On June 22, 2008, at 0915 eastern daylight time, a Cessna 152, N757HA, collided with a fence during an emergency landing near Leesburg, Florida. The airplane was substantially damaged. The certificated private pilot received minor injuries and the passenger was seriously injured. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed for the personal flight, which departed from Orlando North Airpark, Zellwood, Florida at 0900. The flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91. The pilot stated that about 12 minutes into the flight, he noticed that the rpm began to decrease after climbing through 1,900 feet. He said that he applied carburetor heat, but the engine "froze" seconds later. He then made an emergency landing, and struck a fence post. Examination of the airplane by a Federal Aviation Administration inspector and a Teledyne Lycoming engine representative revealed frontal impact damage to the engine. The carburetor and engine controls were impact damaged. The engine was removed from the airframe to facilitate detailed examination. Examination of the engine showed exterior corrosion and hardened fluid hoses. The spark plugs, valve covers, and accessory components were removed and bore scope. The examination of the top end components revealed no anomalies. The combustion chambers exhibited a gray color as did the spark plugs. Removal of the valve covers revealed heavy rust deposits on the interior. The oil suction screen was opened and free of debris. The oil filter was removed and opened which revealed small fine ferrous metallic particles both within the filter element and in the oil that remained within the canister. The rear accessory case was removed which revealed no anomalies. Internal gear train continuity was confirmed. The oil pump was opened and the gears were intact. Dirt particles and score marks on the interior of the pump housing was observed. The oil sump was removed which revealed that the No. 3 connecting rod was detached from the crankshaft and was heat damage. The No. 3 rod cap was found broken and sustained heat damage. Associated rod bolt fragments were retrieved and exhibited overload signatures. Extruded remains of bearing material from the No. 3 connecting rod were also retrieved from the oil sump. The engine was further disassembled, and the cam followers exhibited spalling wear. The mating surfaces of the center main crankshaft support web showed signs of fretting. Review of maintenance records revealed that the engine was field overhauled on May 21, 2001. At the time of the overhaul, the engine had a total time of 3,552.6 hours. On April 18, 2008, during the annual inspection, it showed a total time of 1036.8 hours since overhaul..