Early investigations into a helicopter crash that killed Northern Territory crocodile wrangler Chris "Willow" Wilson indicate the aircraft's engine stopped before the chopper hit the ground.
However, the Australian Transport Safety Bureau's (ATSB) examination of the engine found there were no defects likely to result in engine failure at the time.
The bureau's preliminary report, released on Tuesday, is part of an ongoing investigation into the circumstances surrounding Mr Wilson's tragic death on February 28.
Mr Wilson, a cast member of National Geographic's Top End adventure show Outback Wrangler, was on a job collecting crocodile eggs in King River, west of Maningrida, when the chopper crashed.
The 34-year-old father, who was attached to a sling, was found fatally injured about 40 metres from the main wreckage, according to the report.
The helicopter pilot, Sebastian Robinson, 28, was airlifted to hospital about two hours later with serious injuries.
The bureau's report said the aircraft was one of three Robinson R44 helicopters conducting crocodile egg collection in the area, where a 'sling person' is strapped into a harness attached to a 30-metre long line to access crocodile nests.
At about 9am, the other two helicopters left the landing zone to start collecting eggs about 12km to the north-east.
"Crew members of the other two helicopters became concerned when they had not heard any radio communications from the third helicopter," ATSB director of transport safety Stuart Macleod said.
At about 10:30am, one of the pilots returned to the area to investigate and found the wreckage at a paperbark swamp, about 300 metres from the group's landing zone.
The sling's long line attachment rings were not connected to the helicopter's cargo hooks, and the pilot was found lying beside the aircraft.
No eggs had been collected, indicating the accident likely happened about 90 minutes before the wreckage was found, according to the report.
Chopper crashed shortly after take-off
Mr Macleod said early analysis of the crash site suggested the accident happened while the helicopter was travelling in a north-west direction, shortly after it left the landing zone.
"Initial assessment indicated the engine had stopped prior to the helicopter colliding with the ground," Mr Macleod said.
The helicopter's two fuel bladder tanks were found intact, despite damage to the surrounding metal tanks.
However, the helicopter's main rotor blade had struck and cut through the trunk of at least one tree at several points before the aircraft collided with terrain in an upright position.
The base of the pilot's seat had crushed to absorb the impact.
The helicopter's emergency locator transmitter and radio beacon were found in the helicopter and had not been activated.
ATSB investigators drained about 250ml of fuel from the main tank's bladder.
The report said fuel may have leaked into the creek that flowed beneath the wreckage, as the fuel system was broken in the accident.
Investigators will continue to examine the parts collected from the accident site, as well as assessing maintenance records, operational documentation and regulations.
The ATSB will release a final report at the end of the investigation.
