[GKnut]

During dimpling of the horizontal stabilizer skin, I missed one of the holes. After a breif interlude of adult language, I then began to ponder, how am I going to fix this!?!
Like a game show:
Door #1: Ignore it and the radial crack sprialing to the left from the top of the dimpled hole.
Door #2: Fabricate a small patch and place atop the area, making it rather unsightly and un-aerodynamic
Door #3: Order another skin

Any door out there that I didn't see?

 

[flion]

It looks like you went ahead and dimpled the proper hole. Otherwise, I'd have said flatten the mis-dimple before proceeding. But, anyway, here is what to do: drill out the mis-dimple until it is gone. You don't want it pushing the skin away from the structure, and you also want to be sure that crack is gone.

When you rivet, set all the rivets near that hole except for the one you missed. Then, put a dab of structural epoxy in the mis-dimple. If you can get it between the skin and structure, so much the better, but you basically want to fill the hole. Once it has cured, you can make it flush with the skin and touch up the real rivet hole with a countersink in case the epoxy ran into it. Then, set your rivet. Once painted, no one will be able to tell what happened.

 

[GKnut]

Makes sense. I knew I'd be making mistakes but not this simple and early. I guess the structural epoxy gets pretty hard. Not that I'm planning on it but if drilling out the mis-dimple takes some acreage, when should I start thinking about another rivet for support (i.e. when will the hole be too big)?

 

[brad walton]

Another rivet

I did the same on the top skin of my horizontal stabilizer. My EAA Advisor reminded me that rivet spacing is not structurally critical, but that the number of rivets called for in a particular row is structurally critical. A misdimpled rivet is probably inadequate and placing anther half way between the misdimpled rivet and its adjacent rivet would restore the structural integrity of the row. I don't see the radial crak you refer to, but if it is there, it should be stop drilled to prevent it from propagating, too.

 

[GKnut]

I'll look closer. Perhaps, during my , I mistook the radial of the dimpling as a crack. A mid-spacing rivet does seem the most prudent as well as a permanent reminder to me. The structural epoxy sounds like the best way to "cover it up". You guys are awesome!

 

[flion]

I guess the structural epoxy gets pretty hard. Not that I'm planning on it but if drilling out the mis-dimple takes some acreage, when should I start thinking about another rivet for support (i.e. when will the hole be too big)?

If you drill out the mis-dimple completely, from your photo you will have intruded into the desired dimple, creating what is referred to as a 'figure 8'. The beauty of the epoxy fix is that it will tend to glue the skin to the structure at that spot. Also, if you dress the desired dimple with a countersink after the epoxy has hardened, then the epoxy will support the rivet there. Little, if any, strength will be lost and this will be Ok for a single rivet (don't do this for adjacent rivets). More importantly, any cracks caused by the dimple die must be completely removed. Brad is correct in that you can add extra rivets if you are concerned about the strength but I personally would not worry over a single rivet. Multiple adjacent rivets would require it, but I'd be tempted to replace a skin in that case. It's really up to you and your level of comfort; if you will lose sleep over it, put in the extra rivets.

 

[longranger]

If the cosmetics of it don't bother you, you might consider adding a rivet on either side of the bad hole. This one is on the bottom of my HS:

This is the fix: