On December 20, 1996, about 2100 eastern standard time, a Cessna T210M, N732UH was substantially damaged during a forced landing on a highway, and subsequent collision with two vehicles in Lexington, Kentucky. The two pilots and two passengers on the airplane were not injured, while a third passenger received minor injuries. The occupants of the two vehicles were not injured. Night visual meteorological conditions prevailed for the flight which departed Birmingham, Alabama, at 1847. The flight was conducted on an instrument flight plan under 14 CFR Part 91. The airplane owner held a private pilot certificate, occupied the left seat, and was operating the flight controls. A commercial rated flight instructor occupied the right seat. The owner reported that they were cruising at 11,000 feet, 15 to 20 miles northeast of Lexington, when the engine began to run rough and a partial power loss occurred. The owner advised air traffic control, and requested to land at the Blue Grass Airport in Lexington. About 5 miles northeast of Lexington, the engine lost total power and the pilot positioned the airplane for a forced landing to a divided highway. During the forced landing, the airplane passed over the top of a power line, and then went under a highway overpass. The airplane struck two vehicles moving in the same direction as the airplane, and then came to rest on the highway. Both pilots reported that oil was visible on the underside of the fuselage. The airplane was examined by a Federal Aviation Administration (FAA) Airworthiness Inspector, who reported that a hole was found in the top of the crankcase near the number four cylinder. Further inspection revealed the number four connecting rod cap was separated from the connecting rod which disconnected the rod from the crankshaft. The engine was shipped to Teledyne Continental Motors (TCM), Mobil, Alabama, for further examination. The examination was conducted for the Safety Board by a FAA inspector assigned to TCM. According to the TCM report: "...Crankcase main bearings exhibited oil starvation signatures...Number 5 exhaust valve, part number SA643873 broken in the transition of the head to the valve stem...could not determine cause of fracture due to extreme impact damage to the fractured surfaces. " "The number 4 exhaust guide, part number SA636242 was broken just below the flange that seats the guide into the cylinder head. The fracture exhibited fatigue...." "Number 5 intake valve, part number SA539988 head was partially broken up. Most pieces of the valve head were not recovered. The fracture of this valve appears all overload due to impact with debris inside the cylinder."