On September 12, 2000, at 1600 central daylight time, a Cessna 152 single-engine airplane, N64921, was substantially damaged during a forced landing following a loss of engine power near Saspamco, Texas. The airplane was registered to and operated by Wright Flyers Aviation of San Antonio, Texas. The flight instructor sustained minor injuries and the student pilot was not injured. Visual meteorological conditions prevailed, and a VFR flight plan was filed for the 14 Code of Federal Regulations Part 91 instructional flight. The local flight originated from the San Antonio International Airport at 1500. The flight instructor had demonstrated basic flight maneuvers to the student pilot. The student had been practicing the flight maneuvers for about 30-40 minutes when the flight instructor noticed a drop in engine rpm and altitude. He instructed the student pilot to apply full power; however, the rpm continued to drop. The flight instructor confirmed that the student had applied full power and took control of the airplane. The engine began to run rough and immediately lost power with a loud noise, smoke, oil and debris coming from the engine cowling. The flight instructor tried to restart the engine, but there was no response. He initiated a forced landing, and the airplane touched down in a plowed field aligned with the furrows. During the landing roll, the nose landing gear sunk into the soft dirt, and the airplane nosed over coming to rest inverted. Examination of the airplane by the FAA inspector revealed that the vertical and horizontal stabilizers were damaged. The nose landing gear was damaged, and the right wing was wrinkled. A teardown examination was conducted of the Lycoming O-235-L2C engine. According to the FAA inspector, the #4 connecting rod was found disconnected from the crankshaft, and the connecting rod journal displayed "moderate" scoring. The #3 connecting rod was found disconnected from the crankshaft and deformed. The #3 connecting rod journal on the crankshaft showed signs of "sever[e] stress and overheating." Pieces of bearing were found in the oil sump. The remaining rods and journals appeared "normal." The oil filter did not show "abnormal" contamination. Only traces of metal were observed. The pump and impellers "were covered in residual oil and did not appear to have metal contamination or obvious scoring." The engine had accumulated 3,023 hours since the last major overhaul. The engine time since top overhaul was 262.2 hours. The manufacturer's recommended time between overhauls is 2,400 hours.