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Fuel Tank Attach Plate Nuts

DRBuilder

Well Known Member
For Mitch Locke... Why are 1100-08 plate nuts (countersunk) used here instead of 1000-08 plate nuts? The spar flange is countersunk to accommodate the dimpled fuel tank skin with 8-32 flat head screws. The 1100-08 plate nut creates a void between the flange and the plate nut threads.... not good. Not to mention, the 3-3.5 rivets are too short to create a good head on the 1100-08 due to the thickness of the plate nut. I installed the 1000-08 plate nuts in 2 of the locations and they work perfect, with no void between the spar flange and the plate nut threads. Can you comment?

Links to pictures below.... (I tried to post them in the thread but they are HUGE and you need to use the toggle bar to slide back and forth to see the entire photos)

http://www.drrv7.com/files/IMG_0004.JPG
http://www.drrv7.com/files/IMG_0005.JPG
http://www.drrv7.com/files/IMG_0005.JPG
 
For Mitch Locke... Why are 1100-08 plate nuts (countersunk) used here instead of 1000-08 plate nuts? The spar flange is countersunk to accommodate the dimpled fuel tank skin with 8-32 flat head screws. The 1100-08 plate nut creates a void between the flange and the plate nut threads.... not good. Not to mention, the 3-3.5 rivets are too short to create a good head on the 1100-08 due to the thickness of the plate nut. I installed the 1000-08 plate nuts in 2 of the locations and they work perfect, with no void between the spar flange and the plate nut threads. Can you comment?

I'm not Mitch but I know the answer.

This is the exact same thing that has been done ever since the new spar design began being used (RV-8), and the void you are concerned about is not an issue. The majority of the strength is from the dimple acting in shear on the countersink.

The nutplate is used to guide the pilot of your countersink cutter when doing the countersinking.
If you use K1000 nutplates, the cutter will begin cutting into the nutplate before you get to the full depth required for the countersink.

Couple of other comments...

The rivets that are used to install nutplates provide zero strength to the fastener joint. They only hold the nutplate in position and prevent it from rotating while installing the fastener.
Sometimes a rivet a bit on the short side is spec.ed because the next longer would be maybe a bit on the long side and more difficult to set straight.


Everything about the RV14 kit was done for a reason, and the way the kit is supplied is a copy of how the wings were built when the structural testing was done.
So my advice would be a recommendation that builders not make changes without knowing the specifics of why something was done a particular way.

But, as always, this is experimental aircraft and you are free to do it differently if you choose.

BTW, the countersinks in your photos are not deep enough. The countersink depth needs to except the skin dimple, not the screw head, which requires a deeper counter sink than the screw does.
 
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If the countersink needs to be deeper, that would explain why they chose to use the 1100 vz 1000 nut plate. I'll dimple a scrap piece of .032 and use as a gauge for the depth of the countersink. Thanks!
 
That is a good idea. I dimpled two small plates I made from .032 scrap. One has a -3 and a -4 dimple and the other has #6 and #8 dimple. I have used them a lot throughout the build, very handy. Just got to make sure you know which holes get rivets and which get skins,:).

Bird
 
Late Night Snack Attack!

Went to fridge for a late night snack, couldn't sleep so went to garage instead and found a man in a red Santa suite working on this!:eek: After a closer look
It was just Rdog in a red jacket.;)

7f2c8e0845a15dc5cf1f8386dd075803.jpg
 
Countersinking wing skin holes?

For Mitch Locke... Why are 1100-08 plate nuts (countersunk) used here instead of 1000-08 plate nuts? The spar flange is countersunk to accommodate the dimpled fuel tank skin with 8-32 flat head screws. The 1100-08 plate nut creates a void between the flange and the plate nut threads.... not good. Not to mention, the 3-3.5 rivets are too short to create a good head on the 1100-08 due to the thickness of the plate nut. I installed the 1000-08 plate nuts in 2 of the locations and they work perfect, with no void between the spar flange and the plate nut threads. Can you comment?

Links to pictures below.... (I tried to post them in the thread but they are HUGE and you need to use the toggle bar to slide back and forth to see the entire photos)

http://www.drrv7.com/files/IMG_0004.JPG
http://www.drrv7.com/files/IMG_0005.JPG
http://www.drrv7.com/files/IMG_0005.JPG

Hey I noticed in img-005 you had not countersunk the skin attach holes?
I did mine before riveting the plates and was just wondering if there was an issue doing this after riveting?
 
Countersinking Skin Attach Holes

Hey I noticed in img-005 you had not countersunk the skin attach holes?
I did mine before riveting the plates and was just wondering if there was an issue doing this after riveting?

There should not be any issues countersinking them later. There is nothing in the way. I haven't read the entire instruction book yet but so far, there has been no instruction to countersink all the skin attach holes yet. I remember doing that on my 7 with no issues....
 
Missed That

It sure is. I missed that. That also explains the other post about countersinking the rib attach holes. They are listed together in step #3 on page 11-03. Thanks!
 
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