Made up a jig to pull the miss-drilled hole as far as possible toward the skin pilot hole. Then made a plug from 0.016" 6061 aluminum to fit the resulting half moon shape of the skin pilot hole. When I rivet through the full size hole, the skin plug will be captured by the external head of the rivet and the rib flange. I will add a new rivet to the pattern adjacent ot the repaired hole to make up for the lost strength.
