Category Archives: Center Section

Uavionix AV-30

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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!

Throttle Quadrant Support Bracket Redo

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Time: 4 Hours

Since my arm rests and throttle quadrant are all custom, meaning I deviated from what Van’s calls for, I had to do some engineering that’s unique for the support of the throttle quadrant cables. I took the idea from my buddy Glenn and made a bracket out of some large aluminum angle. I had completed this task and installed it some time ago and moved on to other tasks. Since then I was really happy with how the arms of the quadrant were moving and it felt like there was some binding. So yesterday I decided to investigate and see if I could fix the problem. What I found after a closer look was that I had actually measured the distance from the side skin to where the holes for the cables needed to be by about 3/8″. This meant that as the cables left the quadrant they angled outboard to hit the bracket holes. This caused each cable to cause a torquing action on the levers and caused the mixture and propeller cable ends to actually touch as they went through there motions in one spot. That was not good and needed to be fixed. So I decided to make a new bracket that would extend 3/8″ farther inboard. So I went about removing each cable from the quadrant then removed the two bolts holding the bracket. This allowed me to slide the bracket off of the three cables and remove it. I used it as a template and just extended the arm length by 3/8″. With the new measurements I went about drilling and trimming the angle to create a new bracket. I then did the task of getting the bend of the arm where the two bolts attach the bracket to the angle on the side skin. This was the time consuming part as it’s a little bit of a task to get the cables in and situated while checking the angle. Once that was done I bolted the bracket down and went through the process of setting the correct throw of the cable ends. These all looked good so I removed the bracket and primed/painted it so it would look presentable. Today the paint was dry so I reinstalled the bracket and worked the cables from outside to inside. First was the throttle cable as it’s the outermost cable on the quadrant. Once I had the throw all set and got the throttle arm on the servo to hit the full and idle stops I locked the cable arm in place with the nut and attached it to the throttle lever with the pin and cotter pin. I repeated this process for both the propellor and mixture cable. The propellor arm has given me the most problems part due to the angle that it goes through the bracket and the arm length on the propellor governor. What I ended up with was the prop lever goes to the full forward position on the quadrant and is short of the full aft portion by 3/8″ or so. I’m ok with this as it will never be in that full aft position and only off the full forward position a little as you increase the propellor pitch and reduce the engine RPM. The mixture arm works perfect allowing the full rich and idle cut-off.All three cables operate much smoother and there is no binding at all. I’m happy about that but I’m happy I spent four hours repeat a process but that part of experimental building. One other thing I did was to give the RV-8 some fresh air so I could sweep out the hangar. She really looks good stretching her legs after a long winter being cooped up!

Wings Back On

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Time: 6 Hours

We have been busy getting all the things done in the new home to make it ours. Like ripping up old ceramic tile to make way for new hardwood. That was not a fun project but it’s all ripped up and ready for the installers. In-between that work I have been doing little projects in the hangar to get it organized. I also got my hands on the RV to start building again. One of the items I was unhappy with when I put the wings on the first time was the length of the wire bundles coming out of the wings. I found them to be a little short to work on with the tight space you end up with when the wings are on. So since I had the wings off again I decided to add 12″ to each of the bundles to give me plenty of length. I also figured that I would finish up the little bit of fiberglass tasks to the control surfaces, the rudder and elevators. I just needed to fill some pin holes and smooth the transitions out a little. A composite pro I am not and hope to get some help when it comes painting time to make these perfect. I used some filler primer to identify the holes and used Super-Fil to make the corrections. With the rudder pin holes taken care of and a coat of primer on I put the rudder on the vertical stabilizer and bolted it in place. I also put the AeroLED tail light in as well.I then spent two hours putting in the new close tolerance bolts in to secure the wings…again. The process was just the same as before, I froze the bolts and used LPS lubricant. The rivet gun at low pressure worked to drive them into position. The hardest part of the whole ordeal, as before, was to torque the bolts. I worked one bolt and then took a little break as leaning over the side wall of the fuselage even with padding was not very comfortable. So that’s a good start to being in my very own hangar that’s ten feet from my back door! I can not wait to be able to just walk out and go for a flight or a trip.

Wings On!

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Time: 6 Hours

This morning I had breakfast with my buddy Glenn in preparation for helping me put my wings on. Now that the RV is at an airport I can put the wings on permanently so that I can continue to work on stuff while I wait to save up for my propellor. Since we have had my wings on and off two times before the process was pretty easy for us. We used the temporary bolts initially to hold the wings in place while I prepped for the final close tolerance NAS bolts. I had put all the bolts in the hangar freezer in hopes that they would shrink ever so slightly. I also picked up a can of LPS-2 lubricant that Vans recommends. Then I laid out several different tools, hammers and my rivet gun with the flush set in place. I started with the hard to get bottom bolts with the larger ones first. I pulled a bolt from the freezer and sprayed the shank with the LPS. Then I inserted it by hand as far as they would go followed by a few hits with a mallet. Then to drive them all the way I used my rivet gun and flush set with some duct tape on the face to drive the bolt thru. I just used a low PSI setting and it worked really well. I drove the two lower large bolts then the top followed by the two smaller bottom bolts then the top two. This process worked pretty slick and only took an hour.

Now the fun job of putting a washer and nut on all these bolts and torquing them. The large bolts get torqued to 520-630 in/lbs and the smaller ones to 80-100 in/lbs. not much to show on that process other than is was very time consuming and a pain to do. It didn’t help that it was 91° today and a little humid. After I finished I put some orange torque seal on to show that they were torqued.

There are also two AN-4 bolts that screw into nutplates from the aft side of the center section, I torqued those as well.

Fun day and felt good to sweat and swear a little while working on the RV! It’s been a while and I’m glad to be back at it. I have so many projects and tasks to do now that the wings are on and I’m excited to get at it!