In which I get my fill of nutplates

Having had a couple of days to rest up from the four building sessions over the weekend, I was ready to replace the worn down Dremel cutting wheel and remove the piece of metal from the seat rib that had to come out to make an opening for the autopilot servo control arm to fit through. Or something related to the autopilot, anyway. I really have no idea. It's ongoing mysteries like this that keep it interesting.

The Dremel is an absolute marvel for this kind of thing. I'm not sure how I would have done this without it.



At this point, the only thing being installed for the autopilot is a doubler that (I assume) one of the servos will get bolted to. The standard rib wouldn't have been strong enough to support the torque of the big servo motor pushing against the aerodynamic forces acting upon whichever control surface this part of the autopilot ends up controlling. Hence, this relatively beefy doubler. It required a few match-drilled holes first.



There are three holes that the plans insisted be left open, so I stuffed them full of clecos to remind me not to rivet them. That is anything but a foolproof method, of course, because the act of remove-cleco-insert-rivet is fully ingrained into my psyche at this point. Still, I thought I could manage to leave a measly three holes unmolested.

Just to help with the math, the separate page of autopilot bracket instructions called for six holes to be riveted in the case of what they call a PRECONST installation. The other option is POSTCONST; that's for the pitifully burdened people that are trying to install these things into a completed airplane. Not only do they have to drill out some very hard to get at rivets, they get to put in nine rivets for this step. I was happier to only have to deal with the six, thank you very much.



There were another three rivets after those six, but trying to determine that from the plans was a bit of a chore. I think Van's must have had Obscuro the Obfuscating Ostrich come in on Mondays to write some of these directions. Foreshadowing: it got worse. I finally figured out that the three rivets went in the flange of the bracket and the "aft intercostal." What's an intercostal? I have no idea. Ask the darn ostrich.



Here's where Obscuro really got me. See, I'm in the PRECONST clan, so I skipped ahead to Step 3, as directed, completely skipping over Step 2. Well, no, that's not right. I did my Step 2, which was to ignore the POSTCONST Step 2. Which, as it turns out, was not the right thing to do at all. Well, it was the right thing in that it's what I was told to do, but not the right thing in that one of the steps of POSTCONST Step 2 is also necessary for us PRECONST folk. Confused? Here, let me show you.



The part that I was instructed to skip but needed to do had to do with removing a rivet (one that I had just put in two days ago; I think they want me to skip this step out of embarrassment for making me remove something that I wouldn't have put in at all if they had thought to edit the directions on the prior page) in order to swing a nutplate out of the way of a screw that needs to be put in. With the nutplate still in place, that screw ain't going in, PRECONST or POSTCONST.



Of course, what with my having skipped the meatier of the Step 2s, I had no idea why this was the case. I figured I'd just have to remove the nutplate. I went back and read the real Step 2 and realized I only needed to drill out one of the rivets, so there is that. Fifty percent less rivet removal using their method. That ain't nothing.



Unfortunately, the drill bit went through the hole and nutplate as the rivet was drilled out and bent the nutplate down. To get it back where it belonged so I could rivet it back in, I had to clamp it.



I thought it might be a good idea to get the don't-rivet-here clecos out onto the other side of the rib so that I wouldn't end up building so much airplane around them that I couldn't get them out. That was also beneficial in reminding me not to rivet into those holes as I riveted all of the rest of them. Obscuro's drawing showing where rivets needed to go was obscured (or course) on the far side of the ribs and there was no "LP4-3, 12 places" (or whatever - I don't remember exactly how many it was) to tell me how many to expect - just "LP4-3 TYP." That usually means fill every hole you can find with a rivet, but doesn't necessarily countermand a "LEAVE OPEN" directive. Man, this stuff can get confusing!



So what's my beef with nutplates? Well, I thought that I was at a pretty good stopping point, but the next step was simple: put eight nutplates in the brackets that will hold one of the seat belts and rivet those brackets into the three holes that I had been obediently keeping open. How hard could that be?

