Karmy Flying Adventures

Here’s the before and after picture. You can see the 1″ extra clearance that you get. It’s nice that Vans figured out all the geometry to make everything fit in exactly the same place so no changes to the mounting brackets or nosegear parts was necessary.

Well, the first thing to do is get the plane jacked off the ground. The easiest way I have found is to weight down the tail and jack it down with a tie-down strap.

I used a wood brace to work as a backup since the nose gear leg would be out for at least a week (or so I thought). Turns out the parts were backordered so It was actually strung up for a month or so.

Here’s before and after of the nose gear leg. I had it shortened and re-threaded by Langair down in Portland to make sure it’s done right. It was painless, just cost $75 to get done. I had it easy as Earl, one of my local flying buddies, decided to drive down and get his done so I just sent mine along for the ride.

A bit of poking and prodding was required to get the bolt out that holds the gear leg in place. I had made the hole in the firewall initially, so it was simply a matter of getting out the plug and proseal. Then reversing the process to re-install.

Finally when it’s all done, there is no external visible difference… You just pay some money to take some metal off the plane! Typical for aviation projects I guess.

Well, during this year’s annual inspection I decided to install an AOA system. I got the AOA sport from Advanced Flight Systems. The install took about 2 full days when mixed in with my inspection tasks. It was a good time to do it since I had all the inspection panels opened up anyways. First came the wing ports. 2 small holes are drilled in the last bay of the wing and some tubes connected and routed back to the panel. The only hard part about this was reaching in the inspection holes on the wing to route the tubes. It would help to have small arms!

Next came the AOA brain box install. I decided to mount it with some velcro on the rear sub panel behind the other instruments. This proved to be a fine locaiton, however as the years go by it seems like things are filling in behind there. Not much room left for more toys to be installed. You can see the CPU box and tubes hooked up in the picture. Another job was to figure out a way to detect the flap position as the AOA needs to know when you have lowered the flaps. The best way ended up being to make a slip ring out of UHMW plastic that I attached to the flap torque tube. You can also see the microswitch that was installed to sense the rotatio of the tube. With all of the remote sensors installed and wires / tubes run back to the CPU, it was time for the display indicator. As the primary purpose of having an AOA is to get your head outside the cockpit and really add some safety to flight at the edges of the envelope I decided to create a custom mount. I first tried to make an aluminum box to house the light bar, however I could not get it to work out to my satisfaction, so I fabricated a fiberglass enclosure. I simply made a male plug out of wood, waxed it, and layed up the fiberglass. After some sanding and filling, etc… this is the result. I think it worked out great. It’s just large enough to hold the LED light bar for the AOA display.

I then installed it on the glareshield directly in the line of sight. This gives easy visibility without ever taking your eyes off the runway when on final.

So how does it work you ask? Well, after flying my RV9A for 550 hours I was not really sure that I needed an AOA. I was told by my friend Jim that it would really be usefull and he really sold me on the safety of flying by AOA when in critical phases of flight. So here we go. I took off and got the unit calibrated. Initally you need to do a few manuevers to get it all setup. A zero G push over, and some slow flight with flaps up and down takes care of it. I then few a few approaches with it. Each one worked great just flying with 2 yellow lights lit all the way to the ground. You arrive in the right place, right time, right speed, right AOA, ready to land. So far so good.

Now the real test was the next day when flying to the EAA meeting. This time of year that means night flying. So as I approached Thun field, I had been flying with the panel lights turned off. As I got setup on the aproach and capture my 2 yellow lights, a quick cross check with AS indicated an expected airspeed value, so I continued the aproach and landing never once turning on the panel lights, or looking anywhere but out the front and at the AOA. Perfect night landing, most likely one of my best landings. Hum, there must be something to this navy carrier AOA stuff.

I’ve taking it up for accelerated stalls at high G, unusual attitudes, etc and it always gives plenty of warning just before the plane let’s go into the stall. In short you can’t fool AOA, it really is what keeps you in the air. So I say it’s a great success. I think this will provide much safety over the years.

Here’s picture of my new fuel lever. I found it offered on VAF last month and decided it was a quick upgrade without re-plumbing for an Andair valve. It’s interesting that after flying with this new valve a bit, it’s actually much easier to turn the lever as the new handle has some material on both sides of the pivot point. It makes it balanced when you rotate it, compared to the paddle flipper style that was on originally.

As the years go by, I’m always looking for small upgrades to make the plane safer. If you do a bit of research on the internet forums you can find much information about brake problems and even some brake fires. Of course there are also thousands of planes that have had no problems at all. Here’s a little snip of a recent post for some solutions.

Two other easy upgrades. First install caliper piston o-rings with a higher temperature rating. Nitrile is only good for about 275F, while fluorocarbon (Viton) o-rings hang in there to 450F. A Cleveland engineer told me the only reasons they stick with nitrile are (1) certification, and (2) better sealing at very low (like -50F)temperatures. Unless you live in the Arctic, Viton is the way to go. Nobody in the brake world still uses nitrile except us goofy airplane people.

The second painless upgrade is a switch to MIL-H-83282 fluid. It was developed to replace good ‘ole MIL-H-5606 for a very good reason; fire resistance. The flash point of MIL-H-5606 is 220F vs 460F for Mil-H-83282, and 83282 is self-extinguishing. Replacing 5606 with 83282 is no trouble; they are completely compatable. Drain one, pour in the other. Mil-H-5606 isn’t useless. It retains its low viscosity at -40F, so if you fly your RV at 30,000 feet you’ll be happy to know the brakes will work

Consider the fluid specs in light of the failure temperature of nitrile seals. Get your stock brakes hot, 275F or above, and you start dumping 5606 brake fluid with a flash point of 220F on brake parts already well above that temp, all in the nice calm air inside a wheel pant. Can you say “brake fire”?

I decided to order up some parts and add this to my winter project list for this year’s anual inspection. I got the o-rings from o-rings Inc and the new brake fluid from ACI Lubes on the internet.

218 V75 (1.234 X 0.139) is the o-ring to get

It should be great fun draining the brake fluid out, pumping new in, etc… but once it’s finished will provide some extra safety margin in case it’s needed.