On November 14, 1994, at 1820 central standard time (cst), a Piper PA-28-180, N7556W, registered to Howard Samuelson of Orland Park, Illinois, and piloted by a commercially certificated flight instructor, was substantially damaged during a forced landing following a total loss of engine power. The 14 CFR Part 91 instructional flight was not operating on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The instructor and student pilot reported minor injuries. The flight departed Peoria, Illinois, at 1800 CST. According to the student pilot and owner of the airplane, the airplane was in level cruise flight when the engine's oil pressure went to "0" indicated pressure. He said the instructor declared an emergency and landed in a soy bean field. During the landing roll, the airplane collided with trees that bordered the field's edge. The instructor's statement confirmed the student/owner's statement, adding that the engine ran for an unspecified time after the oil pressure went to "0." The on-scene investigation revealed that the engine's number two cylinder connecting rod bolts had failed. Connecting rod components forced a hole into the engine's case top near the number two cylinder tappet position. The connecting rod bolt that was retrieved had necked fracture ends. The surfaces of both fractures had a grainy appearance with many impact marks on them. The camshaft's number two cylinder intake lobe was round and had machining marks on its surface. Examination of the engine oil pump revealed its screen was contaminated with metal particles. The oil sump was contaminated with metal pieces that were similar to bearing parts. Approximately two quarts of oil was found in the sump. Examination of the airplane's powerplant logbook revealed the engine had been overhauled approximately 21 years before the accident.