Normally? Pretty easy. Especially since four of them used flush blind rivets - the easiest kind! Except this time, one of the nails broke off in the rivet puller, leaving an obnoxiously long remainder in the rivet. Obviously too long to just leave in there, but too short for the rivet puller to get a grip on.



That's never happened before!

But good things? They come in three. It was only a couple of rivets later that it happened again!



The third time it happened, I decided to remove the broken nails and call it a night. The only way I could get them out of there was to remove the tip from the rivet puller so that it could get a grip on them and pull them out. Without the tip, though, the head of the rivets extruded themselves up into the rivet puller. When that happened, they were no longer flush and had to be drilled out. When I was putting the replacement rivets in, I found that using the next smaller size tip would pull them without breaking them as the larger tip had, but the nails would jam in the puller. I had to take it apart after each rivet to get the nail out.

And that is how I came to have my absolute fill of nutplates.

I did go ahead and cleco the parts together, though.

In which I end with an emphatic NO!

Well, I started a new page which I shall call 21-05. There's something you need to know right up front about old 21-05: there's a lot of room for mistakes to be made on this page. All eight of the seat ribs will come into play, but they are divided into four groups of two, each group being subtly different in its mix of belt restraints and nutplates.

Here's some free advice: as each of the pairs get completed, use the Sharpie to mark which step you were on when you put them together. That's how they're going to be referred to when you have to select them in later steps.

The first strange thing I noticed was that those factory-made dimples I was so happy about? They missed a few.



Odd. As with things like this that I've noticed in the past, I'm sure there was a reason for it. I'm less than certain that I will ever know what that reason was. It's not a problem by any stretch - I'm so used to dimpling now that I do it almost robotically.

I struggled with the math again, though. Step 3 has four nutplates to be dimpled, but they then get riveted onto two seat ribs. That math flat doesn't work. I had to assume that I actually needed to do eight of these.



The riveting too has become second nature, although every now and then I run up against something like this that appears to be completely impossible:



And it appears to be impossible because, well, as much as I hate to admit it, it is. A blind rivet gets used here.



A little acronymal advice for you there on the picture. If you don't get it, google it. Although, it may be NSFW. (Google will know that one, too)

On the opposite end of the confusion spectrum, I saw this little tidbit:



Long time readers will remember how put out I was when a similar notice was NOT given when the same type of flush blind rivets were to be used on the horizontal spar box. I only found out about it before making an expensive mistake by seeing it mentioned on someone else's blog. I still wonder why (well, "if" - it's not like I've gone back and checked) Van's hasn't released a revision for that page in the empennage kit.

The parts that were to be countersunk are a pair of braces that will provide additional beefitude to the ribs that hold the mystery mixer box and the other little box that I built.



These braces were interesting because while it was the case that they would only match the holes in the rib in one direction, they would still match if you flipped them over. For a perfectly flat piece, that would make absolutely no difference whatsoever. In this case, though:



They aren't. Perfectly flat, that is. They're bent. Curved. Parabolic, as it were. Is this a problem? I don't know. It is not mentioned at all in the plans. I tossed a coin and decided that I'd install them bowed down into the ribs. It didn't seem to matter.



From the other side:



The plans specifically said to rivet on the brace; they said nothing about riveting the rib to the flanges of the mystery box. So I didn't. I marked them so I remember to keep an eye out for the step during which those rivets get installed. Just in case.



I have to apologize that I can't provide any help regarding how to keep track of the eight ribs and which goes where (or when or why, for that matter) - I puzzled my way through it and ended up with another pair of ribs holding a mystery box. In this case, the mystery box. Yes, it's the magical flaperon mixer!



I had been wondering when the autopilot servo brackets were to be installed. The autopilot kit came out after the RV-12 was in production, and I wasn't sure if the standard plans included instructions regarding when to install the brackets. The brackets and a single page of instructions came with the fuselage kit, though, so I knew it had to be done eventually. I'm keen on getting it done during the build because I've heard that while they can be installed later, it's a PITA. (You'll have to go to www.urbandictionary.com for that one. Hint: it's not bread.) In light of that, I was happy to see this:



I was less thrilled about this:



A single-word command: REMOVE.

I replied with a single word myself: NO!