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.
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.
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.
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.
7 hours.
Today was more progress on the cabin electricals/electronics. I wired the aileron trim servo into the relay and the stick, as well as the sensor output for trim position. The only thing that sucks about the Ray Allen gear is that the wires are too damn small. In the RV-7, the trim servo is bolted to the innermost left seat rib. All the screws are a pain in the ass to get to, and access to the cotter pin on the bellcrank is pretty much denied. But remove it I did, so I could attach all the necessary wires.
I also ran the crossover wiring that takes the 10 stick wires and routes them across the plane to the other stick’s terminal strip. The idea is that both sticks will be able to perform various functions, including engine start. Engine start has ceased to become an issue, because I picked up a 12v accessory relay that only requires 160mA to close a circuit up to 30 amps, so now all the stick functions are low current. This means I can use a DB15 or a little DIN plug instead of the CPC I bought. Maybe I can repurpose the CPC for wing connections.
Once that was done, I actually did the DB9 connector on the elevator trim. End result is that the pilot’s stick now operates flaps and both trim servos, which means I’m terribly close to being able to put the seat rib covers on for a while.
Tomorrow I need to finish up the stick wiring and dress the wires back by the AP servo so I can forget about them for a while as well. I also need to make a wirebook showing what color wires go where. This could be important later.
20 hours.
Yes, I know I’m supposed to keep track of this on a daily basis, but I really didn’t get a lot significant done until today, just little bits and pieces here and there, tasks taking less time than actually making one of these blog entries. Even so, the last month has been a wash. The EFIS was in the shop, work went crazy on me and I had to go out of town for a few days on a pre-planned vacation, and I just flat out lost my mojo. Let me tell you, working all through Memorial Day weekend sucks big time, and I haven’t had to do that in years, even in production. But now with two working knees, and all the fiddly bits I’ve needed finally coming together, I’m in a good place. It all started with a good shop cleaning. A couple of weeks ago, I hung up the control surfaces on the walls, in an attempt to de-clutter the work area, and this worked out brilliantly, so much so that I can actually test the trim wiring with the elevator hanging on the wall near the tail. But the workbench was a blast zone. Shipping materials alone accounted for a good half of the mess, tools and hardware the other half. Yesterday I put things away and recycled boxes and got most of my workspace back. Then it was all about knocking down all the dominoes I’d been setting up for myself over the last couple of months.
At one point I got the control stick wiring all done, thinning out the bundle in the big blue casing so I could actually work with it. Here I am, happily wiring away, combining all the ground wires into one, reducing the bundle of wires from 17 to 10. This is wrong. More on that later.
The replacement pax stick came in, and I managed to cut it and drill it without incident, but I’ve come to the conclusion that working with steel sucks. I’ve been picking little slivers of steel out of my hide for two weeks now.
When we got back from vacation in Yellowstone, I found a package from Infinity Aerospace waiting for me: my 3-circuit relay deck, which handles 2 axes of trim and flaps. Here it is being fitted for a stand so it can sit in between the middle seat ribs:
It also included the spacer necessary to fit the Infinity stick grip to a 7/8″ tube, which is the OD of the pax stick. Here’s the pax stick installed temporarily, and you can see the terminal block betwen the two ribs.
Yesterday was a ton of work aimed primarily at having a lot fewer little half-done tasks laying about adding to that feeling of frustration. First on the list is something that’s been bugging me for two months: the AHRS mount. I dragooned Shelley into helping me for a bit, first we did the dimpling for the relay deck hardware, then the rest of the dimpling for the AHRS mount. This thing has a LOT of rivets along the bottom. The dimpling’s done, but the rivets aren’t, and that was on my list to finish, but it got pushed in favor of actually finishing some other things that have been nagging at me for a while. Here’s the AHRS mount, nestled near the floor, creating a level spot for the SP2 and SP4 sensors:
In the pic, you can see the sensors fastened to standoffs on the mount platform, with DB9 connectors coming out of them. Originally, I had the ribbon cable supplied by MGL, but mounting the single connector with the ribbon cable was awkward and the longer ribbon cable I made (after a long-ass drive to the Valley) didn’t fire up both sensors, so I just made each one its own DB9 connector. The MGL-supplied ones had RCA audio connectors for data, which didn’t sit too well with me, so now I have proper crimped connections on both sensors. I still need to dress and secure the wire bundle a little bit, but it’s working pretty well.
