Eurocopter faces the "biggest issue" in its 20-year history, according to its chief executive, as the airframer attempts to deal with the fallout from two related ditchings of EC225s in the North Sea.

Speaking at a Helicopter Safety Steering Group (HSSG) meeting in November, according to minutes seen by Flightglobal, Eurocopter boss Lutz Bertling admitted the UK's oil and gas industry had "lost confidence in the EC225 helicopters and in Eurocopter".

Although the EC225 fleet used for offshore transportation in the oil and gas sector has been grounded in the UK and Norway since October, after rulings by both countries' civil aviation regulators, Bertling says Eurocopter's first priority is not to return the Super Pumas to service, but to "regain confidence in the aircraft, company and solution".

Eurocopter is still attempting to identify the root cause of the cracks in the main gearbox bevel gear shafts that forced the ditchings of helicopters operated by Bond Offshore Helicopters and CHC Scotia in May and October respectively.

Eurocopter chief technical officer Jean-Brice Dumont told the HSSG meeting the company believes the fractures were caused by "resonance" and it has embarked on a flight- and ground-test campaign to verify its hypothesis. Although speculation has focused on the potential need to replace hundreds of the gearbox shafts, Dumont says if its theory is correct, "the fix will lie in the internal operating conditions as opposed to the part itself".

However, helicopter operators and oil and gas companies may need further convincing before regaining their trust in the company. Speaking at the meeting, Richard Mintern, Bond Aviation Group chief executive, said industry should form part of the validation process.

Bertling supported this suggestion and, in addition, offered industry representatives the opportunity to visit Eurocopter's Marignane plant to see "details of the investigation, testing, general design and maintenance processes".

The minutes also highlight a disagreement between European regulator EASA and the UK's CAA on how to proceed following the second ditching. Giles Porter, representing the UK regulator, says it requested that EASA include operational limitations in its airworthiness directive, issued on 25 October, "however, they were resistant". Therefore, the CAA went ahead with its effective grounding notice.

To lift the overwater flight ban, Porter says: "CAA airworthiness experts must be satisfied that all problems have been fully resolved so that there will be no recurrence of the incident."

Source: Flight International