On December 28, 1997, at 1225 eastern standard time, a Mooney M-20F, N9717M, was destroyed during a forced landing near Ferncliff, Virginia. The certificated private pilot and passenger received minor injuries. Visual meteorological conditions prevailed for the local personal flight that originated at Wakefield, Virginia, approximately 1100. No flight plan was filed for the flight conducted under 14 CFR Part 91. In a written statement, the pilot reported the airplane was in cruise flight at 10,500 feet when the engine began to run rough, and "...within 30 seconds the engine seized and would not turn over." He turned towards the nearest airport, the Louisa County Airport [LKU], contacted Richmond Approach Control, and adjusted to best glide speed. The pilot stated: "At 5,000 feet I knew I would not make LKU [and] selected largest open field for forced landing. Was probably going to be long on landing, made 90 [degree] turn, and landed gear up across [the] field. Went through two fences and came to a stop." The pilot said a thorough preflight revealed no mechanical deficiencies with the airplane. He said he added one quart of oil to the engine, bringing the total to 8 quarts. According to an FAA Aviation Safety Inspector, the airplane was in the vicinity of Fork Union, Virginia, 4 miles west of the Fuma Airport at the time of the power loss. However, the pilot chose to turn towards LKU, 20 miles to the north, because it appeared on the "Nearest Airport" display of the LORAN equipment on board the airplane. The Inspector stated "several" airports were available to the pilot between Fork Union and LKU. Examination of the wreckage by the FAA Inspector revealed the propeller did not turn by hand. Removal of the engine cowling revealed an oil soaked engine compartment and that 2 quarts of oil remained in the sump. The oil temperature probe was free of the engine case; attached only to the electrical lead. The threaded portion of the probe and its corresponding attachment point on the engine were undamaged. The probe's copper 'crush' washer displayed evidence of compression, however, no evidence of safety wire was found on the probe or the engine case. The pilot reported the engine was overhauled during the airplane's most recent annual inspection. The inspection was completed 30 days and 10 flight hours prior to the accident. The oil temperature probe was an airframe item that was removed prior to, and reinstalled after, the engine overhaul. In a telephone interview, the mechanic who installed the probe stated the probe was tightened to the manufacturer's recommended torque value.