October 3, 2010

Vent Line Fitting Washers; Brake Pedal Cotter Pins - 3.0 Hrs.

Jamie and I returned from a nice little vacation on Friday, so I finally got back to work on the project today. Just before leaving on our trip, my good friend Stephen Christopher helped me solve the washer question I've been wondering about on the fittings for the vent lines. I looked through my inventory of stuff and found the washers he was talking about. They fit these fittings perfectly. I was still undecided, however, whether to go ahead and use them. They're smaller and thinner than the big aluminum washers that I had previously installed. I would prefer to use a larger one if I could get it to work. So I decided to trim down the aluminum washers and see how they fit.

The picture above shows an untouched original large aluminum washer, the one I trimmed down, and the smaller one in consideration. I know it doesn't look like it in the picture, but the holes in these 3 washers are all the exact same size. It's an optical illusion. Anyway, next, I put the large trimmed washer in place on the fitting and tightened up the nut. This would have been my first choice. Looking closely, I could see that the wing root fairing and the rubber seal would clear it okay now but it's actually too thick. I would prefer to have at least one thread showing on the fitting after the nut is tightened up against the washer, as is conventional with aircraft hardware. So in the end, I decided to go with the brass washer instead, just as my friend Stephen has done. Thanks for the tip, Stephen!

Above, the washer is loosely in place, the other large aluminum washer is inside the fuselage, the nut is on and ready to be tightened. Below, everything torqued in place and the vent line hand-tightened to check the fit. Everything looks good. This is finally done and I'm happy with it.

I spent the rest of my time today working on the brake pedals. Before I put this assembly back into the fuselage, I want to install the hardware and get as much done as possible. It's much easier out here on the bench than it would be down inside the fuselage.

It's kind of hard to see in this picture, but I installed all the little cotter pins that secure the castle nuts on the brake pedal assembly. There's about half a dozen of them for a single brake system like mine. The trick here, after reading a lot about sticky brakes that other builders have experienced, is to not tighten or torque these castle nuts too much, because as the brakes are applied and released, these parts rotate a little bit around the bolt, or move about. The bolts here function as axles as well as fasteners and the parts must be able to rotate freely. It's just common sense. So they're tightened enough to avoid any slop, but no more. They're left loose enough to avoid pinching or locking them up. I hope that makes sense. The cotter pins hold the castle nuts on securely, so there's no worry about them vibrating loose because they're not torqued on.

Before this assembly goes back in the plane for good, I will also remove the red plastic plugs on the master cylinders and install the right-angle fittings for the brake lines.

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