December 20, 2009

Topcoat Painting; Landing Gear Legs and Mounts - 6.0 hrs.

My first objective today was to shoot the topcoat paint on all the cabin covers I've been working on. Once again, I love this JetFlex water-based paint. I know I've said that a lot, but it's so easy to work with, and I'm now getting excellent results. Here's my batch of parts, all painted.

I set them aside to dry and moved on. Well, I've deviated from the order in the plans again. Only slightly, however. The next step called for is working on the flap actuator, but before putting drawing 34A aside, I got to thinking I should just finish up this one mini-project and then go ahead with the flap actuator. So I got out my gear leg weldments and the gear legs. The plans have you drill the gear legs to the weldments, so you know they will fit and a bolt will go through, when the legs are installed. So I spent a bit of time deburring everything and preparing to drill.

When everything was ready, I used my 5/16" reamer to do the job. Boy, this big reamer is about all my little hand-held palm drill can handle! But it's very exciting to be working with these parts, anticipating the day my plane will be on her gear.

The leg is in the weldment, the hole is drilled, and the bolt is inserted to make sure it fits right. Then repeat for the other side. Then, take them all apart for deburring.

Here they are, all finished. Boy, it was exciting to be working with these parts! These gear legs are gorgeous! (and HEAVY!)

UPDATE: December 16, 2012. I made a HUGE mistake about 3 years ago when I did this. Now that I'm getting ready to put the airplane on her gear, I found that the AN5-22A bolts that hold the gear legs in the weldments don't fit right. They're sloppy. Since the entire assembly... the gear leg, wheel, brake and tire... are held in place with this single bolt, it's critical that it has a tight, close-tolerance fit. A little sloppiness in the bolt hole translates to a lot of movement (and potential shimmy) down at the wheel end of the leg. All that shimmying around wears on the holes in the weldment and makes them even bigger, so the problem can potentially become even worse! I should have read the plans more carefully and NOT used a 5/16" reamer to drill these out. As you can see in Drawing 34A, you should use a 0.311" reamer on these holes. I didn't have one at the time, but I bought one later to use to drill the rear wing spars when I mated the wings. My advice, do NOT use a 5/16" reamer or drill bit! Get yourself a 0.311" reamer. You're going to need it anyway when you mate your wings and drill the rear spar holes.

My solution to this mess? I had to order new special hardware, the next size up, along with a new reamer, and drill this all over again. With shipping and all, it cost me almost $100. Expensive mistake! You can read more about this on my December 16, 2012 page in the Firewall Forward part of this site, right here.

When that was done, I decided why not install the weldments in the plane? It's the next step right after the flap actuator, and this won't interfere with that task. So I'll do them now. I'd rather put them in the plane than back on the shelf. So I started on the left one. Boy, was I in for a surprise.

I had these gear leg weldments in and out of the fuselage many times last May, when I fitted them in place, cut the holes through the bottom skin for the tubes to stick out through, and drilled through the side skins, etc. One of my objectives back then was to make sure they would go in easily, with no hassles when THIS time came. Well, I don't know quite what happened between then and now. Perhaps riveting everything together on the fuselage did it. I don't know. All I know is, it was a bear to get this thing put in. What I thought would be an easy task turned into a major project. First, I removed the little cover bracket seen below on the left. It was in the way. I finally ended up drilling out two nutplates from the F-704 flange. You can see the empty holes in the shot below, near the top of the picture. There was just no way I was going to get this thing in with those nutplates in the way. It's no big deal, really. Just more time and work.

Then, the fun of trying to get the bolts in place. I struggled with this thing for a long time to get the bolts put in, one at a time. Once a few were in and tightened down, things began to go a bit easier. But for a while there, I didn't know if I would ever get this done. It's a challenge to reach the bottom bolts to install washers and nuts, in between the F-704 bulkheads. My hand won't fit in there. I literally taped a washer to a long skinny rod to reach in there and slip it over the bolt. Then, the same with a nut, turning the bolt from this side to get the nut put on. I duct-taped my 7/16" wrench to an extention to reach in and torque the nuts. When I had all the bolts in place, I torqued them down and sealed them. I thought I'd have both of these done in a short time, but I'm only half way. I dread the work on the one for the right side. I hope it goes easier than this one did.

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