Pilot Debrief

BELL 206 near Galliano, LA — 2009-03-02

Final reportCEN09LA198
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Date
2009-03-02
Location
Galliano, LA, USA
Airport
GAO
Aircraft
BELL 206
Registration
N410RL
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Ground

Probable cause

The failure of the tail rotor driveshaft and coupling during engine start due to the mechanic's failure to properly reattach the tail rotor driveshaft and coupling during maintenance.

NTSB narrative

The commercial pilot was starting the single-engine helicopter's engine when he heard a loud bang and vibration. He immediately shut down the engine and exited the helicopter. Examination of the helicopter revealed that the tail rotor driveshaft and coupling had severed just forward of the gearbox, which resulted in substantial damage to the tail boom. The helicopter had undergone recent maintenance to the tail rotor gearbox input seal which included the removal of the tail rotor drive shaft from the coupling. When the two components were reattached, the mechanic only hand-tightened the bolts, figuring additional maintenance was still planned for the gearbox. He then installed the tail rotor drive shaft shaft cover. The mechanic moved on to another project and did not make a logbook entry of the work that he had completed or that the bolts were only hand-tightened. Another mechanic later performed additional maintenance to the gearbox, but the bolts were not checked since the maintenance manual did not require the removal of the tail rotor driveshaft cover. A .2-hour maintenance flight check was conducted and the helicopter was returned to service. The accident occurred on first engine start after it had been returned to service.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Mechanic should have properly tightened bolts before returning helicopter to service.

NTSB coding

Evidence available

  • 3 docket documents
View NTSB final reportView NTSB docket

Docket documents3

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