Not literally on… in the airplane that is.  But definitely on the list as the primary thing to work.

Ok, enough banality!

I started off today installing the push-pull cable on the top of the heat exchanger (HC) for the heat restrictor butterfly valve.  I quickly realized that the attachment assembly on the valve lever arm was not happy with the offset alignment I had with the Adel clamp set a bit more inboard, so I whipped up a little L-bracket to allow the Adel clamp to be mounted on the top edge of the HC vs the side.  It worked like a champ.

I then set about determining where the #2 Clickbond should get mounted on the surface of the heat exchanger.  I played with the alignment for a bit, and ran through a number of maintenance and troubleshooting scenarios in my head, all requiring the HC to be removed.  This mandated in my mind which side the cable needed to go (on the forward side so that by simply removing a cotter pin it frees up the lever arm so that the HC can be removed).

After determining where the Adel clamp would go and the configuration of the cable run for the fresh/heater air valve, I sanded down the area around it approximately 2″ x 2″.

I then 5 min glued the Clickbond in place and set it under a heat lamp.

After the 5-min glue cured, I then glassed the Clickbond in place with a ply of BID covered by a ply of Carbon Fiber [Yes, I know the weave is not aligned with the original CF weave, but this was the only spare carbon fiber I had on hand and I wasn’t about to waste any by cutting it off the roll…]

Here is the mounted and glassed Clickbond…. jumping ahead a couple of hours.

I then finalized my design for the 3-lever heat/air valve panel that will get mounted in the top middle of the left armrest, just aft of the throttle quadrant.

I then cut the top surface of the mounting plate out of 0.040″ thick 2024 aluminum.  As you can see it extends out further than what will be seen through the hole that I’ll cut into the top of the armrest.  I’ll mount 4 nutplates in the corners of this plate and mount it to the bottom of the armrest so that I can then unscrew the mounting screws and remove the plate from the armrest whenever the latter needs to be removed.

Since I had the sheet of 0.040″ thick 2024 aluminum out, I went ahead and cut the 3.3″ x 3.5″ plate for the 2 “Mag” switches (we’ll say, although both are electronic ignition) and the master switch.  As you can see by the pic, these switches will get mounted just forward of the control stick on the right armrest.

I then marked the area to be removed from the top of the left armrest for the 3-lever heat/air valve panel.

I then cut out the area using the “Fein” saw.

I then spent some time developing my plan for the actual cable runs coming from the heat/air valves to the 3-lever heat/air valve panel.  Yes, developing mods and incorporating all of them in one place like the left armrest can definitely be a slow process at times.  But I think a very necessary one in deconflicting all these components that are to be mounted. So often one decision begets another one, and even more so it may countermand a previous decision.  It’s all a balancing act when cramming this much stuff (grant it, stuff I think is the right stuff to have on hand) into this bird.

For example, having just really dug deep into my cable runs, I know have to reassess my mounting location for the fire extinguisher.  I may be able to simply move it to one side or the other, but right now it looks like I’ll now have to remove it from the armrest completely. I think I should be able to still mount it in the location I chose, but now the variables have greatly expanded again on where the fire extinguisher may possibly need to get mounted.

Ok, back to the actual build.  I used a bit of the flox that I made up for mounting the click bond to the HC for helping to secure the 2 crimped aluminum cable ferrules that attach the valve cable to the valve plate on valve #3, the Pilot/GIB air distribution valve.

[NOTE: I made a major boo-boo in that I measured the throw of the top edge of this valve at 2.3″, which is what I used to design the lever slot for the Pilot/GIB air distribution on the 3-lever heat/air valve panel.  However, a bit later when I mounted it, I determined that the cable geometry would work better if mounted it lower on the valve, closer to the fulcrum. When I tested out the valve cable runs a bit later (below) I then realized the cable only has a travel of 1″ since I relocated the cable attach point on the valve plate.  Oops!]

I then drilled the holes for the #1 and #2 valve cables (the fresh/heater air valve and heat restrictor valve, respectively) into the pilot seat back right next to where the duct traverses the pilot seat back as well.  The #3 valve cable actually travels through the duct until it exits out.

