THE ENGINE QUIT WITH A LOUD BANG ABOUT 15 MINUTES INTO THE CROSS COUNTRY FLIGHT. THE AIRCRAFT WAS OVER MOUNTAINOUS TERRAIN AND THE PILOT ATTEMPTED TO LAND IN A SMALL PASTURE. THE AIRCRAFT ENCOUNTERED ROUGH TERRAIN DURING THE LANDING ROLL OUT AND NOSED OVER. INVESTIGATION REVEALED THAT THE NUMBER 2 MAIN BEARING HAD SPUN, CLOSING OFF THE INTERNAL OIL PASSAGE IN THE CRANKSHAFT AND JOURNAL. THE ENGINE SUSTAINED A RESULTING OIL STARVATION FAILURE OF THE NUMBER 2 AND 3 CONNECTING RODS. REVIEW OF THE MAINTENANCE RECORDS ESTABLISHED THAT A MAINTENANCE FACILITY HAD FOUND A LARGE AMOUNT OF METAL PARTICLES IN THE OIL 40 HOURS PRIOR TO THE ACCIDENT. THE MAINTENANCE FACILITY WARNED THE PILOT ABOUT THE EXCESSIVE INTERNAL ENGINE WEAR, RECOMMENDING 'FURTHER INSPECTION PRIOR TO FLIGHT.' NO CORRECTIVE ACTION ENTRIES WERE NOTED IN THE LOGBOOK. THE ENGINE WAS FOUND TO HAVE ACCRUED 1,520 HOURS SINCE OVERHAUL. THE MANUFACTURER RECOMMENDS A TIME BETWEEN OVERHAUL INTERVAL OF 1,700 HOURS.