Drilled the longerons to the skins. Trimmed the ends forward of the longerons to 3/4 from the front of the 770 side skins. Drew a center line on the lower aft flange of the firewall. Clamped the firewall to the longerons and side skins. Installed the lower 772 skin. Aligned the centerline with the second row of holes from the forward endge of 772, and clamped them in place. Drilled the outboard holes threw the angle of the firewall.
