WorkSafe has released its findings into a one-tonne eagle that fell down on the food court in a 2014 earthquake.

A list of failings led to a "rigorously engineered" one-tonne eagle falling down on the Wellington Airport food court.

WorkSafe NZ has released its investigation report into the incident, which happened when a 6.2 magnitude quake hit the lower North Island in January last year.

The sculpture, and another one like it, were unveiled with fanfare by Weta Workshop boss Sir Richard Taylor just a month before it came down, ahead of the second instalment in The Hobbit trilogy.

The WorkSafe report lists a number of engineering failures and says that while engineers Dunning Thornton Consultants (DTC) did not beyond reasonable doubt breach the health and safety act it had laid a complaint with the Institute of Professional Engineers (IPENZ) against a DTC engineer.

An IPENZ spokesman confirmed an investigation was underway.

Dunning Thornton refutes most of the findings because its scope was limited to "specific items" and Weta Workshop was in charge.

The report, released under the Official Information Act, shows that in order to get a clear picture of what went wrong, investigators did an "experimental reconstruction" of the eagle's suspension.

They found that wire loads were calculated "significantly in error" and four of the nine suspension wires were below safety levels.

A wire rope "integral to the calculations" was dispensed with during installation.

Because the one-tonne eagle was described as an "artwork" it did not need a building consent.

Jack Mains, a chartered professional engineer brought in to review the failings, said Wellington City Council appeared "far too relaxed about the concept of large suspended objects over public spaces" when it said building consent was not needed.

"From a major structural engineering consultancy's perspective, this project would have been considered a little job," Mains said.

"It is quite likely it did not get the allocation of resources needed to do it properly."

A Wellington City Council spokesman said it considered an application for exemption of building consent carefully.

"We ensure, as part of that, it is being dealt with by suitably qualified professionals as the case may be.

"This structure was installed via an exemption with the understanding it would be fully designed and supervised by engineers.

"It's not unusual for this type of installation to be given an exemption, where we would rely more on the expert opinion of engineers who deal with these types of structures."

The WorkSafe report also found that Weta Workshop, which made the eagle, had used a crimping tool that was out of adjustment. All nine failed suspension wires were crimped using the tool.

Tests were done on the crimps showing they had breaking strengths of 800 kilograms but when DTC was told this a director of the engineering firm told Weta "that should be okay", the report says.

This was listed by WorkSafe as another reason for the failure.

Airport infrastructure general manager Geoff Eban said the airport had worked closely with WorkSafe and supported the findings.

"The safety of the travelling public is paramount and we have gone to considerable lengths to ensure that these installations are safe and secure for people to enjoy."

After the one-tonne eagle came down, airport spokesman Greg Thomas said it was "rigorously" engineered and should not have fallen down in the quake, which was far from the biggest it should have been able to withstand, he said.

Weta Workshop General Manager David Wilks said the public should be confident the popular sculpture is safe.

"Together with Wellington Airport and our partners we have put a lot of effort in to re-engineering these installations to give the public every confidence in them," he said.