Introduction
On 4 July 2020, a Robinson R44 Raven I helicopter, registered VH-NBY, departed from an industrial property 3 km north of Broome Airport, Western Australia, for a private local flight. On board were the pilot and three passengers.
Sequence of Events
The pilot performed a vertical departure to clear obstacles before transitioning to forward flight. Witnesses then heard a loud bang, and the empennage and tail rotor system separated from the helicopter. The helicopter initially continued climbing and began rotating to the right with increasing angular velocity. Control was lost, and the helicopter collided with terrain on its right side in a nose-low attitude. The pilot and the passenger seated on the right side were fatally injured; the two passengers on the left side were seriously injured. The helicopter was destroyed.
Investigation Findings
Examination revealed an overstress fracture of the attachment lugs of the tail rotor gearbox input cartridge. The source of the loading that caused the fracture was not conclusively determined. However, shortly after takeoff, this led to the separation of the tail rotor gearbox from the helicopter. Subsequently, the aft tail cone bulkhead fractured, and all attached components, including the horizontal and vertical stabilisers, separated.
The pilot did not apply the pilot's operating handbook procedure for responding to a tail rotor emergency. Prompt application would have reduced the likelihood of loss of control and improved survivability. The pilot's response may have been influenced by not having a valid flight review for the helicopter type at the time of the accident.
Vibration in the tail rotor pedals had been reported during the previous two flights. Maintenance personnel conducted ground running and found no fault. However, since the vibration was reported only in flight and no defect was identified, it was reasonable to conclude the problem might still be present. The manufacturer recommended a graduated flight check by a solo pilot as the safest next step. Instead, the next flight involved a high-power towering take-off from a confined area with three passengers. The unnecessary carriage of passengers resulted in a significantly more severe outcome after the in-flight breakup.
Safety Messages
The pilot's operating handbook states that the onset of unusual vibrations can indicate impending failure of a critical component. Pilots should land as soon as possible and formally declare the helicopter unserviceable. The helicopter should not be returned to service until the vibration source is identified and rectified.
The registered operator bears ultimate responsibility for airworthiness. This accident highlights the importance of a conservative troubleshooting process that minimises risk. Tools for managing airworthiness are published by the Civil Aviation Safety Authority, including proper use of the maintenance release to communicate aircraft status.
Private pilots lack the regular flying and frequent training of commercial pilots. It is recommended that private pilots assess their risk profile and seek opportunities to maintain and develop skills with a flight instructor, rather than relying solely on minimum training and currency requirements.