Avionics harness continued.

August 1, 2011 / posted in Panel / No Comments

7 hours.

That’s 3 yesterday, 4 today.

The two biggest challenges for me in this wiring harness debacle seem to be keeping good records (which colors go where), and puzzling out the connections between pieces of equimpent. The GNS430 and GMA340 have way more options than I’m ever going to need. Most of the 430’s outputs are for various navigation instruments that I don’t have, and the audio panel has options for 6 passengers and various pieces of navigation equipnent like DME and ADF, neither of which I will be using. The 430W to EFIS connection is dirt simple, six wires and the EFIS makes use of the ARINC429 data feeds for fully legal IFR navigation. The connectors themselves, however are quite intimidating. The 430W has 3, two of which are high-density d-sub connectors, but very few pins are actually in use.

But the key is to take good notes. I’ll post my wiring system here next chance I get, but I’ve basically set it up this way:

For mono audio, White is HI (+) and white/blue is LO (-). For stereo audio, White is return, white/orange is right, white/blue is left.

I wrote something down for the ARINC and Mic connections, but I don’t remember it offhand. It’s important to take notes, because when the backshell is on the connector, you can’t see the wire colors anymore. I’m sure this is old hat to you avionics experts out there, but my experience runs more toward DJ and club sound systems, MIDI keyboards, and computers, so this is indeed different.

I also make my first shield ground pigtails today. This is the Nuckolls method. You strip off the insulation on the shielded cable, then cut the shield back so only 1/4″ is left. Then you make a 22ga pigtail. On this, you strip off about 1″ of insulation, then unwind 4 strands, then cut the rest of the wire off to 1/4″ of length. Lay the 1/4″ of wire along the 1/4″ of shield, then wrap the strands around both. Then flow a little solder into the connection, cover with heat shrink tubing, and done. This is how all the audio panel connection shields are grounded.

Shields are all grounded at the audio panel, because that’s the best way to eliminate noise.

OH, and for some reason, I seem to have the worst luck with all the litte attachments for my d-sub pin tool. I’ve already mangled the lo-density attachment, and today, I managed to get one caught in the mechanism of the AFM8 crimper. Freak accident. But fortunately it wasn’t an attachment I’ll need for this project.

Doublers and other little stuff.

July 25, 2011 / posted in Firewall Forward, Fuselage / No Comments

4 hours.

Shelley, who is totally awesome, helped me out yesterday by bucking some rivets back in the tailcone. With her help, I was able to rivet the doubler plates for the ELT and marker beacon antennae, as well as install the marker beacon antenna in its permanent home. We then riveted the AHRS bracket along the bottom, which has been hanging in the breeze for weeks now, and after all that, I was able to finish the MKR antenna cable.

I also remounted the EFIS, which was stupid, because I should have taken the opportunity to install the ELT’s remote switch. Now I’ll have to swaddle the EFIS in something to keep metal chips from raining into it when I’m cutting a rectangular hole directly above it. Not a big deal, just annoying.

Finally, I replaced the upper left engine mount bolt. Back when Dave and I hung the engine, I overtorqued the living crap out of it because I hadn’t realized that my torque wrench had already clicked. You can barely feel 15 ft/lbs, and I’d only used that wrench once before, on my Buell, and the torques were way higher. It was pretty easy though. I lifted the whole kaboodle by the engine’s hoist lug, enough to get most of the weight off the wheels, popped the old bolt out, and stuck the new one in. Torqued down to 15 lbs, cotter pinned, done.

Today, I’m off to Michigan, but before that, I get to go to the post office to send my exhaust system to a gentleman in Australia. Hopefully Larry Vetterman sends me my 4-pipe system soon and I can continue the ugly process of firewall forward installation.

OK, just one more thing.

July 24, 2011 / posted in Firewall Forward, Fuselage, Panel / No Comments

2 hours.

Relabeled antenna wires, applied thread seal to brake fittings (yeah, stupid, I know, shoulda done it back when I installed the brake pedals), and installed sensor manifold fittings. Little things, you know, they add up.

More avionics wiring.

July 24, 2011 / posted in Panel / No Comments

6 hours.

That six hours includes both avionics wiring and mounting the phone/mic jack tabs to the bottom of the panel. The day didn’t start out so great. I’m missing a tool and some wire. The tool is a Daniels K42 positioner. It clips into the AFM8 crimper so that when a wire with a d-sub pin on the end is inserted, it crimps at exactly the right place. I have the K13-1, which is great for standard density d-sub pins, but everything in on the GNS430W and the audio panel are high density d-sub connectors. These puppies are spendy, I can tell you that. Little device about the size of a lug nut will run you $65 new from SteinAir. I found one used on crimptools.com for $25. Hopefully it’s not trashed.

