On May 8, 1994, at 1135 Pacific daylight time, a Schweizer G- 164B, N3629E, collided with a canal ditch near Gridley, California, during a forced landing attempt. The forced landing was precipitated by a loss of engine power. The aircraft was operated by Williams AG Service, Inc., of Biggs, California, and was engaged in aerial application operations. Visual meteorological conditions prevailed at the time and no flight plan was filed for the operation. The aircraft incurred substantial damage. The certificated commercial pilot, the sole occupant, was not injured. The flight originated from the Jones AG airstrip at Biggs about 1115 hours on the day of the accident. In a telephone interview, the owner of Williams AG Service, Inc., stated that the pilot was spraying seeds in a farm field when the engine failed. The pilot attempted to land in a nearby field and collided with a canal ditch. Postaccident examination of the engine revealed a crack in the number 8 cylinder head from one spark plug hole to the other spark plug hole.