NTSB Identification: ATL82FA092
14 CFR Part 91: General Aviation
Accident occurred Monday, April 05, 1982 in BACONTON, GA
Probable Cause Approval Date: 04/05/1983
Aircraft: PIPER PA-31-350, registration: N123CB
Injuries: 3 Serious,2 Minor.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

AS THE PILOT WAS DESCENDING FROM 7000 TO 5000 FT, HE HEARD A LOUD BANG, FOLLOWED BY A TEMPORARY VIBRATION AND A VIOLENT SWERVE TO THE RIGHT. HE LOOKED OUT THE RIGHT WINDOW AND THOUGHT THE RIGHT ENGINE HAD FALLEN OFF SINCE ALL HE COULD SEE WAS THE TOPS OF THE ENGINE MOUNTS. THE AIRCRAFT WAS CONTROLLABLE ONLY AFTER REDUCING THE LEFT ENGINE POWER TO IDLE. DURING A WHEELS UP/FORCED LANDING, THE PLANE TORE THROUGH A FENCE, SLID ACROSS A PAVED ROAD, WENT OVER AN EMBANKMENT AND BEGAN BURNING AFTER IT CAME TO REST. THE PILOT RECEIVED A BACK INJURY AND HAD DIFFICULTY EGRESSING. AN INVESTIGATION REVEALED THE PROPELLER HUB HAD FAILED FROM FATIGUE WHICH RESULTED IN BLADE SEPARATION AND SUBSEQUENT ENGINE TEARAWAY. THE ENGINE HAD REMAINED ATTACHED TO THE AIRFRAME BY CABLES. METALLURGICAL EXAMINATION OF THE HUB REVEALED THAT THE FATIGUE ORIGINATED AT A THREADED GREASE FITTING. GOUGING WAS VISIBLE ON THE INNER WALL. A SET OF INCORRECT COUNTERWEIGHTS WERE FOUND ON THE PROPELLER. THE COUNTERWEIGHT'S FUNCTION WAS TO REDUCE VIBRATION.

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

PROPELLER SYSTEM/ACCESSORIES,HUB..FATIGUE

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

PROPELLER SYSTEM/ACCESSORIES,BLADE..SEPARATION

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

ENGINE ASSEMBLY..SEPARATION


Contributing Factors

PROPELLER SYSTEM/ACCESSORIES,COUNTERWEIGHT..INCORRECT


Contributing Factors

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


Contributing Factors

PROPELLER SYSTEM/ACCESSORIES..VIBRATION


Contributing Factors

PROPELLER SYSTEM/ACCESSORIES,HUB..OTHER


Contributing Factors

MAINTENANCE..IMPROPER..OTHER MAINTENANCE PERSONNEL



Contributing Factors

OBJECT..FENCE


Contributing Factors

TERRAIN CONDITION..ROUGH/UNEVEN

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