QB wing spar holes too small ?

Jeff Vaughan · #1 06-20-2005, 07:49 PM

I am just about ready to test fit my wings with the fuse. I am concerned that I can not get a bolt through the wing spar fuse holes only on the bottom row. I have test fit with both close tol. bolts and hardware bolts. The bolts go into the top holes but will not even start to go in the bottom holes. I talked to Vans about this a few months ago and they said there is no way all the holes were not the correct size. Now that I am about to mount the wings I am revisiting. Has any one else had this problem. I will call Vans tomorrow again. I was not satisfied with their answer a few months ago. I had a machinist look at the holes and he agreed that there is no way the bolts were going to fit. He suggested reaming to the correct size. Just wondering if anyone else has experienced this.

Jeff Vaughan

FrankK90989 · #2 06-20-2005, 08:08 PM

Jeff,
Have your machinist measure all the holes, maybe some one did goof.
I fit my wings to fuse a couple days ago using grade 9 bolts and they fit tight but they all fit. use some lube on both the spar and the bolts. my spar was quite snug also!
Good luck
Frank

rv8ch · #3 06-21-2005, 12:43 AM

Quote:

Originally Posted by Jeff Vaughan

The bolts go into the top holes but will not even start to go in the bottom holes.

Can you post a photo? It does sound amazing that this type of error would occur. If you do end up needing to ream, I would spend a lot of time with Van's discussing it. You'll probably want to ream with the wings on, so you get a nice hole through the spar box and the spar. As I understand it, this is the way it is done at the factory. Of course, they don't have the fuselage all around it to get in the way! Good luck.

Highflight · #4 06-21-2005, 04:53 AM

What's the possibility of any primer or paint having ended up in those holes?
They are "precision" fit after all, and just the thickness of a primer would give you fits. Also look for a burr on an edge that would do the same thing.

Rick6a · #5 06-21-2005, 05:40 AM

I would certainly revisit your installation techniques before reaming those holes! I'm not saying it is impossible, but seems extremely unlikely that the factory somehow undersized those critical holes. It seems likely the factory used the same reamer and tooling application for both the top and bottom holes. First off, make certain no primer overspray is inside them. Surely, your machinist friend has a set of ball gauges and a micrometer in his tool box. Have him verify the correct diameters once and for all. If correct......consider this idea.... though I really cannot comment with certainty because of unfamiliarity with the design. You say you can get the top bolts in but not the bottom bolts. Have you tried loading or unloading the wings, the idea being to generate enough of a flex to get the bolt holes to line up? Another alternative. Try inserting an inboard bottom bolt first, then a top outboard bolt etc.etc. A technique used especially with close tolerance holes is to keep the bolts frozen until just prior to insertion.

Rick Galati RV-6A "Darla"

Jaypratt · #6 06-21-2005, 06:35 AM

If you have a RV 8, you must put the bottom bolts in from the rear.

Bob Axsom · #7 06-21-2005, 07:13 AM

Regardless of what the company says, they do make mistakes. I can identify several in mine. When you run into them, you just have to work through them and contacting Van's is an important part of the process. If there is a known error they will usually tell you but they deal with a lot of very inexperienced people every day that make a lot of mistakes. They are predisposed to expect builder errors because the vast majority are builder errors. Usually they listen kindly and try to give you the needed help to work through your current problem. It doesn't take long before you become your own best problem solver and you develop the judgement to proceed. The danger is that you make a judgement call that compromises safety. I made one of those with the aileron mounting bracket installation to the rear spar where the factory had drilled 4 holes in one side of the interface (spar or bracket - I can't remember which) and 5 in the other. As I always did when running into these things I contacted the factory and told them the problem and my fix. In this case they said "Oh yes we know about" that and the fix involved drilling over size holes in the top and bottom locations to pick up the total range of the mismatch and install screws inplace of rivets, add one hole in the four hole part to allow installation of the proper rivet for this application and install rivets in the other locations which were properly aligned. The factory sent me a kit containing the screw attachment hardware. I had already made a fix that was not adequate but fortunately the factory fix eclipsed my deficient fix. Note that I called them and learned of the known error and fix before any attempt was made to notify me the builder. A similar situation occured with improperly made elevator horn weldments. I really like Van's Aircraft and the people that work there but you do have to watch out for company errors as well as your own.

In your case the bolts wouldn't go in the free standing spar bolt holes so this is not a case of preloading the interface and causing misalignment, etc. The bolts simply do not fit! The fact that you got them in the top is a clear indication that these similar holes were not prepared the same way. A guess is they had a lunch break and an operation on the bottom holes was missed but the cause is unimportant to you in builder's isolation.

My plans book says: "If the bolts are just too tight, careful work with an expansion reamer and clean the holes sufficientlyto let the bolts fit. DO NOT remover too much metal -- the reamer should be adjusted so that only fine, dust-like, particles are removed. This, and coating the shanks of the bolts with lubricant (Boelube, Loctite #771, or something similar) will help them tap home with the proper fit."

This is after a paragraph that says "These fit so tightly that they must be driven in by tapping them with a hammer." and "A large C-clamp used as a press also works well." and "Any paint, primer, or slight mis-alignment of the holes will require excessive force to insert the bolts, so cleaning the holes is essential."

Ream the holes as required to get the job done is what I would do.

Bob Axsom

LettersFromFlyoverCountry · #8 06-21-2005, 07:42 AM

Before doing anything, I'd try to fit the bolts into each part individually. That'll at least tell you if the problem is a wrong hole size or incorrect alignment.

Jeff Vaughan · #9 06-21-2005, 01:19 PM

I have not put the the wing in place yet. I am only test fitting the open spar box holes. Calling Vans today ! Will keep you posted.

Thanks for your help.

Jeff vaughan

gmcjetpilot · #10 06-21-2005, 01:38 PM

I was a structures engineer for Boeing many moons ago. I don't have the exact specs in front of me but these holes are probably "transition fit" holes, may be even interference fit. Before you START to blame Van or REAM holes. DON'T ream holes until you call Van's. This tight fit is CRITICAL for even load transfer and fatigue. Trust me I know.

First the bolts have tolerance and the holes have a tolerance, so they may be at the tight end (max interference) of the acceptable fit range. Also if you did prime them you will have affected the fit. If you must prime or want to add extra protection to the bolts cad plate, then install them "WET". Which means prime them and install them with wet primer right away.

This tight fit is the reason people use undersized pins and hardware bolts for initial or temporary fit up. These bolts take some effort to fit. You DO NOT want to install and remove the actual bolts multi time for test fits. It is best to use the structural bolts for a one-time final installation. If you want to test fit use undersized pins for test fit-ups.

If you don't have micrometer you can get a decent digital one for $20-$40 from harbor freight. Check the bolt dia and hole dia. You can check bolts to see which ones are smaller for the harder to fit holes. Nothing has a +/- 0.0000 tol, the fit will vary from tight to very tight.

I think your situation is normal but you don't give any numbers. Again don't ream them until you measure and talk to Van's. Chance of the holes being not to the proper size is slim. However if the holes a loose, you better look into it.

Cheers George