On July 15, 1997, about 1520 hours Pacific daylight time, a Cessna 180K, N2914K, collided with terrain during a forced landing at the Lake Mead National Recreation Area in Lake Mead, Nevada, after a loss of engine power. The airplane sustained substantial damage and the certificated private pilot received minor injuries. The airplane was being operated as a business flight under the provisions of 14 CFR Part 91 by the pilot/owner when the accident occurred. The flight originated from the Boulder City Airport, Boulder City, Nevada, at an unspecified time, and was destined for Spanish Fork, Utah. Visual meteorological conditions prevailed and no flight plan was filed. The pilot reported that he had been flying over Lake Mead, about 3,500 feet msl, and was climbing slightly to remain underneath the inbound traffic to McCarran International Airport (Las Vegas). He stated that he heard a "bang" from the engine, followed by a "major vibration." He reversed direction to head back to Boulder City. The pilot reported that the engine continued vibrating and he was unable to maintain altitude, so he pulled the aircraft into a stall to stop and feather the propeller. He stated that he attempted to land in a parking lot, but came in too high and too fast. He touched down on a dirt road. The road curved to the right and the aircraft continued off the road and onto the beach approximately 400 feet. The pilot stated that he was approaching a large berm with excessive speed. He pulled back and was able to get enough lift to hit the berm with only the aircraft belly. The aircraft bounced and came to a stop on the opposite side of the berm. The landing gear was sheared. The airplane was examined by the Federal Aviation Administration and two holes were found in the engine case above the forward cylinder's connecting rods. Further examination of the powerplant revealed that the Nos. 2 and 6 cylinders were intact. Neither piston displayed any sign of heat discoloration around the skirts. Combustion deposits were noted on the piston crowns. There was no staining or piston crown edge erosion. Both skirts were failed. Inspection of the No. 4 cylinder revealed that the piston was disintegrated around the pin. The piston rod was bent and the piston pin was still intact through the rod wrist. Neither the rod nor the pin displayed any indication of heat distress. There was no scoring noted inside the cylinder barrel. The No. 4 bottom sparkplug was fouled with metal. The sump contained oil and large chunks of pistons. The pilot reported that at the time of the accident, the aircraft engine, Continental O-470-U, had 2536.1 hours of total time, 75.2 hours since the last inspection, and 806.8 hours since the last overhaul. The maintenance records revealed that the six pistons, each with a Superior Air Parts, Inc., part number SA 648029, were installed during the last major engine overhaul on February 19, 1990.