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Preparing to final install the wings

dbaflyer

Well Known Member
I've been getting ready to install the wings on my 9A and I was checking to see how the close tolerance bolts fit through just the wing spar. There was only 1 hole out of 16 that was so tight I did not think the bolt would go through. I had to keep hitting it with a rubber hammer and then tapping it back out. Repeat until it finally went through. You can see how the bolt looks after all this. All the gold plating is gone.
I have not checked the center section yet, but that's on the list. I figured if they didn't go through separately, it was going to be a long day trying to get them installed and aligned to both. This image shows where it started to get very tight.

phfEiGPdkVYgyEPDPAdWClI_MbXq5pF3aTkuQx69mJqRmIrRnkimlgJBExYN30uh3j7TcnZVI0NcnNHRqqIW0FqKCuT6Dh-wcjcNXXE5VQt-gQD9dSB7gMisGG5VwSUBODAcQHTqbeA284cEog0pUOld7YqyTUNDq49oB07dnlxpz3izDE1hXz0EfmNXHGqwpLeCXjSUo0LWeGlxM76GwlopuL9K5m4VWWqzu-Rjz3vBFjopoBQEVuG6kgwKlSC9M3xMZYNBTxeoXeuiLrOf8jHyD3tX3UtIUEB5VTjfn7oMl6llwI5CV0-GqeWLDcThzxbVpU51aBD_VyiKF2qs4baMOEp9GO5FBefjL1Ss71WAx40sbOfz4NT9lbX-8VAa1GyOkV7d1XpsXNiEwVpCaKpUo4Zi-0F7-_b-QA6LsHrOKIRuAV1iiskDenDNr_vNYG2mipTVe7BdJ7KKB8dU2D5AS-o_guwvCmPGjV9i_DHSKVHz8U-dZ9oJDEN-lMG7zbQvcqZKGnHRdqkfm4G6KhqymUxFxsitUb2iCbdCsRkSzoPN6Bt0azebVAFWbVgAirHc_8_YefiNqRFZDcEl5B8lYzsxYfV21nLyUViJB8aeufkhZN4eiFBSPeUuwCWF4P01NXshR7SsEjRBoMo9dYzQwhyrE_0=w1420-h1892-no


This is what the bolt looks like afterward compared to a bolt not previously installed.
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I wouldn?t do any dry fitting. There is nothing wrong with your bolts, the center section or spar holes, they are supposed to be that tight!
Per VANs, they do not want any of those holes reamed, drilled or even touched prior to installation.
Do your initial fitting of the wings using hardware store bolts rounded at the ends into drift pins. These will be a bit under size, but good enough for fitting. You will only need two or three per side, not every hole. Then do all the drilling for the root fairing nut plates, drill the rear carry through spar bolt, etc.
Put your close tolerance bolts in the freezer until ready for final install. I put them in a freezer bag so they stay dry.
Finally... Get the wing in and set with the temporary drift bolts that are slightly under size. Then install the close tolerance bolts one at a time. Lube them with LPS-2 or something like that, and install. You may have to tap or even hammer them in.
As for the bolt you scraped, you can either replace it or spray some primer on it, instead of lube, just before you install it. The wet primer will also act as a lube for the bolt.
Surprisingly, you will find that they will all probably go in without too much trouble.
Good luck.
 
I did the same thing to my close tolerance bolts before reading about the ?hardware store bolt? trick. Vans advice was to not replace the bolts unless they are ?severely gouged?.

Unfortunately I also made a huge mess of the spar holes in the center section in the process of initially fitting. The fix for this was to gently pull a small bit of scotch brite through the inside of the damaged holes to clean them up best I can and get them smooth. I?m not super happy with these holes but at this point in the build, replacing the center section probably means rebuilding the whole fuselage.

I?ve learned the hard way to treat the spars and center sections as though they were $1000+ parts, because, well, they are.
 
A couple tips:

Use hardware store bolts to get the wings in place. It only take 2, maybe 3 to hold everything in place. Get bolts that are an inch or two too long, then use a bench grinder to sharpen the threads to a point (like a pencil). This removes the threads and prevents it from removing material from the center section and helps them like everything up more gently. Put them in with a liberal amount of wheel bearing grease. The grease is important, it helps alot.

Once you got that done, putting the close tolerance bolts in is easy. Again, use grease, especially on the threads. It makes it go in fairly easy. Much easier than dry bolts.

Grease wont hurt anything and makes it much easier to Install.
 
This is a very critical fastener install, I would not trial fit the CT bolts for fear of galling, if all the hardware bolts go in Ok during the rear spar fit and alignment you should be ok, when the final install goes together there should not be any play, I was surprised how tight they fit, some say tap in with a rubber mallet, for me this was not enough, I'm not saying how to install these but for me, I installed all the hardware bolts, then one by one replaced with the CT bolts, used anti seize lube and low PSI on the rivet gun with multi layers of heavy duct tape on the flat set to drive them home, going very slowly and monitoring the progress of the bolt and the rate it was going in, watching for any increasing resistance that would indicate a problem. This may or may not be the recommended way, just the way I did it. Check with the mothership for guidance here.
 
Wings install

What I found that worked for me is (a) putting the bolts on dry ice, (b) a little LPS #2 oil on the shank and (c) light taps with the rivet gun (around 20 psi).

Doug
RV-7
7th inning stretch
 
dry ice - do the bolts really shrink?

Has anyone done the math on how much the bolt will actually shrink if cooled to dry ice temperatures? (about -70c) Seems like it would not be enough to make a real difference, but several people have said that it helped.
 
Once you got that done, putting the close tolerance bolts in is easy. Again, use grease, especially on the threads. It makes it go in fairly easy. Much easier than dry bolts.

Grease wont hurt anything and makes it much easier to Install.

Just remember to use solvent and remove the grease from the threads prior to installing the nut. Final torque specs are for dry hardware.
 
One thing you also want to do is make sure hardware store bolts will go through the center section holes and the landing gear weldment holes on the A models before you slip the wings in, the landing gear weldment holes are not precision plus could have some powder coating on them. You could a feeler probe for this also to detect if is gross misalignment.

I went the slip my wings on and the bolts would not pass through the landing gear weldment. I already interior, wiring an plumbing complete so it was a pretty big setback to have to jack up the plane, remove the weldments to open up the holes.

If your kit is really old, you might want to get newer nuts from Van, at some point they started using a nut that takes a slight smaller wrench and is easier to get on. One of mine nuts got miss placed and was shocked to see the replacement was smaller OD wrench size. Sure would have made getting the lower ones on a lot easier, which involved custom grinding a wrench.

Steve
 
If my rusty old maths brain is right

Has anyone done the math on how much the bolt will actually shrink if cooled to dry ice temperatures? (about -70c) Seems like it would not be enough to make a real difference, but several people have said that it helped.

It would be about 0.012mm smaller in diameter, assuming cooling from 25 deg C to -70 deg C. Every little bit will help. Aluminium has a co-efficient of thermal expansion almost twice that of steel, so it might also pay to sit the wings in the sun for a while before attempting to fit.
 
Has anyone done the math on how much the bolt will actually shrink if cooled to dry ice temperatures? (about -70c) Seems like it would not be enough to make a real difference, but several people have said that it helped.

In other applications I have chilled bearings in dry ice and can say that on some with a 1-2 thousandth press fit that after chilling the bearing just dropped into place instead of having to drive or press them.
 
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