Finished fitting mid cabin covers

Whew…so after a weekend of distractions (and ok, also laziness), I got back to work tonight. The next tasks seemed pretty simple, really. Compared to the left cover, where I had to tinker with the fuel selector mount and locate/cut/drill the appropriate holes for that, I figured I was home free. After all, with the right cover I just had to match-drill the two holes in the auxiliary longeron.

And actually, yeah, that part was easy. Then it was just a matter of drilling the holes for the four nutplates for these four screws. And that is where things got interesting. You see, the one downside to working in this area it that it’s right up against the skin. And the skin is curved in such a way to further limit working space.

Drilling the nut plate mount holes wasn’t bad; in fact, it was pretty quick work with the angle drill. But then came the real fun – countersinking those rivet holes for the flush rivets. For four of the eight rivet holes, I was able to use the countersink cage OK, again by making use of the angle drill attachment (man am I glad I bought that chuck adapter for stuff like this). The other four holes…well, on three of them I got partial countersinks, and the fourth was too close to the skin to get the cage on it.

So I got to finish those three countersinks and make the fourth one entirely by hand. I do have an adapter so I can use the threaded countersink/deburring bits in a normal chuck drill, and I thought maybe I could use that to run the countersink bit in the angle drill attachment, but the shank of the adapter was too big for the chuck adapter. (though it occurs to me as I write this that I might have been able to thread the countersink bit directly into the angle drill attachment. Hooray hindsight!)

So instead my strategy was to hold the bit + adapter in place with one hand and turn the shank (which has a hex profile) with a 1/4” wrench, 1/6 of a turn at a time. I would describe this process as “painstaking.” Just tons of trial-and-error and slow going all rolled into one. I’m pretty sure I spent 15-20 minutes just making that one countersink.

But this was just the beginning. The new problem was how in the world to shoot or squeeze these rivets in these tight quarters. There was absolutely no way I was going to get in there with the rivet squeezer, and it seemed equally impossible to get a rivet gun on these things. Maybe if there’s such thing as an offset flush set for the thing, but if there is such a thing, it’s not in my toolbox.

So I decided to just use blind rivets here. The total material thickness here is actually a bit more than the max grip length for these rivets, so this would be unacceptable for actual structural use. But for securing nutplates, the only purpose of the rivets is to keep the nutplate in place – the screw actually takes all the load. And this is just a cosmetic cover anyway, not any kind of structural piece. Thus I rationalize my departure from best practices in this particular instance.

And that’s it for tonight. Looks like things should be a bit simpler from this point forward – next up will be fitting the front seat ramps, and probably working some more with the rear seat rudder pedal setup, which I did some prep work for before getting the fuselage canoe together, in addition to some more work on the right console and throttle quadrant assemblies. After that, I can get back to working on the rear seat floors.

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