You'll find a shit load of results from here (many of them recent) if you Google "skateboard on airplane slap magazine" or something like that.
I've never had an issue bringing a skateboard as a carry-on. But I usually strap to bottom of duffel or wedge between my back and backpack, so it's as inconspicuous as possible.
If I'm traveling somewhere for a month or longer, most of the time I'll just pack the trucks/wheels in my carry-on and buy a shop deck wherever I'm visiting.