Thursday, November 1, 2012

Adding Hardware Onto The Inboard W-1208 Ribs

Prior to attaching ribs onto the wing’s spar, the plans call for a few of the ribs to receive some hardware. First in line for such treatment … the plans call for selecting a W-1208 left and right rib which has had the forward and aft flanges removed. Both ribs will receive a nutplate as well as a W-00028 doubler plate. Looking forward in the drawings revealed both of these ribs will become the inner most rib of each wing and the doubler plate will be the mounting plate for an electrical connector used for the stall warning and wing lighting wiring.

The plans call for using AN426AD3-3.5 flush solid rivets to attach the nutplates to the ribs. As such, the two nutplate rivet holes on each rib require dimpling, as well as the rivet holes on each of the nutplates. The center screw hole for the nutplate on each rib also requires being drilled out using a #19 drill bit.
                          Using the drill press to drill out a W-1208 rib’s nutplate center hole using a #19 drill bit.
                                             Riveting a nutplate onto a W-1208 rib using the pneumatic squeezer.

If one does not look very closely at the plans, a mistake could easily be made while riveting the W-00028 doubler plates onto the W-1208 L&R ribs. The plans call for using six rivets to attach the doubler plate onto the rib … however, the doubler plate and rib have eight holes in them. Close scrutiny of the drawing and looking ahead in the plans revealed only the upper and lower row of rivet holes in the doubler plate receive the rivets. The center two rivet holes on the W-00028 doubler plates DO NOT receive rivets because they will be used later to mount the previously mentioned electrical connector onto the rib. The plans call for using LP4-3 pop rivets to attach the doubler plates onto the ribs but I elected to use AD470AD4-4.5 solid rivets instead because access for the pneumatic squeezer was good.
                           Using Clecos to attach a W-00028 doubler plate onto one of the W-1208 ribs for riveting.
                         Front and back views of the W-1208 L&R ribs completed nutplates and doubler plates.
                         Note the center two rivet holes in the doubler plate are left open at this time.