Air Vents and EGT wiring

Time: 5 hours

I purchase a pair of 2″ AIrKit anodized aluminum vents from Aircraft Spruce. These things aren’t cheap, they’re around $160 each, but seem to be well made and are a good size for what I need to do. I also have AitKit cabin lights so everything kind of looks similar. I made up some fillers out of anodized aluminum (for the front) ¬†and fiber glass sheet (for the back) with a 3 1/8″ hole saw. I then cut a 2″ hole in the middle using another hole saw. The cuts came out well enough. I had to modify the fiber glass ring a bit to get it to sit a bit flatter. The thread on the vents seemed to be long enough, but it was a pain getting the back to screw on. I epoxied the fiber glass ring to the rear of the dash and the front is just held in place by the pressure of the backing nut. I’m happy with the way these came out. They look a lot nicer then the plastic vents and they will seal off much better as well.

I also finally was able to finish up the wiring of the 2 EGT sensors. I had order some K Type ¬†thermo coupler wire which appeared to be exactly what I needed at a reasonable price, but after running the wire and starting to wire it up I found that they had sent the incorrect wire (knew it was too good to be true). They said they will send the correct wire, but it’s back ordered (of course) and they weren’t sure when it would ship out. I decided to go back to my original place called Omega to purchase the wire. Their wire is really high quality but it’s pretty expensive. I purchase 25ft of armored K-Type thermo coupler wire for around $80. It arrived a few days ago and wow, it’s nice stuff. The wire I used (GG-K-20S-SB-25) is a 20 gauge glass insulated 2 core wire with an other glass insulator and then a stainless steel outer sheath. There are other sheathing you can get, but I wanted to use the braided stainless steel. The connection to the EGTs is made by 2 ring connectors, Unfortunately I could only find spade type connectors that are usable with the K-type wire. The spade connectors are made from Alumel and Chromel which is the same material as the K-type wire so the temperature characteristics will be the same. The yellow wire is Chromel so you use the Chromel spade connector on it and the red wire is Alumel so the Alumel connector is used on that. I used a standard open barrel crimper to crimp them on. Working with the K-type wire is a bit of a pain because the wire insulation is like a cloth material and doesn’t cut well with wire stripers. After the wires are bolted together a final length of heat shrink is put over it.

Lastly I roughed in the CEET tubing for the air vents. Because I’m using 2″ air vents I had to find a 3″ to 2″ reducer to tie into the NACA duct. I found some on Amazon for around $6 each and they look like they will work. The NACA duct is a little smaller than 3″ so hopefully it will seal up OK. I’m waiting on my hose brackets to be able to actually connect everything together. The one issue I ran into is that the bar that I’m going to install to hold the avionics shelf gets in the way of the tubing run.

Finer glass backing rung epoxied in.

Vent mounted in the 3 1/8″ anodized aluminum ring. It’s all just held in place with the pressure of the backing nut. The vent moves fairly easy so I don’t think it will be an issue with it coming loose. The fiberglass ring also creates some tension on the nut so it holds very tight and won’t spin loose at all.

EGT wire connection. I could only find spade connectors in Alumel and Chromel, but this all get wrapped in heat shrink so that will keep everything together and offer some strain relief.

Big piece of heat shrink covers up the join.

This 3″ to 2″ reducer looks like it will work. I may cut down the flange a bit to give more room. I need to use 3″ CEET to join it to the NACA duct and then 2″ out to the air vent.

Test fit of the CEET tubing for the air vents.The tight bend may cut down on air flow, but not much I can do about it. I don’t want to put the bar on the other side of the tubing because it may interfere with the fuel selector.

Rear Cabin Lights Complete

Time: 1.5 hrs

The copper washers came in today so I was able to finish up wiring the rear cabin lights and get them mounted in the canopy. To my surprise everything fit into the space in the canopy just fine. I also did a quick test by hooking up the power supply to the canopy power feed wire.

Got these from e-bay. They’re 32mm copper crush washers which fit around the mount on the light. The copper is easy to solder to.

