I'm half expecting a "wrong-kind-of-air" excuse, bit like the "wrong-kind-of-leaves" excuse that British Rail use every few years or so,
Even more apposite was the Wrong Kind of Snow excuse, also by British Rail, when unexpectedly fine snow got drawn into the cooling system of some locos in northern England. The snow promptly melted and shorted out the electrical system. Ironically, we then have the MUCH more recent classic example of failure to read history - by Eurostar. You'll remember that various Eurostars stalled in the Channel Tunnel, when snow / ice that had got into the locos crossing France melted in the (warm) tunnel and, guess what?, shorted the electrics.
Clearly, volcanoes have been around for a while and VA has presumably been a (potential) problem for turbines since they took over from propellors! Quite shameful, really, that proper research and development effort starts only after a major incident.