I prepped the cables and Adel clamps on the HC for valve cables #1 and #2, and installed valve #3 with the cable attached right to it.  I then mounted the GIB heat/air ducts and the HC in place (temporarily).  I ran the cables through their respective holes into and through the pilot seat back.

Here’s a bit closer look at the valve actuation, cables and securing Adel clamps on the HC. Plus, you can see the cable runs through the pilot seat bulkhead.

I then configured the cable for valve #3, which travels through the duct for about 6″ then, again, exits out of the duct shortly after it enters into the pilot area.  To be clear, the cable conduit only barely enters into the duct via the rubber grommet, so the 6″ of cable in the duct is just the wire, not the entire cable assembly.  This helps limit any negative impact on the volume of air traveling through the ducts.

Here’s the final shot of the evening, with the 3 heat/air valve cables coming into the pilot area under the left armrest.  I have to say, it was a good feeling crossing things off my 3×5 card task lists that I made up months and months ago….

I won’t get much farther than this since tomorrow is packing day.  I don’t think I’ve advertised it much, nor mentioned it on this blog yet, but I am in the slow process of moving down to North Carolina.  I say slow because my priority is still to finish this airplane first, if possible, before completing the actual move sometime next summer timeframe. Thus, tomorrow I’ll pack up a bunch of stuff, then Thursday I’ll load it up in a trailer to take down with me on Friday when I leave.

I’ll update my blog when I’m down there, but in general my plan is to give myself one more week to finish installing cockpit components after I return, with my focus back on the GIB area and the nose area.  After a week, I’ll hard reboot into working on getting the lower engine mount extrusions glassed & mounted in place, the engine mount itself drilled and installed, and then after I configure the few components mounted in the hell hole, glass the firewall onto the fuselage.  Then comes the prep for the top nose and canopy build, which will be a concurrent build to get the lines smooth all the way from nose to tail.  Shortly into that prep, I will be building my engine and bringing it home.

Then the fun really begins!

Today I had the goal of getting the inside & outside of the top armrest cupholder ring glassed.

I started off by creating some mini-trenches at the top & bottom edges of the inside armrest foam where it meets the top and bottom glass.  I only really did this on the aft side of the cupholder ring since this foam has some mass to it.  The front side of the ring is just a narrow fragile piece of foam with a bit of glass on the top & bottom surfaces.

A bit later you can see that I had successfully glassed a ply of BID on the inside of the left armrest’s cupholder opening ring.

Once the internal armrest cupholder ring had cured, I glassed the front external side of the ring with 1 ply of BID where it mates with the heating switch panel. In addition, I peel plied both of these layups.

While I was waiting for one of the cupholder ring layups to cure, I quickly drilled a 3/8″ hole into the fuel vapor sensor mounting bracket to mount the handle for the nose hatch latch release.  I had originally labeled and clear coated a red T-handle to use for this function (below) that I still really like, but it just doesn’t fit well on the right side and mounting it on the left presents too much of a hassle to get it mounted, and specifically to get the conduit where I need it to go over onto the right side.

I then installed the smaller round nose hatch release handle in the fuel vapor sensor mounting bracket.

I then mounted the fuel vapor sensor to ensure there was no conflict of space.  Clearly I still need to label my new nose hatch latch release handle, but I think this will work out fine.

I then got to work figuring out the size and configuration for the cigarette lighter charger bracket in the corner just forward of the lower instrument panel bulkhead and on the left side of very front edge of the nose gear cover (NB)…. all just to the left of the nose gear viewing window.

After getting a paper template made out of a 3×5 card, I then transferred the shape to a 1/16″ thick piece of G10.

I drilled the hole first, then cut the bracket out of the G10 stock.  I then test fitted my new bracket in place.  It looked good, so I 5-min glued it in place.  When the 5-min glue cured, I then micro-filleted the edge where it mated with NB, and glassed the top surface with 1 ply of BID.

