On July 17, 2000, at 1513 Eastern Daylight Time, a Cessna P210N, N5256W, was substantially damaged during a forced landing in a field near Richfield Springs, New York. The certificated private pilot and passenger sustained serious injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The flight originated from Fulton County Airport (NY0), Johnstown, New York, about 1450; and was destined for Port Columbus International Airport, Columbus, Ohio. The pilot stated that during the climb from NY0, the climb performance of the airplane was less than normal, and "the engine was not acting right." About 3,700 feet mean-sea-level, the pilot heard a "pop", and the engine lost all power. The pilot performed a forced landing to a field. During the landing, the airplane struck a rock, and came to rest inverted. Examination of the wreckage by a Federal Aviation Administration (FAA) inspector revealed that metal was present in the engine oil filter. A representative from the engine manufacturer, under the supervision of the FAA inspector, examined the engine at the facility that previously performed maintenance work on the airplane. The examination revealed that the crankshaft had separated between the number two and number three connecting rods. Further examination revealed that the main bearing from the number two cylinder had shifted rearward. The representative noted material transfer between the bearing and the area of the crankshaft near the fracture. The material transfer was consistent with the bearing rubbing against the crankshaft. Review of the maintenance records revealed that all six cylinders were replaced about 100 hours of operation prior to the accident. The representative and the FAA inspector checked the torque on the cylinder through-bolts. They found that one of the bolts was at a torque setting that was less than the specified torque setting. However, they could not determine if the bolt was not at a proper torque setting before the accident, or if the impact had loosened the bolt. The owner of the maintenance facility said that the bolts were set to the correct torque.