On June 29, 2006, about 1800 central daylight time, a single-engine Mooney M20J airplane, N5662M, received minor damage during a forced landing following a partial loss of engine power near Beaumont, Texas. The private pilot and passenger were not injured. The airplane was registered to and operated by the pilot. Visual meteorological conditions prevailed and no flight plan was filed for the 14 Code of Federal Regulations Part 91 personal flight. The 23-nautical mile cross-country flight originated from the Southeast Texas Regional Airport (BPT) near Beaumont, Texas, and was destined for the Chambers County-Winnie Stowell Airport (T90) near Winnie, Texas. According to the pilot, he arrived at BPT to pick up his airplane after the completion of its annual inspection. During the preflight inspection the pilot noted that the engine contained seven and a half quarts of oil. The pilot proceeded to perform three takeoff and landings to meet the 90-day currency requirement prior to taking a passenger. After the third landing, the pilot picked up the passenger without shutting down the engine, and proceeded to depart on runway 16. The 257-hour pilot further reported that shortly after takeoff, the propeller revolutions per minute (RPM) begin to fluctuate and at one time exceeded the engine's 2,700 RPM redline. The pilot reported that he immediately reduced the engine's manifold pressure, which resulted in the RPM decreasing and subsequently fluctuating in the 1,500 to 2,000 RPM range. The engine started to make a "clicking" noise that was followed by a "loud noise" before it began to emit "copious oil smoke" and shaking "violently." The pilot elected to shut down the engine and perform an emergency landing to an open grassy field. During the landing roll, the airplane impacted a barbwire fence, which resulted in damage to the leading edge of the wings. The airplane was recovered to a hangar where large amounts of oil were observed dripping from the airplane's belly. An initial examination of the engine, by a Federal Aviation Administration (FAA) inspector, revealed that no oil was present on the engine oil dipstick. The inspector further reported that there was a hole in the crankcase near the upper spline in the area above the number four piston to crankshaft connecting rod. The airplane was powered by a four-cylinder Lycoming IO-360-A3B6D engine, serial number L-23480-51A, rated at 200 horsepower at 2,700 rpm, and was driving a two-bladed constant speed McCauley propeller. The engine's source of ignition was a Bendix D4LN-3000 dual magneto. The propeller governor was a rear mounted McCauley C290D5-F/T17. The engine logbook revealed that the engine was last inspected in accordance with an annual inspection on June 23, 2006. At the time of the incident, the engine had accumulated 1,684.8 hours since major overhaul and one hour since the last inspection. The logbook also revealed that at the time of the annual inspection, an overhauled propeller and propeller governor were installed. A teardown examination of the engine was performed. Metal particles were found throughout the engine. The engine oil sump contained residual oil and large pieces of metal. The connecting rod bearings for pistons number two and four exhibited thermal distress. A number four piston to crankshaft connecting rod cap bolt was found separated, and the crankshaft end of the connecting rod was found wedged between the camshaft and broken crankcase opening. The oil pump was free to turn and revealed no anomalies. The exterior of the engine was mostly absent from oil with the exception of the area below the rear mounted propeller governor. An examination of the governor revealed that it had been installed with one MS9144-01 gasket. A review of the Textron Lycoming IO, AIO-360-A, B Series Parts Catalog, PC 406-1, dated April 1991, revealed that the IO-360-A3B6D engine with a dual magneto requires two P/N 72053 governor gaskets and one LW-12347 propeller governor pad plate. According to Textron Lycoming Service Instruction (SI) number 1438 dated July 9, 1987, and updated SI number 1438A dated December 9, 2005, "The use of a P/N LW-12347 propeller governor pad plate and two P/N 72503 gaskets on dual magneto engines with rear mounted propeller governor drives is necessary with some propeller governors to eliminate the possibility of oil leakage between the propeller governor and the accessory housing."