Drilled Tank Drains and Fuel Cap Flanges

I positioned the fuel drains and match drilled them to the skins.



For the fuel cap flanges, I drew reference lines at the top and bottom.



I then positioned the flanges in the precut holes in the tank skins so that the hole is centered and the lines I drew are visible in the top and bottom rivet holes. 



Before drilling, I confirmed that the fuel caps are centered in the hole in the skin.



Both fuel caps are now match drilled to the skins.