Clamp the Wd-605 control horn around the corner formed by the E-902 spar and the E-906 rib (carefully center the control horn on the rib and the spar). Match drill the E-902 and E-906 using the prepunched holes in the Wd-605 as drill guides.Rivet the E-902, E-906 and Wd-605 together. Back-rivet the skin stiffeners to the upper E-901-R skin.Rivet the E-902 spar to the skin where it can be reached by the squeezer.
