Wreckage of the seaplane being pulled from the river. Photo / AAP
Wreckage of the seaplane being pulled from the river. Photo / AAP
A seaplane that crashed into a river north of Sydney on New Year's Eve suffered "severe damage" when it struck the water, authorities have said after recovering most of the wreckage.
The shredded fuselage, one mangled wing and the floats of the DHC-2 Beaver have been hauled onto a barge in Jerusalem Bay during a day-long retrieval operation which used slings and a crane.
"From the time the wreckage was brought on the barge, we saw that there was severe damage to the plane, and it appeared there'd been quite an impact on hitting the water," Detective Superintendent Mark Hutchings told reporters on Thursday afternoon.
Police divers - working in zero visibility at a depth of almost 15 metres - and barge operators are still retrieving the final pieces of the plane that crashed on December 31 killing five British tourists and the Canadian pilot.
The Beaver is a Canadian-built aircraft and the Australian Transport Safety Bureau says their Canadian counterparts will assist during the 12-month investigation into Sunday's crash.
"They have significant experience in investigating incidents with this type of aircraft," ATSB executive director Nat Nagy told reporters.
The first pictures have emerged showing the wreckage of the seaplane that crashed into a river north of Sydney. Photo / AAP
"That will be definitely of help to us in the course of our investigation."
The wreckage of the Beaver will be taken by barge to Bayview where it will be placed on a truck and taken to a secure facility to be examined by bureau investigators.
They'll "carefully assess all aspects related to the aircraft's airworthiness", a spokeswoman said in a statement, adding the bureau would "examine in detail the history of this aircraft".
Experienced Canadian pilot Gareth Morgan died along with high-profile UK businessman Richard Cousins, his two adult sons Edward and William, his fiancee Emma Bowden and her 11-year-old daughter Heather when the plane plunged into Jerusalem Bay on the Hawkesbury River.
It was revealed on Thursday the plane was previously involved in another fatal incident in November 1996.
The Beaver was being used as a crop duster near Armidale when its left wing hit the ground causing the plane to cartwheel and crash, killing the pilot, a safety bureau report states.
It was rebuilt and has since been owned by several businesses including, most recently, Sydney Seaplanes.
Civil Aviation Safety Authority spokeswoman Peter Gibson told AAP the plane was repaired according to the manufacturer's specifications and checked by qualified engineers.
In addition to recovering the plane police are investigating the cause of the crash. Photo / AAP
"They submitted the paperwork and it was re-registered and away it went again," Gibson said on Thursday.
The ATSB is working to determine why the seaplane went down on New Year's Eve.
One possibility is the plane stalled.
CASA has confirmed the Beaver didn't have a stall warning system but also notes they aren't required in Australia.
A Canadian report, published in September 2017 following a fatal crash involving a DHC-2 Beaver in Quebec two years earlier, recommended that warning systems be made mandatory.
But Australian aircraft maintenance engineer Michael Greenhill told AAP this week "even if the Beaver (that crashed in NSW) had this system fitted there's a large possibility there would have been insufficient time to rectify the situation due to the low altitude and approaching terrain".
An ATSB preliminary report is expected to be ready by the end of January.
A more comprehensive report will take a 12 months to complete.
