Oil Breather & Plug Wires

I'm bouncing around to all sorts of FWF tasks these days.  Something I purchased a while ago and need to install is the crankcase vacuum modification.  As a standard approach, Van's has you route a rubber tube from the oil breather port back to the firewall, connect it to a large aluminum tube, then terminate that tube just above the exhaust.  The idea is that oil that is blown out the breather will drip onto the exhaust and be burned up.  In reality, people find that while it may mostly burn up, it still creates a huge mess on the belly of the plane.  One option to fixing that is to put an air/oil separator in the loop to remove the oil from the air and send it back to the crankcase.  I chose to go with kind of a hybrid between the two approaches.  Antisplat Aero has what they call a crankcase vacuum kit.  It's supposed to be used in conjunction with an oil separator, but is commonly used on its own.  It takes that rubber tube from the oil breather port on the engine and connects it to a one way valve that is piped directly into the exhaust pipe.  This essentially serves the same function as the Van's approach, but because it goes into the actual exhaust stream, the oil is truly burnt up.  Pilots say that this alone keeps the belly clean, even without an oil separator in the mix.  The other advantage to this is the slight vacuum that it creates in the crankcase (hence the name).  It keeps a slight negative pressure in the crankcase, and people say that it essentially stops oil leaks from happening.  Many people have commented that they had leaks around the crankcase that went away completely after installing the vacuum kit.  So that's what I'm going with.

This does come with a maintenance gotcha though.  You need to pull the valve off of the exhaust during oil changes to make sure that burnt oil is not clogging up the tube.  You don't want the passage to get blocked, which would then cause pressure to build up in the crankcase and potentially blow out seals.  As a safety measure, Antisplat provides a second .25 psi pop off valve that gets T'd off of the main rubber hose.  If the exhaust port were to get blocked, the safety valve would open to keep pressure from building up.

I couldn't fit the saddle mount fitting and valve right by the firewall exhaust exit, so I moved it upstream a bit.  Antisplat said the valve can sit anywhere on the pipe as long as it's at least 45 degrees or less from vertical.  I drilled the hole to accept the tube that sets down into the exhaust.

The saddle mount fits fairly closely, but not close enough.  For now I used a piece of fiberfrax heat barrier material as a gasket to keep any exhaust gasses from leaking out (although so close to the cowl exit, I'm guessing they would be sucked right out anyway).  I may switch this over to some gasket material at some point, but the thickness of the fiberfrax made filling the gap easier than a thin piece of gasket material would.  I thought about silicone gaskets, but silicone can't withstand the extreme heat of the exhaust pipe.  Once I'm done sorting some of the other wires in the area I'll connect the oil breather tubes.

Next up, I routed and connected the oil cooler lines.

There is a bolt that goes through the engine block, through a 7/8" aluminum spacer and into the rear baffle.  You can barely see it to the right of the pushrod down by the cylinder fins.  The fit of the baffle was bugging me because it was being distorted in a weird way here.  I pulled out the bolt and made a slightly longer spacer.  Just getting the bolt back in took me a solid hour of course.  Real estate for hands is getting hard to come by behind the engine!  But the longer spacer made a huge difference and made the baffle fit much more evenly across the cylinder.

The mechanical fuel pump has a drip line that comes off of it and has to be dumped somewhere.  This is essentially a plastic tube that gets connected to the fitting on the pump, then also connected to a small aluminum tube that exits under the engine mount.  I bent the aluminum tube to fit around the mount.  I don't have a final picture, but it then got safety wired to the plastic tube.  There is no space on the engine mount to put an adel clamp, so a zip tie is the only way to hold all of this (although it's pretty solid anyway since I also put RTV around the aluminum tube where it exits the firewall).  I don't want to have a bare zip tie attached to the engine mount since they have been known to be able to saw into the steel over time though.  I've ordered a few grip lock zip ties to replace this one.  The grip locks are ridiculously expensive for a zip tie, but they have a rubber pad on the back side.

On to wiring routing!  Since the spark plug wires are the bulkiest, I started there.  The wires for Pmags have to be kept separate.  I use high temp zip ties with a chunk of rubber hose as a separator.  I did both left and right side the same way.  After I took this picture, I also added an adel clamp to the engine mount to keep the wires from bouncing around.  I haven't figured out how to handle the top wires yet.  The are longer than they need to be (these cross over to the opposite side Pmag for redundancy) so have more slop to deal with.  I could cut them down, but I'm hoping I can make them work without having to do that.

