Fuse shelf feed wiring finished

Again, not a ton of time out in the shop today, but I didn’t need much to finish terminating all these branches and make things all nice and shiny. Just lots of trimming, stripping, crimping, and heat shrinking. But this mostly finished up the shelf, with the exception of adding the actual power feeds from the engine compartment. I guess I could go ahead and pull those feeds and just leave them unterminated on the forward firewall side, though I’d also need to order the right terminal lug for heavy-gauge main feed wire; I don’t have that on hand right now. But all that will be relatively simple compared to this somewhat tedious work.

Anyway, enough talking, it’s time for photos. As probably mentioned before, the branch circuits all exit the shelf on the right side, and from there split off into a few smaller bundles going to different fuse block spots. I like how neat this all ended up, though a really picky part of me wants to shorten up that M5 wire (rightmost branch on the top-right bundle). Pretty sure I can live with that, though…

Note: all the securing of the bundles here is temporary. That’s likely obvious where the bundles are secured with twist-ties, but that also applies to the zip ties; I used those where I needed the bundles held a little more securely while working in here. When this is final-assembled, the bundles will be wrapped in silicon tape anywhere a zip-tie is used for security, to prevent the zip-tie cutting through insulation.

So yeah…I can’t exactly point to a lot of shop hours this weekend, but I like what I have to show for what time I had.

Posted in Electrical, Fuselage | Hours Logged: 1

Even more fuse shelf wiring

Well, between the late summer heat and multiple things to do around the house today, I didn’t get a ton of time, but it’s still more than I’ve done in a day for a while, which felt pretty nice. I think it helped a bit to be able to tune in the OSH arrival audio on LiveATC while I was working…a bit of a reminder of what I could be doing with this plane in a year’s time if I can keep my work ethic up.

Anyway, first step was continuing with lacing and branching out the fuse block bundle. Last time I’d gotten as far as the end of the essential bus, this time I got the rest of the run all the way around the main bus, with all the individual circuit branches separated as needed. I did run into a couple iffy wire lengths, which resulted in me shuffling some circuit assignments around, but nothing really troublesome at all. I just made sure I was updating my schematics as I made those decisions.

It’s not the great to look t, but here’s the bundle all routed around the main bus. With the branches sticking out every which way it’s still pretty chaotic:

Next was the real fun: starting to terminate the branches. I only got as far as on side of the essential bus, which consisted of four whole circuits, but the results are pretty satisfying:

Since the individual wire runs are pretty short, I had to keep the heat shrink labels minimal, which is why they’re only labeled with the block position. The main purpose of the labels here is so that if I ever have to disconnect anything here, I can reliably reconnect the runs to the proper fuses. Actual identification of the circuits will come from a little table I plan on printing out and attaching to the open area of the fuse shelf – it’ll be pretty similar to how cars generally have a diagram and key to identify which fuse is which.

I’m looking forward to getting the rest of these terminations done – just seeing that one side of the block, I think this is going to look really slick when it’s complete. Of course, probably no one but me will ever see it again once the airplane is done, but at least I’ll get to enjoy the satisfaction of good workmanship.

In other news, I got my Mouser order in, which includes the Molex housings I need to complete the switch console plugs. Probably something to look at once I finish with the shelf. After that, I need to worry about getting the ground bus installed and all the terminations done…once that’s complete, I think it’ll be about time to try powering some fo this stuff up, which will be a nerve-wracking exercise…

Posted in Electrical, Fuselage | Hours Logged: 2

Wiring experimentation

Yet again, just some incremental work. I wanted to figure out how to address the two seat heat feeds to the fuse box so I could get moving on that. First up was the question of whether I could actually just put two 14AWG wires into a single terminal. I tried that with a couple short pieces, and I did get them to crimp sort of OK into a larger terminal, but only by using the wrong (one size smaller) die in the crimper. I didn’t feel too crazy about that idea, even if it did feel secure.

OK, well what about doing a good old-fashioned window splice? Here again, my test for this worked ok, but I wasn’t to happy with it. Wrapping one wire around another is a good bit harder to do cleanly when they’re this big, and wetting them out with solder is a bit more work, too.

So instead, I’m going to terminate the two wires individually, and use a piggyback blade terminal on one. The piggyback terminal has both the female portion that’ll go on the fuse block, plus a male blade that another terminal can attach to.

Of course, I don’t have these, but hey, this was a good time to finally get those Molex connectors I need ordered. Digi-key now says they won’t have the part I need in stock until…November…so I just ordered from Mouser instead. Looks like that stuff should be here by the end off the week.

