Sunday, November 18, 2018

Special Mods

I really look forward to working on the fuselage for a couple of reasons.  First its simply because the fuselage is "where the people go".  It also, and probably because of the first reason, is an area where I plan to do most of my modifications to the airplane.  This week was a week (actually 2) of modification.

On the firewall I plan on mounting a parking brake.  This requires a mount of some sort and there happens to be a bracket that gets riveted to the upper left side of the firewall that is designed to connect the brake lines with the lines coming from the pedals.  This seemed like a good place to mount my parking brake and there happens to be a company (Airward) that makes a "kit" that allows you to do exactly this.  I like this company's products but I don't care much for the prices....or at least thats what I thought at first.  For $197 they will send you everything you need to mount the parking brake valves in the required location.  Being the cheapskate that I am I decided I would just use my CNC and make my own kit for about a quarter of the price.  Sounds logical doesn't it?  Well, having spent about 10 hours of my time coming up with a similar "kit" I am starting to see a lot of value in that $197.  :-)  None the less I did manage to get the parts I needed and am ready to move forward on that project.

F-6122-1 is the bracket that I will be replacing with a parking brake mount.

This is my CNC noisily cutting away at the square bar that I purchased to make the bracket replacement.

Another view of the CNC cutting away.  This is a huge mess to clean up by the way.

Anyway after many hours this is what I ended up with.  It doesn't look like much now but soon it will have a parking brake valve bolted to it and it will be riveted in place of that F-6122-1 bracket you saw in the plans above.

Next up on the modification list is a tunnel access plate.  The electric fuel pumps are located in the center tunnel.  Working on those pumps and associated fuel lines and power leads requires you to work from above with very limited space.  The company I mentioned above (Airward) makes a "kit" that you can purchase and install in the side of the tunnel to give you a nice open way to access the tunnel components.  Unfortunately the kit they make is not the size I needed so so once again I took to the CNC and made my own access panel and backing plate.  This was much easier than the bracket above but it did take about 8 hours total to design, cut, and install the access panel.  As of this time it is not riveted in place but its ready.

This is the tunnel side wall.  The pen marks are the size of the access cover that I will be installing.

And after many hours of cutting, deburring, drilling, dimpling and even a little riveting this is where we stand tonight.  

Finally I have one more customization that I completed today.  My good friend Ben let me borrow his lathe again so that I could turn a couple of inserts that will go inside the step support tubes.  The RV-10 has a problem where the bolt used to fasten the step support tube in place has a tendency to loosen due to the bolt collapsing the thin tubing. There is another company that makes an insert that prevents the tube from collapsing.  Well since Ben has a lathe I decided to spend $8 on a piece of aluminum and turn it myself.  This wasn't a long project but it sure is a satisfying one.

HAH, this picture makes it look like the bar is all white but as you can see below its actually just simple 6061 aluminum.  The spinning motion must have given it the white appearance.

Here is the aluminum stock turned down to the proper size.  The grooves you see are where I will be cutting these "blocks" off of the bar with my band saw.

A bigger picture of the entire lathe and bar set up.

After turning the bar I used my dowl centering jig (the blurry thing sitting on the bench to the right of the picture) to drill these holes into the exact center of the blocks.  Once these holes are drilled I simply cut the blocks off of the bar using my band saw.

And finally the blocks get slid down into the step tube after the bolt holes are drilled.  You can see how these new blocks prevent the collapse of the thin aluminum tube when bolts are tightened.