Saturday, April 24, 2010

The threat of rain

Saturday morning and the immense lawn of my palatial estate requires mowing. Again. Seriously, in my opinion grass is nothing more than the weed that had the best PR department when suitable lawn coverings were being decided. But, the threat of rain! Granted, it was about the same level of threat as a Chihuahua giving you an irritated glance, but I latched onto it like Wile E. Coyote when a new Acme Products catalog shows up in his mailbox. No mowing today, might as well head down the shop!

Having deferred the installation of the last two baggage floor supporting riblets the last time around, I knocked those out pretty quickly. With those in place along with all of the other ribs that will support the baggage floors, it's not surprising that the next step is to rivet the baggage floors onto those ribs. A few different rivets get used; the first are regular LP4-3 blind rivets which go into all of the undimpled #30 holes in the baggage floors. I clecoed about half of the holes and pre-placed rivets in the rest.

The next set of rivets are flush blind rivets - those go into all of the dimpled #30 holes. I chose to do the ones that are in the same row as the non-dimpled holes first.

That just left the holes that run along the tunnel section. I used the silver clecos in the #40 holes since there are only three of the #30 holes and the baggage floor skin was curling away from the baggage rib flanges. I needed a bit more than the one or two #30 clecos I would have been able to use.

I think the most defining factor of the work I've been doing lately is installing nutplates. It seems that every other step involves dimpling and installing nutplates. And the K1000-08 nutplate in particular has achieved a level of ubiquity rivaled only by GEICO commercials. That's why it came as somewhat of a surprise to notice (and I'm glad I noticed! This would have been very easy to miss) that this particular batch of nutplates was comprised of two variants.

The blue indicates K1100-08 while the red shows K1000-08. The numbers are so visually similar that it would be easy to miss the distinction. Conversely, the rivets themselves are quite distinct.

The K1000-08 is on the left. The K1100-08 on the right will be used in the holes under the right side baggage floor. As I've surmised before, those holes will eventually be home to screws that will sit flush to the floor to make room for the fuel tank.

With the rivets selected and positioned near their ultimate resting places, all that was left to figure out was how exactly some of the nutplates were to be put in position, considering that access to the holes was blocked on all sides by the bulkhead and floors. See the back row of nutplate holes and how there's no access to the bottom of the baggage floors? Yeah. Bummer, that.

The trick is to flip the whole assembly up onto its side and install them from the bottom.

Note how I managed to focus the camera on my emerging bald spot instead of on the nutplate I was clecoing into place. Nice. I'd have been better off mowing.

With one cleco in each of the rivet holes, it easy to rivet them into place. Note that these are the CSR flush blind rivets, not the normal LP4-3 blind rivets.

The remaining four nutplates were accessible from the sides of the floors, so they were installed with the normal AN4263-3.5 flush rivets and the rivet squeezer. Once those were done, I wiped the whole deal down with MEK to remove the Sharpie writing and my grubby paw prints.

So, do you remember those bearing brackets that I put together last time? The ones with the gap between the plates that I was worried about? The ones that I was wondering why I was putting together at that stage in the first place? Well, here we go. The next step is to install a plate between two of the floor riblets to provide support for them.

This was another of those cases where it was going to be easier to get at the riveting by flipping the whole thing over and coming at it from the bottom.

Having grown accustomed to working inside these parts to rivet through the flanges, I just automatically bend the rivets and grab the little close-quarters wedge thingy right away. Doing it that way helps get sufficient clearance to get the rivet puller down in there. This is probably the best picture I've been able to get that shows what a difference the wedge thingy makes.

The bearing assemblies go in with the heads of the flush rivets up against the skin. That shouldn't surprise anyone - can you imagine how poorly it would fit the other way around? Here's some good news: look at how the cleco in the back pulls the plates of the bearing assembly together! I was worried that the gap between them was going to be a problem. It looks like it won't! Unfortunately, having that cleco there made the rivet inaccessible enough that I had to use the wedge thingy again, and it is the wedge thingy that I blame for this:

Can you see the part of the mandrel sticking out? It seems to have broken in a different spot, probably because of the way it got pulled when I used the wedge. I doubt that it would have made any difference to just leave it that way, but I thought it would be easy enough to file away that I might as well take a couple of minutes to do it.

Ok, everyone that thinks filing that mandrel off with a tiny little file was likely to be really, really boring and take way too much effort, raise their hand.

[My hand is raised.]

I quickly tired of it and found a faster way.

I swear, if the Roman Empire had had Dremel tools and duct tape, it would never have fallen. There's nothing they can't do!

It cleaned up right purty, iffn' I does say so myself.

There was only one more little thing to do on the page, so even though I was ready for a break (I have this little known malady called "coffee hands," the primary symptom of which is a rapid decrease in manual dexterity as my morning caffeine jolt reaches its second half-life) I decided to get it done. It's basically "go find three parts on the shelf, band saw one of them into two parts, and rivet it all together."

Voila! We'll figure out what it's intended to do next time.

Here's where we are so far:

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