CO Detector, Cowl Fit

The miscellaneous accomplishments of the night:

I don't like that the backup latch at the top of the canopy swings under the roll bar and doesn't have any barrier to keep it from banging against the paint.  Since this is just a backup up catch to keep the canopy from lifting if the main hooks fail, I thought about just setting it up so it didn't touch the roll bar at all in normal use (although if the canopy does try to depart, I don't really care if the latch destroys my paint keeping everything in place!).  I can see myself accidentally swinging the latch around before the cockpit is fully seated though, and in that case it would gouge the roll bar pretty good.  So I dropped the latch down about 1/8" below the roll bar height and installed a strip of UHMW on the aft roll bar channel.  This at least gives me a little protection.

Next up was installing the Aithre CO detector.  It's a super lightweight box that can go anywhere in the cabin.  At first I was looking for a place to bolt it, but it's so lightweight that I decided a strip of adhesive velcro was plenty (and in turns out, that's an option in the install instructions).  I put velcro on the cross bar forward of the subpanel and slapped it in place.  I actually prefer this approach because for anything hidden by the subpanel, maintenance involves crawling underneath the panel.  If the CO monitor has to be taken out, it's going to be far easier to just pull it off the velcro than contort myself to undo nuts and screws.

I spliced the power, ground and data wires onto longer pieces and ran them up to the Backup EFIS Dsub connector on the ACM.  Getting to the ACM connectors is easier said than done with all of the wires in place now, so I took the easy way out and just removed the PFD screen.  That gives easy access to working behind the panel.

Once it was all wired up, I configured the MFD for the monitor (serial port 2 on the MFD) and set some basic alert levels.  Anything in the caution or danger levels will have alerts that show on the screens, as well as provide audible warnings.

I believe that's actually the last bit of wiring that has to be done behind the panel itself!  There's still all of the engine sensor wiring, but that's already in place and is just a matter of cutting wires to length on the engine side and connecting to the sensors.

Now comes the part I've been dreading...working on the cowling.  I made the first cut on the top cowl to cut it to length so the fit is fairly close to the firewall outline.  I came very close on it, but it looks like I got off about 1/8" in one section where the firewall changes angle.  So unfortunately I'll have to do some surgery there and add a little fiberglass to extend it again (it's only about 3").  Given the horrid state of the cowl, I'm going to have to get used to doing fiberglass repairs.  The fiberglass parts are the laughing stock of Van's, and I see why.  It's going to be a nightmare to make it all fit together nicely.

I spent an hour slowly sanding away the flanges of the nose bowl where the top and bottom cowl nest together.  While I got it close-ish, it's still horrendous and has a long way to go.  I just need a decent fit for now so I can start to work on the hinge connections and firewall connections.  Once that's all done I'll come back around to making it all pretty.

Canopy Latch and New Purchases

I haven't gotten much done lately, mostly because I've been waiting on random parts or hardware to arrive.  Today I finished up the backup canopy latch.  This is just a bar that rotates under the roll bar as a backup to the main canopy latch hooks.  I'll have to figure out a way to protect the roll bar from the latch.  As-is the paint on the roll bar will get destroyed pretty quick.  I have some 1/8" UHMW plastic that I might attach to the roll bar for the latch to seat against.

I measured the routing for the throttle and mixture cables about 1000x over the past few weeks and finally bit the bullet and ordered them from McFarlane.  Technically I needed 46" and 47" cables, but the choice was to order those lengths as custom builds or just try to make do with their standard 48" cables.  Given that the cost of the custom lengths was 2-3x as expensive, I decided I'd figure out how to deal with a little extra length!  McFarlane now makes a new type of vernier cable that is all the rage called a vernier assist cable.  It's hard to explain the difference, but it essentially makes large push/pull actions doable without needing to push a button, like with standard vernier.  It still allows fine adjustments by turning the knob as well.  I received the cables today, and they are definitely the best of the best.  They are buttery smooth compared to other cables I've tried.