The wire is 2-conductor shielded 22 gauge. This runs all over the place connecting audio from and to various devices. I have some single-conductor left over from the mag wiring, and I have some 3-conductor I bought a long time ago, but no 2-conductor anywhere.

I did manage to get aircraft power and aircraft ground wired into the COM connector. One’s for transmit, one’s for receive, I guess.

At that point, I figured I was done wiring, so I trimmed and painted my panel extension tabs for the mic and phone jacks.

They actually look OK. I noticed that from the side, you can see the wiring tabs on the backside, but there will be black shrinkwrap tubing wrapped around them, so you won’t really notice.

Both sides seem OK.

Then I threw on the Synthpop/Futurepop stream on di.fm and started going over the 430W installation manual. Handily enough, there’s a diagram in the back, page H-4, I believe, that shows the interconnects between the 430W and the GMA340 audio panel.

The Mic audio connection uses a 3-conductor shielded wire, so I was able to wire the 430W end of that.

This’ll probably be my last entry for a few days. Going to MI to see my dad. When I get back from my trip, my K42 and my 2 conductor cable should be here, so I’ll be able to finish the harness and plug it all in. Then we see if I can catch tower and ground at SMO on my newly installed stack.

Avionics wiring begins.

July 22, 2011 / posted in Panel / No Comments

1.5 hours.

Finally, all the bits and pieces are here. I have my connector kits for both the GNS430W and the GMA340. That bloody connector kit for the 340 is $75. Truly the aircraft premium applies. But the folks at SteinAir shipped it out as soon as it came in, and by the way, SteinAir is an excellent company to deal with. They are personable, know their biz, and have just about everything you need related to avionics.

So I started out by mocking up the protrusions of the trays, with blocks of wood, measured and cut to match the shapes of the equipment, with the intention of just fastening the backplates to the wood blocks and not having to pull the trays out from behind the panel. After a while, I realized that was a stupid idea and the time to dismount the avionics trays would be less than making and setting up a mockup. So now it’s on the bench, ready to rock.

Maybe the clecos holding the D-sub connectors in there are a bad idea, but it’ll work for now. I need to print out a GMA340 manual so I can have it nearby with my GNS430w manual when I do the interconnects. This whole process shouldn’t take more than about two days, but I don’t want to jinx it. Plus I’m going out of town for a couple of days next week, which won’t help. Then I have to go out of town again the 2nd week in August. I need to get this avionics business done because I need to start working on the cowling. And order my interior. And my prop governor.

Jackholes.

July 19, 2011 / posted in Electrical, Fuselage, Panel / No Comments

1 hour.

No, really. Jackholes. For the Mic and Phone jacks. I fabbed up two plates for mounting the headset jacks and drilled two 1/2″ holes in each one. Each plate is a piece of .063 bent 90 degrees with about an inch and a quarter of metal on each side. This will be riveted to the panel where it bends horizontal at the bottom. This should give me enough room to move around, but we’ll see. If I catch a knee on it, I’ll have to think of alternatives.

ELT to go.

July 18, 2011 / posted in Electrical, Fuselage / No Comments

6 hours.

Saturday and Sunday got the ELT installed. I’d been waiting for this thing for about 5 months, and it finally showed up.Of course this device goes back in the tailcone behind the baggage bulkhead, so it’s a lot of contortion and crawling around. I’m beginning to hate working back there almost as much as I hate painting. But it went fairly quickly, since I used the same technique I used for mounting the strobe controller, which is:

blind-rivet 2 angles along the J-stringers, then blind rivet a plate to that, with platenuts attached at the mounting points for the device. Easy. Only issue though is that the screws stick out far enough into the space between the side skin and the mounting plate for possible interference with the rudder cable. I’ll need to set it all up, but it’s not likely, and even if it is, I’ll make a guide of some kind. Somehow.

I also got my Odyssey battery charger and charged up my battery to full capacity. When the EFIS docs say 11-33 volts, they mean it. At 10.9v, my AHRS and compass no longer had sufficient power to provide data.

I’m still waiting on a connector kit from Steinair for my GMA340. When I get that, I can start wiring the avionics stack. Still not sure what to do about my stick grounds though. My PTT switch (the trigger) wants to be connected to the proper terminals on the audio panel and radio, but it’s currently got a positive and a ground, grounded at the airframe near the stick. This might have to change, because I’m not sure it’s cool to just pick up mic key ground from the airframe.

Fuel flow sensor mounted.

July 11, 2011 / posted in Firewall Forward / No Comments

3 hours.

