The Australian Transport Safety Bureau (ATSB) has called on US and European regulators to improve the safety of helicopter fuel systems.
The call comes as the ATSB today released the investigation report into the fatal crash of an R44 at Bulli Tops, NSW, in March 2013.
R44s have been subject to directives that require the standard aluminium fuel tanks to be replaced with bladders. The aluminium tanks have been blamed for several post-crash fires because they tend to split open on impact.
ATSB Chief Commissioner Martin Dolan said the bladder tanks reduce the risk of post-impact fires in R44s, but the ATSB remains concerned that aircraft not yet fitted with the modification remain at risk.
"We believe the US Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA) can help improve the safety of many helicopter pilots and their passengers," he said.
"We have issued safety recommendations to the FAA and EASA. We ask them to take action to increase the number of crash-resistant fuel systems fitted to existing and newly-manufactured helicopters.
"Under international convention, we would expect to hear from the FAA and EASA about their proposed responses to these recommendations by early September 2015."
Robinson R44 VH-HWQ had just landed at a convention centre at Bulli Tops on 21 March 2013 when it became airborne again and drifted towards trees. After the rotor struck branches, the aircraft impacted the ground and rolled over. A fuel fire then prevented bystanders from rescuing the four people on board.
Damage to the helicopter cabin prevented the ATSB from determining why the helicopter became airborne again, but the report suggests is was most likely due to accidental cyclic or collective input.
The full report is available on the ATSB website.