Category Archives: Wiring

New EGT Probes

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After I hit the 170 flight hour mark I started to see some fluctuations on my number one cylinder EGT(exhaust gas temperature) gage. It started with slow but ended up showing an extremely high temp them going to zero. This happened on two separate flights. On the second flight the number three cylinder started showing similar signs.

So off came the edging cowl to inspect the probes and their wiring. First I checked all the wires for any signs of chaffing or cuts. Then the connections to make sure they were tight and intact. Last thing I did was to remove the number one probe from the exhaust pipe and bingo there it was. So I removed the number three probe as well and it looked the same.

Here is what they looked like when I removed them:

Luckily we have a Aircraft Spruce location an hour away. I looked up the part numbers and they were in stock so I made a drive down there and picked up four new probes. Figured I would replace all four since I was at it. Good thing because the other two looked similar to the first two. l

This photo is of a new one and you can see how the probe is supposed to look. Not sure if this is a normal wear pattern for the Dynon probes but will do a little research

After replacing all four probes and a quick run up on the engine we are back in business and indications are all normal.

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!

Garmin VIRB Audio

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Time: 2 Hours

I had planned on having several Garmin VIRB cameras on the RV to record some great angles while flying. One cool feature of the cameras and other is that you can record audio from the intercom and air traffic control as you are recording video. This adds a really cool aspect to videos and lets your viewers get the whole experience. In order to do this you need a cable that intercepts the audio that the headset hears. The cable plugs into the jack that the headset plugs into and then you plug the headset into the cable. There is another cable that comes off that setup and plugs into the camera. This all works great but doesn’t look good with all the cables running everywhere. I could do better so that’s what I did. I decided to run a second headset jack, just the one for the output and not the microphone, that is tapped off the passengers jack and run it to the sidewall support aft of the pilot seat back. I created little storage areas there with small sidewalks for things like checklists. I figured I could install the jack down inside there and you wouldn’t see it. Then I could plug the cable in there and run the other end straight up to the camera. This keeps the cable all cleaned up and looks a lot better.

I powered up the RV and turned on the camera to record. I played a little music from iPhone and waited for some traffic to make call while in the pattern. Everything recorded great and the music muted when someone made a call on the traffic frequency. I can’t wait to see some of the cool videos I will make in the future!

Passenger iPad

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Time: 0 Hours

We got our new iPad mini delivered from Apple last week. So I mounted it in the back seat for the passenger to see flight information or watch a movie. I used Ram Mount parts including a 1” ball round bar mount, the large arm and the low profile case. This set up is sturdy and allows the iPad to be tucked up under the roll bar. The Dynon system allows for the flight information to be displayed on the iPad via a WiFi connection.

Garmin GTN-625xi

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Time: 1 Hour

My new Garmin GTN-625xi arrived this week which is about two weeks earlier than Garmin said it would get here. I had already bought and installed the rack, backplate and wiring harness for this GPS several years ago while working on the panel and all my wiring. My original plane was to get the GTN-650 which includes the COM radio and VOR/ILS radio. I later decided that I would never need an ILS or VOR for my needs as RNAV approaches will suite all my missions. So the GTN-625 was a better choice as it has the same GPS but not the COM or VOR/ILS radios. The rack is the same for both units and the backplate is as well you just have less connectors. So when this is it arrived there really was t much to do except to slide it in the rack, tighten down the mounting mechanism and power it up. Well you also keep your fingers crossed that all the wiring you did several years ago was right! With the flick of the master battery and avionics switches the GTN popped to life. I had one small issue that revealed itself after power up…configuration module needs service.

I had no idea what that was so I went online to research it. Turns out there is this little device, looks like a very small motherboard, that has four wires/pins off of it that resides inside the back shell of the wiring harness connected to the backplate. so what does this module do…apparently it stores all your settings for the unit. That way if you remove the unit for service and it comes back in a factory setting mode you can restore all the settings. Well I didn’t know about this little device back when I installed the rack/backplate/wiring harness. Luckily for me I received a wiring harness/rack/backplate with the unit. I opened up the new backplate and removed the module and it’s four pins. I then opened up my harness and installed said module and pins. With the module in place and the harness reconnected I powered the GTN back up and boom the error was gone and all was right in the GPS world. It took about 15 minutes to configure both the GTN and the Dynon SkyView ARINC module to allow the two devices to talk to each other. I then put in a quick flight plan from our home C77 to Omaha OMA to see if it was depicted on the SkyView. There it was and the autopilot would fly it perfectly. I put in an approach, RNAV 14L, at OMA and it displayed all the points including the holding pattern. That was just a quick test to make sure it displayed correctly on the map. I have a lot to learn on how to properly operate this unit. What this GTN allows me to do is utilize the air traffic system under instrument flight rules, IFR, since this unit is certified by the FAA and enhances the missions I can fly tremendously.

A nice thing about Garmin is they have an iPad app that allows you to virtually do everything the real unit can do. That allows you to practice and work along side a Garmin instructor led online class.