| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. |
What happened
On the morning of 8 September 2018, a Bell 206B helicopter departed a caravan park on a private flight with a pilot and three passengers on board. Approximately 30 minutes into the flight, the pilot conducted an orbit around a cleared area intended for landing and completed his landing checks. During late downwind, the pilot reports that the helicopter experienced an uncommanded yaw to the right. To counteract the yaw, the pilot applied left pedal, however the helicopter continued to yaw to the right and subsequently began an uncontrolled descent into trees. As the helicopter entered the trees, the pilot rolled off the throttle and pulled on the collective[1] and the helicopter contacted the ground, resulting in the tail rotor severing. The main rotor also sustained damage from contact with the trees. The pilot and passengers exited the helicopter without injury.
At the time of the accident, the pilot reports that gusty, variable winds were encountered which may have caused a loss of tail rotor effectiveness (LTE),[2] contributing to the accident.
Safety message
There are various factors that can contribute to a loss of tail rotor effectiveness. The NTSB Safety Alert, Loss of Tail Rotor Effectiveness in Helicopters identifies these factors and the subsequent risks associated with LTE.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.
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- Collective: a primary helicopter flight control that simultaneously affects the pitch of all blades of a lifting rotor. Collective input is the main control for vertical velocity.
- In helicopters, loss of tail rotor effectiveness (LTE), or unanticipated yaw, is an uncommanded rapid yaw that does not subside on its own accord.