Trim horn Question/survey...

[DBeaulieu]

Today I spent the afternoon doing the initial setup of the elevator trim system on my quickbuild Patrol. I may have messed up...not sure, hence a survey/query to the group. In the picture to the left, you will notice I have drilled the horns to the tubes. Also note that the two horns do not meet and have a separation of approx 3/16". This happened because I bottomed out the horns to the tubes. Picture on the right, where the horns make contact is the setup prior to drilling.There is still good offset to the left side of the centerline and no interference issues that I can tell at the moment - though I do not know the full range of the horns during trimmimg. I have two options at this point: (1) weld up the holes on the tubes, reposition horns to make contact and drill new holes. (2) Just use spacers and connect trim cable via turnbuckle to space between the horns. I would rather not weld up the holes, reclock and redrill if spacers will do the trick. Let me hear your thoughts pleae - thanks so much all! As a side note, there is an advantage to using spacers between the horns as that would eliminate the need for the aluminum spacers alongside the outboard side of the horns to keep them shifting about.

elevator trim horns drilled.jpg elevator trim horns.jpg

[geraldmorrissey]

For me, when in doubt, build per print. Get some raw stock, remake the affected parts and call it a learning experience. Just my .02.

[Paul Johnston]

Dido this-replace the tube that’s drilled wrong

[davzLSA]

You dont want the trim horn to be in the center of the longerons, your elevator horn will need to occupy that space. As for the 2 horns matching, I made a single horn that both trim torque tubes fit in to. It seemed to work well.

[DBeaulieu]

Made bushings (5/32") today to check out any interference. The horns are only displaced toward respective outboard sides by 5/64". Tomorow I will connect the elevator control tube to and bearing to see if there is any issue. I have a couple backup ideas to consider if there is an issue. (1) Using original items, place horns where needed on tubes and crossdrill 90 degrees to the current "wrong "holes - I like that idea. (2) Fill holes via welding on tubes and horns and place again to mark and drill. Still not totally convinced that I need to start anew to resolve this satisfactorily...

My followup questions to the group:

(1) Does the orientation of the bolts holding the horns to the tube matter? I initially drilled vertically for ease of marking with center punch. If no matter, then crossdrilling is a viable option.
(2) How is the horn clocked in the vertical, what is a relative reference? I went 90 to the elevator chord (best I could tell) and same with the tabs the adjustable push/pull rods to the trim on the elevator are connect to.
(3) For those who are far ahead of me and rigged or flying, how much of an arc does the trim horn move? Is it specified somewhere in the plans for travel of the trim?

Appreciate all thoughts and concerns/ideas! Meanwhile here is a pic for an updated view

Dave from Maine

Trim horns with bushings.jpg

[geraldmorrissey]

Bolt shanks are pointed down, inbd and aft when possible.

[jaredyates]

I once had an elevator cable get hung up on the trim bellcrank bolts. Be sure to orient them so that this isn't possible.

[DBeaulieu]

So Jared, my elevator horns are now able to be bolted together without the bushings I was contemplating, In the picture above, are you suggesting that I place the bolt head inboard/shank and nut outboard for the bolts? Depending on travel arc of the horns, I mayhave interference with the longerons that way? The bolts from the horns to the trim tube are correct...Y/N? Thanks

[jaredyates]

Just study it once you have the cables in place and pick the best option.

[DBeaulieu]

Follow up to my elevator horn problem...which turned out to be builder problem. Seems like on the kits, the trim horns are suppose to bottom out on the tubes they are drilled to as I did. But, today I discovered that when I brought the rear elevator spars inboard on the rear elevator mount (and fully seated them) the gap between horns no longer existed. Yay! The factory did a great job with the fabrication/fitment, I just had to figure out the fitment a bit better.

[Nev]

When you drill the outside horns part of the trim tubes, check for the best orientation. I ended up doing mine again because the bolts contacted the fabric.

[DBeaulieu]

Hey Nev, on my kit those "outside" horns are welded on. I oriented them at a 90 degree angle down relative to the stab bottom surface and the "inside horns" were just the opposite (90 up) for drilling to the tube