I find this interesting (I'm weird like that), so I looked into it a little more.

I just don't know if you made a mistake in saying they referred to a ruling in The Hague or the EU ruling of Wallentin-Hermann?! That decision did make it possible for airlines to claim extraordinary circumstances when tech faults were in play, even though there had been regular maintenance or if parts broke, even though life expectancy wasn't reached yet (for instance). Also a possibility of malfunction on new parts/aircrafts were mentioned.

However, in the CJEU ruling C-257/14 this has pretty much been scraped (for the most part). Although malfunction can be in play, even though all precautions/maintenance and safety measures have been followed, it doesn't mean that it can then be explained as extraordinary circumstance.

Quote from the ruling:
"While the Court admits that such a technical defect could occur unexpectedly, it perceives it as a defect intrinsically connected to the airline's operating business (para 41). When could a technical defect then be seen as an extraordinary circumstance? "where it was revealed by the manufacturer of the aircraft comprising the fleet of the air carrier concerned, or by a competent authority, that those aircraft, although already in service, are affected by a hidden manufacturing defect which impinges on flight safety."

There is more here:
http://recent-ecl.blogspot.nl/2015/0...technical.html

Make sure you use this ruling to undermine their argument for the ruling of 2013.

Good luck!