Lightweight PLA is some awesome stuff, but its just not working for control horns. On my model I have succeeded in snapping every one of them now. Fortunately it hasn't been a failure in the air, but rather ground handling, or let's be honest ground looping. It's frustrating to end a perfectly good flying day over something this simple. At this point I'd recommend removing them from the control surfaces after printing. In the next update I will have these removed from the parts altogether.