[eduardo]

Good Day Gents: I have one of my two elevator servos (Futaba 9202) on a 30 cc Graet Planes Yak 54 humming when in neutral. If I gently nudge the control surface with a finger, or slightly tap the control stick on the Tx, the humming goes away. I know this humming probably implies a current drain, but I am not overly worried about it since I have a brand spanking new 2400 mAh 6 V (5 cell) JR NiCd battery in there, so juice probably shouldn't be an issue. Anything else I should worry about gents? Much obliged.

[CHEVPRO]

If the servos are digital, humming is common. The servo is trying to centre. On some servos the deadband can be adjusted to eliminate it.

[Eye Can Fly]

If its a Futaba S9202 it is an analog servo. Here is where you can look up what you have http://www.servodatabase.com/servos/all?page=32

Humming should be looked in to, could be as simple as the servo hunting for center, the weight of the control surface causing it to look for center or binding. By what you described it sounds like it is searching for center.

When I see this happening I usually hook a meter into the lead and find out how much draw there is. Current draw causes heat, servos hate heat.

There probably are other issues I've overlooked.

[stegl]

After much use the spot that the internal pot button sits on will wear ( neutral point ) and may have created a dirty spot. This is more common on high vibration installations like gas or nitro . If you use the same servo with the throttle ; do a swap and if it still happens, there could be excessive resistance in the linkage or hinges. The throttle servo never really sits at the same spot for very long and has more even wear. Consider buying another 9202 and when you have time send in the problem one for servicing and keep it as a spare.

[VA6WGO]

Hi Eduardo,
Chances are there is slightly more resistance on that stab than the other and/or there is a bit of dirt where the centering of the servo sits.
Either way, it's not a big deal. The 9202 is a plastic gear servo and there is a fair amount of vibration with a 30cc engine, depending on your flying style, you may want to upgrade the servos in the stab to a metal gear and a higher torque.

Regards,

Will