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Empennage Mistake

Floresb18

Member
So I made my first mistake when I misread the plans while countersinking the flanges on the VS-1003 spar. The holes at the top of the spar where the skin mates to it but the stiffeners don't on the back side, I countersunk all the flange holes instead of dimpling the top 5 or 6 holes. I actually found it quite miraculous that the holes didn't elongate and cause the countersink to chatter in the holes. Anywho, probably going to order a new spar tomorrow, yalls thoughts?
 
You can take pics and bounce it off people. Ultimately I always talked to Vans to see what they thought. 9 out of 10 times it was to reorder parts, I also had to reorder a new Spar after messing up on some match drilling.
 
I think Vans will tell you that the countersunk holes will be just fine. The below was shamelessly stolen from an old post.


Excerpt from Vans FAQ:

"For AD3 rivets, .032 is the minimum allowable skin thickness [for countersink], and for AD4 rivets, .050 is the minimum thickness. Metal thicker than this is difficult to dimple, so it is common practice to machine countersink for AD4 rivets.

While it is acceptable practice to machine countersink metal as thin as 0.032? for an AN426AD3 (3/32?) rivet, we recommend dimpling in metal 0.040 and thinner. There are a couple of reasons. First, although RVs are designed so that a countersunk joint is acceptable, the interlocking nature of a dimpled rivet line is stronger. Second, dimpling leaves a thicker edge for the shop head of the rivet to form against, meaning that the metal deforms less and there is less chance of ?working? rivets later.

This recommendation is meant as a guideline, not an absolute rule. There may be instances where countersinking in 0.032? stock makes the job easier, and certainly can be used. "
 
Thanks Bill and Justin, appreciate both of your feedback

I just went ahead and ordered a new spar. I thought I was reading far enough ahead in the plans but my focus was mainly on the assembly as a whole and not so much on the dimpling/countersinking piece of it. My education lesson for this week. On a good note my AKZO primer comes in today so I can begin priming prepped parts and move onto the rudder until the VS spar comes in.
 
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