. He reported that during the landing roll the main landing gear sank into a hole and was severed and that the airplane pitched to the side and damaged the right wing. An examination of the engine failed to reveal any anomalies that could have caused the loss of engine power. The airplane was released to the owner by the FAA inspector following his examination of the accident scene and the airplane.