JB-weld fill of upper- and lower-most elongated 4mm rib holes

Some time ago I tackled the matter of correcting tolerances in the main spar rib attachment brackets, I was able to upsize many of the rib attachment holes from 4mm to 4.8mm to take 4.8mm rivets, so fully absorbing these tolerances.

The upper- and lower-most 4mm holes were the exception, as these are too close to the bracket edges to make upsizing appropriate. Instead these holes were left unchanged and the holes in the thin rib material elongated as required. In some cases this elongation is up to 1mm, but in most cases a small fraction of a mm.

I sat on this issue for a while, as to whether I should rivet over these elongations with the 4mm rivets (this is I understand the factory practice when such tolerances occur beyond what can be accommodated by finessing the skin fit, with all the holes - no upsizing done at all) so leaving a void under some of the rivet heads, or use JB-weld (steel loaded epoxy) to fill these and presumably make a stronger attachment.

Today I decided in favor of the JB-weld, fairly satisfied there would not be a consequential corrosion issue despite the epoxy being steel loaded. My reasoning is that the steel particles are in a non-conductive suspension, so even if some of these particles are in contact with the aluminum there will be no complete circuits and cell formation even in the presence of an electrolyte. Given this, I see only advantage in using this epoxy.

LH ribs 2, 3, 4, 5, and 6 and RH ribs 2, 3, 4 were given this treatment. The rivet had a small amount of epoxy applied under the head, in an amount sufficient to fill any voids. On setting, the excess readily escaped from under the head, with some also from the tail, making one confident the voids are fully filled with resin.

LH and RH ribs 2, 3 and 4 had already been rivetted but these were extracted readily and cleaned up without incident.

Now the path is free to rebolt the spar caps with some close tolerance AN173 bolts I obtained, because otherwise its AN3 bolts would have obstructed access to the 90 degree drill chuck needed to extract the rivets. I removed the AN3-13A that I had installed, and cleaned up, some time ago. I can then rivet ribs 1 and 201 into place.