Safety concerns see 60% of North Sea's Super Pumas left grounded SIXTY per cent of the North Sea's entire Super Puma fleet is to remain grounded indefinitely because of renewed safety concerns about the aircraft following Monday's dramatic ditching in the seas off Shetland, it was announced last night. The ban on fights will apply to all 16 EC225s - the model involved in the controlled ditchings since May of this year - and a number of the earlier versions of the Super Puma fitted with the same suspect gearbox component now linked to both major emergencies, The decision to impose the indefinite flight suspension, which could last for weeks, was welcomed by offshore union leaders who are calling for a flight ban until the source of a "potentially catastrophic design fault" can be identified in the wake of Monday's latest ditching of a Super Puma, operated by CHC helicopters. Read the AAIB's report here Concerns about the safety integrity of the Super Puma, manufactured by French aviation company Eurocopter,have intensified following the publication of special bulletin by the Government's Air Accident Investigation Branch which found that the ditching of the CHC-operated Super Puma EC225 was caused by a serious mechanical failure in the gear box of the North Sea workhorse. The failure is identical to the fault found in a Bond-operated Super Puma which ditched in the North Sea off Aberdeen in May In both incidents the main vertical gear shaft had suffered a complete 360 degree crack near a weld that joins two sections of the shaft. It was claimed six months ago that the faulty gearbox had been traced to a batch of only ten spare parts, one of which was supplied to Bond and used in the downed aircraft. But helicopter industry sources have told that the Scotsman that the gearbox at the centre of the latest ditching involving the CHC Super Puma was not included in the batch at the centre of the safety alert in May - a claim which has now been confirmed by Eurocopter.. Jake Molloy, the offshore organiser of the RMT union ,called for every Super Pima being used in North Sea crew change flights to to be suspended until assurances can be given to workers about the fundamental safety of the aircraft. A total of 86 helicopters of various types are used in the North Sea. Sixteen are EC225s and 13 are the earlier L2 version of the aircraft. Mr Molloy said: "We are deeply concerned. We were given assurances in May by Eurocopter that a manufacturing fault was associated with very small batch of shafts and that none of those were now in use. Less than six months later exactly the same situation has happened again with a completely different shaft on an aircraft that was never on the list of those with a manufacturing fault. And that, to my mind, means we cannot be confident about any aircraft which has this type of vertical shaft in it. Eurocopter assured us that this was manufacturing fault related to one specific batch. It now appears - on the face of it at least - that this is potentially a design fault and the blame lies fairly and squarely at the door of Eurocopter. He said that Monday's ditching could have ended in catastrophe. And Mr Molloy continued: "We don't want workers to be exposed to what is clealy now an inherent danger and could have ended in fatalities. It was only by the Grace of God that we had good weather when the Super Puma ditched. Richard Toome spokesman for BALPA, the pilots" union, also voiced his concerns about the latest revelations. He declared: "There is now growing concerns amongst pilots of the safety of this helicopter, as there is amongst the oil and gas workers who regularly fly in it. Whatever action has been put in place has clearly not been sufficient if the AAIB's initial investigation proves to be correct Derek Sharples, Eurocopter's executive vice president in charge of support, confirmed that the CHC-operated Super Puma involved in Monday's emergency had not been include on the list of aircraft affected by the safety alert related to the May ditching. Mr Sharples said there was no "obvious" reason why there had been two ditchings involving Super Pumas since May - "At this stage I frankly think it was an unfortunate coincident." And he refuted the union claims that a potential design fault was to blame for the incidents. Said Mr Sharples: "We are fully confident in the safety of the product. It is safe by design. There is no fundamental design flaw -neither in the aircraft nor the procedures which apply to the aircraft. My message to the passengers and the crew of these aircraft is that Eurocopter will not compromise on your safety. You can be confident in the aircraft. It is designed to be safe.