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Wing replacement

Tsabean

Active Member
Rebuilding an RV4 and have a new set of wings and matching F404 bulkhead. I need to remove the original F404 bulkhead from the fuselage and replace it with the new one. Any advice on how to remove the original bulkhead?
Thanks, Tom
 
Tom,

If the original 404 bulkhead isn't damaged, you might consider leaving it alone. I don't have an exact count, but I recall nearly 50 bolts holding those wings to that bulkhead.

The important connections are in the spar splice plates. Make sure those are matched to the wings.

The next most important bolts are the outboard bolts near the fuselage side walls, but still inside the fuselage. Do your best on those.

Lastly, run this past Van's tech support to see if it's OK.

Of course, you'll have to enlarge some of the original holes, but the clamping pressure of almost 50 bolts is likely more than adequate to compensate for a few ugly holes.

YMMV.... check with Van's then report back please!
 
Tom,

If the original 404 bulkhead isn't damaged, you might consider leaving it alone. I don't have an exact count, but I recall nearly 50 bolts holding those wings to that bulkhead.

The important connections are in the spar splice plates. Make sure those are matched to the wings.

....

Check the size of those spar splice bolts. Sometimes Pholgiston drilled spars needed to over-size a hole and the factory supplied an oversize bolt for that specific location.

My -6 spar had one of these bolts, and it wasn't an anodized spar.
 
Tom,

I?ve done this. It was a bear, but it can be done. I did it by making the F-404 assembly into two sub-assemblies. One set of F-404A uprights was one assembly, the lower F-404 D and the other uprights were the second sub-assembly. They had to be riveted together after they were in place. This required some back riveting, but it can be done. In order to remove the old F-404 assembly, I had to first remove one set of F-404A uprights also. I didn't see any other way to accomplish this.

I built a 4 that had been started by another builder. They didn?t keep the F-404 assembly properly positioned when riveting it into position during fuselage construction. The gap for the main spar shifted slightly making it too narrow for the spar. The bolt holes had also shifted. I had to purchase all new parts for the F-404 assembly and match drill them to the existing holes in the main spars. This required setting up the completed wings in my living room (my wife still talks about this) with the proper dihederal, clamping the new parts to the spars, then match drilling each hole. It was a big job. It took me 160 hours to complete the repair. If your new F-404 bulkhead and wing kit (spar) are already drilled, it should not be as difficult for you.

Mine is an early kit (#68). The early RV-4 kits didn?t come with these components drilled, it was up to the builder. At some point Van?s started drilling these at the factory. My guess is that they built a drill fixture and drilled them on a drill press but that?s pure speculation on my part.

A call to Van?s could be made to find out if they feel a different spar may line up well enough to be used with the existing bulkhead assembly. It states in the construction manual that even the assemblies drilled at the factory should not be considered interchangeable. They emphasize how critical this assembly is.

Be certain to make a spacer the same thickness as the spar and keep it bolted in place in the F-404 assembly when you rivet your new assembly into the fuselage. Hardware store bolts are good enough for this. If the first builder of my kit would have done this, I wouldn?t have had to remake the F-404 assembly.

Good luck.

Cameron Smith
RV4 #68
 
I ran into a guy who had to swap wings on a -4 about 20 years ago. IIRC, the original wings were the pre-built spar variety, and the replacement wings (bought from another builder) were also pre-built spar wings. He decided to at least try the replacement wings in his original center section before digging it out of the fuselage, and discovered that everything lined up perfectly.

No guarantee that it will work with the next plane, but at least there's a chance.

Charlie
 
$ rv4 $

assuming the wings are removed from the fuse you want to use, see if your new center section will bolt up the the old wings. if it does then it seems to me that the 2 sets of wing and center section are a match. and no need to tear into the fuse, make sense?, and of course ask vans mountain.
 
Been away on a work cycle, just getting back to project. I had spoken with Vans a couple of months ago re using the original fuselage bulkhead and they suggested the it would be better to use a new bulkhead and splice plates. Since it looked like it wouldn't be that difficult I started to remove the original bulkhead. Turns out it is way harder than I thought. Wish I would have posted here prior to starting the removal process, let's just say the original is not going to be reusable.
Cameron's suggestion above looks workable and I will proceed along those lines. Thanks to all for suggestions.
Cheers, Tom
 
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