Machine countersunk nutplate rivet holes and dimpled screw holes in upper fuselage doubler. Clecoed doubler to upper firewall, then clecoed and match drilled F-1201J and F-1201K cowl hinges. Machine countersunk rivet holes in upper fuselage doubler. (page 29-02, steps 4 and 5; partial only since both steps include riveting that's not done yet).
