ORIGINAL: gosk8ing
With the fixed servo arm, if the screw comes out, the servo arm should still stay on the servo because there is some force required to pull it off the servo.
In theory, yea...but in practice...it will come off at the worst possible time - when there is a load on the surface. Back side of a loop and all of a sudden, you have no elevator
You can put a dab (TINY drop) of canopy glue on the back of the screw head and tighten it down. The screw basically gets glued to the arm. Canopy glue is more shock/vibration resistant and easy to break off when you need to remove the arm/screw. Also, it doesn't dirty up the threads like loc-tite does.