Don't put the Futaba S-3003 or S-3004 (or Tower TS-53 which is a S-3003) on for your .30 size heli's tailrotor. The constant motion and vibration of the heli combine to wear the things out prematurely.

It turns out that Futaba's servo info on thier website recommends against using the 3004 on a heli at all. The difference between the 3003 and 3004 is a ball bearing. (which means the 3004 should handle it better...)

It is not fun to have the tailrotor suddenly go to full throw.