I also broke down and bought a CO sensor that can integrate with my AFS screens.  These puppies aren't cheap, but the alternatives that people use are iffy at best.  A lot of planes use the "black dot" sensors that are just cards that change color when the CO levels reach a certain level.  Considering once the levels reach that point, you're impaired enough to not make good decisions, I don't see the safety value of a device that you have to just happen to notice is slowly changing color.  The Aithre sensor will trigger visual and audible alerts on the EFIS, which seems far safer to me.

I was going to finally get the backup alternator installed today since I received the hardware I needed.  Unfortunately, even with the new oil filter spacer block I got from Titan, the alternator won't fit.  I emailed B&C to see if they have any other options to make the alternator fit.  If not, I'll have to return this one and try to find another alternative.

Canopy Latches

Little by little, I'm tidying up loose ends.  I measured the mixture and throttle control cable routing about 500 times so I can get cables ordered.  I'm hoping I don't have to have cables custom made, but I haven't found any that match what I need, given my "non-standard" engine and routing.

I think my wire runs up to the panel are finished, so I drilled a hole in the vertical firewall brace on each side of the firewall recess and clamped the wire bundles in place.

I bolted the glare shield fans in place and tested them.  They actually move a decent amount of air, so I think they'll do a good job of both clearing a fogged canopy as well as keeping the avionics cool.  I will wrap the wires and heat shrink the connections once I'm sure the canopy doesn't need to come off again.

I designed and 3D printed fan grills (a new version - my first version a month or two ago was too thin and warped under the screws), just because I can.  I used a high temp PLA filament that's good to about 300 degrees, so hopefully they last. If the heat on the glare shield is too much, I'll either reprint in even a higher temp filament, or I'll send the design off to get cut out of aluminum.

Back to the canopy!  The next step is getting the latching lugs mounted.  These are the fingers that drop down through the canopy deck on the fuselage and get captured by hooks to secure the canopy.  Since there's no way to actually clamp the lugs in place to get them fitted, this seemingly simple task turned into an all day affair.  I wish Van's would make the top portion of the latch a little wider to allow for some side to side cheating after the bolt holes are drilled.  As is, they don't have much wiggle room since the nuts barely fit.  So I bolted them in place aligned as close as I could get to the holes they have to drop through.  Unfortunately, close was not close at all.  The canopy has a tremendous amount of flex when it's lifted and closed (since you lift from one side, so it's not symmetrical force), and the lugs were off by more than 1/8", so they wouldn't cleanly drop through the holes.  I used the dremel and iteratively ground away at the holes until the lugs finally fit.

Even when the lugs would drop cleanly through the holes when I held the canopy from the center (vs the side, as would normally be the case) the issue of the canopy flexing still caused problems.  This is a common issue, and one of the most common fixes is to make some guides for the lugs to hit as the canopy is closed.  I grabbed some scrap UHMW plastic and made some guides that I screwed through the roll bar.  It sounds simple, but this is all off book, so took most of the afternoon to get the guides made and laid out exactly where they need to be.  I put one guide on the outside of each side of each lug.  As long as I don't let the canopy slam down and I guide it down to the last 3 inches or so, the lugs hit the guides and the canopy slides into place.

I'm happy with how the canopy closes now, although I'm still contemplating making a fiberglass and carbon fiber top strip that goes over the canopy at the roll bar.  I've heard that carbon fiber can really stiffen things up so the canopy doesn't flop around like a wet fish when closing and opening.

The other thing I discovered in my testing - the lugs cleared the front of the hole just fine when I would manually push the canopy into place and wiggle it a bit to get the aft clearances good.  However, after 2 or 3 opening/closing cycles where I just let the canopy do its own thing, the lugs would start hitting the front of the holes and make opening the canopy almost impossible from just one side.  I'd heard that a lot of people run into this, but I was really hoping I'd be one of the few who didn't.  Apparently the issue is that during closing, the geometry of the struts pulls the canopy forward.  You wouldn't think that the setup would allow that much movement, but it does, at least without the forward skin on.  My guess is that the forward skin will stiffen the subpanel (where the canopy hinge pins are) up considerably and keep this forward migration of the canopy to a minimum, but I'm not sure.  A lot of people put adjustable bumpers at the subpanel - basically something for the canopy frame to butt up against to keep it from shifting forward.  I'll leave things as-is for the moment, but I may have to go ahead and add these bumpers before I fit the rear window, otherwise the canopy and rear window gap will be hard to judge.

