NTSB Identification: LAX99LA134.
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Accident occurred Monday, March 29, 1999 in MOORPARK, CA
Probable Cause Approval Date: 01/18/2001
Aircraft: Cessna 172RG, registration: N9451D
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The instructor and instrument student were in level flight at 4,000 feet msl at the initial approach fix for a practice VOR approach. After hearing a loud bang in the engine compartment, smoke and flames were observed entering the cockpit by the rudder pedals. The instructor immediately turned the fuel selector valve to off and nosed the airplane over to land. The fire went out and he set up to land in a plowed field. He secured the airplane, opened the doors, and then executed a soft-field landing with full flaps. When the nose wheel dropped into the soft dirt after touchdown, it dug in and the airplane nosed over. The number two cylinder assembly with its intake and exhaust tubes exited through the cowling and were not recovered. Pieces of piston, compression ring, a push rod, and a piston pin were found in the cowling. The connecting rod 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.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The failure and separation of the number two cylinder for undetermined reasons. A factor was the soft terrain at the forced landing site.

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