The wing ribs are in two pieces, the nose rib and the main rib.

The nose rib goes ahead of the main spar and forms the curved front of the airfoil.

The main rib goes between the main and rear spars.

The sharp trailing edge of the airfoil is formed by the flaps and ailerons, which attach to the rear spar.

Each wing has 14 main ribs and 15 nose ribs.

The wing ribs are made from one piece of metal, with the edges bent over to make flanges.

The ribs are delivered bowed, because the outline is curved, and the flange causes a bow when it is bent over. You can see that the bow in the rib causes the ends to lift up off of the work bench.

The bow in the ribs must be removed. This is done by forming flutes in the flanges.

The flutes basically shorten the flanges slightly, which removes the bow in the rib.

The flutes must be carefully placed so that no rivets will end up going in the area where a flute is.