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Front Floor Side Alignment

jwilbur

Well Known Member
This seems a little weird. When match drilling, all was good and right. But now that I am installing the front floors, the outboard-most hole alignment is off (These are the holes on top of the joggle that attach to the channel which is in turn attached to the skin). The miss-alignment is off the same amount on both sides of the airplane. I can flex the skin/channel enough to get clecos in, but it seems to take a lot of force. Has anyone else encountered this?

IMG-20140413-00052-1024x768.jpg


IMG-20140413-00053-1024x768.jpg
 
while im not even close to this part. is it possible you put the left on the right and vice versa?
 
My floors required quite a bit of force in that area, too. I'd cleco it up, take a look at the outside contour, and if good install those rivets!

David
 
oil can

My floors required quite a bit of force in that area, too. I'd cleco it up, take a look at the outside contour, and if good install those rivets!

David

Thanks David. I'm glad to hear this. The contour does look OK after I get the clecos in place, but then I noticed a bit of oil-canning. Temporarily installing the forward fuselage rib (with clecos) does help with the oil-canning, but it's most definitely still there. Any oil-canning with you?
 
Hi Joe,

I don't have any noticeable oil canning in that area, but I didn't check for that before installing the ribs. I'd like to believe that riveting in your ribs (vs. just clecos) will stabilize everything nicely.

David
 
Hi Joe,

I don't have any noticeable oil canning in that area, but I didn't check for that before installing the ribs. I'd like to believe that riveting in your ribs (vs. just clecos) will stabilize everything nicely.

David

It's been too long since input those parts,together that I don't remember all the details. I do recall using a 4ft pipe clamp to pull things into alignment. What I can't recall if it was the floor or the outside skin that was my problem.
 
I too had that problem

I also remember having that problem. Maybe not quite as bad as yours but I do remember pushing on the side to get the clecos in.
 
I also remember having that problem. Maybe not quite as bad as yours but I do remember pushing on the side to get the clecos in.

Any oil-canning? Google tells me that others have had oil-canning in this area in the past. I wonder if this is why. What Google doesn't seem to know for sure is if those who have had oil-canning at this stage see it disappear as the build progresses. There were some suggestions that it would (or might) when top skin is in place and when engine is installed. I'm trying to figure out if I should install an additional stiffener. It'll be pretty easy to do now - not sure how easy later.
 
None

Don't have any oil canning (At least in the fuselage). I do have stick-on sound insulation in that area as well. (In case it has an effect)
 
As I recall, I had about the same gap. I believe that the floors help with the shape of the outer skin in that area. Just a little inward pressure on the fuse skin, and mine went right together.
 
As I recall, I had about the same gap. I believe that the floors help with the shape of the outer skin in that area. Just a little inward pressure on the fuse skin, and mine went right together.

Any oil-canning after it was all riveted together?
 
I wonder why

Mine were not anywhere near that far off in alignment.

I wish I could understand why anyone's are off at all. They most definitely were NOT off when I match drilled everything. They must bow outward somehow when the side skin gets riveted on. What else might cause this?

Also, to get the clecos in I have to push pretty hard on the side. I'm wondering if it makes sense to add a few more rivets to the floor/channel to increase the strength of that connection. Any thoughts on this idea?
 
I'm at this point now.

I believe the landing gear weldments are installed just prior to this. Could that have something to do with it? I know my weldments are going to have to be flexed inorder to get them in.
 
I believe the landing gear weldments are installed just prior to this. Could that have something to do with it? I know my weldments are going to have to be flexed inorder to get them in.

That's not it. The gear weldments are installed after the floors. One segment of the weldment, in fact, sits on top of the floor. Good thought, though.
 
I remember it took a lot of "easing" to get the rivets in. The problem is that the fuselage angle that you rivet to is slightly angled away. Basically, I had to put a cleco through whichever floor hole looked the closest and then guide it into the longeron and then push up to get it in place. Once you have one in, the others are easier.
 
I noticed that when I did my first inspection and took off the top floor panels it was very difficult to put the outboard screws back in. The trick was to install the outboard fasteners first and work toward the middle of the plane. I don't know why this went together easier but the center holes lined up perfectly using this method. Perhaps it will work the same way when attaching the riveted area of the floor. Might be worth a try.
 
Can you describe oil canning? I am just installing the side skins and longerons so not to this step yet.
 
Can you describe oil canning? I am just installing the side skins and longerons so not to this step yet.

Imagine the sound you hear when you squeeze one of those old-style metal oil cans when empty. In this case my front side skins are all riveted to the skeleton but when I cleco on the floors in place (in my case) it results in an ever-so-slight "deformity" or bubble in the skin so that I can press on the skin in that spot and cause this bubble to jump to another spot with a little "ka-chunk" sound.
 
I don't have any oil-canning.

I believe that the amount this is off may be variable based on how the builder made the bend in the front fuse side skin.
 
I don't have any oil-canning.

I believe that the amount this is off may be variable based on how the builder made the bend in the front fuse side skin.

... And probably also the twist in the channel. Now that I think about it, the pressure I have to apply to get the floor clecos installed is probably not removing an outboard "bow" in the channel, but rather twisting the channel to where it needs to be. If the bend in the skin wasn't exactly right, this, I think, will also contribute to the same twisting problem.

I wonder for future builders if it would be better to rivet the skins to the structure while the floors are clecoed in place (aside from the lower rivets which are covered by the floor). If I had done it that way, I'll bet I would have no oil-canning.
 
Well I had to use much force while my wife placed the clecoes. I have oil canning, more on the right than the left. It looks symmetrical and almost as though it was meant to be there. For the life of me I cannot imagine how the floor pan can accept the tension it does with those few clecoes in the lower fuselage channel and not rip apart. Actually the oil panning I have looks a little stylish and I too wonder if it won't disappear as other structures are added. I plan to let the clecoes hold things in place a few days and watch to make sure a gremlin doesn't creep into the structure and make things worse.
 
I'm thinking it would be better to drill using the outboard floor pan holes as guides into the lower fuselage side channel after the skins are riveted in place, not before. I don't think the floor pan should be used to twist the side channel into the correct position.
 
Floor Panel (F1050) & Lwr Fuse Channel (F1041) Matched Drill Holes no longer line up?

Resurrecting an old post. I am having the same issue with mis-alignment between the match drilled holes in the the front floor panel (F1050) and lower fuselage channel (F1041).

Now that the skins are riveted in place, the holes do not line up. I saw in earlier posts, folks putting a knee to the outside of the skin to force it into alignment.....not sure if this is the approach I should take or just drill new holes an inch or two down from the first holes..... sure would like to understand why the no longer line up.

You can notice in the photo, the edge of the floor panel and edge of the lower fuselage channel are diverging. Do other see this same divergence in these two parts....?

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Same problem..but hope to avoid

As I am muscling my way through chapter 29 I have come to the point of clecoing the front skins on for the first time. I have noticed what everyone has pointed out.
The lower F1040 side channel gets pulled away from the floor pans. I took all the steps necessary:
1.) twisted to 20 degrees-digital level confirmed
2.) Bent the skins to nearly be tension free on the bottom when in position (some builders have remarked that under bending can cause this problem)

I have not match drilled anything yet. Is there a sequence that I can do to avoid the possible oil canning or need to use brute force to get something to line up. It has been stated so many times that if something doesn't line up right you probably did something wrong, because Vans makes such a precision kit.

I was thinking about drilling the lower firewall bracket and the lower channel to the floor pans BEFORE doing the skins and leaving the tight curve underneath for last.

Any ideas
 
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