Heated Seat Rewire & Starter Wire

I can't remember if I wrote about the heated seat wiring before or not.  Basically, when testing my panel wiring and going through all of the circuits to make sure things work, I discovered that the heated seat wiring was problematic.  Anytime I'd flip the switch to turn them on, the fuse would blow immediately (I have the power going through a fuse block with blade fuses).  The wiring is really complicated because of how the relays work to switch the seats from low to high - they switch between running in series to running in parallel to pull different amounts of power through the resistor in the seat pad.  Because of that, I figured I had just swapped some wires in my setup, so I dug the relays out from between the spar carry through space and spent days trying to understand how it should all work.  It doesn't help that the seats didn't come with a wiring schematic.  I finally found someone on VAF who had drawn up a schematic for the same heating pads.  That helped a lot.  In the end, in addition to a swapped wire, my biggest problem was that the DC panel jacks I had mounted on the seat pans were not insulated, so they were causing a short to ground.  I couldn't find any jacks that were both insulated and also beefy enough to handle the amperage of the seats, so my nice and tidy setup had to go.

It's not as slick as just having a receptacle in the floor, but with the wiring changes I needed to make, I just decided to throw on some molex connectors.  All of the changes worked and I now have fully functioning heat.  Making small wiring changes like this sure takes time now that most of the wiring is all zip tied down and in places with limited access.  Hopefully this is the last time!  I had to splice wires in a number of places to swap them around.  I think it's fine given it's just power (vs data), but if I ever have trouble, I'll just pull the spliced wires out and re-run new, uncut lengths.

Back to the FWF wiring!  Things are really starting to get tight.  The starter wires have to route from the left side over to the starter relay on the right.  Given the big elastomer puck on the nose gear, that's easier said than done.  I clamped the starter wires, as well as the CHT sensor wires to the engine mount.

Then the wires swing down towards the firewall.

I made a 90 degree bracket to clamp things to the engine mount right by the nose gear.  From here, the starter cable swings around the elastomer puck and over to the relay.  So another full day and one more wire to show for it! 

PMag Wiring

Continuing on with FWF wiring, the PMags are up next.  All of the wiring for each PMag goes into a green connector that then gets screwed into the body.  There have been quite a few reports of wires coming out of these connectors if they are just inserted and clamped down with the screws.  Out of the many solutions people have tried, I decided to use barrel connectors (at least that's what I call them).  The wire is inserted into a hollow tube and then crimped with a 4 sided crimper.  It gives the screw of the PMag connector more to bite into than just the wire strands.

The routing of the wires to the PMags took a lot of head scratching to figure out how to get around all of the other random things and still be supported.  The left PMag has the wire connector on the bottom and the right PMag has it on the top.  I did the wire contortions and got it all sorted out, only to later stumble on the fact that the PMags can actually be rotated to different orientations.  So I could have changed the left side to be wire side up had I known.  That would have been easier to wire, but that ship has sailed.  While I was messing with the area around the PMags, I also connected the oil pressure sensor (brown/white wire under the oil filter).

The PMags use manifold pressure to assist with ignition timing (although it's not required, so they will still function even without it).  The manifold pressure line goes from the engine, through the firewall to the manifold pressure sensor, then T's off and comes back out the firewall to go to the PMags.  The same line can be used for both PMags by using another T.  It's hard to see where all of these pieces are in pictures - the manifold pressure line is the black tube that runs along the front/top of the engine mount.

Last up for today was finalizing the wire bundle that goes around the battery for some power connections.  I added the two power wires for the PMags.  I didn't have the right size ring connectors for 16 AWG wire (they need to have a much bigger hole for a 1/4" bolt).  I do have some large hole 10-12 AWG ring terminals though, so I just crimped both 16 AWG wires together in the larger terminal and connected it to the stud on the starter relay.

