On July 27, 1998, at 1026 eastern standard time (est), a Stinson 108-1, N483C, operated by a private pilot, was destroyed when during cruise flight the airplane's engine lost power. During the subsequent forced landing, the airplane struck a bridge guard rail. A post-impact fire ensued. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under 14 CFR Part 91. There was no flight plan on file. The pilot and passenger on board sustained serious injuries. The cross-country flight originated at Pekin, Indiana, at 0820 est, and was en route to Oshkosh, Wisconsin. In his written statement, dictated by the co-owner of the airplane, the pilot said that they were approximately 15 miles north of Bloomington, Indiana, cruising at 4,500 feet mean seal level (msl), when the airplane began to vibrate excessively. The pilot looked at his oil pressure gage and found it reading zero. The pilot shut down the engine and began executing a forced landing to a field. The pilot said that when the airplane started to settle, he saw a guard rail by a road in front of him. The pilot pulled back in an attempt to clear the rail, but the airplane did not have enough airspeed. The airplane struck the guard rail and stopped. The pilot and passenger got out of the airplane before is caught fire and burned. A Federal Aviation Administration (FAA) inspector examined the wreckage at the accident site. The remains of the airplane rested against a guard rail located on top of the leeward side of a county road bridge. The propeller blades were bent aft. The airplane's cowling was crushed inward. The engine and firewall were intact and showed heat discoloration. The airplane's forward fuselage, cockpit area, aft fuselage just behind the cockpit, and inboard 5 feet of the right wing were melted and consumed by fire. The airplane's left wing was broken off at the attachment fittings and consumed by fire. The aft 4 feet of the airplane's fuselage and empennage were intact and undamaged. Flight control continuity was confirmed. Examination of the airplane's engine revealed that the number 5 and 6 cylinder connecting rods were broken. A six-inch by 4-inch hole was found in the top of the engine crankcase just above the number 5 and number 6 cylinders.