The Australian Transport Safety Bureau is continuing to investigate the cause of a Robinson R44 crash that killed one person in February this year, with fuel supply one of the factors being called into question.
The helicopter crashed on 28 February at King River, in the Northern Territory’s West Arnhem Land, with one pilot onboard, and a second who had been suspended below the helicopter in a harness, during a crocodile egg retrieval mission.
The aircraft was one of three that had been sent out on the morning of 28 February to collect crocodile eggs, with the crew of the remaining two helicopters being the first to flag concerns after a period of no communication from their teammates.
“Crew members of the other two helicopters became concerned when they had not heard any radio communications from the third helicopter,” ATSB director transport safety Stuart Macleod said.
One of the other helicopters ultimately found the wreckage of the R44 approximately 90 minutes after it crashed.
The harnessed passenger was found deceased while the pilot onboard was found alive, though critically injured.
In its preliminary report into the incident, the ATSB noted that the aircraft’s engine had cut out prior to impacting the ground, and just 250 millilitres of fuel was able to be drained from the helicopter’s main fuel tank after the crash.
The bureau did, however, note that fuel could have escaped from the fuel tank in the immediate aftermath of the impact, and the cause of the crash is still in question.
“Preliminary analysis of the site by ATSB investigators indicated the accident sequence had occurred while the helicopter was travelling in a north-west direction, shortly after it left the staging area,” Macleod said.
“Initial assessment indicated the engine had stopped prior to the helicopter colliding with the ground.”
There was no visible damage to the tail rotor blades and drive system and flight control continuity was established, the ATSB said.
An examination of the engine and associated components found no defects likely to result in engine stoppage. The helicopter’s two fuel bladder tanks were intact despite breaches of the surrounding metal tanks, and there was no fire.
“After initial assessment, the wreckage was removed from the site, and ATSB investigators drained about 250 ml of fuel from the main tank’s bladder,” the ATSB said in a statement.
“It was possible fuel escaped into the creek that flowed beneath the wreckage as the fuel system was compromised in the accident.
“This preliminary report details factual information established in the investigation’s early evidence collection phase, and as such does not detail analysis or findings, which will be outlined in the investigation’s final report,” Macleod added.
“As the investigation progresses, the ATSB will include review and examine of electronic components retrieved from the accident site.
“Fuel system components, refuelling practices and fuel quality will also be reviewed and examined, as well as relevant maintenance records, operational documentation and regulations.”
Survivability aspects of the accident will also be considered, the ATSB noted.