Firewall Forward Wiring

Yesterday was a cold, rainy day, so I decided to spend it sitting in comfort and fiddling with my panel.  I put a seat in and fired things up.  While I had stumbled around a bit with configuration when I first powered everything on the other day, I hadn't really gone step by step yet.  I loaded the ACM and EFIS install manuals on my ipad and spent a couple of hours going line by line through all of the settings.  The system starts by doing a scan through all of the peripherals that are on the Skyview network (all of the Dynon stuff), then you have to manually set all of the devices up to talk to the correct screen.  I was really confused about this, so Friday I had put in a call to AFS and they walked me through what all of the inputs needed to be set up for each screen to handle the combination of devices I had.  This is what makes AFS more of the Android kind of experience vs Garmin, which is for sure the iOS approach.  With Garmin, you get what you get.  With AFS, you have incredible flexibility.  I love having that ability to make it what I want it to be, but it definitely comes with more of a learning curve to get it all set up.

Once I got everything talking to each other, I went through all of the various displays to set up the flight values specific for my plane.  There will still be many hours of configuration and calibrations remaining once I get the plane put together and ready for first flight though.  At least I know that everything is working as it should!

One thing not working - the heated seats.  I flipped the switch to test it out on the pilot seat and it immediately blew a fuse.  I put an ohmmeter on the DC jacks and found that the center pin is grounding out, even though it should go to power.  All four jacks are doing that, so I obviously swapped some wires in my design.  The system uses a couple of relays, and after reading up online about them, it sounds like I'm not alone in having issues with the wiring.  I didn't really have the motivation to contort myself to trace the wires, so that'll wait for another day.

Fast forward to today.  Now that the panel wiring is largely complete (famous last words, I know), it's time to get cracking on the firewall forward wiring.  I have most of the wires laid out in the general vicinity of where they need to go, but the actual routing and attaching is quite the puzzle.  With every wire and hose that gets added, another routing obstacle is created.  Unfortunately, being the first time I've ever done this, I don't know what I don't know yet, so I'm sure I'm going to end up having to redo my routing a few times before it's all said and done.

I started with the power side of the firewall - attaching the amp shunt sensor wires and the starter switch (I had already attached the master switch wire the other day).

I also added a ground strap to the engine case (attached it to a bolt on the accessory cover - where the backup alternator will go).  Next up was routing all of the wires from the left side firewall passthrough over to the various exit points they need along the top engine mount.  For now I just want to get things set up in the general vicinity of where they need to be.  I will attach wires to end points after I have the basic idea sorted out.

I used solder sleeves to attach the pre-existing fuel and oil pressure sensor wires to the wires going to the EMS.  That was my first step at getting things organized.  Next I'll probably need to tackle the Pmag wiring.  It's not complicated wiring, but I think it's going to be a pain just because of the difficulty of access.

Panel Power

Most of my work these days is spent fiddling with individual wires here or there, so not a lot to take pictures of.  I do have what I think is the final shot of the area behind the panel though.  I had forgotten to pull the two wires for the defrost fans that live in the canopy frame.  I didn't feel like undoing a bunch of zip ties, so I just added them to the bundles and ran them to the center area of the panel.  I have to provide enough play that they can move around as the canopy is opened/closed.  Once I get the canopy back on, I'll put some protection over them.

I also ran the static air tube to the G5.  I put a T on it to take it to the alternate static switch first.  With the switch off, the static air is pulled from the ports at the rear of the plane.  If I ever need to (unlikely), flipping the switch up opens the valve at the back of the switch and allows cabin air to feed the G5 instead. Once I'm flying I'll have to document what the difference is between the two so I know what to expect in terms of changes in instrument indications with the different air sources.  The only time it would ever be used is if the static ports ice up or get clogged with something - again, unlikely since this plane is not one that I'll get anywhere near icing, and there is a port on each side of the plane, so clogging one doesn't necessarily mean a complete clog.

With all of that base wiring done, I decided it was finally time to flip the switch and bring the panel to life!  I still have to do all of the FWF sensor wiring, but want to at least make sure the rest of the wiring is correct before I get too deep into the rest of it.  When I first flipped the master switch....nothing.  Turns out it's important to actually connect the master relay wire to the relay itself.  Duh.  I had left that off until now, not wanting to accidentally let power through when I wasn't ready.  Once I remembered that and connected the relay, everything powered up right away and all of the smoke stayed in the wires!

