Elevator horn height challenged...

Hi Folks,

This will warrant a call to the mother ship, but I wanted to see if anyone else had some experience with this.

I'm nearly done with the empennage (I did riblets, thank you very much!) and am fitting the elevators to the HS. The fit up went well and everything is in good alignment and ooh so smooth, however, I found that the elevator horns are not stacking up to the same height. See photo:



One horn is about 0.2" lower than the other. Anyone else see this on their bird? is this a tolerance issues on the horns, or something else? I'm not sure it would actually make much difference one everything drilled and bolted together, but it took me a bit by surprise.

Thanks much,

-Bill

normal

This is very normal , they just don't line up on most of the Rv's must be
from the welding process..

Yup! Just make sure the elevators are in trail and drill a nice straight hole.

Roberta

Horn alignment

I looked at your picture and I noticed the the rivets that would be at the bottom in the picture covered by the torque tube of the elevator horn are not covered equally as they would be if perfectly mirrored of each other. Also, look at the bottom (in the picture) of the horn plates, they are not matching. It appears there is an alignment problem on one elevator. Maybe its the photo playing tricks on my eyes, but worth checking out.

What Roberta said - a common occurrence and easily taken care of in that fashion.

Thanks to all for your comments and observations ... I wanted to double check the alignment of the HS this evening to be sure I didn't muss anything up.

First, I checked the alignment of the HS brackets onto which the elevators mount. I thread a string through the bracket holes and pulled it real tight. If the string is centered in the outer two brackets, it is nicely centered in all the others. Good to see!

Next, I refit the elevators and carefully aligned them and brought them into trail. Then, I carefully set up the camera to take a photo of the horn assemblies from as nearly perpendicular as possible, as seen below.



Pulled the photo into the Visio as drew a set of parallel lines. The key reference lines are the white ones aligned with top and bottom of the HS rear spar, and the green ones that point across the to corresponding rivets on both elevators. these lines are parallel and seem to line up very well with the expected points on both elevators.

The red lines are references that show the lack of alignment of the horn brackets. It's not shown here, but each elevator fits beautifully onto the brackets, shows a very consistent reveal between the HS and elevator skin, and probably most telling of all, is that the counterbalance arm aligns perfectly with the HS skin ... a beautiful, consistent gap. If there was enough misalignment in the rudder install to push the elevator horns out of alignment to this degree, I'd surely see it mirror image at the outboard end of the elevator. Appears to be an elevator horn issue.

It seems that this situation is not inconsistent with others' experience. I'm waiting for the official read from the factory to see if I'm off base or not.

While fore and aft mis-alignment of the horns is normal, the lateral alignment I see in your pictures is not. It appears to me that the torque tube was not welded onto the flange 90 deg. Can you measure the angle?
Since they are mirror images of each other, if they where not welded on square they would align near the root but go out of alignment as you went out towards the horn. This is exactly what I am seeing in your pictures.

Very well done photo's and editing by the way.

Vans sez..

A quick update, Vans says that as long as the edge distances for the holes on the elevator horns is good, there will be no problems. Looks to be a primarily a cosmetic issue due to manufacturing tolerances on the horns...

"The inconsistencies you are facing is in the WD-605-L-1 PC and WD-605-R-1 PC, This will not cause any problems with the movement of the elevators. The tube welded in the WD-605 is nothing more than a spacer to go from the aileron to the center bearing and the location is irrelevant. When the two parts are built they build a run of 50 or 100 lefts and then build the same number of rights. All of these parts have a tolerance and if one is built to one end of the spectrum and the corresponding part is at the other you will get the result you have.

Sterling "

Build on!

My elevators horns are much worse than yours! My right horn is significantly shorter than the than left horn from where they attach to the elevators. They are also angled outward. I used a longer bolt and a bushing instead of using the washers. Vans said that its just differences in manufacturing the horn. My elevators line up, and I made it work. Vans said that its no problem.

After the hole for the pushrod is drilled, and assuming that you have proper edge distance, you could trim the "long" one to match. This would be mostly cosmetic, although you could save a gram or two weight that way.

But only if there's enough edge distance!

Dave