A Sydney company that failed to properly inspect a window-cleaning platform that plummeted 12 storeys to the ground — leaving two workers with permanent disability — has been fined $300,000 by SafeWork NSW.

Key points: The 2015 incident saw two window cleaners working on a platform plummet to the ground

The 2015 incident saw two window cleaners working on a platform plummet to the ground An investigation found a major 10-year inspection of the platform had not been carried out

An investigation found a major 10-year inspection of the platform had not been carried out The two workers, who were lucky to survive, sustained "life-changing" injuries

In an act of negligence described by the judge as one of "objective gravity", Building Maintenance Unit Service Pty Ltd was handed the fine in the NSW District Court this week after an investigation found it failed to carry out a basic inspection of the platform.

David Wilson and Colombian native Edwin Acero-Castellanos were cleaning windows on the platform outside the Australian Stock Exchange building on Pitt Street in October 2015 when it plunged about 30 metres — or 12 storeys — to the ground.

During the 30-metre fall the platform fell onto one side, with Mr Wilson landing on the awning while inside it.

Mr Acero-Castellanos went over the edge of the awning of the platform, saved from hitting the concrete by his safety harness.

The incident drew huge crowds on the streets on Sydney at the time, with Mr Acero-Castellanos yelling out "help me" to city workers, with one passer-by driving his ute underneath his dangling body to create a platform.

A bystander drove his ute underneath Mr Acero-Castellanos to help rescue him. ( AAP: David Moir )

The two survived the incident.

But according to Judge Andrew Scotting its impact has been "life-changing".

Mr Wilson sustained fractures to his right shoulder, right tibia, left knee, ribs, jaw and teeth — which required 30 dental visits to repair — as well as head and spinal injuries and a punctured lung.

The fall caused Mr Acero-Castellanos's spine to fracture, with spinal cord decompression. He also suffered a fractured ankle and a dislocated finger.

In his judgement, Judge Andrew Scotting told the court about Mr Acero-Castellanos's ongoing back pain and how he had suffered "humiliation and depression" following the incident.

"I will not set out the matters he stated in the victim impact statement to save him further embarrassment, but I consider those matters to be substantial and life-changing," Judge Scotting said.

"The incident has placed his family under considerable financial strain."

The platform, which was unique to the building, was due to have a major 10-year inspection worth $2,000 — which Building Maintenance Unit Service was aware of — but it was not carried out.

The platform after the 2015 incident. ( AAP: David Moir )

Building Maintenance Unit Service was engaged by Investa Asset Management — one of Australia's largest office real estate companies — to carry out the maintenance.

An investigation into the incident found it collapsed because the right-hand bolt within the connection box fractured, causing a sudden transfer of load to the left-hand bolt, which then became twisted and also failed.

It found the fracture was the result of extensive cracking in each of the bolts, caused by "recurring cyclical loading of the plant during operation".

"More than one worker was exposed to the risk," Judge Scotting said.

"The risk included a risk of death.

"The means of preventing the risk were simple and inexpensive. The offender (Building Maintenance Unit Service) could have refused to set up the BMU (platform) until it had been properly inspected."

The maximum penalty for the offence was $1.5 million.

Mr Acero-Castellanos on a ute with the crumpled platform above him. ( AAP: David Moir )

Building Maintenance Unit Service ceased trading in December 2017 after it was sold to pay off creditors.

"The directors of the offender gave unchallenged evidence that the offender does not have any other funds or assets," Judge Scotting said.

"I am satisfied that the offender has a limited capacity to pay, but I do not think that this is an appropriate case to exercise my discretion because of the seriousness of the offence and the need for general deterrence."

The ABC contacted the law firm representing the company's insurers. They declined to comment.

The ABC also attempted to contact Mr Acero-Castellanos.