So at least I know that all of the devices work.  Now the big hurdle is configuring them to actually talk to each other and read all of the sensors.  The big upside to the AFS setup vs Dynon is that it has a lot more serial port options to allow for more peripheral devices (5 per screen).  The downside is that those serial ports aren't all shared between screens, whereas with Dynon (which only has something like 5 ports total) shares all of the port data with both screens.  That means with Dynon, if you lose one screen, you still have control over all of your peripherals via the other screen.  With AFS, if you lose one screen, you lose the peripherals that are linked to that screen and not shared with the other screen.  It gets even more confusing, because that's just the serial ports.  With AFS, all of the devices that use the "skyview network" are shared between screens, regardless of which screen dies.  So that means you'll always have ADAHRS, com panel, autopilot panel, and engine data info on both screens, even if one screen dies (so basically, all of the "get me on the ground" info is available on both screens - plus also having the backup G5).  Risk mitigation with AFS is just about ensuring you configure the serial ports on each screen so that you have necessary controls on the other screen should one die.  For example, once I put in my IFR GPS and second radio, I will configure one screen to be connected to comm 1 and the Dynon GPS, and the other screen will connect to comm 2 and the IFR GPS.  That way if one screen dies, I still have a comm and GPS input coming through the other screen.  Likewise, if both screens were to die, then the G5 would still show all flight attitude info, and I could still use the radio control on the panel itself (vs controlling through the EFIS).  The only things I could potentially lose completely would be my transponder and ADSB, if that screen they are linked to went belly up.  Neither of those present a flight risk though.

All of that is a long winded way to say that my next step will be to sit in the plane for a few hours and configure each screen.  I'll have to take the install manual out on my ipad and just go page by page through it.  It's a lot of configuration!  Everything from entering in the tail number so it can generate the right ADSB code to entering in all of the flight envelope speeds, sensor types, and hundreds of preferences.  One thing I noticed is that I haven't been able to get a GPS signal in the garage.  I temporarily attached the GPS pucks on the plane, but at least with the garage closed, they haven't been able to connect.  I'll open the garage and see if that makes a difference.  I'll probably go ahead and connect the comm antenna as well (even though all of the antennas will have to come off when I paint), just because I don't want to accidentally hit the transmit button without an antenna attached.  That can blow the control module.

Wiring Never Ends

Most of the wire routing directly behind the panel is cleaned up now.  The only remaining connection to finish is the "front" airframe connector to the ACM.  I just need to pull the field wire from the alternator and pin it in that Dsub, then it'll be all set.

The area forward of the subpanel is getting close.  There are just a handful of random wires to run yet, then it will be as organized as it can be.  While it's not pretty because of the various wire lengths I had to deal with (lesson learned - the next plane will be better), it's all solidly mounted.

To do the rest of the firewall forward wire routing, I needed to get the scat tubing for the heater muff inlet in place.  I temporarily put the right aft baffle in place and got the scat tubing routed around the engine mount.  No matter what I did I couldn't keep the tubing from rubbing against the engine mount though.  I used a couple of adel clamps and put RTV between the tubing and engine mount to minimize chaffing. 

Routing the alternator power and field wire back to the firewall is a little awkward.  I made some steel standoffs and attached them to the engine using the oil sump bolts.  Then I attached the adel clamps to the standoffs.

I used the same approach on the other side of the engine for the starter power wire.

More Panel Wiring

There isn't much I can share that looks different in photos, but I'm continuing to truck through the panel wiring.  Even though I have most of the wiring sorted out now in terms of connections, the fiddly part is in figuring out the routing.  I'm trying my best to keep it as organized as possible.  I'm succeeding in some areas and failing miserably in others.  Except for a couple of remaining connections to the fuse block on the right side, most of the wiring behind the panel is in place and solidly supported.  The left side between the ACM and the PFD is incredibly tight, which makes clean routing next to impossible, but I think I've got it about as good as it can get given the space limitations.

