Returning the grounded EC225 fleets in Norway and the UK to unrestricted overwater flight status is Eurocopter's "highest priority", as the company grapples with a technical issue "more severe than anything in the past".
Lutz Bertling, the airframer's chief executive, says he is confident the type can be brought back into service by April, through the implementation of "additional safety barriers". This is despite Eurocopter being unable to identify the root cause of the cracks in a component that caused two ditchings of the type in the North Sea in May and October 2012.
The proposed interim solution outlined by Bertling includes shorter inspection intervals, tighter monitoring of the EC225's vibration detection system - which can identify the beginning and propagation of a crack - and potentially limiting the power available in certain situations.
"We need to install these additional safety barriers to convince the regulators that we can fly safely," he says. "But even if [the regulators] say they will lift the restriction, we need to convince the oil companies and the passengers that it is safe to fly."
Bertling says talks are ongoing with the safety regulators to get the restriction rescinded. Speaking in Paris on 23 January, he said he is confident this can be achieved by April, or even March, "if everything runs perfectly".
In the meantime, bench and flight testing continues as Eurocopter strives to come up with a more permanent fix.
"Let's not forget this design has more than four million flight hours, then it failed twice. We need to be able to find the parameters that led to the failure of this shaft," Bertling says.
Engineers have artificially induced cracks into a number of test shafts to observe how the fracture propagates. But, as Bertling observes, this is a lengthy process. "We need hours and hours of testing to get to it, there is not a one-shot catastrophic failure."
Bertling has also apologised for the "very severe impact" the grounding has imposed on the oil and gas sector, which is "one of the most important customer groups we have".