I finally found a home for the FloScan sensor. It’s now on the firewall, just below the RDAC, fed by the mechanical pump. This arrangement will let me get a hose around to the throttle body fairly easily. I agonized for months over this stupid thing. Originally, i was going to put it in the cabin, under the tunnel cover or near the bulkhead fitting for at the firewall, but allegedly this is not a good place for it as it tends to read high when the boost pump is on. The current arrangement will keep it relatively free of engine vibration, but downstream of the mechanical pump. The best place to put it is inline between the throttle body and the flow divider, but that’s not going to happen.

I’m also faced with the ugly reality of having to get a new exhaust system. The Vetterman crossover pipes fit just fine, but there’s no room for cables or brackets. I think we discussed this once before. Anyway, the issue here is that the butterfly linkage on the AFP throttle body is way too close to the downpipe of the number 1 cylinder, so close I can’t get a finger between the end of the linkage and the pipe. That’s a non starter, especially if I need to get a heat muff on there, which I will. So it looks like I might have to go with the 4-pipe exhaust, which will sound like a couple of straight-pipe Harleys, but will give me all the clearance I need.

If I’m lucky, I can sell the crossover exhaust on VAF. I haven’t drilled any holes in it for temperature sensors and whatnot, so I might get a few bucks for it.

Antennae.

July 10, 2011 / posted in Electrical, Fuselage / No Comments

4 hours.

finally figured out the magic of crimping RG400 connectors on. With the standard cheapo coaxial stripper from Fry’s, the cuts aren’t exactly precisely what you need for RG400 cable, which is actually the same as RG142. For RG58, it works fine, but RG400 is a superior cable for this app. Less loss, better shielding, etc. RG58 is perfectly acceptable as antenna cable, but only the best for yours truly. It just means things are a little less straightforward. Eventually, I got the cutter tuned right (you can adjust the blades so they cut more or less deep), and figured out how to get the right length of conductor to go in the pin. I redid the transponder antenna connector because now that I think about it, I didn’t crimp the pin conductor, which is dumb. I got the TNC connector on for the 430W’s GPS antenna as well, which has been up in my grille for months. Now it’s done.

I cleaned up the wires in back and secured the sensor wire bundle, so that job’s totally done too. What I did get into was the antenna doublers for the marker beacon antenna and the comm antenna. The comm antenna is going in just forward of the main spar. Under the seat would have gotten it too close to the strobe cables, and since there’s a strobe connection nearby, I’d rather not risk it. Now we get to see if the comm radio makes the EFIS go all funny, and if that happens, I find a better solution than the RAMI bent whip antenna I currently have. It’s the only antenna in the collection that uses a soldered lug connection instead of a BNC or TNC, but it should work just fine as long as there’s not much stripped wire exposed at the connection.

What’s left is a ton of rivets to put in. I still have to rivet the AHRS bracket along the bottom skin, plus the two doublers I made for the antennas.

Then comes wiring the avionics stack itself. That’s going to be a hoot, let me tell you.

Both sticks done.

July 6, 2011 / posted in Electrical, Fuselage / No Comments

2 hours.

Almost done. Yesterday before 4th of July festivities, I was able to finish up the pax stick wiring. I ran to Fry’s and picked up a DB15 connector. Some of you oldschool computer geeks might remember this connector as the “game port.” It’s got enough contacts to handle all 11 stick wires, and it’s small enough that it doesn’t interfere with stick travel. I don’t have any photos of it right now, but it goes something like this:

Stick wires exit detachable stick through 3/8″ snap bushing. These wires go to the DB15 plug, where there are multiple layers of heat shrink tubing protecting and securing them at the connector. I even found heat shrink tubing large enough to go around the back side of the connector. Backshells were out; they took up nearly as much space as the CPC connector. On the stick side, the wires going to the terminal block were done in the same fashion, with the socket connector zip-tied to the base of the stick. When the connector is plugged in, the two holes normally used for the screws in the backshells will have zip-ties holding the connection together. I settled on this as a semi-permanent install. I don’t expect to take the pax stick out except for special occasions like XC trips where I need all that space for Shelley’s in-flight activities or cargo, so for the most part, it stays in.

Some questions though.

Will wiring a panel switch into the ground wire of the pax stick for Enable/Disable of the stick cause a big fat ground loop?
Is having the start relay (not the starter contactor) always live when the master switch is on a good idea?
Am I asking for trouble running the trim, trim sensor power, and flaps off the same power feed? The trim motors hardly draw anything (they use 24ga wire FFS).

I now get to move on to the ugly process of wiring the avionics stack, but after finishing up this job, I’m a lot more confident that I won’t let all the magic smoke out of $10k worth of gear.

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