The pic below right is after the layup had cured, and I pulled the peel ply, razor trimmed it and cleaned it up.

I then test-fitted the cigarette lighter charger into its new mounting bracket.

Below is another shot of the new cigarette lighter charger installed at the base of the instrument panel bulkhead.  Now, the underside sleeve of this charger is actually a bit too wide in diameter to fit comfortably under the bracket, so I’m going to have to kick the hole outboard about 0.1″ to get it all to install smoothly.

I wanted the cigarette lighter charger in this location so I could use it inflight, both with the bigger old style charging adapters, and also with a USB charger insert.  Another major factor for picking this spot is that I wanted easy access to this charger specifically, since it will be wired to the battery bus.  Then, when I want to charge the battery, I simply just take the cigarette lighter charging adapter that I have for my charger and plug it in…. EZ PZ!

Friday I’ll be heading to NC for the Thanksgiving Holiday, so over the next couple of days I’ll be working less and less on the build.  However, once I get back I plan to hit it really hard again!

Today I started off by heading about an hour north to help out some friends do some household repair stuff.  I was there about 4 hours before returning back home, so it knocked a good half a day off my build tasks.   Plus, I have to admit I was exhausted when I got home so I took a good nap.

Before I left to help my friends though, I was able to configure both USB thumb drives for my respective HXr and Mini-X EFISs.  I then upgraded the software on my Mini, which is something that I haven’t done since I bought it in 2014.  I also backed up the configuration of each box to its respective thumb drive in case I need to reload my specific configuration of either EFIS for whatever reason.

After my nap, I got to work doing some small layups.  I had planned on doing the first one before I headed up to help my friends so that it would be curing, but didn’t get a chance to do so.  It was a real simple layup: just 1 ply of BID, securing the top part of the parking brake handle mounting bracket to the left side of the nose wheel cover (NB).  I used a floxed fillet as well, then I peel plied it.

This is a number of hours later after I pulled the peel ply, razor trimmed the excess glass, and then remounted the parking brake handle assembly and cable.

Concurrent with the layup above, I also micro’d the foam, created thicker-micro’d edges and glassed in a ply of BID on the very front, top, interior corner of the left armrest.  I peel plied this layup.

I also did pretty much the same thing for the heat/air duct plenum clearing notch I made in the inside of the left armrest at the bottom center of it.  I did not peel ply this layup though (although when I cleaned it up after it cured it ripped some fibers loose on the edge, so maybe I SHOULD have peel plied it!).

I then spent well over 2 hours updating my electrical diagrams and printing out the freshly updated ones.  I did a fairly significant overhaul on my heating systems diagram before I printed that one out as well.  Tomorrow I’ll get back to it!

Today was one of those days where I didn’t seem to get a lot actually done, but I got a lot of stuff figured out . . . which is also important.

I started off by pulling the peel ply from last night’s layup, razor trimming the layups and then cleaned them up.  I have to say they all came up pretty good.  Since I added glass to an area that I had been trimming a lot for clearance, I then test fitted it to ensure I still had the proper clearance.  It was a little tighter, but it still fit fine.  I think if I sand it down well it should fit very nicely.

I then worked a fair amount more on the parking brake.  I’m sure this may be the bane of my build for many builders/readers of this blog, but it’s one of those things to me that I should work now since I have access, and once the airplane is done it will be a nice extra to have.

I took another 20 minutes to carve out about an inch more of the 1/4″ Nylaflow conduit buried under glass and micro to free it up so I could get the slope angle right from the conduit to the parking brake T-handle bracket.  Once I got it right, I then 1-minute glued it into place, clamped it, and let it cure a good 10 min under a heat lamp while I prepped for the 1 BID layup.

I cleaned up the excess glue and then filled in the gaps around the now exposed –and trimmed– 1/4″ Nylaflow and the nose wheel cover (NB) with thick micro.  I then laid up 1 ply of BID over top of it, and set up a heat lamp on the layup.  I didn’t bother peel plying this layup (I know…crazy!)