This morning I had intended to finish that process, as well as do some other things in the back of the plane, like install the TNC terminal on the cable for the Garmin GPS antenna. Of course I screwed up the terminal pin, so I had to replace it, somehow. It was an amazing SoCal day, so I took the Buell, went to Fry’s and got my TNC and BNC connectors. funny thing though. RG58 connectors don’t work on RG400 cable. The center conductor is too thick to fit in the pin housing and the ferrule is too small to go over the insulation and leave enough room to get the connector body between the braid and the center insulator. Mouser to the rescue. Apparently the type needed are RG142/RG400 terminals. ACS sells these bad boys for $38 a pop, but Mouser has them for $7.95. I also got a bunch of BNC connectors for the backplate-side connections. The only thing is, you have to slog through Mouser’s online catalog, which blows chunks, at least until you light up the enhanced catalog, which is like an interactive version of their PDF catalog. That’s easy to figure out. I also took the opportunity to order a threaded CPC (circular plastic connector) for the pax stick disconnect.
This pic shows two DB9 connectors attached to the MGL Com Extender. These are the connectors for the Trio Gold Standard Autopilot servos.
I finished up the connectors and ran power, and guess what? The autopilot servo works. There’s a menu in the EFIS, where you select your AP mode, and which servo is connected to what port. Another menu is testing and diagnostics. I can report that the pitch servo definitely does what the test suite asks it to do. This is one of the reasons I didn’t get the AHRS mount riveted (plus Shelley was baking bread, and I can’t ask her to buck rivets when there’s bread in the works). This also meant I had to wire the AP panel switch as well, which I’d been putting off. It is now DONE!
I also got the backup instrument going, a MGL AV-2.
It has an artificial horizon, compass, and turn coordinator, so if the EFIS ever packs up, I have that to fall back on. It’s using the same sensors as the EFIS, but the rate of failure on the SP2/SP4 combo is so low as to be almost statistically impossible.
Remember when I said, regarding the stick wiring, “this is wrong?” This is why.
I put ring terminals on the pilot stick wires and attached them all to the terminal block, then tested them all with a multimeter just to make sure I had contact on all the switches. I’m glad I did. Every switch beeped except the thumb-operated flaps-up. The reason for this is that stupidly, I wired the flaps-up wire into the bundle with the grounds. I have no idea why, total brain fart. Maybe I thought the black/red wire was a ground of some kind for that switch. Fortunately, I saved all the excess wire from the bundle-thinning operation and was able to salvage the red-and-black wire that I’d cut off. I spliced it back in, and now I have redo the double-layer of shrinkwrap, put on new ring terminals, and reinstall.
But I feel pretty good about this week.. I think I can get the flaps and trim wired up, and be pretty much done with control wiring, assuming I can figure out how to make the start buttons on the stick work the starter.
1 hour.
I drilled out the steel platenuts on the AHRS mount and replaced them with the aluminum standoffs I ordered from McMaster Carr. Now there is no ferrous metal fastening the SP2 magnetometer to the ship. I also finished wiring the flap motor and switch, then wired the load side of the strobe head. I think I’m close to being able to take the panel out for paint, labeling, and avionics stack wiring. Once that’s done, I can do the stick wiring, I think.
2 hours.
Friday I left work early with a low fever and some pain in my left knee. Overnight, that pain grew itself up tall into an epic gout attack. You ever heard of kneecapping? The IRA used to do it to reprimand those they felt deserving. That’s where they put a pistol at the back of your knee and shoot a small-caliber round out through your patella. That’s what it feels like. Along with that, the fever went up to a classy, special 102F, which always makes for a good night’s sleep. Yesterday was a complete wash. I sat on the lounge outside while it was nice, then went in and sat on the sofa and watched The Hunt For Red October. Davai!
Today was a little better, I was able to walk and move a little bit, and I made good use of the shop stool I got for Xmas. I made my own twisted pair of 18AWG for the flap motor and ran it up the tunnel to the switch on the panel. But it was slow going. Every move had to be carefully choreographed so as not to twist or push the knee the wrong way, and there was absolutely no way I was going to be clambering around in the cabin. After that was done, so was I. I still have to run the feed wires and make the jumper connections on the DPDT switch, but that’s no big deal.
6 hours.
This is going to span the last three days, so bear with me. My AHRS mount from Van’s showed up last week, but stayed in its box until Monday, because I had to go up north for family birthdays. Monday I spent a good chunk of time on the AHRS mount, which is basically a rib that attaches to the floor and a platform that attaches to that rib and also to the rib running between the baggage bulkhead and the one aft of that. The idea is that the platform lays flat relative to the longeron and gives you a safe, out-of-the-way place to stick your Attitude, Heading, and Reference System sensor. It’s also a decent place to put in the remote compass. It’s far enough away from any big steel that it ‘should’ give you a nice accurate reading. Van’s designed this part as a retrofit. It works on the 6, 7, and 9 models, and I believe the 10 as well. To install it, I have to crawl down the tailcone, drill a crapload of holes, make everything level, then drill in place. The process is this: Attach the platform to the rib, then snug the platform up to the bulkhead and center rib. Then drill the rib to the floor. After that’s all clecoed in, measure for level. I have a tailwheel model, this is difficult, so I measured the down angle of the longerons and the angle of the main spar and made the platform match that. The rest angle of the aircraft with my fat ass in it is 11.6 degrees. The spar was surprisingly level. I got the whole mess drilled in tonight.
