On May 15, 1983, a Bell 47G (registration N739B) operated by James T Lewis was involved in an aviation accident near Zachary, LA. No fatalities were reported. Investigators recorded the probable cause as: The tail rotor gearbox studs failed due to fatigue. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a practice autorotation, the tail rotor gearbox separated, causing a rapid spin and crash. The occupants escaped. Investigation found fatigue failure of gearbox studs.
Incident Narrative
During a practice autorotation, the tail rotor gearbox separated from the aircraft. Following the separation, the aircraft began to spin rapidly, and the nose pitched down. The pilot increased power, which raised the nose but caused the rotation speed to increase. The aircraft subsequently struck the ground on a single skid while still rotating rapidly. The occupants were able to exit the wreckage and crawl away from the site.
Investigation Findings
The tail rotor gearbox was located approximately 100 yards from the main wreckage. An examination of the gearbox revealed that the mounting studs had failed due to fatigue. No other mechanical issues were reported.
Probable cause
The tail rotor gearbox studs failed due to fatigue.
What happened in the 15 May 1983 Bell 47G accident near Zachary, LA?
During a practice autorotation, the tail rotor gearbox separated, causing a rapid spin and crash. The occupants escaped. Investigation found fatigue failure of gearbox studs.
Were there any fatalities in the 15 May 1983 Bell 47G accident?
No fatalities were recorded in this accident.
What aircraft was involved and where did it happen?
The accident on 15 May 1983 involved a Bell 47G, registration N739B, operated by James T Lewis, at Zachary, LA.
What was the probable cause of the accident?
The tail rotor gearbox studs failed due to fatigue.
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