On July 8, 1993, about 1445 central daylight time, a Mooney M20J, N3896H, registered to the pilot, William R. Capps, was substantially damaged during a forced landing near Magee, Mississippi, while on a 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The private pilot, the sole occupant, sustained minor injuries. The flight originated about 1415 from the Paul Pittman Memorial Airport, Tylertown, Mississippi. The day before the accident flight, the engine oil was changed but the mechanic did not run the engine after to check for oil leaks. The pilot stated that before departure, the oil quantity was full. The flight departed and during cruise flight, the engine seized. The pilot landed the airplane landing gear up in a field. The engine was removed from the airplane and sent to the manufacturer for further examination. Examination of the engine revealed that a section of gasket between the accessory case and the oil filter adapter plate was missing. Also, the threaded bolt which secures the oil filter adapter plate to the accessory section was an incorrect part. As a result, the adapter plate could not be tightened against the accessory case. According to the teardown report, the engine failure was due to the loss of lubrication which was due to an improperly assembled oil filter adapter plate and gasket. The wreckage was released to Joel Clark of Clark Aviation, Inc., on November 15, 1993.