control linkages
 

Hello all,
I am flying a Sig Extra(74") that I got used. During a flight one of my elevator linkages fell off(redundancy sure is nice). The previous owner set it up w/ rocket city offset on the control horn and ball links on the servo. Is this a standard setup? Why not just use a metal clevis on the servo? Do ball links wear out and how does one check for wear?
I cant say enough what a great resource all of you are, thanks in advance.
Douglas

control linkages
 

I have the Sig Extra as well as a number of other arfs. I use ball links with 4-40 rods on all of my control linkages. I like them because they eliminate all the slop that you'd get using clevises and such. The hardware that comes with most arfs are junk. I also use aluminum servo arms and very stiff horns (currently Sullivan metal horns on my 1/4 scale arfs) on the control surfaces. I've never had one fall off or wear out, and I've never had any flutter either.

I'd recommend you stay with the ball links and good stiff rods. Make sure you're using servos that are rated 70 ounce/inch of torque or better on that plane. (You'll want more torque on the rudder of course)

Have fun...

control linkages
 

Rocket City offset swivel/horns and ball links are a pretty good setup. Which one came loose? I've never had either of these develop any wiggle, much less come un-linked.

You test for looseness by grabbing it and wiggling it, looking for any slop whatsoever. Both ends should go on tight and stay tight (but swiveling freely). If your educated finger finds any play, pull the part and replace it.

control linkages
 

The ball link side came off. Cant say who the manufacturer is. The previous owner may have mistreated the link?? The one on the other side is rock solid. I will replace this one and see how it goes. Thanks!

control linkages
 

Rocket city is the way to go, if you can find it now.