Left Flap Done

Time: 8 Hours

I had beautiful weather again today so I had the Hangar door open to enjoy the day while building. The first task was to get out the tools to dimple the skins of both flap skins. I had to use the DRDT, pneumatic squeezer and my close quarters rivet puller dies to get to all the holes. I didn’t take any pictures of this as you have seen them before. Before I did any riveting I decided to work on the V block jig Van’s describes. I used the boards that I used to sandwich the ailerons. I cut two of them 14″ and left one factory end on each of them so I had a square surface. I then lined them up and screwed them together. I then used one of the exterior ribs to come up with the V angles.

A couple of minutes at the bandsaw and I had 2 identical V brackets.

I then added a couple of 2×4 legs to allow me to screw them to the workbench. I just used one of the flap top skins to determine how far apart to put the brackets.

So now was the time to start riveting. I decided that I would do an item on one flap then repeat it on the other. The first task is to rivet the single hole at the aft end of the interior ribs to the rear spar that is actually the bottom skin curled up. The interesting this is that during mock up I needed 4 shims on the left flap and when I set it up after dimpling I no longer needed them as the rib was right up against the spar! Go figure.

Next was to rivet the main spar angles to the spar making sure you leave the holes that attach to the inboard rib open for later.

I then decided to work on the piano hinge attachment point. Van’s gives you two options for the pin, leave it as one length and cut it in 2 pieces removing a couple eyelets of the hinge to access them. I chose the second as it is pretty popular and makes for easy removal of the flaps. My buddy Glen gave me a photo from his build on how he did it so I just replicated his. First up was to measure out where I wanted the ends to layout which told me which 3 eyelets to remove(2 from one side and 1 from the other). It ended up being that I wanted to leave 65 eyelets from the outboard end of the hinge, removing 66-68 eyelets. I then had the area that I would need a nutplate on the spar. I drilled matching holes on the left and right spars. I used that hole and a screw to align the nutplate to drill for the 2 rivets.

I then cut 2 eyelets to make my retaining brackets(you will get the idea at the end) and drilled them together for the screw and hit both sides with the scotch-brite wheel so the were perfectly matched.

The inboard rib gets riveted to the double plate as well as the nutplate that connects the flap control arm to the flap.

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Now I had all those items done on both flaps I reassembled the flaps and set the right on the shelf and put the left in the V jig I had made.

Once you have the flap tight in the jig you can remove the spar so you have access to the inside to rivet. I got one of my bucking bars and taped it all up except on on the faces so I didn’t scratch up the inside of the skins.

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20140511-214606.jpgI took a couple of photos to see if you can see how I used this bar. For the top to bottom skin overlap the bar just rested on the rear spar and worked like a charm.

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I was able to rivet all the skin overlap holes pretty easy. For the skin to ribs I ended up using my little 3/8″ thick 1.5″x1.5″ bucking bar since it’s pretty tight in this space. It took me several hours to get all these interior rivets.

On the inboard rib there are 4 rivets at the aft end on the top and bottom that are aft if the rear spar and you have no choice but to use MK319 blind rivets here.

After you get all the interior ribs done you can slide in the spar and start riveting the spar to ribs with LP4-3 blind rivets. The lower side rivets are easy to get to but the top ones require a little manipulation of the rivet stem and the top skin. I found that my cheaper rivet puller fit pretty nice.

I then moved on to the top skin to spar holes. I tried a couple of different bucking bars with different amounts of success. I ended up using my longer 1″x1″x6″ that had an angle on one end. I also tried this one too and it worked ok as well.

Those rivets went really fast as I worked down the line. You then can work on the bottom skin to spar to hinge holes.

So that was all the rivets on that flap! It was a long day but I still wanted to finish the hinge pins so I could clean the flap and call it complete. I cut the pin in half and made several measurements and took them to the vise to make some bends. One bend to follow the spar flange and one to send it to the nutplate and retaining clip I made earlier. Once I had all the bends right where I wanted them in bent the ends just a little to keep the retaining clips from falling off when removing the pins.

I was real happy with how the pins came out. I just need to do a final trim of the other ends as I left them a little long. I then took the flap out of the jig and cleaned it all up. 1 down and 1 to go, sometime this week.

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