I use a bit of a variation when installing ca hinges. First, I put a crayola line across the hinges at the mid point. Both top and bottom. Then I insert the hinges up to that line in the fixed half of the control surface. Flex the hinges past the point that the servos will push them and glue with a couple drops of thin ca on each hinge. Fifteen seconds or so later, flex the hinges in the opposite direction and glue that side of the hinges. The crayon line is still visible. Now slide the control surface onto the hinges. Flex the surface one way and glue. Then flex the control surface the other direction and glue. The crayola line is still visible when the surface is thrown one way or the other. If the same color crayon is used as the covering is, it looks kinda neat when the control surface is flexed. As an added attraction, the ca will allegedly not pass the crayon line in either direction. Don't know if that works in controlling the flow of the ca or not but the end result looks kinda nice and it can't harm anything even if it doesn't work. And if it does work in ensures you a nice flexible point at the mid point of each hinge.