Investigators from the Australian Transport Safety Bureau (ATSB) have determined a lack of fuel caused the engine on a Robinson R44 to stop moments before it crashed into terrain near the King River in the NT.
R44 VH-IDW was being flown on a crocodile egg collection mission in February 2022 when the engine stopped, prompting the pilot to begin auto-rotation and release the human cargo on the end of a 100-ft line. The collector on the sling died in the fall and the pilot was substantially injured when the aircraft impacted the ground.
Effective auto-rotation proved difficult because too much forward energy had been lost from the rotors.
The helicopter departed Noonamah near Darwin at 0703 that morning with a plan to refuel at Mount Borradaile en route to the King River. According to the ATSB, the pilot did not refuel the helicopter as planned.
Also, the sling was released at a height above ground that is normally considered not survivable for the human cargo in the case of a fall or release.
“Based on an analysis of fuel samples and other evidence, the ATSB investigation found that the helicopter was likely not refueled at a fuel depot about three quarters of the way between Darwin and the crocodile egg collecting area, and that the pilot did not identify the reducing fuel state before the helicopter’s engine stopped due to fuel exhaustion,” said ATSB Chief Commissioner Angus Mitchell.
“As such, this accident illustrates the importance of effective fuel management, which is especially critical when operating a helicopter where a fuel-related power loss offers few safe options.”
The investigation found that the operator was not using its safety management system to systematically identify and manage operational hazards.
“As a result, the operator did not adequately address the risks inherent in conducting human sling operations, such as carriage of the egg collector above a survivable fall height,” Mitchell said.
The operator had a CASA approval for egg collection, but according to the ATSB, the authorisation was inadequate.
“The ATSB found that CASA did not have an effective process for assuring an authorisation–the instrument issued to the operator–would be unlikely to adversely affect safety,” Mitchell said.
As a result, the ATSB could not find evidence that CASA delegates used the available structured risk management process to identify and assess risks, which resulted in CASA removing the instrument’s mitigating conditions limiting the height, speed and exposure for the sling person.
CASA responded to the finding, stating that action had since been taken over the approval process.
"Specialised operations with external loads such as powerline inspection, aerial firefighting, and search and rescue require diligent compliance with safety procedures," a CASA statement says. "CASA assesses applications from operators and considers the actions that they will take to mitigate the identified risks prior to approving any activity.
"The report also made a finding that CASA could have better documented our decision making, and the internal risk management methodology we use when considering applications from operators. That finding has now been addressed and closed.
"CASA’s assessment on the reliability of the helicopter hook led to a height limitation being imposed. Once the hook was assessed and approved, the height restriction was removed."
In the statement, CASA CEO Pip Spence zeroed-in on the fuel exhaustion issue.
"Fuel management is a critical part of flight planning and something that all pilots know and learn early in their training," she said.
"We encourage pilots to refresh their skills on effective fuel management by either attending one of our aviation safety seminars or by using the resources we have available on our pilot safety hub.
"We also encourage operators conducting specialised operations to ensure they understand the procedures in place to manage the safety risks and follow them diligently."
The full report is on the ATSB website.