I went through several 2721's on Kingcat flaps. I would not use them on a primary flight control surface. They are also not a digital servos so won't center quite as well, and won't have the torque around center that a digital servo will. JR and spektrum also make an inline 2 channel regulator http://www.horizonhobby.com/Products...odID=JRPVR5203 that works very well. I have one on the gear servos for my Electra.

DR