The ATSB has released the final report from its investigation into a fatal R22 helicopter mustering accident at Limbunya Station, near the NT-Western Australia border, on 27 June 2023.
The helicopter was one of two Robinson R22s mustering cattle when the pilot of the second helicopter reported not hearing from the other for some time.
The wreckage of the helicopter was located after a short search, and the pilot was fatally injured.
ATSB transport safety investigators deployed to the accident site, a flat and moderately wooded area, and determined that the helicopter impacted terrain in a nose-down, right side low attitude. However, there were no witnesses to the accident and no recorded data to accurately determine the accident sequence.
"The site and wreckage signatures were consistent with the helicopter being in a low rotor energy state with low-to-nil engine power," Director Transport Safety Kerri Hughes said.
"Investigators were able to confirm continuity of the flight controls prior to the accident, while an examination of the helicopter's engine found no damage or defects that may have affected its pre-accident operation."
Ms Hughes noted that the investigation considered the possibility of the pilot experiencing some level of incapacitation, which could have explained the low rotor energy and/or helicopter trajectory into terrain. However, after a review of the pilot's medical history and post-mortem examination results there was insufficient evidence to determine if the pilot experienced an incapacitation event.
"Therefore, in the absence of an identified problem with the helicopter and having considered other plausible explanations, the reason for the engine reduction and loss of control could not be determined.
"This accident is a reminder of the complexities of low-level flight where there is reduced time to respond to emergencies and a reduced likelihood of finding a suitable forced landing area," Ms Hughes noted.
While not found to have contributed to the accident, the ATSB's investigation also identified that the helicopter's maintenance release contained no endorsements for daily inspection certification, hours flown, total time-in-service, or engine oil uplift.
"This was despite the helicopter being operated every day since the maintenance release was issued 13 days earlier," Ms Hughes said.
"Aircraft owners and pilots should ensure maintenance releases are updated at the end of each day's flying, to ensure pilots can be aware of the operational status of the aircraft, and avoid unintentional flight beyond maintenance."
You can find here the report: Collision with terrain involving Robinson R22 Beta II, VH-PSC, near Limbunya Station, Northern Territory, on 27 June 2023
