On July 8, 1986, a Bell 47G-5 (registration N1316X) was involved in an aviation accident near Porterville, CA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an aerial application flight, the pilot lost control of the helicopter and collided with a building. Examination revealed the tail rotor driveshaft lacked required coating and plugs were incorrectly installed.
Accident Details
While conducting an aerial application flight, the pilot lost control of the helicopter. The aircraft subsequently collided with a building.
Examination Findings
A post-accident examination of the helicopter's tail rotor driveshaft was performed. The inspection disclosed that the inside diameter of the tail rotor driveshaft was not coated with aluminized lacquer as required by the Bell finish process specification.
Specific Deficiencies
The Bell drawing specifies that two #2 short plugs must be installed at a defined distance from each end of the tail rotor driveshaft. Additionally, the ends of the shaft are to be sealed with adhesive to protect the inside diameter from corrosion. A dimensional check of the shaft revealed that the plugs were not installed at the correct distance from the ends as specified in the drawing.