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Crooked Elevator

asw20c

Well Known Member
On page 11-02 you mount the left elevator to the horizontal stabilizer for the first time to check travel up and down and for rubbing. I discovered that my inboard bottom leading edge of the elevator rubs against the lower skin of the horizontal stabilizer and after much close examination it appears that the hinge line that runs from the outermost hinge to the center slopes downward; enough that the lower leading edge of the elevator extends about an eighth of an inch or so below the level of the lower horizontal stabilizer skin. How can this be? Everything else has been spot-on; plus the hinge brackets on the elevator as well as those on the horizontal stabilizer were prepunched. What can be done about this? There is no adjustment for up and down; only for and aft with the rod end bearings.
 
Photos would help. If you run a string through the HS hinge brackets end-to-end, does that line stay parallel to the aft HS spar web? Or if you measure from the spar web to the hinge bracket holes that were final drilled #12 in Section 08-02 is that distance consistent? If you sight down the aft spar web, is it straight? (Is there any twist in the HS aft spar web or elevator forward spar webs?)

On the elevator if you can do the same with the rod ends - measure to be sure center of the rod end nutplates on the forward spars to spar web is the same.

I did have to extend the rod ends out about 2 turns to get full motion on the elevators without binding.
 
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Great suggestions. I won't get a chance to try these these ideas until this next weekend, but I'll post my results.
Thanks!
 
Still trying to figure out what's going on here, but now I'm thinking it was my own fault and that I may not have bent the leading edge shape of the elevator to the correct profile at the point where it rubs and extends above the horizontal stab skin as described above before blind riveting. I'm planning to pull the elevator tomorrow and rebend the leading edge to see if that fixes the problem.
 
Before you start drilling the thing out see if you can work it a bit with your hands.
The metal is not very heavy, be careful, but you should be able to gently press and move the curve a bit in the direction required.
 
Well, it's not the hinge line. I pulled a tight string through the entire hinge line from one end of the stabilizer to the other and it was dead-nuts on. So, the problem lies either in my elevator leading edge profile or rod-end bearings, and I'm pretty sure it is the leading edge profile. As Tom suggested, I have been massaging it by hand without removing the blind rivets and after having the elevators on and off about 5 times now it is MUCH better than the first time. I also made two half-turn adjustments to two of the rod end bearings, and then another half turn adjustment to all four on both elevators to ensure minimum distance between the torque tube and spar web. I think I just about have this issue licked at this point. I'd post pictures but despite very clear directions it just doesn't seem to work for me on this site.
 
Well, it's not the hinge line. I pulled a tight string through the entire hinge line from one end of the stabilizer to the other and it was dead-nuts on. So, the problem lies either in my elevator leading edge profile or rod-end bearings, and I'm pretty sure it is the leading edge profile. As Tom suggested, I have been massaging it by hand without removing the blind rivets and after having the elevators on and off about 5 times now it is MUCH better than the first time. I also made two half-turn adjustments to two of the rod end bearings, and then another half turn adjustment to all four on both elevators to ensure minimum distance between the torque tube and spar web. I think I just about have this issue licked at this point. I'd post pictures but despite very clear directions it just doesn't seem to work for me on this site.

It's very possible you may need to adjust one rod end more than the other - I did quite a bit of tweaking to get good clearance, ensure the minimum distance from the elevator horn to the spar, and have even gap between the counterbalance arm and HS. Not hard but very time-consuming as each rod-end adjustment requires removing the elevator. I used a pair of fine needle-nose pliers with tape wrapped around the jaws to remove and replace the bolts (didn't use nuts until I was ready to final-drill the elevator horns as there was no side-to side play anyway).
 
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