On April 26, 1996, about 1535 central daylight time, a Cessna 210M, N722PD, registered to Two Papa Delta, Inc., nosed over while making a forced landing following loss of engine power at Meridian, Mississippi, while on a 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the private-rated pilot was not injured. The flight originated from Key Field, Meridian, Mississippi, about 5 minutes before the accident. The pilot stated the engine oil cooler had been replaced since the previous flight. He was picking up the aircraft and flying it from Meridian to Olive Branch, Mississippi, the home base. He began to feel a vibration during climbout after takeoff. The vibration became more severe and he turned back to the airport. As he turned to a field for landing the propeller stopped. While making a forced landing in a field the aircraft struck a drainage ditch and the nose landing gear separated. The aircraft then nosed over. Postcrash examination of the engine by an FAA inspector showed there was a substantial amount of oil covering the belly of the aircraft, and there was a hole in the engine case near the Nos. 5 and 6 cylinders. The oil filter contained a substantial amount of metal debris. The oil cooler showed no evidence of leakage. Tear down examination of the engine showed the No. 5 connecting rod had separated from the crankshaft. The connecting rod bolts had been heated and stretched prior to failure. The No. 5 and 6 connecting rods and crankshaft connecting rod journals had been discolored by heat and showed evidence of oil starvation. The crankshaft main bearings had suffered oil starvation damage and begun to smear and melt. The engine oil pump gears had damage from hard particle passage through the pump. Bearing debris was found in the oil pump and oil pressure relief valve. (See the Continental Analytical Inspection Report.) The pilot who flew the aircraft before the accident flight stated to an FAA inspector that he experienced an oil leak while en route from Hattiesburg, Mississippi, to Olive Branch, Mississippi. He landed at Meridian to check out the engine. He found oil on the cowling behind the propeller and thought the propeller seal was leaking. He added 2 quarts of oil and departed Meridian for Olive Branch. During climbout from Meridian, the oil pressure dropped into the red line area and he returned and landed at Meridian after about 10-15 minutes of flight. He did not inform the owners or mechanics that he operated the engine with the oil pressure in the red line area for about 10 minutes. Mechanics who repaired the aircraft after it returned to Meridian, on the previous flight, stated the oil cooler had cracked and had to be replaced. Additionally, they added 8 quarts of oil to fill the engine to the full mark of 9 quarts.