CHAPTER 29 - Closing the Wing
With a huge mass of primed parts arriving all at once, I decided to finish the control surfaces first. The aileron stiffeners were back-riveted to the skin, as were the flap ribs to the flap bottom skin. Next, the aileron skeleton was assembled and finally riveted into the skin. This is when I finally discovered my mistake with the rib rivet positions, so I had a bit of work to do as I fit the brackets on. Next, the top flap skin was riveted on and finally the flap spar riveted in place. I should mention that the flap hinge had the center eyelets removed so that the hinge pins could be inserted through the center; loops in the pins are meant to be captured by a screw and nutplate installed in the flap brace.
Once the control surfaces were finished, the assembly of the skeleton began. All but the four most inboard ribs were installed on the main spar and riveted in place. The rear spar was attached and also riveted, along with the aileron brackets and reinforcements. Did I forget the customization of the bellcrank rib? No, that was done prior to attaching it to the spar, as well as the assembly of the pitot mount parts. However, the bellcrank, wiring, and pitot mount were not yet put in place.
Now the aileron was attached to the mounts, the spacers for the inboard bracket fabricated and installed, and the pushrod installed, with the bellcrank temporarily in place. The hole in the rear spar was gradually enlarged until the aileron was capable of full movement. Then the aileron, pushrod, and bellcrank were removed and the edges of the hole touched up with primer.
Now the top skins could be riveted on. With easy access to both sides, this was a day's work for me and my helper, Mike Sherry. Mike is a coworker who was bullied into providing help; Judi and I later treated him to dinner and a movie. Would you believe he wants to help again?
The wing wiring, which runs close to the top skin, was installed. Each rib had a plastic grommet and the bundling was maintained between ribs by spiral wrap plastic. Generous strain relief was left at the tip, for the landing light, and at the pitot tube. The aileron was re-attached to allow fitting of the gap fairing, which had been pre-primed and was trimmed to fit and pop-riveted in place. The nutplates for the access panel were riveted in place at this time, as well.
The bottom skin began with the inboard piece, which was clecoed in place. The first wing-walk rib was emplaced, with the positioning of the wiring bundle, and riveted into position. The remaining ribs were installed in turn. Then I proceeded to work the other direction, toward the tip. Judi did the riveting and I bucked, working largely by feel. I found I could actually get a look at the rivets on the ribs by peeling the skin back and using a penlight; it was awkward getting my head in position around the wing skeleton. The spars were done completely by feel. It was difficult working around the pitot mount; I had to ease the skin onto it and work it into place gradually as the riveting got closer to it. We also had to rivet the attachment on the top skin once the mount finally settled in place. I'm glad I don't have to do this on the other wing!
All that was left was the flap. The brace had been riveted to the rear spar during the assembly of the skeleton. Now I clecoed the flap hinge and skin to it, with the flap attached to ensure alignment. Since it still looked good, I removed the flap and squeezed the final row of rivets. I am not perfectly happy with my hinge arrangement, because it is difficult to work my hands into the space between flap and wing spar, even with the flap fully deflected. The hinge pins went fine until the last few inches, which were both tight and difficult to reach. I'm not sure what a better arrangement might be, but you can bet I'm thinking about it.
Once the access plate was done, I was finished for the time being. The tips won't be installed until the airframe is assembled and the lights connected. Mostly I just spent a day or two looking at it, beautiful even though I could see each dinged rivet (not many, but I dropped a bucking bar once while doing the last skin. It put a couple of small marks on both top and bottom skins, with only one that required careful flattening with a bucking bar and flush set. Other than that, it is straight and the control surfaces have the required throw (though just barely on the aileron). I'm really happy to be done, but ready to go on to the next wing. Hopefully, those pictures will fill in these chapters.
(August 2002) Some explanation for the pictures is due because they were all taken after the fact due to camera problems mentioned in an earlier chapter. In fact, the wing has been in storage for four years, so it has a fair coating of grime everywhere. However, in the first photo you can see the bell-crank and the wiring run through the access hole. On the other wing, the wiring runs straight along the spar but this wing has to have it routed around the pitot mount.
The next photo shows the inboard aileron mount and the hole needed for pushrod clearance. In the shot after that, we look again into the access hole to see where the wires for the pitot heat run to the pitot mount. We can also see the top of the pitot mounting and, through the lightning hole in the spar, the pitot line running to the mount. The next shot shows the pitot tube in the mount.
The last two shots show the small notch cut into the outboard flap skin to clear the aileron linkage when the aileron is fully deflected and the flaps are up.