Built a tool to push the flang back into position for the installition of the pop rivets. I was able to inert a stick that pushed on the flange on one end and the forward spar on the other… making the hypotenuse of a triange between the rib and the forward spar, at a small angle between the the stick and the rib. This was pushed into positon, held in with a long stick and wedge in the open area between the HS halves, then the rivet was popped. Worked great .. and didn't have to remove the skin to fix