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Rivet call outs for the Flap Brace to Aft Spar

claycookiemonster

Well Known Member
It's a bit unclear. For the majority of the rivets in the center of the Flap Brace the rivets are AN 470 4-4. They look about right. But then then there is this note on page 14A of the instructions that says, "Rivets may not NECCESS. go through wing ribs." Huh? So, use them even if they're a bit short? Seems a 4-5 would solve that, but it's not called out that way, so I'm confused.

Then the three most inboard rivets require a dimple on the brace and countersink on the aft spar. OK, I guess there are clearance issues requiring a flush rivet. But, I don't see any rivet call out for the outermost two rivets, which must go through the reinforcement plate, and one seems like it NECESSARILY must go through a wing rib?

Phoning a friend....
 
I think the comment about not necessarily going through the ribs refers to the fact that the brace installs down the span of the wing. The rivet spacing is much tighter than the rib spacing.

Take a look at drawing 10A for the whole rear spar callout, which includes 4-5s in the ribs and even longer in the reinforcement forks.

Where are you seeing flush rivets on the flap brace to rear spar?
 
Ok. I'll look at 10A. I've been referencing 14A which shows the flaps and flap brace in profile. Section B-B.

There is a note attached to an arrow pointing to rivets direct onto the spar where there is no additional layers. "AN470AD4-4 Rivets do not necess. go through spar."

A different arrow points to the split section of the flap brace on the inboard end, the note there says, "AN426AD4-9 (flush head) at inbd end. Dimple CTSK W-721 flap brace, machine countersink W707D to fit dimple."

There is no note referencing the outer split section of the flap brace that "steps up" onto the reinforcing plate.

Maybe 10A is a better source.
 
Ok, page 10A makes it clearer, and I'm going to go with it. Not sure why the profile view on 14A mentions 426 flush rivets while the 10A says 470's. Mis-print?
 
Just spoke to Van's. There is indeed a conflict between page 10A and page 14A regarding the rivets used to attach the flap brace to the rear spar. Apparently the same conflict is in the -7 plans too.

Page 10A, when detailing all the rivets along the rear spar, specifies round head 470 rivets the whole way.

Page 14A in section B-B specifies 426 flush rivets at the innermost part of the flap brace where it's "stepped up" onto the thicker section of the spar.

Van's said both are legal, but he recommended going with the dimple and countersink method on those three innermost rivets. The only reason I can see to do this is if there's minimum clearance between the nose of the flap and the structure.

Can anyone comment on how their flap-spar distance looks and whether they did flush or round head rivets here? Is there another reason anyone has run into that might require a flush rivet here?
 
Can I just check the drawings you’re using?
I don’t have a drawing 14A, mines a 14B.
 

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Can anyone comment on how their flap-spar distance looks and whether they did flush or round head rivets here?

I remember doing flush rivets there for those inboard most few. There isn't much clearance with the flap up, could try to take a picture this weekend, working on my condition inspection so will have the wing root fairing off.
 
That would be fabulous! That flap nose to spar clearance is the only reason I can imagine that would justify a countersink into the spar.
Now that I've found the 10A page with the rear spar rivet callouts, I'm not sure why I got so wrapped up on the 14A page, but I guess I found it first? Thanks.
 
I am at this stage also on my QB wings. I looked at a -7 on the field, it has an AN470 rivet on the inboard most hole (not to plans). On the right wing it doesn't appear to hit the nose of the flap, on the left wing the inboard most rivet is just barely scuffing the protective tape that is on the nose of the flap.

I just countersunk the inboard 3 holes and dimpled the flap brace for the CR3212 rivets.
 
I wonder how many people built it all up according to 10A and hadn't even looked at 14A to see the difference? i.e., have AN470's in those three holes and none the wiser.....
 
I have QB wings. I used CherryMax flush rivets on the 3 inboard rivets. If I remember I dimpled the flap brace and counter-sunk the spar double plate W-707. I'm sure I was looking at a rivet call out that specified those rivets. But, I cannot find it in the PDF file right now.


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Again, I spoke to Van's Builder Support this morning, and they confirmed the apparent conflict in the drawings. The -7 plans have the same incongruity too, according to the guy on the phone. I was told that this was "Builder's Option" but he said he'd favor the dimpled and countersunk version. Personally, I'm very leery of ANY cutting into the spar without good reason, so unless there is a real clearance problem, I'm going with the 470's.

Though small, Van's apparently has it's own empires. I asked why they didn't just change to one direction to eliminate the confusion I've fallen into. His reply? "Do you know how hard it is to get Engineering to change...?"

I assume there are plenty of -8's and -7's happily and safely flying around with the 470 rivets specified on the 10A page where all rivets on the rear spar are called out. Why look anywhere else? If there was interference between rivet heads on the rear spar and flap leading edges, I think we'd have heard about that.
 
Well I'll admit I have 470's there because I faithfully followed the plans on sheet 10A, not thinking that excellent detailed drawing would have a conflict somewhere else. I have to think it doesn't much matter if it hasn't been fixed on the drawings in 20 years. If my flap rubs I guess I'll massage something or not worry much about it.....
 
Resurrecting this thread to survey clearance issues with the flap using round vs csk on the outer three rivets on the flap brace.
 
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