Other projects involved some wiring. This is the bad part about multitasking. Blog entries become… Mushy. Monday morning I decided to finish wiring up the E-Bus, alternator field, and ignition/start switches. I got the E-Bus done, and it functions as designed and diagrammed on Bob Nuckolls’s Z11 drawing. I also installed the 5A pullable circuit breaker and started working on the ignition and starter switches. This is kind of a weird configuration, but it works, and even kind of makes sense. It’s hard to explain, because I’m tired, but basically these enable the magnetos in the up position. Center position is off, and spring-loaded down position on the left switch is start. The idea is you enable the left mag with the left switch, then engage the starter with the right switch, switching the right switch to the up/on position after the engine catches. Elegant, really. I got this all wired up, but didn’t hear the clunk of the starter contactor. What I got for my trouble instead was a blown fuse. I rechecked my diagram, rechecked my switches, I got out the multimeter and checked for voltage potential and continuity in various switch positions, then replaced the fuse, thinking maybe it just blew sometime earlier maybe I’d left the master on and grounded a wire or something. Blew that one. Changed to a simpler test: the starter circuit engaged by two known on/off tabs on the switch. Poof. By this time It was time to go to work, so off I went. This morning, I had a hunch in the shower: check the surge protection diode on the starter contactor. Sure enough, that was the problem. I had wired the diode with the band towards ground instead of towards the S terminal on the contactor, which meant that every time that circuit was completed, it would short to ground and fry the fuse. Good to learn this stuff in the initial stages of electrical work before letting the magic smoke out of a very expensive part. The suck of sucks was getting the diode wire off the firewall. I had to take off the current limiter, the battery cables, and the copper bus bar between main and starter contactors before I could get it loose. After I installed its replacement, with the band facing the right way, everything worked fine. Go figure.
Tonight it was back to the AHRS mount, down in the Jeffries tube, which I already described. It’s about to get sucker still: I have to dimple all the rib attach holes in the bottom skin with a pop-rivet dimpler, which means I’ll need a helper, or I’m going to have to climb in and out 24 times just to do that. I’ll also need a helper for bucking those rivets.
4 hours.
I took a drive down to Earl’s on Hawthorne at the 405 freeway to pick up the fittings I need to plumb the purge line. I wanted to save the 11 bucks for shipping, which is ricockulous considering it’s all of 15 miles away from my house. I’m glad I went. The place is an absolute gold mine of high performance vehicle plumbing. They have everything, including the weird stuff, and best of all, they can custom-make hoses while you wait. Still a pricey run. The stainless steel bulkhead elbow for the firewall was not cheap by any stretch. After I got back, I pulled the wings out of the garage to finish up all the old business, which was fabbing conduit support angles, installing Adel clamps, fitting and plugging in the pitot tube, and wiring the autopilot roll servo. I also spent a good amount of time rubbing off old masking tape glue with MEK. Don’t leave masking tape on anything for too long, especially in a hot, dry place The tape turns brittle and the glue turns solid. On the right wing I got wise and heated up the old tape with a heat gun which let me get most of it off in one piece. The rest came off like the stickers Van’s still puts on every part, which never peel off cleanly. This process took a while and by then I was completely beat. I only got 4 hours of sleep last night for some reason, so I was a zombie all day. I figured I’d nap for an hour and go back too it, but I started reading the last chapter of William Gibson’s “Zero History” and I was asleep before the end of the first page. I woke up two hours later, still exhausted, but I went back out there and wired up the autopilot pitch servo.
Both autopilots got wired using the D-Sub method: Use barrel-crimp d-sub pins and sockets on the wires, then individually shrink-wrap them, then put a big shrink tube around all of them. I did this for a couple of reasons. First, the Molex connectors didn’t have a decent locking mechanism. I’m sure it’s fine, but I didn’t like it. Second, I somehow lost a couple of the pins. Embarrassing, but whatever, this should work fine.
I didn’t get around to plumbing my purge line, and common wisdom seems to be to wait until the engine is hung for this. But the longer I wait, the more stuff is going to be in my way when I do a triple-bypass on the fuel system, so I want to get the tubing roughed in as much as possible.