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Wing kit page 13-03 “spot priming”

RV-Ogler

Active Member
Step 2 has you machine counter sink for nut plates. Step 4 has you rivet them in place. Step 8 has you spot prime where the anodise was removed during countersinking in step 2. Should the priming not be done before riveting in that case?
 
I don’t have my planes in front of me, but I believe they have you machine the river holes, install the nut plates, then machine countersink the center holes where the tank skin nests into. They want you to prime those areas, but you could also touch up where the -3 rivets were machine countersunk too. I believe they aren’t concerned with the rivet countersinks because they are riveted tight with the nut plate rivets?
 
Yeah could be, I’ve never heard of priming under the head of a countersunk rivet. The way to steps are worded makes it sounds like they want it done here though
 
Step 2 has you machine counter sink for nut plates. Step 4 has you rivet them in place. Step 8 has you spot prime where the anodise was removed during countersinking in step 2. Should the priming not be done before riveting in that case?

That does seem a bit out of order. You could just complete all of the countersinks and do the nut plate installation after you prime the C/S.

Another option is to coat the bare aluminum with Alodine (Bonderite). I just picked up some Alumaprep and Bonderite 1201 today from Aircraft Spruce for this very reason.
 
I just hit the whole flange with a light coating of primer. I suppose you could use a q tip on the individual holes as well.
 
That does seem a bit out of order. You could just complete all of the countersinks and do the nut plate installation after you prime the C/S.

Actually you couldn’t. At least not if you are following the instructions as intended. The K 1100 plates are riveted in place and used as a guide for the pilot when you cut the countersinks for the screw dimples, so they have to already have been riveted in place when you are doing that step. There is not a concern of not having primer under the rivet heads. In fact it could potentially be a problem if you got carried away with the thickness because primer is not a hard material and it could cause loose fitting rivet at a later time.
 
Step 2 has you machine counter sink for nut plates. Step 4 has you rivet them in place. Step 8 has you spot prime where the anodise was removed during countersinking in step 2. Should the priming not be done before riveting in that case?

I think step eight is priming the counter sinks that were done for the screwed dimples, not the countersinking done for the rivets that attach the nut plates. But I haven’t actually looked at the text to confirm.
 
That does seem a bit out of order. You could just complete all of the countersinks and do the nut plate installation after you prime the C/S.

That’s exactly what I did. I made up a little backing plate jig to hold the pilot of the cutter when countersinking for the screw dimples. Worked great and is the same idea as using the nutplates to do this job for you. Then I shot a light coat of primer along the whole spar flange.

https://tasrv14.blogspot.com/2020/03/chapter-13-main-spar-wings-have-begun.html?m=1
 
Step 2 has you countersink the #40 fuel tank nutplate attach holes and step 7 the #40 skin and rib attach holes. Step 8 then says to spot prime the countersunk holes in steps 2, 5, and 7. So the instructions have you prime all countersunk #40 holes, as I read it, so that's what I did using the q-tip method.
 
Actually you couldn’t. At least not if you are following the instructions as intended. The K 1100 plates are riveted in place and used as a guide for the pilot when you cut the countersinks for the screw dimples, so they have to already have been riveted in place when you are doing that step. There is not a concern of not having primer under the rivet heads. In fact it could potentially be a problem if you got carried away with the thickness because primer is not a hard material and it could cause loose fitting rivet at a later time.

The potential excess primer thickness possibility is exactly why I decided to use Bonderite applied with a Q-tip instead of primer.
 
There is not a concern of not having primer under the rivet heads. In fact it could potentially be a problem if you got carried away with the thickness because primer is not a hard material and it could cause loose fitting rivet at a later time.

So Scott- in general unless the directions explicitly call out spot priming countersinks you recommend not priming them due to the variability of the thickness of the primer under the head?
 
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