Maybe I should work on some of my antenna coax runs in the meantime. Or I guess I could get my ground bus located and mounted, so I can start terminating all those wires. I’ll need all that done before I can power everything up anyway.

Posted in Electrical | Hours Logged: .5

More fuse shelf wiring

Did some more work on making the fuse shelf nice tonight. Basically I’m working through lacing up the wire bundles and getting them routed. The first part of this was pretty easy, just lacing up the main trunk as it enters the shelf through the adel clamps I put in place last time. From there I needed to think about splitting the bundle as needed, so I ended up sitting in the fuselage for a bit splitting off the four branches (one for each side of the two fuse blocks) and arranging the entire bundle so that each branch could split off fairly cleanly.

From there, I got as far as pulling out the first branch for the essential bus, then lacing up the rest of the trunk as it passes down and along the other side of the essential bus, with the individual leads branching out of the trunk. Terminating these will come later; I figure I’ll deal with that after I get the routing taken care of.

Starting to look more organized, but still plenty to do:

Before I continue lacing over towards the main bus, I need to decide how to handle the dual power leads for the seat heat circuits. In most other spots, I did window splicing down in the harness for split leads like this, but here I brought both power leads all the way to the fuse blocks. Notably, I also did this with the com radio circuit; there’s a lead for the remote radio as well as the actual panel. In that case, it’s easy to handle since they’re small gauge wires; I’ll just combine both wires into the terminal. But that’s probably not doable for the 14AWG seat heat wires, so I think I’m going to need to work a window splice into the harness here. That should be a fun one to work out with the heavy wire…I’ll probably want to do a test run on the workbench before I try it on the real harness…

Posted in Electrical, Fuselage | Hours Logged: 1.5

Fuse shelf wire routing

Well, for some reason I went out and tried to work tonight and it clicked and I actually got some stuff done. This isn’t the only time I’ve touched airplane stuff since I last posted, but between then and now it seems like I’d touch something every now and again for a few minutes but just never seem to actually get going. Motivation is a weird thing…

Anyway, this is what I’ve been trying to tinker with for a week or so now; getting the hardware mounted to secure the wire bundle. The idea here was to have two adel clamps, one mounted to the shelf, and the other to the baggage bulkhead, which will secure the bundle in both spots and provide an area where it can flex when the shelf needs to be pivoted down. So all I needed to do was lay out and drill a couple mount holes.

But hey, that’s done now. I’ve got the clamps temporarily mounted just to check routing, but this seems good to me. I think next I’ll need to get this portion of the bundle laced, then I can start working on the rest of the routing around the shelf, which will involve even more lacing, plus just in general working out the splitting of the bundles.

(Note: the screws I’m using with the adel clamps right now are absurdly long. I need to get some that are less ridiculous, but these work for mocking things up.)

Posted in Electrical, Fuselage | Hours Logged: 1

Let’s look at this fuse shelf

Well, it was only half an hour, but half an hour is something, and I need to get back in the habit of doing something. I still don’t have the parts to finish up the switch console – Digi-Key still doesn’t have the right plug in stock. Guess I might break down and order them from Mouser or somewhere else at some point.

Anyway, I figured to quit putting off the fuse shelf. Tonight I disconnected the avionics shelf stuff and got the shelf out of the way so I could look at the fuse shelf. And I’m happy to see that my concerns about the fuse wire lengths appear to have been unfounded – looks like I should be able to route the wire bundles like I want and still reach everything. So I shouldn’t need to add a disconnect or extend anything here.

Now I just need to actually do some of this work, starting with securing the bundle to the baggage bulkhead and shelf, which will control the portion of the bundle that’ll allow the shelf to actually pivot down as needed.

Posted in Electrical, Fuselage | Hours Logged: .5

Switch console wiring plug

OK, so technically this is the summation of a few really short work sessions, none of which (until today) seemed worth writing about, but I guess in the end it comes to the same general conclusion, which is that I haven’t done much in the past week or so. I really need to make my transition to my summer schedule, by which I mean getting up early on the weekends and getting as much done as I can before it gets stupid hot out in the hangar.

In any case, I just put up with the heat around midday to get some measurable progress done on this switch console. I’d been putting this job off, figuring it’d be not much fun to do – after all, the harness end for the console is tucked over by the right gear tower, and will only have a short stub coming out of the tower. Good makings of some tight-quarters work.

Eventually I bit the bullet, put all the supplies and tools I needed in the fuselage, laid a few 2x4s on the seat ribs, and climbed in to get to work. And like most tasks on this build that I’ve somewhat dreaded, it ended up not being too bad at all, though it was still tedious.

