The wings have doublers under the main skin next to the cabin sidewall to add strength and help support the loads imposed by people entering and leaving the airplane. I made the wing walk doubler from AS3-025×9 3/8×26. Then I laid the top inboard wing skin on a bench and slipped the doubler underneath it. The doubler nearly butts against the aft edge of the main spar channel and overhangs the rear spar by about an inch. I aligned the inboard edges and set the forward edge of the doubler 9/16″ aft of the forward edge of the skin. Using the skin as a guide, I drilled all the holes for each rib in the wing-walk doubler.
I clecoed the forward row of holes in the top and bottom inboard wing skins to the matching holes in the main spar. I then clecoed the top and bottom inboard skins to the ribs using a cleco in every fourth hole. I inserted the doubler between the ribs and the top inboard skin.
The main skins overlapped at the eighth rib from the root. The outboard skin fit on top of the inboard one. I gently pulled the ribs into position so the matched holes aligned with the skin holes.
I then drilled all the holes to final size. I start drilling in the upper middle of the panel and worked down and out toward the edges and worked out any slack as I went. I moved the clecoes down one hole (into the drilled holes) and drilled all the remaining holes. I repeated the procedure for the inboard and outboard bottom skins.
I drew a couple of lines on the main skins that intersected at the center of the hole for the tiedown eye. I removed the bottom main skins before fitting the leading edge and tank skins but left the top skins clecoed.
Time: 8 hours.
Leonard's RV-7A Build 