[Mohammed]

Another stupid mistake that may cost me a third VS rear spar assembly and a lot of valuable time!

All the rivets in the lower part of the rear spar should be flush rivets. Mindlessly I dimpled, counter sunk and flush riveted only the 10 rivets connecting the 410 hinge brackets. The remaining I just installed universal head rivets. You can see that very clearly in the spar assembly to the left and top.

Can I just drill out the rivets and then counter sink the attached spar and doubler?

Or should I just use the old assembly with bad rivets on the 410 brackets and deformed spar flanges (right and low assembly in the picture)

I really don't want to do this for third time

Mohammed

 

[YellowJacket RV9]

On my -9 VS, that piece is .032", which is generally accepted as the minimum accepted thickness to machine countersink. If your 8 is the same, or thicker, I think you could probably just remove the standard rivets, countersink those holes, and redo with flush rivets. Option #2 would be to remove ALL the rivets, dimple where needed, and then re-do. This brings up more room for error with all the rivet removal, however. I would ask Vans, but I'll bet they tell you you can remove and countersink.

Chris

 

[Mike S]

Can I just drill out the rivets and then counter sink the attached spar and doubler?

This sounds like a question to ask Vans---------countersinking removes material in a part that is a major structural part of the tail assembly.

 

[az_gila]

On my -9 VS, that piece is .032", which is generally accepted as the minimum accepted thickness to machine countersink. If your 8 is the same, or thicker, I think you could probably just remove the standard rivets, countersink those holes, and redo with flush rivets. Option #2 would be to remove ALL the rivets, dimple where needed, and then re-do. This brings up more room for error with all the rivet removal, however. I would ask Vans, but I'll bet they tell you you can remove and countersink.

Chris

The numbers you quote are for 3/32 rivets.

Those are 1/8 rivets shown and the minimum countersink thickness is 0.050.

https://web.archive.org/web/20061015190951/http://www.vansaircraft.com/pdf/section 5r9a.pdf

A call to Vans is definitely in order, perhaps they might allow NAS1097 rivets, but they are structural and holding on the rudder hinge points.

 

[Mike S]

Gil, take a good look, the ones holding the hinge mount are done correctly.

It is the ones above them where the V stab mounts to the rear fuse bulkhead that I believe he is talking about----------need to be flush so the spar and bulkhead can mate up correctly. At that is how my 10 is put together in this area.

 

[Mohammed]

I sent an email to Vans with this topic link.

I just want to point out that the image is not photoshopped to show both sides of one spar, those are actually two different spars. The old one is the one to the right with brackets shown. The new one to the left is the one with the wrong rivets being set. Note that one the new one the rivets of the brackets are the correct ones and they are set properly. The rivets above the brackets are wrong ones. In the old spar all the rivets are the right types, but the brackets ones are not set perfectly.

 

[Mohammed]

Gil, take a good look, the ones holding the hinge mount are done correctly.

It is the ones above them where the V stab mounts to the rear fuse bulkhead that I believe he is talking about----------need to be flush so the spar and bulkhead can mate up correctly. At that is how my 10 is put together in this area.

You are exactly right Mike S.

 

[az_gila]

You are exactly right Mike S.

They are still 1/8 rivets though....

Van may permit less rivet "power" here due to the assembled sandwich effect after the vertical fin is installed, however it's certainly a structural question for the designer.

 

[rvbuilder2002]

The numbers you quote are for 3/32 rivets.

Those are 1/8 rivets shown and the minimum countersink thickness is 0.050.

https://web.archive.org/web/20061015190951/http://www.vansaircraft.com/pdf/section 5r9a.pdf

A call to Vans is definitely in order, perhaps they might allow NAS1097 rivets, but they are structural and holding on the rudder hinge points.

Gil, take a good look, the ones holding the hinge mount are done correctly.

It is the ones above them where the V stab mounts to the rear fuse bulkhead that I believe he is talking about----------need to be flush so the spar and bulkhead can mate up correctly. At that is how my 10 is put together in this area.

Yes, but Gil is correct.
All of the rivets that attach the spar doubler to the spar web are 1/8" rivets. The bare minimum material thickness that can be mach. countersunk for 1/8" rivets is .050. The spar web is only .032, so it should not be machine countersunk for flush rivets.
The only way I see to salvage this assembly would be to carefully removing all the rivets, dimple the spar web, and machine countersink the doubler for the dimples... then re-rivet.

 

[xblueh2o]

Because I know me, when I do parts like that I am the king of blue tape and sharpie notes. If a part is supposed to have multiple kinds/lengths of rivets I will pick one type and run a line of tape across the holes that use any other kind. When I switch to the next kind/length I re-tape. I use up lots of tape but it keeps me moving forward.