KISSIMMEE, FL, USA
N1389W
MOONEY M20C
THE PLT RPRTD THE ENG STARTED & RAN NORMALLY BEFORE TAKEOFF. HOWEVER, DURING FLT, IT BEGAN RUNNING ROUGH. THE PLT REDUCED THE POWER SETTING WHICH INITIALLY ELIMINATED THE ENG ROUGHNESS. HE CHECKED EACH MAGNETO & NOTED NO MALFUNCTION; HOWEVER, WHILE DIVERTING TO A NEARBY ARPT, THE ENG AGAIN BEGAN RUNNING ROUGH & A SEVERE LOSS OF POWER OCCURRED. ACCORDING TO WITNESSES, THE ACFT STRUCK A PALM TREE DURING A LEFT DESCENDING TURN AT LOW ALTITUDE & CRASHED. THE ENG WAS EQUIPPED WITH BENDIX MODEL S4LN-200 SERIES MAGNETOS. DURING A BENCH CHECK BOTH MAGNETOS BEGAN MISFIRING AFTER ABOUT 15 TO 20 MIN OF OPN. DISASSEMBLY OF THE MAGNETOS REVEALED THE NONCONDUCTIVE MATERIAL IN THE COILS WAS CRACKED & WAS BEGINNING TO LIQUEFY; THIS RESULTED IN MISDIRECTION OF THE HIGH VOLTAGE SPARK. THE MAGNETOS HAD APRX 2316 HRS IN SVC. ACCORDING TO AD 73-07-04, THE COILS IN THE MAGNETOS OF THIS ACFT SHOULD HAVE BEEN REPLACED AFTER ACCUMULATING APRX 2000 HRS OF OPN. THE ACFT HAD FLOWN 11 HRS SINCE THE LAST ANNUAL INSPN.
MALFUNCTION OF BOTH MAGNETOS DUE TO DETERIORATION OF THE COILS, FAILURE OF MAINTENANCE PERSONNEL TO COMPLY WITH AN AIRWORTHINESS DIRECTIVE, AND FAILURE OF THE PILOT TO MAINTAIN ADEQUATE VISUAL LOOKOUT WHILE ON AN APPROACH FOR AN EMERGENCY LANDING. FACTORS RELATED TO THE ACCIDENT WERE: THE OBSTRUCTION (TREE) IN THE EMERGENCY LANDING AREA, AND DIVERSION OF THE PILOT'S ATTENTION WHILE APPROACHING TO LAND.
Source: NTSB Aviation Accident Database
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