‘Fault on North Sea helicopter before fatal crash’

However, records show they spent only ten minutes carrying out checks on the aircraft the previous day, a timeframe that “did not seem feasible”, according to solicitor advocate Tom Marshall.

The evidence to the fatal accident inquiry (FAI) in Aberdeen echoed the findings of an Air Accidents Investigation Branch (AAIB) report in 2009, which said confusion, mistakes and miscommunication had been to blame for a faulty gearbox not being replaced prior to the crash.

The FAI heard the helicopter’s “health and usage monitoring systems” (Hums) had flagged up a potential mechanical problem with the Bond-operated aircraft exactly one week before the disaster. A metal particle had been found on a “chip” detector in the gearbox on the same date.

The Eurocopter AS332-L2 suffered a catastrophic gearbox failure as it was flying 14 oil workers back from the Miller platform to Aberdeen on 1 April, 2009. It crashed into the sea off Peterhead, killing all 16 men on board, including two pilots.

Yesterday, the inquiry into their deaths heard Bond offshore helicopter engineers had uncovered two problems with the aircraft on 25 March.

Bond’s then director of engineering, James Gilmour, 57, said staff contacted specialists from the manufacturer, Eurocopter, when the problem arose.

He told the FAI: “At the time, their main concern was the Hums alert that was flagged up. They actually thought the Hums problem was a serious problem with the bevel gear.

“The Hums specialists then contacted the dynamics department within Eurocopter, seeking advice.

“Normally, we would deal with that in-house but, because this was seen as a serious problem, we decided to seek advice from the specialists.”

The inquiry heard the Hums alert was later identified as an avionics problem – an issue with the aircraft’s electrical system.

Relatives of the victims watched as photographs of damaged parts retrieved from the aircraft were shown to the inquiry.

They were told that plates and magnets designed to stop debris contaminating the main module of the gearbox had never been recovered from the sea.

The magnets, which picked up metallic particles, were included in the gearbox designs of only the two most recent Super Pumas models – the AS33-L2 and the EC225.

Air accident investigators warned helicopter operators two weeks after the tragedy that the magnets should be removed from gearboxes.

The inquiry heard technical logs suggested checks carried out on the helicopter took only ten minutes – less time than it should take just to shut down the aircraft and start it up again.

Mr Gilmour said there appeared to be an “anomaly” in paperwork relating to maintenance carried out on the aircraft the day before the fatal crash.

But he insisted the company had enough staff on shift on 31 March to carry out the required work.

The inquiry was shown technical logs demonstrating that checks carried out on the helicopter that day were completed between 9:30am and 9:40am.

Mr Marshall, representing many of the families of those who died, said the timeframe “did not seem feasible”.

Mr Gilmour told the FAI that in those ten minutes, an additional recurrent inspection would have needed to be carried out, the aircraft would have to be refuelled with 1,140kg of fuel and a pre-flight inspection would have been required.

He said he did not believe ten minutes was long enough for all the work to be carried out.

“It would take longer to shut down and start up the aircraft, and the window for refuelling doesn’t seem right to me,” he said. “I would have thought you would at least need 15 minutes.

“Sometimes, we do have incorrect times we have to rectify. It appears it’s a ten-minute window, but it seems a very small window to do all three tasks.

“There is an anomaly there, I think. Ten minutes seems very tight.”

Sheriff Principal Derek Pyle, who is hearing the inquiry at Aberdeen’s Town House, said a test might need to be carried out to check the time it would take to refuel the aircraft and establish the correct time the engineers had to carry out the work.

Mr Marshall questioned the number of engineers who were on shift the day before the fatal crash. “Four men looking after eight helicopters seems quite a low number,” he said.

But Mr Gilmour said: “With the rosters we have, when the aircraft are actually flying, we have turnaround inspections. I would say that was a good number to have involved in that.

“All they were doing was turnaround inspections, which take between 20 to 50 minutes. From my side, it’s the correct number.”

Maintenance staff were also on call if there was a problem with any aircraft, he added.

The 2009 AAIB report found the aircraft suffered had a “catastrophic failure” of its main rotor gearbox. It said that caused the main rotor on the AS332-L2 to break away and its tail boom was severed from the fuselage.

The FAI is expected to last about six weeks and will examine the circumstances of the crash in order to try to prevent any future tragedy.

The crash claimed the lives of captain and co-pilot Paul Burnham, 31, from Methlick, in Aberdeenshire, and Richard Menzies, 24, from Droitwich Spa, in Worcestershire.

Five men from Aberdeen died – Alex Dallas, 62, James Costello, 24, Stuart Wood, 27, Vernon Elrick, 41, and Brian Barkley, 30 – as did two from Aberdeenshire: Leslie Taylor, 41, from Kintore, and Warren Mitchell, 38, from Oldmeldrum.

The other victims were Raymond Doyle, 57, from Cumbernauld; David Rae, 63, from Dumfries; Gareth Hughes, 53, from Angus; Nairn Ferrier, 40, from Dundee; James Edwards, 33, from Liverpool; Nolan Goble, 34, from Norwich, and Mihails Zuravskis, 39, from Latvia.

Some of the victims’ families have expressed anger that there have been no criminal prosecutions following the crash.

There have also been calls for a full public inquiry into helicopter safety.