Eurocopter considers the EC225 technical problems which led to the two controlled ditchings of EC225 in the North Sea in 2012 to be fully understood.
The safety measures have been approved by the EASA. We expect the operational restrictions imposed by certain national aviation authorities to be lifted shortly.
The exceptional corrosion phenomenon ("active corrosion") results from combination of gear corrosion pitting and specific environment
- Presence of a "paste" inside the shaft in the welded area trapping moisture
- The "Paste" is a mix of residues produced from the splines usual wear, MGB oil and water
The preventative measures are designed to significantly reduce the possibility of a crack initiating as they directly reduce one of the 3 necessary factors of the root cause ("active corrosion").
More info on http://www.ec225-news.com