Event Description
A flight instructor and an instrument student were conducting a practice VOR approach. The aircraft was in level flight at 4,000 feet mean sea level at the initial approach fix when a loud bang emanated from the engine compartment. Smoke and flames entered the cockpit through the rudder pedals.
Immediate Actions
The instructor promptly turned the fuel selector valve to off and nosed the airplane over to initiate a landing. The fire extinguished, and the instructor set up to land in a plowed field. He secured the airplane, opened the doors, and performed a soft-field landing with full flaps.
Landing and Outcome
Upon landing, the nose wheel dropped into the soft dirt, dug in, and the airplane nosed over.
Engine Examination
Following the event, the number two cylinder assembly, along with its intake and exhaust tubes, had exited through the cowling and were not recovered. Pieces of the piston, a compression ring, a push rod, and a piston pin were found inside the cowling. The connecting rod was fractured at a midpoint along both sides of the wrist pin. Mechanical continuity was established for the remaining engine cylinders; no discoloration was evident, and all fracture surfaces were grainy and angular.