On June 14, 2001, at 1315 central daylight time, a Commander 114-B airplane, N114BW, was substantially damaged when it impacted the ground during a forced landing following a complete loss of engine power near Okmulgee, Oklahoma. The airplane was registered to a private individual and operated by the pilot. The commercial pilot, sole occupant of the airplane, sustained minor injuries. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan was filed for the 14 Code of Federal Regulations Part 91 personal flight. The cross-country flight originated from the Kyle-Oakley Field Airport, Murray, Kentucky, at 1000, and was destined for the Wiley Post Airport, Oklahoma City, Oklahoma. The pilot reported that after three hours of normal flight, he detected a change in the sound of the engine. The oil pressure gauge needle dropped to zero; however, the cylinder head temperature and oil temperature gauge needles remained in their green arcs. The pilot contacted the local flight service station and requested vectors to the nearest airport, which was in Okmulgee. The pilot noticed an increasing vibration and reduced the throttle. Subsequently, he heard a "loud bang" and the engine lost total power. He executed a forced landing to a field, located 2.5 miles northeast of the Okmulgee Airport. During the landing roll, the airplane contacted dirt mounds that were 4 feet high, before it came to a stop upright. The FAA inspector, who examined the aircraft at the accident site, reported that both wings, the engine firewall, and landing gear were structurally damaged. He observed a film of oil extending from the engine cowling along the fuselage to empennage. He removed the engine oil dipstick and it indicated 2 quarts out of an 8 quart capacity. The Textron-Lycoming IO-540-T4B5 engine was examined in Oklahoma by an NTSB investigator and a representative from Textron-Lycoming. The oil sump plug was removed and only two drops of oil could be drained. The oil appeared black and smelled as though it had been exposed to heat. The engine's oil system was examined and no evidence of a leak was noted. A hole, that was 2.5 inches in diameter, was observed on the top of the engine crankcase, between the #5 and #6 cylinders. A rod end cap and bolt from the #6 cylinder's connecting rod were extracted from the hole. The connecting rod end cap and bolt were sent to the NTSB Materials Laboratory in Washington, D.C. for further examination. The bolt displayed features typical of bending and torsion overstress while heated. The rod end cap displayed features typical of bending overstress while heated. Additionally, the bearing surface of the rod end cap exhibited fretting and metal transfer, which are signatures consistent with relative movement and looseness in the joint. The engine was transported to Air Salvage of Dallas, Lancaster, Texas, and examined by the NTSB investigator and the representative from Textron Lycoming. The #1 through #5 cylinders were removed; the #6 cylinder was internally damaged and could not be removed. The crankcase was separated, and the #6 cylinder's connecting rod was observed to be separated from its piston and the crankshaft. The #1 through #5 connecting rod cap bolts were torque tested using a flexible beam torque wrench. According to the Textron-Lycoming representative, all of the bolts were within acceptable tolerances. The connecting rods were removed from the #1 through the #5 positions on the crankshaft. The #1 through #5 connecting rod journals on the crankshaft were not scored and there was no apparent thermal damage. The #6 connecting rod journal displayed thermal damage and metal transfer. Ferrous debris was found in the oil filter, at the oil suction screen, and in the oil sump. The oil pump was disassembled and no anomalies were noted. At the time of the accident, the engine and airframe had accumulated a total of 1743.9 hours, and the airplane had flown 150.0 hours since the last annual inspection on January 5, 2001.