Here’s a shot a bit later when it was cured.  I didn’t get an exact alignment between the Nylaflow conduit and the parking brake handle assembly, but it’s close enough and causes zero operational issues.

Here’s yet another shot of the final install on the parking brake T-handle.  Obviously, I like this location, and it works well for me.

I then spent about half an hour using a piece of cardboard to make up a template for my parking brake engagement panel LED indicator lever switch mounting plate.  This will mount over 3 of the 4 screws that were used to mount the NG8 plates to the inside of the left NG30 plate, at the nose wheel pivot mount.

I then transferred the dialed-in template to a 1/16″ thick G10 plate and cut it out.  I then slowly drilled the holes one by one to allow it to fit onto the exposed NG8 screws, and then once I got the upper 4-40 switch holes drilled (small holes, upper right), I then drilled 2 x 5/8″ lightening holes on the lower side.

I then labeled the switch.  I also verified, cut, terminated and labeled the wiring running to/from the parking brake engagement panel LED indicator lever switch.  I then mounted the bracket and switch combo and verified the switch functioning and angle… it all looked good so far.

Below is the switch in the closed, parking brake and LED indicator OFF position.

In this shot, the parking brake has been engaged, which opens the switch and closes the circuit, turning the LED indicator ON.

Finally, here’s a closeup of the parking brake engagement panel LED indicator lever switch and its mounting bracket.

During the process of wiring up the parking brake engagement panel LED indicator lever switch, I also verified my panel LED indicator lights Push-to-Test button operation, circuit design and configuration… and the panel indicator lights dimmer function as well. Tomorrow I have to help some friends out with some household maintenance stuff, but I should be able to continue on with my in-cockpit configuration quest.

I started out today by pulling off the huge pile of weights that I had encased the left armrest with to keep all the mounting brackets aligned properly.  I then unscrewed and removed the left armrest.  I cleaned the protective tape off the edges of the armrest, then assessed the damage.  I think the heat lamps made the flox flow a little a bit more than it would have in a low-to-mid-70 degree shop.  Still, the 4 mounting brackets were on nice and secure, and that’s the main thing I cared about.

I was heading out to meet some from friends for lunch, so I quickly remounted the left armrest and then got to work laying up 2 plies of BID over the taped up part of the cupholder that was protruding out of the slot on the left armrest.  I then peel plied it and set a heat lamp on it since the shop is a bit chilly.

About 5 hours later I returned home, pulled the peel ply off and cleaned up the layup.  I was going to take another picture (uh, no joy) so there is no confusion on what I did, but what you’re looking at along the side of the left armrest is not the cupholder as before, but the new side of the armrest covering the cupholder.  It just so happens that at the point of where the cupholder is located, the side of the armrest just happens to be 2 plies of BID thick.  This layup not only serves to hide the ugly cupholder, but it greatly increases the strength of the very forward part of the left armrest.  In addition, it will allow me a much easier time when it comes to painting this area.

As I pointed out last night, when I floxed the left armrest mounting brackets into place, I also floxed on a bracket for the parking brake handle.  Well, here is the cured bracket and a test fitting of the parking brake handle.

Before I got in to test the ergonomics of the parking brake handle, I trimmed the bracket a fair bit closer to the mounting hole in the bracket, and curved the bracket into a half circle shape.

I then prepped the front seat to climb into the fuselage.  I would like to point out that the pic below is a bit historic for my build in that it’s the first time for my plane that the left & right armrests are bolted into place, and that the pilot’s seat thigh support is in place as well.

I then tested primarily the fit of the parking brake handle and its associated mount.  I love the location because I can’t accidentally engage the parking brake without –again– loosening my top shoulder straps and then leaning forward to grab the handle.  Plus, there is zero interference with my left leg.

As I was sitting there, I assessed possible locations for the nose hatch cable release handle and the pilot headset jacks location.  I originally was going to mount the nose hatch cable release handle on the other side of the nose wheel cover (NB), but since the right leg hole is tad smaller than the left, I decided that I’ll either mount forward and above the existing parking brake handle [if I use the T-handle] on the left side as well, or over on the right side of NB but using a much smaller pull knob…. much to decide.

Here’s a closer shot of the parking brake handle location and its clearance with my left leg.

And one final shot of the parking brake handle’s mounting location.

My last act of the evening, that took just shy of a couple hours, was to cut and remove the foam adjacent to the inside glass to created micro corners in the cupholder ‘U’-shaped area on the inside of the left armrest.  I also shaped a micro corner in the aft side foam of the small flat area at the very front of the armrest (left in the pic below).  After applying the appropriate micro, I then laid up 1 ply of BID at the front flat edge of the armrest, and along each side of the cupholder ‘U’ overlapping onto a ply of BID at the very bottom of the cupholder ‘U’.  I then peel plied the layups and set the heat lamps up to help them cure.

Tomorrow I plan on finishing the minute layups on the front side of the left armrest and move on towards working the middle and aft area of the armrest.  I’ll continue to work cockpit component configuration and installations as well.

I started off first thing this morning pulling the peel ply off the top heater switch panel layup and then razor cutting the glass.  The plate looked good, and moreover it was really sturdy with it being glassed on 2 edges.

I set about immediately laying up another ply of glass on the bottom side of the heater switch panel and then peel plied it.  I was going to use 2 plies of BID originally for the bottom side, but the plate felt really strong with just the top ply in place, so I figured just one more ply should do the trick in securing the switch plate.

Here’s a shot from above of the heater switch panel bottom side BID ply layup.

Concurrently, I also laid up a small ply of BID on the outboard edge of the top left armrest just behind the narrowest part of the armrest at the cupholder opening.  I peel plied the inside of the layup in prep for glassing the inner ring of the opening at the top.  I’ll eventually layup a ply of glass along each of the inner vertical sides of the cupholder opening as well, but for right now I’m more concerned about the top ring.

I really didn’t get a lot done in the shop today since the weather was forecasted to be about 70° F and overcast… instead it was in the mid-40’s and raining.  Clearly not a good day for painting.  Well, since I was so close on the right armrest, I decided to clear coat it in the shop, then I headed out for about 4 hours running errands and stocking up on Nitrile gloves and other shop consumables while the concentration of fumes died down a bit.  When I returned, I was quite pleased with the clear coating results!

I spent a bit of time cleaning up the final ply of BID on the heater switch panel (Yes, I realize it looks just like the pic above, but in the pic below it’s finished!).  Since it was getting later in the evening, after I cooked dinner I took the rest of the night off and actually turned into bed at a much more decent hour than usual…

Tomorrow I plan to continue my in-cockpit tasks to try to get all these components installed before moving on to the big build stuff.

I started off today by digging out the foam in 5 spots on the edges of the left armrest to create divots, that once filled with flox would become mounting hardpoints.  After digging out the foam, I whipped up some flox (actually flocro, heavy on the flox) with fast hardener, filled the divots with the flocro, then popped the armrest under the heat lamps and all was done in about an hour.

I’ll create some more mounting hardpoints in the left armrest in a few more spots, I just haven’t yet determined those hardpoint locations.

I had an idea last night where to place the Pilot & GIB seat warmer relays, but this morning I determined exactly where I wanted them and pulled the trigger on mounting a clickbond to mount the 2 relays back-to-back.  I used 5-min glue to initially mount the clickbond, then about 20 minutes later I used flox to transition around the edges of the clickbond and laid up 2 plies of prepregged BID over top of it.  I then peel plied it.

A couple of hours later I pulled the peel ply and test mounted the relays…. ah, good fit!

I then got to work on cutting the front left corner armrest heating switch panel out of G10. Somewhat analogous to the Dynon Intercom bracket on the right armrest, the heating switch panel will be a G10 plate that holds all the heating related switches and will become the front top surface of the left armrest.  The current foam and glass of the existing armrest in that area underneath the G10 heating switch panel will get removed, all but a small ledge on the inboard side for alignment purposes.

