NTSB Identification: FTW90LA102.
The docket is stored on NTSB microfiche number 42270.
Nonscheduled 14 CFR
Accident occurred Friday, April 27, 1990 in TULSA, OK
Probable Cause Approval Date: 01/23/1992
Aircraft: PIPER PA-32-260, registration: N7732J
Injuries: 1 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.

WHILE ON FINAL, THE ENGINE QUIT WITHOUT WARNING AND THE PILOT WAS FORCED TO EXECUTE A FORCED LANDING INTO A HEAVILY WOODED BIRD SANCTUARY. EXAMINATION OF THE ENGINE REVEALED THAT THE CRANKSHAFT GEAR ATTACHMENT BOLT WAS LOOSE WITH 0.196 INCHES OF PLAY AND THE DOWEL PIN WAS SHEARED. GEAR INSTALLATION INSTRUCTIONS CALLED FOR THE GEAR TO BE SEATED WITH A DRIFT AND HAMMER WITH NO MORE THAN 0.001 INCHES OF CLEARANCE. OTHERWISE, THE DOWEL PIN WOULD BE OFFSET AND WORK. BOTH THE BOLT AND THE DOWEL PIN SHOWED EVIDENCE OF WORKING. SHEARING OF THE CRANKSHAFT DOWEL PIN WOULD HAVE RELEASED THE GEAR TO ROTATE ABOUT THE BOLT, THUS DISCONNECTING THE GEAR AND THE IDLER GEARS WHICH TRANSMITTED TORQUE TO THE MAGNETOS. SECONDARY DAMAGE WAS OBSERVED IN THE LEFT MAGNETO. MAINTENANCE RECORDS INDICATED THAT THE ENGINE HAD BEEN OVERHAULED 88.7 HOURS PRIOR TO THE ACCIDENT.

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

AN ENGINE FAILURE DUE TO A DISCONNECT IN THE MAGNETO DRIVE TRAIN CAUSED BY THE CRANKSHAFT GEAR NOT BEING PROPERLY INSTALLED AND SECURED DURING A RECENT ENGINE OVERHAUL.

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