I did discover one issue, though…after clipping each harness wire to final length and sliding on the heat-shrink label…I had an extra label. Apparently I never did lay in a ground wire for the Flyleds wig-wag switch I put over here. This is mildly annoying, but in the scope of issues I might have run across while working on this harness, this is way on the minor end. It’s also easy to fix – rather than running an additional wire from the ground bus over to the switch console, I’m just going to tie the wig-wag ground into another switch inside the console. Since none of these are signal/audio type grounds, there should be no danger at all in combining them. This is all handy since it’s just work I have to do on the console itself, which means I can do it on the bench vs in the airplane.

Anyway, with that obstacle addressed (in theory at least; I haven’t done the fix yet), I got to work terminating all the wires with sockets, and then started loading up the connectors. The large micro-fit connector which constitutes the majority of the circuits was straightforward. The other connecter is a mega-fit, required for the higher current circuits, and here’s where things got interesting. Try as I might, I could not get these sockets to go into the connector.

Eventually I retreated inside for some research and discovered something really important…it turns out Molex makes two different series of mega-fit connectors, and the housings and contacts for each series are only compatible with that series. Well, I bought one variety of housings and pins, but got the wrong type of sockets.

Given the tight confines inside the fuselage, I think the best way to handle this is to leave the sockets I installed today alone, and swap out everything else for the TPA mega-fit hardware…again, much better to rework the stuff in the console, on the bench, vs in the airplane. But it also means I’m done with this housing for a while, depending on whether I decide to go ahead and place a Digi-Key order now (probably) or put the parts on my list for a future order.

Update: After some research, turns out this distinction only applies to the connector (female) side, so in fact all I need to order are new connector housings for the sockets I’ve already installed. This both simplifies things, and makes the resultant order more annoying since I’ll probably pay twice as much for shipping as I do for the actual parts.

But hey, at least I’ve got one nice-looking connector to show off:

Posted in Electrical, Fuselage | Hours Logged: 2.5

CPI wiring complete (for now)

Again, nothing to really go in-depth about tonight. I got the two ignition control switches wired up, with the power/ground feeds from the main harness and the switched power and kill leads to the ECU. There was a little bit of thinking here about how to orient everything, but nothing too crazy. In the end I’ll probably zip-tie the two switch plugs together just to help stabilize them a bit and decrease any stress on the connections.

I also decided to take care of the ELT switch while I was over here. This ended up being one spot where I didn’t make the wires quite long enough, so I ended up doing a solder splice on each wire to give them an extra few inches to reach the switch without stretching. So now all this stuff on the right panel wing is wired up:

The wires over to the CPI ECU need to be bundled up so they can be all nice and neat, but since I still have the coil and crank trigger harnesses to fish into here, there’s not much point doing so. So for the moment they’ll just look kind of disorganized:

What’s next? Well, I guess maybe I’ll see about the switch console…getting all those wires trimmed, terminated, and pinned up should be fun, since there won’t be a ton of space…but it’s got to get done.

Posted in Electrical, Fuselage | Hours Logged: 2

CPI wiring

Well, I made it a whole hour. Turns out that when there’s a significant mosquito population, waiting until after dark and working in a brightly-lit hangar is maybe not the best choice. Oh well, I still got things done.

The handful of preinstalled wires for the CPI ECU are done – these were just the four ground wires and two tach wires to the EMS. I went ahead and installed the power wires into the connectors as well, but didn’t get to the next point with those, which will be terminating them at the two panel switches. Then I’ll just need to add the kill switch wires and this will be done…well aside from the harnesses that need to be fed in through the firewall from the engine compartment.

In any case, here’s the harness as it stands tonight:

Posted in Electrical, Fuselage | Hours Logged: 1


Well, not an especially productive day, but I did get a few things done. I added a Molex connector for the CO detector unit on the baggage bulkhead, and then did all the terminations for the left panel wing. This includes the three switches over there along with the panel light dimmer:

I also started looking at the switches on the right wing, which need to tie into the CPI2 ECU. Figuring out how to route everything will be a bit more interesting over there, compared to the pretty simple wiring runs on the left. Among other things, I need to figure out which coil kill lead goes to which switch. On the one hand, it doesn’t really matter, since the idea is to just be able to disable them one at a time for preflight checks, but on the other hand, if one of those checks fails, it’d be nice to know reliably which coil pack is the problem.

Posted in Electrical, Fuselage | Hours Logged: 1.5