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Vertical stabilizer countersinking

OrenAir

Active Member
On 6-04 it says to countersink the doubler that connects to the spar. It shows in figure 2 the VS-410PP using 426 rivets but they seem too small to countersink. Do I countersink them?

Also, there is a big area in figure 2 that says "flush head on forward side", but if I countersink on the forward side I'm countersinking into the spar which is thin also, and the directions don't say to countersink or dimple the spar. What am I missing?
 
The info you are missing is Step 5

Step 5: Machine countersink the #30 holes in the
VS-808PP doubler that attach the doubler to the
VS-803PP Rear Spar for the dimple of an
AN426AD4 rivet. See Figure 2 for locations.
Dimple the corresponding #30 holes in the rear
spar for AN426AD4 rivets.

Since dimples and countersinks only apply to flush rivets, this step will only apply to holes where a symbol for a 426 rivet is located (the flush head fwd side zone at the bottom).
So, since the flush head is fwd, you dimple the spar web to be flush on the front and then machine C.S. the fwd face of the doubler to allow for the dimples. (Refer to Section 5 for details on countersinking for a dimple).
 
I see it now, that last sentence. I must have read it ten times but for some reason didn't see the sentence about dimpling the spar. Time to take a break and come back to the build later.

Thanks Scott
 
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