Stabilator Skeleton Assembly Completed

The last six ribs that finalize the stabilator’s skeleton assembly were riveted onto the forward spar completing the skeleton.  Solid rivets were used to attach ALL the ribs to the forward and aft spars. In fact, out of the 84 rivets that attach the ribs to the spars, spar box or inspar ribs, only 6 LP4-3 pop rivets were used and those were the ones that went from the aft spar into the spar box .

There was a small dilemma to iron out where the HS-1206 & HS-1204 ribs mated to the HS-1202 forward spar at both ends of the spar.  The lightening holes on the two ribs created a clearance issue. This is because the lightening holes are not just holes, but also rose up from the web in such a way it created a clearance issue for both pneumatic and hand squeezers … this prevented getting on the rivets squarely or even remotely square.

                          Once enlarging the photo, one can clearly see the problem rise in the lightening holes
                          of the ribs. They even interfered with getting a Cleco squarely into the center holes.

All of the ribs thus far have been riveted with solid rivets so it was hard to swallow just giving up and using pop rivets per the plans. Not to be deterred, I broke out the 3X rivet gun and bucking bar to pound the six problem rivets the squeezers couldn’t get to. The spar material is .040 inch and each of the ribs is .020 inch thick so riveting with the rivet gun posed no issues except for the one rivet I screwed up and safely removed without deforming any components …  but not without a time consuming fight.

                                     A 3X rivet gun and bucking bar was used to pound the six problem rivets.

The row of rivets on the right are the rivets set with the 3X rivet gun and bucking bar. You can see the marks the pliers left while trying to remove the top rivet which needed replaced. Will have to give that area a little spray with rattle can primer.

The final pair of outboard ribs that attach to the forward spar are the HS-1205 and HS-1207. Because the outside ribs have no lightening holes, they were able to be squeezed with the pneumatic squeezer… it was tight, but doable.

                                                         Outboard ribs riveted with the pneumatic squeezer.

                                          Squeezing the last rivet to complete the stabilator skeleton assembly.

                                                                   Finished stabilator skeleton assembly.