The search for a helicopter that crashed off Queensland's Whitsunday Islands killing two American tourists has been called off, with authorities unable to find it.
Honeymooners Peter and Sue Hensel died when the Eurocopter 120 crashed into water 250 metres from Hardy Reef Pontoon.
They were pulled from the wreckage by the pilot and another passenger but died at the scene.
The Australian Transport Safety Bureau says the helicopter sank in about 60 metres of water near Hardy Reef but a cyclone soon after hampered search efforts.
Recovery operations by Queensland police and a salvage company in the two months following the crash failed to find the helicopter, the ATSB said on Wednesday.
The bureau believes the wreckage may have spread across a vast area.
"Personal belongings of one of the passengers were recovered from a beach at Cape Flattery ... about 660 km northwest from Hardy Reef," it said.
"This further demonstrated to the ATSB the potential distribution of the wreckage."
The ATSB said given the length of time the aircraft had spent in the salt water any evidence that could be collected would be of little use.
A preliminary investigation by the ATSB found that as the helicopter approached the pontoon the pilot noticed a warning light before feeling a thud through the aircraft.
The nose of the helicopter then pulled sharply left causing the pilot to make a number of manoeuvres to regain control, the bureau said.
However the pilot was unable to control the aircraft and it crashed into the water before rolling onto its right side.
A 34-year-old man and a 33-year-old woman, along with the pilot survived the crash.
The investigation continues.