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is my center section misaligned badly?

IowaRV9Dreamer

Well Known Member
I'm (finally) ready to do the first mating of the wings. My plan is to mate wings, attach the tail, rig ailerons and flaps, in a 1-2 week burst so I can minimize the time our cars are outside. Then I can disassemble everything and put the fuselage on the gear for cowl and FWF.

This weekend I made 4 drift pins out of 7/16" hardware store bolts. I also made 2 out of 1/4" bolts just for fun. I smoothed and polished the bolts, cut the threads off and rounded the ends.

Before actually mating the wings I decided to check how the pins fit in the wings and in the center section individually.

The pins drop easily into all the wing spar holes. They also go into the left side fuselage holes with light finger pressure. Same story on the top of the right side of the fuselage.

The bottom right part of the center section is a different story. The pins go in about halfway and stop. They are not hitting the gear bracket on the forward side of the spar - they stop when they reach their full diameter.

It appears to me that the bottom 2 parts of the center section are slightly misaligned.

I am 99% sure that I could lube them up and tap them in... maybe with not even too much effort. I haven't yet tried because I don't want to get them stuck in there. I'm going to climb into the fuse and see if there is enough access forward to get something on them to drive them back out.

Does anyone have any better ideas?
 
The pins drop easily into all the wing spar holes. They also go into the left side fuselage holes with light finger pressure. Same story on the top of the right side of the fuselage.

The bottom right part of the center section is a different story. The pins go in about halfway and stop. They are not hitting the gear bracket on the forward side of the spar - they stop when they reach their full diameter.

Can you try inserting the pins from the other side of the offending holes??

You state that they "stop when they reach their full diameter"-----is the hole too small??

Is this a QB ???

Might be best to contact the factory on this one.
 
Thanks Mike - I wasn't clear:

I can insert the pins from either front or rear. They go though the inserted side bar completely, then stop when halfway through the opposite side's bar.

I don't think the holes are too small - I think there is some misalignment between the front and rear bars.

It's a slow build.
 
You might grind one of the drift pins down a bit (slightly smaller diameter) and see if that works. If it's a slight misalignment of the holes, then a smaller diameter pin should go through easier, and will give you an indication of how far off the alignment is. Sounds like you have tried the holes from either side, and the diameter of the holes is not the issue, so the only thing that it could be is some sort of misalignment. I agree with Mike on this, you should call the factory and get their opinion.

Greg
 
Yep, gotta go with misalignment for sure.

You can probably get the bolt in at final assembly time, freeze it with dry ice, lube the bolt and hole with LPS, and drive it in.

BUT, this is going to induce some stress in the bolt and spar assembly, and there is no way to know how much----or the probable effect it will have on airframe safety-----this needs to be discussed with Vans engineers.
 
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I would say a call to Van's would be the safest bet. But I also had a similar issue with one of my bolts (drift pins) "sticking" before I mounted my wings. A slight tap and it would go in just fine. Made sure it was smooth though so as not to score the spar also used some Boe lube. When you put the final NAS bolts in, they are very tight and there is slight movement of the spar as everything gets centered up. As long as it isn't too far off I think you will be fine. I'm pretty sure many others have experienced this, but might not have even noticed.
 
Dave, I had a similar problem, but when the spar was in place, spreading the front and rear center sections just a bit, the bolt would line up. Try a spacer to spread them the same as the wing spar. I assume the 9 is the same as my 7.
 
Use drift pins in ALL holes. It may require a friend to wiggle the wings up and down while you are doing it, even with drift pins. If you can't get all of the hardware store bolt drift pins in then you probably have a problem. Otherwise, you will probably be ok when it comes to the NAS bolts. Hope this helps.
 
Hi Dave,

Tapered drift pins, tap them on it... you will be just fine. Have a friend pickup on the wing and move up and down slightly for the first few to get you started. :)
 
It may require a friend to wiggle the wings up and down while you are doing it, even with drift pins. If you can't get all of the hardware store bolt drift pins in then you probably have a problem. .

He is not able to get the pins in the center section only, no wings involved yet.

Before actually mating the wings I decided to check how the pins fit in the wings and in the center section individually.
 
CS Holes

Dave,
I had the EXACT same problem on my -9A, one hole on each side of the CS alone would not allow the taper pin to pass. Close inspection with mirror showed that the hole in one of the thinner plates that makes up the spar "sandwich" was not aligned perfectly with the other plates. It was BARELY off, but enough. The wing spars were fine. I bought the right size drill and match drilled the offending CS spar holes and verifed the real bolts would slid through the wing AND the CS spar holes separately.. Worked perfectly and the real bolts still went in as they should.
 
Dave,
I had the EXACT same problem on my -9A, one hole on each side of the CS alone would not allow the taper pin to pass. Close inspection with mirror showed that the hole in one of the thinner plates that makes up the spar "sandwich" was not aligned perfectly with the other plates. It was BARELY off, but enough. The wing spars were fine. I bought the right size drill and match drilled the offending CS spar holes and verifed the real bolts would slid through the wing AND the CS spar holes separately.. Worked perfectly and the real bolts still went in as they should.

A small amount of material removal from the web is OK if it has been confirmed for certain that is the cause, but I strongly suggest that a drill bit never be used. It may have worked fine in this instance, but it is Very risky.
 
problem resolved

After some encouraging words from this thread (and a very helpful PM) - I got a bit bolder. I put some boelube on a pin and tapped it in on the bottom right center section (still no wing).

It went in fairly easily with my plastic hammer. The big surprise was that once the first one was in, the pin next to it slid in with only light finger pressure. Whatever misalignment is present was removed by the first pin.

I had to lube and tap on the 1/4" pins with the plastic hammer, but they went in as well.

The hard part was removing them. I found the easiest way was to grap the shaft of the pin with a smooth jawed Knipex pliers, working though the slot where the wing will be. Of course that won't work when the wing is there. I'm going to make a little spacer for each pin, so I can grab the head and twist/pull with the Knipex.

I'm not planning on using the 1/4" pins when mating the wings. I'm going to use 2 of the large pins per wing: one on the bottom inboard and one on the top outboard.

Anyway, thanks for the help guys. I'm now officially ready to mate the wings.... as soon as I make a quick visit to the big airshow later in the week.
 
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Put a washer or two on the pin, so they end up under the head, washer needs to be smaller than the head diameter. This should give you a gap under the outer rim on the head of the pin to get a tool under there.

Then use a heel bar like this to remove the pin.

8277337.jpg
 
Thanks Mike, those look perfect. They have a set at HF for $7 that will work. I would have never known about them if you didn't post a pic. Thanks!
 
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