On August 10, 2002, at 2030 central daylight time, a Piper PA-28-140, owned and piloted by a private pilot, was substantially damaged during an emergency landing in a corn field located three miles northeast of Roodhouse, Illinois. The pilot reported that the engine experienced a partial loss of engine power during cruise flight. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The pilot and pilot-rated passenger reported no injuries. The flight departed from the Jacksonville Municipal Airport, Jacksonville, Illinois, at 2015, en route to the Creve Coeur Airport, St. Louis, Missouri. The pilot sat in the right seat with the intention of acting as a safety pilot for the left seat pilot. While in level flight at 3,000 feet mean sea level and about 18 miles from the departure airport, the airplane experienced a sudden loss of power, a drop in engine rpm to 2,000 rpm, and intense shaking. The right seat pilot then checked the magnetos, applied carburetor heat, varied the throttle and mixture controls. The left seat pilot then turned the fuel pump on, switched tanks, and trimmed for an airspeed of 80 mph. The right seat pilot checked his handheld GPS for the nearest airport, but found none. Both pilots then began to notice blue flashes and smoke coming from the cowling. Smoke began to fill the cabin. The right seat pilot called out 'engine shutdown' and retarded the mixture control to 'idle cutoff'. The left seat pilot turned the fuel selector to the 'off' position. The left seat pilot then transferred controls to the right seat pilot and shut the master switch off. The right seat pilot then committed to landing on a field that he saw earlier and then set up a circling approach over it. During the turn to final, the right seat pilot opened the cabin door and once the landing was assured (about 1/4 mile final) he set full flaps and began to slow the airplane down. About 25-50 feet above the ground, the left seat pilot turned the master switch and landing light on to illuminate the landing area. Upon touchdown, the left seat pilot turned off the master switch. The airplane landing in a field of mature corn about 1/2 mile long in the landing direction and 1/3 mile wide. The landing direction was parallel to the corn rows. Inspection of the engine revealed a hole in the engine case near the front left cylinder area. According to a mechanic, the lifter had exited the engine. The airplane was powered by a Lycoming O-320-E2A, serial number L-14508-27A engine rated at 150 horsepower. The engine had a total time of 2,919 hours, 1,719 hours since a major overhaul, and 25 hours since its last inspection which occurred on July 3, 2002.