Of course it took the usual multiple iterations of fitting, trimming, sanding and refitting to get the G10 heating switch panel’s shape dialed in, but I eventually got it.  I then sanded both sides of the G10 plate for its eventually getting glassed into the fuselage.

Before setting the heating switch panel in place permanently with 5-glue and then floxing & glassing it into place, I made sure to remember to mark the outline of the plate onto the top forward surface of the armrest to identify the exact foam & glass area to be removed.

I then got to work pre-drilling the switch holes into the G10 plate.  First were the 2 round 3/4″ holes that I widened slightly for the respective Pilot & GIB seat warmer switches.

And here are the seat warmer switches installed in the G10 plate that will become the heating switch panel.  (I realize that the seat symbol of the upper switch is “reclined” a bit more than the lower switch and will fix that before final switch install).

I then drilled and mounted the oil heat pump PWM control dial.

And finally the seat warmer/oil heat selector switch in the upper right hand corner.

I then removed the switches and 5-min glued the G10 plate in place in the front corner area of the left armrest.  I then laid up 1 ply of BID on the top surface, overlapping onto the sidewall and instrument panel about an inch.  I then peel plied the layup.

Again, since it was an unexpectedly warmer day for this time of year, I spent a bit of time in-between my tasks prepping the right pilot armrest for paint.  I wasn’t sure if I was going to be able to squeeze it in, but I eventually got a shot to get it outside, get a couple light coats of primer on it, and then hit with a couple coats of the granite gray about 45 later.  It got too cold outside for me to clear coat, but tomorrow is supposed to be another warm day so I’ll shoot with a few coats of clear (since it’s high traffic component).

I had both epoxy and paint drying on different things, and not wanting to start another big task late at night I decided to rivet a couple of nutplates onto the last 2 existing/leftover brackets I have on-hand for installing the left armrest.  I have other material as well, but I’ll have to make up some specific mounting brackets for the other 3 armrest hardpoints.

So with that, I called it a night.  Tomorrow I’ll trim the switch holes on the heating switch panel and then glass 2 plies of BID onto the underside of the panel.   And as usual, I’ll continue my quest to knock out the left armrest and its associated gear to allow moving forward with bigger parts of the build.

A good majority of today was all about marking, removing armrest, trimming, sanding, installing armrest, fiddling, marking, removing, sanding, fiddling, repeat, etc. as I spent well over 2 hours dialing in the armrest to accept the cupholder.  Of course I didn’t want to go too fast here, so patience was the key.  Otherwise fitting the armrest in place around the cupholder would have been a cinch, but I would have had gaping holes at the interfaces.

I also realize this cupholder may stir up some controversy with some of the old guard or pilots viewing it, since it does sit near the front of throttle when in the WOT position. To be certain, I will take measures to safeguard against any inadvertent intrusion into throttle operations by a wayward bottle of soda/water.  Not only will the sidewall be marked with “no riders above this height —– ” but I plan to have a little spring loaded swing out arm that not only tells me how tall ANY stowed drink in the cupholder can be, but also secure the container within the cupholder as I do wonderfully fun feats of aerobatics (within limits!) in my EZ.

Here’s a closer view of the bottle/throttle interface and the bottom of the cupholder armrest notch.  I will layup a couple plies of BID over the cupholder protrusion (taped so it isn’t part of the layup) overlapping onto each side of the notch so that that when it’s painted the armrest will have a nice smooth flow.  More importantly, it will secure the very forward part of the armrest, which isn’t held on by much to the rest of the armrest.  Btw, if you’re thinking this is a good recipe for pinching some fingers on the throttle, I tried a half dozen times and the bottle top comes nowhere my fingers — so no issue there.

Here are a couple more wider angle shots showing more of the left armrest as well.

I then spent about 45 minutes notching the left side of the thigh support cover plate to clear the protruding cupholder in the left armrest.  However, that wasn’t the only clearance issue I had.  With the armrest in place I realized I had miscalculated the required width on my thigh support cover plate by about 0.080″ wider than it needed to be if it were to fit comfortably –and be installed/removed easily– while the left armrest was installed.  Thus, I ended up sanding a lot of the left edge of the thigh support cover to the point that I removed most of the edge glass down to bare foam.  Ahh, such are the pains of a custom design, eh?!

