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Confusion about nutplate for rudder counterweight

B

BrettShaffer

Member
So I'm at the last part of the rudder, section 7-12 step 3. Instructions refer to section 5.16 about nutplates which basically states various ways to accomplish getting a flush rivet in a small nutplate including modifying a dimple die, using a different rivet, etc.

I managed to get the nutplate dimpled for a size 3 flush rivet. But no where does it say to dimple the flange of the skin. I called Vans to confirm and they said to dimple the flange. So I went ahead and dimpled the flange, only to realize that it creates an issue with how the counterweight lays on the flanges. There is no corresponding countersink specified in the aft end of the counterweight. I must be missing something here. Any suggestions?
 
BrettShaffer said:
So I'm at the last part of the rudder, section 7-12 step 3. Instructions refer to section 5.16 about nutplates which basically states various ways to accomplish getting a flush rivet in a small nutplate including modifying a dimple die, using a different rivet, etc.

I managed to get the nutplate dimpled for a size 3 flush rivet. But no where does it say to dimple the flange of the skin. I called Vans to confirm and they said to dimple the flange. So I went ahead and dimpled the flange, only to realize that it creates an issue with how the counterweight lays on the flanges. There is no corresponding countersink specified in the aft end of the counterweight. I must be missing something here. Any suggestions?
Click to expand...

I think I figured it out. Dimpled the wrong direction? Is the flush end supposed to be along the side of the counterbalance weight?
 
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My step 3 does not show using nut plates but rather washers and nuts. Did this change recently?
18.jpg
 
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So that is interesting.

So you are correct. In step 3, drill the #40 holes in the flange of the counterbalance rib and dimple them inboard toward the nutplate (as shown in the picture). The instructions do not mention the dimple of the nutplate or the flange, yet call out the 426 style rivet.
 
catcrew said:
So that is interesting.

So you are correct. In step 3, drill the #40 holes in the flange of the counterbalance rib and dimple them inboard toward the nutplate (as shown in the picture). The instructions do not mention the dimple of the nutplate or the flange, yet call out the 426 style rivet.
Click to expand...

Yep. I can't think of a single place where the shop head isn't on the nutplate when using a flush rivet. They're always countersunk to make the skin flush.
 
I've been using the "oops" rivets for nutplates exclusively. They only require a real light countersink, like a heavy deburring to sit flat, and don't require a dimpling of the nutplates! Saves a step!
 
Doesn't look like I dimpled the flange, I probably counter sunk the flange.
 

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