On June 13, 1993, at approximately 1240 central daylight time, a Reims Cessna FA 150K, N922SZ, sustained substantial damage during a forced landing following a loss of engine power near Willis, Texas. The commercial pilot and one passenger did not receive injuries. Visual meteorological conditions prevailed for the personal cross country flight. Interviews conducted by the Federal Aviation Administration inspector with the pilot and the Pilot Operator Report revealed the following information. During cruise at approximately 1,500 feet MSL and approximately four miles west of the Conroe, Texas, airport, a partial power loss occurred. The pilot decided to make an off airport landing. The surrounding terrain was dominated by woodlands and numerous traffic was along the available highways. The pilot made a visual pattern from 1,200 feet MSL to a field. During the full flap final approach at approximately 100 feet above the ground, the pilot saw a fence along the landing area. The pilot made a descending turn away from the fence and during the flare the airplane dropped to the ground, rolled approximately 200 feet in the wet field when the nose gear collapsed and the airplane came to rest inverted. A review of the maintenance records by a Federal Aviation Administration airworthiness inspector and the investigator in charge revealed the following information. The engine was removed from a damaged airframe and placed into unpreserved storage for a period of time. The engine was installed on the current airframe S/N 0047 on May 1, 1993. On that date, records indicated the total time on the engine was 1458 hours and 445.0 hours since a top overhaul. A compression check for cylinder number three was 75 and cylinder number four was 74. The airplane reportedly had flown 2.6 hours since the last annual inspection on May 1, 1993. The airplane was released to the owner. A subsequent teardown of the engine by a mechanic revealed the following information. The compression on cylinder number three was zero. The number three cylinder exhaust valve was stuck. The number three cylinder intake valve and the number four cylinder intake valve and exhaust valve were tight. The number three and number four valve stems showed carbon buildup.