NTSB Identification: LAX86FVA11.
The docket is stored on NTSB microfiche number 34482.
Accident occurred Tuesday, July 08, 1986 in PORTERVILLE, CA
Probable Cause Approval Date: 03/10/1988
Aircraft: BELL 47G-5, registration: N1316X
Injuries: 1 Serious,2 Uninjured.

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.

DURING AN AERIAL APPLICATION FLIGHT THE PLT LOST CONTROL OF THE HELICOPTER AND COLLIDED WITH A BUILDING. EXAMINATION REVEALED THAT THE INSIDE DIAMETER OF THE TAIL ROTOR DRIVESHAFT WAS NOT COATED WITH ALUMINIZED LACQUER AS REQUIRED BY THE BELL FINISH PROCESS SPECIFICATION. THE BELL DRAWING REQUIRES TWO #2 SHORT PLUGS TO BE INSTALLED AT A SPECIFIED DISTANCE FROM EACH END OF THE TAIL ROTOR DRIVESHAFT AND THE END OF THE SHAFT TO BE SEALED OFF WITH ADHESIVE TO PROTECT THE SHAFT INSIDE DIAMETER FROM CORROSION. A DIMENSIONAL CHECK OF THE SHAFT REVEALED THAT THE PLUGS WERE NOT INSTALLED AT THE CORRECT DISTANCE FROM THE END OF THE SHAFT AS SPECIFIED IN THE DRAWING.

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

ROTOR DRIVE SYSTEM,TAIL ROTOR DRIVE SHAFT..FAILURE,TOTAL


Contributing Factors

OBJECT..BUILDING(NONRESIDENTIAL)


Contributing Factors

ROTOR DRIVE SYSTEM,TAIL ROTOR DRIVE SHAFT..CORRODED


Contributing Factors

ROTOR DRIVE SYSTEM,TAIL ROTOR DRIVE SHAFT..UNAPPROVED PART

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