STOCKTON, CA, USA
N733MQ
CESSNA 172N
THE CERTIFICATED COMMERCIAL PILOT/CERTIFIED FLIGHT INSTRUCTOR AND A CERTIFICATED PRIVATE PILOT/INSTRUMENT STUDENT WERE IN A HOLDING PATTERN, IN VFR CONDITIONS, WHILE ON AN INSTRUMENT TRAINING FLIGHT WHEN THE ENGINE QUIT. THE CFI MADE A FORCED LANDING IN AN OPEN FIELD. DURING THE LANDING ROLL, THE AIRPLANE ENCOUNTERED SOFT TERRAIN AND NOSED OVER. EXAMINATION OF THE ENGINE REVEALED THAT THE MAGNETO ASSEMBLY FELL OFF THE ENGINE. AN IMPROPER GASKET WAS INSTALLED UNDER THE MAGNETO HOUSING THAT PREVENTED THE MAGNETO FROM BEING PROPERLY TIGHTENED TO THE REQUIRED TORQUE SETTING. GASKET MATERIAL UNDER THE NUT PROVIDED A CUSHION AFFECT THAT ALLOWED THE NUT TO VIBRATE LOOSE.
THE INSTALLATION BY MAINTENANCE PERSONNEL OF AN INCORRECT GASKET THAT RESULTED IN THE LOSS OF THE ENGINE MAGNETO.
Source: NTSB Aviation Accident Database
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