The EASA has approved the interim solution Eurocopter devised to address concerns about main-gearbox lubrication on the EC225 after two controlled ditchings last year.
The manufacturer is using vibration monitoring, inspections and part modification to prevent the possibility of an undetected crack leading to in-flight rupture of the bevel gear vertical shaft–a part that is critical to main gearbox lubrication.
Eurocopter says it now understands the root cause of the problem: a combination of several factors, including stress and corrosion.
As a longer-term solution, the company plans to introduce a redesigned shaft in next year’s second half.
Responding to the latest EASA AD, the UK CAA has announced it will lift its restrictions, which essentially grounded the North Sea fleet. The first of 80 EC225s is expected to return to service this month.
The Helicopter Safety Steering Group, a committee of offshore helicopter users, welcomed the move but suggested the workforce is still nervous.