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elevator mounting clearance issue

C

cropdusterdave

Well Known Member
So I just started fitting up my elevators to the stab to drill the horn and get them ready to fit to the fuse. I installed the rod ends to 13/16 " to the center of the bearing hole. when I mounted them up the counter weight arms were binding so tight I couldn't move the elevator. I ended up turning the rod ends out 3 full turns each and they fit fine now. Is this an adequate solution? I took one of the rod ends out and did some measuring and there seems to be an adequate amount of thread left inserted....but I don't know the rule on this. If there is in fact a "rule". For what it's worth...with the jamb nut tightened, I'm showing 4 threads exposed which looks similar to other folks'.
 
When you say they were binding, you mean the forward end of the counterweight arms was binding on the HS skin that extends outboard of the most outboard rib?
 
It is common to have to cut some of the HS skin where the tips of the counterweights swing by. Is this the area you are talking about?
 
The dimensions called out are to keep the elevators parallel to the HS aft spar attachments and as specified will keep all the bearings aligned.

Theoretically you should be able to sight a straight line through all the hinge points of the HS attach points and the elevator rod ends/center bearing. If you adjust the outboard hinges out then you will be throwing the hinge alignment out.
 
thanks, Walt. I was turning them all out the equal amount. They're still aligned....just don't know if lengthening them slightly will be an issue.
 
Something else to worry about if you change the dims called out on the plans are the center bolt hole location thru the elevator horns. If you move them around too much, you may have a problem drilling that hole!
 
cropdusterdave said:
Yes, that's where I'm talking about. Sounds like it's better to trim than adjust the hinges?
Click to expand...

That's the way I'd go. I'd try to keep the rod end extension as short as practical.

Vans scheme of using rod ends for control surface hinges seems to work fine, but loading the threaded shanks of rod ends in bending is not the best of practices. I'd be inclined to keep the rod ends threaded in as far as practical, to keep the bending moment on the shank as low as possible.

Thanks, Bob K.
 
It's actually comming into contact with the fiberglass tip. Shouldn't have been a big deal....but I glassed over the TE of it. Oh well. Guess I know what I'm doing for the next 4 hours....
 
cropdusterdave said:
Yes, that's where I'm talking about. Sounds like it's better to trim than adjust the hinges?
Click to expand...

I believe that's what virtually everyone does. I thought the instructions even said to do that at some point, but I could be wrong.

I set the rod ends per the plans, and double-checked that the gap was straight, and then trimmed the skin so that the horns just cleared.
 
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