Event Summary
While practicing flight maneuvers for approximately 30-40 minutes, the flight instructor observed a decrease in engine rpm and altitude. The student pilot was instructed to apply full power, but the rpm continued to decline. The flight instructor then took control of the airplane. The engine subsequently lost power, accompanied by a loud noise, smoke, oil, and debris emanating from the engine cowling.
Forced Landing
The instructor initiated a forced landing. The airplane touched down in a plowed field, aligned with the furrows. During the landing roll, the nose landing gear sank into the soft dirt, causing the airplane to nosed over and come to rest inverted.
Engine Examination
Post-accident examination of the engine revealed that the #3 and #4 connecting rods had failed. The engine had accumulated 3,023 hours since its last major overhaul. The manufacturer's recommended time between overhauls is 2,400 hours.
No further details were provided.