It is rare but these are huge beasts to come crashing down iv watched a few videos of them collapsing across the world and funnily enough some of them came down the same way as described above very low winds brake failure and it spinning out of control even in low winds

Is this the one in donegal that came down
http://m.independent.ie/irish-news/safety-concerns-after-wind-turbine-snaps-and-falls-during-storm-29151242.html