I finally got the thigh support cover to fit in place without it neither protesting as it was installed nor sounding like nails on a chalkboard as the aft left corner scraped down the side of the left armrest!  Note the blue tape on the thigh support cover as you can barely see the depression in the side of the installed thigh support (pic below).

I then grabbed a piece of spare “trash” glass and used it as a template that was strong enough to actually keep switches mounted in place.  Since this represents the heating switch mounting plate that will replace the front left corner of the left armrest (the armrest front corner foam & glass will get removed), I really only needed the actual shape for the top left side, the left edge, and left half of the cupholder access hole radius.

My primary goal was to see if I could somewhat comfortably get the 2 seat warmer switches stacked one above the other, which I determined I could.  And the secondary goal was simply to fit the inboard switches in place… which as you can see I was able to do as well.

As for the heating switches, I of course stated the outboard switches are the front/PIC & aft/GIB respective seat warmer switches.  The dial knob in the lower right is an OFF/speed control connected to the PWM board for control of the oil heat pump.  Now, on the HIGH setting each seat warmer pulls about 4.4 amps, for a possible max total of 8.8 amps (On the LOW setting –where I plan to use them mostly– the draw is <1.5A each).  The oil heat pump draws up to 7.5 amps.  If I combine the totals of just my heating system output, I’m looking at over 16 amps… on a 40 amp alternator!  Clearly I cannot allow this to happen, especially in flight.  So the upper right button switch is a failsafe that allows me to only use one system at a time, either oil heat pump –OR– seat warmers, not both.

I then checked component installation clearance below the switch mounting plate to get an idea of what all I could fit between the switches and the mounted PWM board, since I had an idea to mount at least one of the automotive relays used to power the seat warmers.  Since I need an armrest mounting bracket along the front edge of the armrest, mounted on the lower aft edge of the instrument panel (about where my first knuckle is on my index finger in the pic below), I determined there was simply not enough space for the relay… so it would have to go somewhere else [I had originally planned on mounting 2 relays for both front & aft seat warmers, but then settled for one… then none!].

I then diverged a bit from the wonderful bouts of seemingly endless sanding foam & fiberglass (and itchiness!) to knock out the wiring harness for the heating control system. As I noted above, the pushbutton switch allows me select one system or the other: oil heat OR seat warmers.  To do this required me to interject a DPDT relay into the wiring scheme.

Here are the initial relay coil power wires and flyback diode soldered in place on the heating control switches’ DPDT relay.

And a couple of hours later here is the wiring “harness” for the heating control system.

To help break it down a bit, the big red wire on the left is the 12V+ power wire that goes from the PWM board to the oil heat pump, via a 10 Amp inline fuse.  The big blue wire on the left is the 12V+ power wire that feeds the entire heating control system (either seat warmers –OR– oil heat pump) from the main buss.  The big black wire at top is the 12V- GND wire for the entire system that ties into the main GND buss (I ran out of a few colors of 16AWG wire so I didn’t run/connect a GND wire from the PWM board to the oil heat pump).  The 2 inline ATC fuses that you see in the middle top area go to the seat warmer relays, one for the front seat warmer and one for the aft seat warmer.  The 2 black wires on the right are the GND returns for the seat warmer relays.  Finally, the 2 thick black wires at the bottom with terminated Molex connectors are the multi-wire cables to the respective seat warmer switches, front & aft.

Here’s a closer look at the setup.  As a point of physical mounting, I will be zip tying the DPDT switch relay to the PWM board to secure it when the system gets installed.

Here’s a final shot of the heating control switches, the PWM board and some of the wiring. I would like to point out that the majority of the wiring for the seat warmers will be replaced with aircraft grade Tefzel wiring.

Tomorrow I will continue my immediate quest to finish the left armrest and all its associated accoutrements.