Time: 6 Hours
All along during my build I was planning on using a portable attitude indicator from Dynon Avionics called a D-3. This device is around 3” x 3” and 1” thick. It’s portable and powered by an internal battery. The purpose for this was to be a tie breaker. I have two Dynon screens each with their own computer that produces the attitude display. The computers can run either screen and provide redundancy. Say one of them failed and was only producing a picture of a climbing left turn for example with the airplane actually flying straight and level. The system is smart enough to say to the pilot that the two items, in this case the attitude, are showing different things. So you hit one button and both displays pop up side by side for you to examine which allows you to disable the faulty one. But how do you know which one is right? Well you could use several things to help you determine that…say the turning picture was the correct one you would expect to see the heading indication change as you turn. The altitude would change as well if you were in a climbing turn. Those items take the brain a bit of time to register and decipher what is going on. So to hep expedite the issue you can have a third independent system that you can use to compare. The D-3 was going to fill that job but at Sun N Fun I looked at the Uavionix AV-30 system and was real impressed. This is not a portable system and needs to be wired for power and have the airspeed tubing, pitot, attached. The instrument fits in a 3 1/8” hole and provides everything that the Dynon does all in a compact design. So I ordered one from Aircraft Spruce and started the process of how to run my limes.
First up was to determine the routing for the pitot line. I would run a T off of the line that comes from the left wing and run it forward along the center section through an existing hole and up through the right hand gear tower. This will provide the required airspeed indication. This would also require another line to run to the static line in the tailcone. The airspeed is displayed as the difference in static air pressure vs air pressure at the tip of the pitot tube under the left wing. As the airplane moves faster the pressure increases compared to the static pressure and indicates a faster airspeed. I didn’t want to run a line for the static all the way back so I will use the air pressure behind the instrument panel for the static source. This will likely cause a slight difference in indicated airspeed as that static pressure will differ from the aft tailcone one. Not a big deal and I might be able to adjust that in the system as a correction factor.
I printed a full size photo of the instrument to see how it will look. I will place it centered on the panel just below the 10” screen. It looks a little off as the instruments are all placers for how they look when powered on.
Once I had the pitot line roughly run and was sure I could get it from point A to B to my liking I started on the electrical. My my setup I’m going to run the power from the fuse block in my battery compartment rather than to the Vertical Power box. This will allow the AV-30 to run right of the battery, as long as the battery master is on, regardless of what’s happening to the Vertical Power system. The AV-30 only needs a power and ground input and optionally can add a audio output, a GPS input and outside air input. I’m only going with the power and ground as I’m only using this as a backup/emergency system. It uses shielded 22g wire that grounds the shield to the back shell of the connector. The back shell is also grounded to the airframe within 8”.
Now that the pitot line was run behind the panel and the electrical part run I started to hole cutting in the instrument panel. I removed all the connectors from the electronics behind the panel and removed the panel from the plane. I knew the fit would be tight so I measure several times to make sure I had it right. I borrowed the hole punch designed specifically for this procedure from my buddy Glenn. With all the measurements done I drilled a pilot hole with a 5/8” drill bit. This allows the centering bolt to go through the panel and allows the other half of the punch to be bolted on. I used a file to enlarge the 5/8” hole to get the punch to line up just perfect. Once satisfied with the position in tightened the nut a little which causes it to “bite” into the metal and securing it in position. I then secured the panel in the padded vise and slowly tightened the the bolt/nut until it punched through. This thing made a perfect and clean hole right where I wanted. Glenn also let me borrow the screw hole jig which you use after you punch the hole. It has ridges that sit inside the just punched hole and all you have to do is square up the jig and drill the four holes. I cleaned up the inside edge of the hole as the punch leaves a little burr. I scratched the paint a little so I decided I will sand it all and put a new coat of paint on it.
As the paint was drying I plugged the AV-30 in to test the electrical connections. I also plugged in the pitot line and did a syringe pressure test on the pitot tube to make sure there were no leaks and the I had airspeed indication. After the paint was dry I installed the avionics back into the panel. I put the panel back in its place and reconnected all of the cables.
I turned on the master switch and wow it looks great!
This instrument has a lot of options to configure and will make a great stand alone item or a backup to my main screens.
Now time to fly!