The Australian Transport Safety Bureau (ATSB) has released its final report on a fatal firefighting helicopter crash in Tasmania’s north in 2022.
The incident, which occurred 36km north of Launceston on February 14, 2022, involved a helicopter supporting the Tasmania Fire Service in fighting the Lebrina bushfire.
In their official report released on Tuesday, the ATSB revealed that their investigation found the engine-to-transmission main KAflex drive shaft had partially failed, likely due to the fracture of a flex frame attaching bolt or a flex frame element during flight.
They said the helicopter collided with the ground in a paddock and was destroyed, resulting in the death of the experienced 41-year-old pilot Andrew Kerr.
distance away from the spot fire (smoke plume). Image / ATSB
“This initial failure resulted in the KAflex entering fail-safe mode, which allows for a short period of continued flight, but necessitates landing as soon as possible,” ATSB Director Transport Safety Stuart Macleod said.
“With the KAflex in fail-safe mode, the pilot jettisoned the water from the underslung bucket and diverted toward clear ground but, while the helicopter was descending, the KAflex failed completely, resulting in instantaneous loss of drive to the rotor system.”
“Following the loss of main rotor drive, the pilot was unable to complete a survivable autorotative descent and landing, probably due to a critical reduction in main rotor speed.”
Macleod said the accident was a reminder to other UH-1H helicopter pilots, operators and maintainers that fatigue cracking can occur in critical flight components.
“Particular vigilance should be applied during the daily or pre-flight inspections of the main transmission driveshaft because it represents an important opportunity to detect for defects such as cracks and to identify evidence of loose or missing attachment hardware,” he said.