The area forward of the subpanel is a different story.  I still have a lot of work to do there.  Part of the issue is a lesson learned from a year ago when I ran my wiring from the other areas of the plane.  Based on what people had said, I made sure to make the wire harnesses just a little longer than necessary to account for service loops behind the panel.  Knowing what I know now, I don't think I'd do that again.  For one, with modern electrical designs, nearly everything in the panel is easily removed just by unhooking Dsub connectors.  With a slider canopy where the back of the panel is only accessible after you've removed the glass screens, a few extra inches is all that's needed to unscrew them, then reach up and remove the connectors.  With a tipup canopy, I don't even have to do that!  All I have to do is open the tipup, and I have unrestricted access to everything.  So I think this "service loops for everything" idea is kind of antiquated at this point, depending on the aircraft design.  For me, the service loops are causing me nothing but grief.  I don't have any room immediately behind the panel to coil up all of the extra wire from my harness runs to other parts of the plane.  That means that I have to bundle up all of that extra wire in forward of the subpanel.  It creates quite the mess!  I'll be able to tidy it up once I sort through my engine systems wiring and all of wires that need to traverse this area to go to the aircraft ground, but in hindsight, I'd cut all of my harnesses shorter and just make them the right length to get to the panel.  Service loops that have to be forward of the subpanel means that if I ever need to remove or change a wire, I have no choice but to crawl under the panel and cut a bunch of zip ties to find my wire in the sea of loops.  It would be far easier not to have the loops to begin with and have no extra wire length in inaccessible areas.  Oh well, lesson learned.  There's no shortening things up at this stage, and it's fine.  It's just an assault to my senses and an extra pound to the plane.

Taming the Rat's Nest

It seemed like there was plenty of space behind the panel until I actually started filling it with wire harnesses today.  I don't think I quite grasped how full the ACM would be.  By the time I was finished plugging things in, it was so full I had a hard time even tightening the Dsub screws.  The downside of having harnesses from AFS is that they aren't the length I would have made myself.  So some fit perfectly, and others have enough extra that I have to make a tiny loop.

I used the panel stiffeners as a place to put adel clamps and run most of the wires from the right side of the panel to the ACM.  That bundle is going to be really close to where the canopy frame swings when closing and opening, but I think it should clear.  If I find it doesn't, I will rotate the adel clamps around and put the wires on the aft side.

I installed the headset jacks.  The lemo plug is the black one on the outside, and the standard 2 plug headset jacks are the silver ones.

Next up was the wiring for the Pmag switches.  I still need to clean up the routing of those wires, as well as run the wire for the master switch. 

Panel Assembly!

The day has finally come to put the panel together!  I'd love to be able to route all of the wires before anything is on the panel and there's a lot of space to work with, but it's too hard to know exactly where everything will set.  I screwed the panel to the longeron brackets and then screwed the audio panel tray in (screws/nuts). The tray for the backup battery and comm transceiver went in next.

The brackets for the audio panel tray stiffen the panel up quite a bit, but the top still has a considerable amount of give when pushing on it, like you would do when pushing the buttons on the radio or autopilot panels.  Since the panel is already painted, the last thing I want to do is put more screws through it, so I decided to make some stiffeners out of aluminum angle attached to the subpanel and the top reinforcement of the panel.  I countersunk the screws on top - the glare shield sits down flush on it when the canopy is closed.  This really stiffened up the panel, and as an added bonus it gives me more places to attach wires routed from one side of the panel to the other.  I had to cut off a big chunk of the angle of the stiffener on the right side to allow clearance for the Dsub that goes into the autopilot panel.  Not ideal, but also not really a big deal given that this isn't a part that will really handle much stress at all.

Then the fun part came that I've been waiting months for!  I put everything in place and locked it down with black button head screws.  I have to admit, it looks pretty cool!  It's especially cool to know that I did it all myself, whereas most people these days just pay a shop to make the panel, from cutting to labeling and wiring.  The only thing of note that I'm not sure about is the fit of the audio panel.  It was very tight going into the tray and is canted just a tiny bit, meaning I got the tray angled down just a little bit.  I know it can go in perfectly straight since it was when I first fit the panel.  I may pull the panel out tomorrow and loosen up all of the screws of the tray to see if I can tilt it back to level.

The remaining things to do are to install the headphone jacks (wired into the audio panel by AFS, so I couldn't put them in before installing the audio panel tray) and 3D print a cover to go where the future IFR GPS will go.  I also need to route the cabin heat control from the heater box up to the panel.

Once everything is in place, the space fills up pretty quick!  Routing wires is going to be interesting.