Eurocopter's hopes that its EC225 can make an early return to unrestricted overwater operations appear to be fading after the UK Civil Aviation Agency poured cold water on the airframer's plans.
The type has effectively been grounded in the UK and Norway since the October ditching of an EC225 operated by CHC Scotia, the second incident of its kind within six months. So far, Eurocopter has been unable to find a root cause for the cracks in a gearbox component that led to the accident.
Lutz Bertling, Eurocopter chief executive, said during a January media briefing that he expected to see relaxation of the CAA's restrictions in early spring on the back of temporary "safety barriers" proposed by the manufacturer.
However, the CAA says it will not remove its operational limitations until Eurocopter is able to demonstrate it has a permanent fix to the problem in place.
"Safety clearly has to take absolute priority, and the EC225 operating restrictions will not be lifted until we are absolutely convinced it is safe to do so," it says.
"We continue to work with all stakeholders, and are liaising closely with EASA in regard to airworthiness issues and any mechanical solutions put forward by the manufacturer."
Nonetheless, it says it may consider temporary fixes if the airframer identifies the root cause of the fracture to the helicopter's bevel gear vertical shaft.
Although Eurocopter is continuing its testing efforts on the component, the ultimate cause remains elusive. Derek Sharples, executive vice-president support and services, says: "We have performed a lot of investigations and a large number of possible causes have been eliminated, so we are a lot closer but we are yet to determine the cause or combination of causes."
The results of its third test campaign on the shaft are due at the end of February, it says.
Executives from the company, including chief technical officer Jean-Brice Dumont, attended a 14 February meeting in Cologne with EASA and national civil aviation regulators to begin the process of "aligning" their policies towards the EC225. However, no firm agreement was reached.
Sharples says he is "convinced" the aircraft is safe, but concedes work remains to be carried out to persuade other stakeholders. "There are 10,000 people who work offshore and we have to work diligently to convince all of them that the aircraft is safe and that we have their safety as the highest priority," he says.