As soon as the ski touches a rail, you can throw the warranty out the window. Some companies are cool about it if the problem was clearly caused by something else (my friend's filthy riches snapped when he caught a tip trying a really small flat three. Even though he'd hit rails a shitload on them, on3p is giving him a new ski because it had to do with a defective core, not rail impact), but they have no legal obligation to do so, so that's all just good customer service. Most big companies like k2 and armada would simply lose too much money if they warrantied every kid who's ski fell apart after hitting rails, so they don't make any exceptions. Which is kind of shitty, but hey, just one more reason to buy skis from smaller local companies!