Lucas Holis, 24, described how he was with John Cousin on the north tower deck of the bridge when the fitter was struck by part of a crane on 28 April 2016.
A Fatal Accident Inquiry into the death of 62-year-old Mr Cousin got under way at Stirling Sheriff Court yesterday, with relatives of the Northumberland man there to hear the evidence.
Mr Holis, a steel workers ganger from the Czech Republic, told the inquiry the crane in question had been out of use the day before the accident due to a burst hose that was leaking hydraulic oil.
The machine was placed in an exclusion zone and crane company GGR Group was contacted to see about getting it fixed, he said.
On the morning of the accident, Mr Holis said he was sent to collect GGR fitter Stewart Clark by boat to bring him out to the bridge and repair the machine.
The witness said that while working on the crane Mr Clark had lowered the boom, causing the oil to leak “more and more” and as a result he went to fetch absorbent granules.
Mr Holis said the two men were joined by Mr Cousin, whom he had met a few times, who had come over “to have a look probably”.
“Normally when something happens we help each other out, we help out to get a job done,” he said. The two men were “just guys talking to each other and laughing,” he recalled.
He said he was spreading the absorbent granules behind the crane when “I heard the noise, I heard steel on steel, when it starts scraping. I heard the noise and just turned around.”
At the time he said Mr Clark was on the middle of the crane while Mr Cousin was somewhere at the front of the boom holding his hands up.”It fell over on him,” he told the inquiry.
“I think (Mr Clark) was still on the crane. I asked him if he’s alright and he answered. I saw John Cousin lying there on the deck and I just ran to him straight away.”
Mr Holis, a first aider, agreed the fitter had “very clear injuries” and put him in the recovery position. “I just shouted for help. I could see the blood and everything, I just shouted for help.”
The crane’s fly jib was on the ground but he did not see how it had become detached, he told the inquiry.
The witness said the injured man was evacuated from the bridge by boat.
The inquiry, before Sheriff William Gilchrist, was adjourned continues today.
Construction of the £1.3 billion new bridge across the Forth began in 2011 and it was officially opened by the Queen in September.