csink wrong side of rear hs spar

[delusional]

On web of the rear of the rear hs spar there are a couple of rivet holes that get machine csink to provide clearence. I mistakenly csinked an adjacent hole, which mates to the doubler. In addition I also csinked the front instead of the rear of the spar web. So this extra csink is on the mating surface between the doubler and spar. I guess the good news is that no one can see it, once assembled.

The question is can I do anything about it other than increased inspection and is it worth making a new spar? The csink is slightly undersized, luckily. Or, where can I buy a double-ended rivet with a flush head in the middle but only facing one way, not the other?

 

[flion]

You can fill with structural adhesive (hysol) or similar. Then re-drill and prime as normal. Since you are not going to countersink the other side (if I understood which rivet you are talking about), you could also fill by gluing in a rivet, shaving both sides flush to the web, and re-drilling. I don't think you'll lose much shear strength, if any. The important thing when using an adhesive like this is not scuffing the part but making sure it is absolutely clean - Naptha or similar with a clean rag just before application works wonders for making a good bond. Don't fill with light fillers or glue with cyanoacrylate ('super') glue as they are brittle and won't survive the riveting process. Structural adhesive is both strong and slightly flexible - intended to withstand shear and tension loads at a joint.

 

[papamike]

Repair washers

In the absence of locating an actual repair washer (which do exist), you can duplicate the countersink in a piece of scrap material, shoot a rivet, then carefully drill out the head of that rivet, making sure you get the hole as centered as possible. When the head breaks off, keep it, clean it up as much as possible, and place it in the bad countersink (we use sealant to keep them in place), then install the doubler on top. The rivet head will support the doubler as a new rivet is placed there in the right direction.

We use these on big airplanes when we drill out factory flush rivets and install a repair over that area.

You can PM me if you want and I can see if I can get you 1 or 2 of the correct size washers.

FWIW

 

[scsmith]

neat trick!

Cool! I'll remember that if I ever have this issue, neat trick, thanks.

Steve.

In the absence of locating an actual repair washer (which do exist), you can duplicate the countersink in a piece of scrap material, shoot a rivet, then carefully drill out the head of that rivet, making sure you get the hole as centered as possible. When the head breaks off, keep it, clean it up as much as possible, and place it in the bad countersink (we use sealant to keep them in place), then install the doubler on top. The rivet head will support the doubler as a new rivet is placed there in the right direction.

We use these on big airplanes when we drill out factory flush rivets and install a repair over that area.

You can PM me if you want and I can see if I can get you 1 or 2 of the correct size washers.

FWIW

 

[delusional]

Thanks for the suggestions

It sounds like there are options for treating this as a repair, but since I have not yet set one rivet in the spar and a new one is only around $20, I think I will go that route.

So, anyone have use for a slightly damaged rear HS spar for a rv-9?

 

[flion]

The spar is only $20, but wait until you see the shipping cost.