Left rear spar riveting

Came home today to find a nice little present courtesy of Avery Tools. Longeron yoke, some long-reach 1/8” clecos, and a tube of Boelube for good measure. Finally, I can get back to this wing skeleton!

IMG 9069

I got Josie to help me pull the skeleton off the stands and put it back on the workbench. Everything was still clecoed together, so it was just a matter of going to town on some rivets. Well, sort of…one consideration on this rear spar is that there are several different material thicknesses together, and thus several different rivet lengths to use. And there are also holes that need to be left open to accommodate the aileron gap seal and flap brace down the road.

I started on the outboard end; this is a particularly unusual spot in that it gets flush rivet instead of the typical universal head rivets. The reason for this is that the outboard aileron hinge bracket sits on top of this spot.

Outboard flush rivets:

IMG 9070

The mocked-up aileron hinge bracket to illustrate why those flush heads are required:

IMG 9073

From there I went on down the line and things progressed pretty quickly. The nice thing about squeezing rivets is that once you’ve got the squeezer adjusted for a particular rivet length and material thickness, you can breeze on down the line making nice consistent shop heads without the trial-and-error that comes with the rivet gun. Things went great until I got to the inboard end. It seems that I had a rib with a slightly bent flange, and I didn’t catch it before squeezing a rivet:

IMG 9075

That’s a problem. I didn’t think much of it at first; after all, I’m to the point that drilling out rivets doesn’t stress me much. I drilled and popped the manufactured head off, then started tapping it with a punch, but it wasn’t moving. Then it occurred to me why: with that kind of a gap between the rib and spar, the rivet undoubtedly swelled up in the space between. I doubt it’d be possible to drive the rivet out without damaging the rib. So this is going to be a more involved repair than I originally thought.

The good news is that this is the fourth-most-inboard rib, and I haven’t squeezed any rivets in the other three ribs. My hope is that I can drill out the other two rivets in this bad rib and then be able to pull the rear spar out of the way enough to get this bad rivet out and straighten the rib flange. Worst case, I might have to drill out the five rivets in the main spar and remove the rib entirely. Hopefully I can avoid that, as the manufactured heads of those rivets are towards the inside of the skeleton, and drilling them out will be a chore…not to mention the concern of damaging the main spar in the process.

It was late by the time I realized the problem I had, so I decided this was a good time to call it a night. Much better to sleep on the problem instead of trying to attack it all willy-nilly. Tomorrow we’ll see if I can get this all fixed up.

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