Soldered the lead from the touch dimmer to the large copper washer. The washer then gets installed between the aluminum mounting plate I made and the mounting ring of the light. Now if you touch any of the metal parts on the light or mounting plate it will turn on or off the light. If you hold then the light dims down and if you release and hold again it dims up.

All wired up. I tested them prior to installing in the canopy as well. The funky clear plastic looking thing is just a crimp butt split with heat shrink. The touch dimmers were around $7 from Amazon.

Both lights mounted in the canopy and tested. These are the swivel lights from AIrkit, LLC.


Rear Cabin Lights (Part 1)

Time: 1 hr

The rear cabin lights (same manufacturer as the front lights… Airkit, LLC) finally arrived from Aircraft Spruce so I made the round mounting plates from the anodized aluminum that I had purchased a while back. The lights are a lot smaller then I thought, but I knew they weren’t going to fit anyways. I also tested the touch dimmer on them and it seems to work fine so I’ll have to wire that up next. The factory cut holes for the rear lights are around 1.9″ (0.4″ larger then the front) so the mount plates needed to be a little larger.

Finished mounting plates. The lights fit a little loose inside the mounting plate so I may use a little bit of RTV when mounting them and make sure the mounting ring is nice and tight so they don’t slip around at all.



Pilot/Copilot Cabin Lights

Time: 1.5 hrs

Today I worked on the pilot and co-pilot overhead cabin lighting. I’m not using the ones available from TAF so I had to do some looking to find something that would work. I was originally going to purchase the Aveo EyeBeam lights, but at nearly $200 each that was a little excessive, plus the reviews I read hadn’t been that good so why pay a bunch of money and still have problems. They do look cool though and I may still get the white light ones for the rear seating unless I come up with a good dimming solution.

The lights I’m going to use were purchased from Aircraft Spruce for around $50 each. The version I purchases has 2 white and 2 red LEDs. I’m also going to use a concentric 100K ohm potentiometer to be able to dim the lights. The dimmer will mount where it is typically mounted in the 1.5″ hole that TAF has cut in the top (inside) of the canopy. The concentric knob will allow me to dim both the white and red LEDs with one physical knob rather then using two separate knobs.

The lights that I purchased have a mount (that is an additional purchase) that allows you to surface mount the lights, but since TAF already cut the 1.5″ holes in the canopy to mount the lights I’m not able to use the mounts because they are 1.5″ in diameter so they don’t cover the hole. I ended up purchasing some 0.063 clear anodized aluminum from Amazon and then uses a 2 5/8″ hole saw to cut the mounting plates out. This gave me just about a 2 1/2″ diameter mounting plate. I had the kids figure out the distance between the three holes that needed to be drilled for the mounting screws (nothing like a real world geometry problem to show them geometry is actually useful). I’m looking to use 3mm button head screws instead of riveting the mounts to the canopy. I’d like to be able to easily remove the lights and especially the dimmer potentiometer. I was considering using countersunk M3 rivenuts, but I don’t know if the fiberglass is thick enough and would rather not drill a large hole in the canopy for those. I purchased some M3 nut plates and will use 3/32″ countersunk rivets to hold them in. I should have them in the few days… I think I have enough rivets, will have to check that.

A few photos of the lights I found on Aircraft Spruce, made by a company called Airkit LLC. They have 2 red and 2 light 12V LEDs and only draw a few milliamps. There are three wires a positive (red), Ground for the red LEDs (green) and Ground for the white LEDs (white). They are very well made lights and are quite a bit smaller then they appeared on the site, but I think they will work well.

I was a litte rusting with my geometry so the kids figured out how far to space the mounting holes using the law of cosines :-). Was a little less then 1.7″.

Made 3 2 1/2″ mounting plates ,two are made from anodize aluminum for the lights and one is made from regular 6061 aluminum which will be painted grey to match the inside of the canopy.

Did a quick test to see if the lights would be bright enough. The red seems pretty good.

The white isn’t bad either… not supper bright, but there will be some lighting on the instruments as well so I think it will be enough light.

Got the concentric potentiometer mounted. I had to drill out the knob a little to get it to fit.

So once I get the nut plates I’ll put those in and put the lights up. Next on the list will be to figure out what to do for the rear passenger cabin lights and mounting the rear canopy windows.