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  • Steve

RV-8 and the 2024 Condition Inspection Part 3

In this case anyway, the third time was the charm. Thursday 3/14/24 worked out better than the last couple of tries did. I got all of the correct parts that I needed and things went together very smoothly. Well, in the end they did anyway.

I started off the morning trying to get enough work stuff done that I could be away for the remainder of the day. I was taking my time since I was really hoping that the UPS package with my Aircraft Spruce order would show up earlier than expected. I had planned to work on the tail today and finish the brakes Friday, but I really wanted to get the brakes finished. UPS said that my package would be delivered between 10:00 and Noon. They rarely ever come in earlier than their estimate and frequently come in over, but I was hopeful.

By 10:20 they still hadn't shown up and I decided to head out to the hangar anyway. I thought that if it showed up early enough, I would go home and get it. In preparation, I started by removing the old brake pads. I know, you're thinking "wait Steve, you said last week you couldn't find your tool and had to order another one". Wow, I was hoping you'd have forgotten about that. OK, so that is a little embarrassing. I wanted to give it one more try to find the tool that I knew was in my hangar. Naturally, I walked in and went straight to it. It was, get this, in my tool box. In my defense, it was in a different box than I was looking for, but it was, more or less, where I thought it would be.

The Rapco Brake Rivet Tool RA825 is a well designed, well built little unit. I know a lot of people just drill out the rivets and beat the shanks out with a punch, but that is so last century. OK, so is the Rapco tool, but it is later last century.

The Cleveland instructions and the Base Leg Aviation video I watched from Vic Syracuse both talk about using an 1/8" drill to drill out the rivet, taking care not to enlarge the hole. I tried his, but the only thing that happens for me is that the rivets spin in the holes.

I think the Rapco tool does a good job and doesn't require drilling first.

The Rapco RA825 tool clamped in the vise.

There is a punch attachment that pushes the old rivet out very gently, no hammer required and doesn't damage the rivet hole. And this can be done without drilling the old rivet at all.

The punch attachment installed.

Just tighten the handle and the rivet is pushed out and drops through the hole on the base of the tool.

The tool pushing out a rivet.

Once all of the old pads were off, I cleaned the backing plates up and then cleaned the wheel pants. By this time I had received the dreaded update from UPS that my delivery was now scheduled to between 9:45 and 1:45. Since it was 11:45, I didn't think the earlier time would come into play and feared it would be even later then their updated window.

Since I forgot my lunch and had to go home anyway, I just hoped that it would show up while I was there. Fortunately, it did. So, after lunch it was back to the airport.

All of the pieces needed to put it all back together.

The tool comes with an anvil that fits into the hole in the base.

Anvil installed in the tool.

The threaded shaft itself is somewhat domed to form the roll on the rivets.

The screw shaft acts as the rivet set.

I start with the middle rivet, placing the factory head on the anvil and the shop head under the shaft. I use two rivets upside down on the other two holes to act as alignment pins.

The middle rivet all ready to go.

I don't think I have read it anywhere, but I find that a dab of Boelube on the shaft as a lubricant helps the "set" to slide on the rivet and reduce cracking of the rivets. I don't tighten the first rivet all the way to start. I snug it up and then set the two end ones, then go back and finish the middle. The pads really only need to be tight enough that they don't move. Too tight and the rivets crack.

The Cleveland Maintenance Manual gives limits for allowable cracks in the set rivets. With practice, I have gotten to where I can get most of them in without any cracks, but there are still a few that insist on cracking.

The finished product.

Nice new pads with shiny new rivets.

The "shop head" side.

All that was left from here was to put them back on their respective wheels and safety the bolts. Since I had left the cylinders hanging, literally, I wanted to do something to keep the piston from coming out. I learned the hard way that left unattended, the piston can work its way out and leak fluid all over the floor. After a couple of minutes of head scratching I came up with an easy fix.

This simple clamp holds the piston in pace so that it can't escape.

It doesn't take much pressure at all.

It doesn't take much pressure to keep the piston in it's place, as long as no one actuates the brakes. This clamp was easy to get in and adjust to a very low tension. The last thing I would have wanted would be to have fluid all over the floor and have to bleed the brakes again.

Once that was all together, I took it out to condition the brakes. There is some disagreement as to whether that is really necessary, but I figured that with new discs and new pads, it was probably a good idea. Another idea that was given to me recently is that if you are going to do the conditioning procedure, to do it with the wheel pants removed as the procedure, intentionally, creates a lot of heat. You essentially drag the brakes at a moderate power setting to maintain normal taxi speed.

On tightly faired wheels, like RVs and other performance airplanes, it is very hard to dissipate that heat since there is very little air space and very little air flow. There have been brakes that got hot enough to catch the wheel pants on fire. That can be even worse when the wheels are under the wing and you can't see them.

Anyway, I think I got them pretty well conditioned and they seem to work well. They are also very quiet. The screeching and wailing of the old ones are gone. So, what should have taken no more than 4 hours took 3 days over 3 weeks to accomplish. Oh well, that must be why they call it an adventure.

I put it back in the hangar, after sweeping a winter's worth of detritus out of the hangar, and put the pants back on. The main wheel are officially done and should be good to go for another year.

On to Firewall Forward (my second least favorite part).

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