You can probably use a fbl controller on flybar heli, as long as you don't connect the cyclic servos to it. Only use it for the rudder channel. The only reason I would see doing this is if you planned on possibly going FLB on that heli in the future. If you are staying with a flybar you would be better served with a Spartan Quark or a GY401 with correctly matched digital tail servo. I have the Quark on my Raptor 50 nitro heli, and the GY401 on a Trex 450 and the tails hold rock solid doing backwards flying, funnels, etc.