NTSB Identification: ATL89LA064.
The docket is stored on NTSB microfiche number 38404.
Accident occurred Friday, December 30, 1988 in PERDIDO, AL
Probable Cause Approval Date: 01/04/1990
Aircraft: MOONEY M20F, registration: N6969V
Injuries: 4 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.

WHILE DESCENDING TO 6000 FEET THE PILOT EXPERIENCED A COMPLETE LOSS OF ENGINE OIL SUPPLY. THE WINDSCREEN WAS COVERED WITH OIL AND THE PILOT HAD TO USE THE SIDE WINDOW TO GAIN FORWARD VISIBILITY. AFTER COMPLETING THE EMERGENCY LANDING CHECK THE ENGINE SEIZED. AN EMERGENCY LANDING AREA WAS SELECTED. THE AIRPLANE COLLIDED WITH A TREE ABOUT 10 FEET ABOVE THE GROUND. THE AIRPLANE CONTINUED ABOUT 200 FEET BEFORE COMING TO A STOP IN AN UPRIGHT POSITION. THE POST CRASH EXAMINATION INDICATED THAT THE PROPELLER ASSEMBLY HAD SEPARATED FROM THE ENGINE PROPELLER SHAFT. THE FRACTURE ANALYSIS OF THE BOLTS DISCLOSED THAT FOUR BOLTS FAILED IN FATIGUE. THE PROPELLER WAS OVERHAULED ABOUT 12 HOURS BEFORE THE MISHAP. THE OVERHAUL FACILITY REUSED THE OLD BOLTS AFTER MAGNA-FLUX AND PLATING. THE INSTALLATION TORQUE WAS NOT DETERMINED.

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

PROPELLER SYSTEM/ACCESSORIES,PROP BLADE RETENTION..FATIGUE


Contributing Factors

WINDOW,FLIGHT COMPARTMENT WINDOW/WINDSHIELD..CONTAMINATION



Contributing Factors

MAINTENANCE,MAJOR REPAIR..IMPROPER..OTHER MAINTENANCE PERSONNEL



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