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Vertical Stab Questions

D

dlomheim

Well Known Member
I started to look closer at the vertical stab. tonight and noticed some issues:

https://www.dropbox.com/s/xey9jx7ipgn3nr0/Rear Spar Attach.jpg

As seen in the picture, the rear spar is pretty banged up for some reason unknown to me. A section at the bottom has been broken off and some holes are elongated, etc. I am tempted to order in new rear spar material and remove the old one, etc. Any thoughts on what might have caused this kind of outcome?

https://www.dropbox.com/s/5lix94icfcfps1r/VS front Spar attachment.jpg
https://www.dropbox.com/s/xuoiufyp96ivo7m/VS front side view.jpg
As seen, the front spar attach bracket is pop riveted onto the VS front spar (VS-2), and the material is really thin. Drawing 16 & 26 of my "preview" plans isn't much help in determining if this is the correct part, as far as rivet call out, or thickness of material. Can anyone tell me if the "real" plans provide anymore detail? I know my 9A attach bracket is quite a bit thicker than this one.

Thanks for any ideas...info.

Doug Lomheim
RV-3 Restoration
 
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Doug,

My thoughts.

Buy new emp for 995. Will save you a lot of grief.

Should be 470-4-x rivets not pops.
And AN3-6A bolts.
 
I would not disagree with Bruce. If the rest of the workmanship is this bad, buy a new tail kit.
However, if these are the only areas that are bad, you can repair the damage quite easily. Before investing in that, make sure the rest is decently built.
One big area of concern with the 3 empenage is edge distance. All of the rivet lines are laid out by hand and there is not a lot of tolerance. It is a challenge to maintain edge distances. I have also seen many 3's with rivet lines that look like a snake. Not necessarily an airworth issue if the edge distances are kept but if they are snaking around, chances are those are not met. It is easy to check the edge distances on the trailing edge. The foreward spar, not so easy but you can look through the lighting holes and get a visual on them.
Double check the hinge brackets. Make sure they are in line with the center line of the stabilizer. Since there are only two brackets, not three like other RV's, you can't simply run a line through them for the alignment. You will have to check against the center line.
Lastly, insure there is no warp or twist in the stabilizers. They where jig built and if not properly laid out and jigged....
 
Looks like it might be reasonable to buy a new rear spar. If you do, for the VS-307 stiffener, don't buy the Van's part - it'll have a manufacturing glitch in it. Instead get a piece of 2024-T3, 4" x 30" and 1/8 thick. It'll cost about the same, be as easy to make and not have the glitch.

While that's off and you're fabricating the new one, you can examine the front spar and it's rivets. It might be worth waiting until the rear spar is off before making the order in case you need anything else.

The connection to the horizontal stabilizer is nominally between the .032 front spar's web and the .063 HS-308 part, which has a leg extending upward. People usually need shims between them, the manual says up to 1/8" I think (check that!) and I believe that Paul and Louise's plane used 3/8" with Van's approval - also worth verifying.

The HS-308 part can't easily be replaced except by significant disassembly of the horizontal stabilizer. But it can probably be repaired if necessary using standard practices.

On the affected drawings, my plans, which came with my kit April 2012, show no revisions for the vertical/horizontal joint at the forward spars. Van's will sell you a new set of empennage drawings - or all of them - if you wish.

Good luck!

Dave
Now on the left elevator - still.
 
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VS Questions

Thanks for all the replies...it helps to get feedback from those who have gone before! At this point I think I will pull off the rear spar and figure out what pieces I need to make it a bit more airworthy. Will also do the same to the front attach piece and redo that part with a bit thicker material...

Doug
 
Doug - if you have not removed rivets before, research how to do it and practice on some scrap before starting in on it. Otherwise, you may end up ruining a lot of holes.
Do not drill through the rivet!
 
While the spar is off, take a good look at rivet lines inside the cavities. I've heard stories about seeing beautiful-looking rivet work, and when you look inside you see that the row of rivets progresses closer and closer and eventually *off* the flange of the rib on the inside.
 
Snowflake said:
While the spar is off, take a good look at rivet lines inside the cavities. I've heard stories about seeing beautiful-looking rivet work, and when you look inside you see that the row of rivets progresses closer and closer and eventually *off* the flange of the rib on the inside.
Click to expand...

Good advice. Really easy to mess this up on the 3.
 
There aren't any ribs on the vertical stabilizer on an RV-3 except at the bottom and the top. But the front spar, ah, there!

Good thing the front spar rivets are visible when the rear spar's removed.

And it might be a good idea to build a jig to keep it straight when you reassemble it.

Don't forget to match the existing rudder hinge locations.

Dave
 
Copy all

Thanks again for all the advice. I'm working FWF now so hopefully in January - Feb. I'll begin to tackle this issue (prior to first flight...).

doug
 
Hey Doug, we waved as we drove through OKC about 0230 the other night....din't think you'd want us to stop in.... ;)

Just saw your thread here, and I agree with everyone - and that you should do some rebuilding. That front spar attachment is downright scary. I might have a little more time available in a few months - maybe I can stop in and see what you're up to - I could probably one-hop up there in Tsam, and you could check out the -3B for ideas.

Paul
 
VS Inspected

I have decided to remake the VS since the bits and pieces aren't that expensive and it will make me feel better about the quality and soundness of the a/c. I drilled out the rear spar this afternoon so as to be able to use it to hopefully match drill the new one down the road (as far as bolt attachment locations and placement of the rudder hinges). If I had to guess after looking at it, I'd say the original rear spar cracked down one side, and the previous owner did a repair by adding another doubler to the VS-307 spar plate...very interesting...

Doug Lomheim

https://www.dropbox.com/s/pvg7rw7f567hmmy/VS Aft Spar.jpg
 
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