NTSB Identification: FTW94LA230.
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Accident occurred Tuesday, July 12, 1994 in DUPONT, LA
Probable Cause Approval Date: 01/26/1995
Aircraft: NORTH AMERICAN NAVION 4, registration: N8648H
Injuries: 1 Serious,2 Minor.
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 AIRPLANE WAS SUBSTANTIALLY DAMAGED DURING A FORCED LANDING FOLLOWING A TOTAL LOSS OF ENGINE POWER. DURING THE LANDING FLARE, THE PILOT INADVERTENTLY STALLED THE AIRPLANE IN AN EFFORT TO CLEAR TREES AND WIRE. TWO 1/4 INCH 20 BY 15/16 INCH HEX SCREWS WERE FOUND LOOSE DURING THE ENGINE EXAMINATION. THESE SCREWS HOLD THE STARTER GEAR PIVOT IN PLACE. ONE OF THE SCREWS WAS OUT 1 INCH AND THE STARTER GEAR WAS FOUND MISALIGNED AND ACCESSORY GEAR TEETH WERE GRINDING. METAL WAS SHAVED FROM THE STARTER GEAR AND METAL WAS FOUND IN THE OIL SCREEN. GEAR TEETH MISSING FROM THE AFT CRANKSHAFT GEAR DISENGAGED THE CRANKSHAFT FROM THE AFT CAMSHAFT GEAR BREAKING ENGINE CONTINUITY. THE ENGINE WAS ASSEMBLED ON JULY 14, 1992. RECORDS DID NOT INDICATE THAT A MANUFACTURER SERVICE LETTER DATED SEPTEMBER 13, 1993, WHICH CONTAINED INSTRUCTIONS FOR THE HEX SCREW TIGHTENING PROCEDURES AND TAB WASHER INSTALLATION HAD BEEN ACCOMPLISHED.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: THE LOSS OF ENGINE POWER DUE TO INADEQUATE MAINTENANCE ADJUSTMENT OF ACCESSORY DRIVE STARTER GEAR SCREWS WHICH DISENGAGED IN FLIGHT. FACTORS WERE THE LACK OF SUITABLE TERRAIN FOR THE FORCED LANDING AND NON COMPLIANCE WITH THE APPLICABLE SERVICE LETTER. Full narrative available
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