« Posts tagged wiring

Wings closed, part 1

April 19, 2013 / posted in Electrical, Wings / No Comments

7 hours.

Yesterday, my friend Derek came by for a few hours and helped me rivet the bottom wing skins on. Derek is peripherally responsible for me being where I am today with regard to aviation: Flying leads to skydiving, skydiving leads back to flying and flying lessons, rental airplanes lead to homebuilts. Before he arrived, I did some pondering about the best way to rivet the wing skins on, and the first two things that needed to happen were the removal of the aileron push tubes and the flaps, so I did that.

Riveting the skins on the wings would have been really tough without help, especially the inboard rows near the bellcrank. As it was, I really had to stretch to get the bucking bar up in there far enough to reach the rivets closest to the aft wing spar. But it gets easier as you move outboard, and we finished off the left wing yesterday afternoon. Derek had to leave at around 3-ish: newborns really don’t care all that much about Daddy’s friends’ projects, but I kept going.

Before he left, Derek helped me get the double row of rivets on the right wing, then I got going on the rest. To say that riveting those big bastards by yourself is awkward would be like saying Stephen King sells a lot of books. Fortunately, the skins do bend quite a bit, and I wish I had a photo to show you how I did it, but the general gist of it this:

With the double row riveted, cleco the spar side and leading edge side holes together. Then climb in between the skin and the ribs, which will allow you to get a hand and a bucking bar in through the lightening holes to just about anywhere you need to go. And it should go without saying, remove the blue stuff from the inside of the skin before it gets riveted on, or you’re going to have a lot of fun later. Good thing I remembered this before we got too far along, but if you’re reading this, I hope it reminds you before you buy yourself a long night of failure-drinking.

I thought the autopilot servo was going to cause a lot of problems, but with the push tubes out of the way, it was really a non-issue. By myself, I got another row done, up to the access panel for the bellcrank, then quit for the day. I was sore and tired. Even with help, riveting wing skins on is like yoga for gearheads.

Left to do: the remaining skin rivets, and some minor wiring cleanup, since I replaced the puny 14-ga wire intended for the landing lights with a much beefier 10-ga flavor.

More odds and ends

April 7, 2013 / posted in Electrical, Firewall Forward, Panel, Wings / No Comments

4 hours.

A few things here and there. I installed the MAP tubing and put a couple of heat shields on the pipes to protect the throttle and mixture cables. I also installed the canopy seal, which is going to need some assistance from some RTV or proseal. I do think firewall forward is just about done, though. The cabin heat SCAT tube rubs on the engine mount a little, but some UHMW tape should fix that. The two things I did that were of major importance were the autopilot test and getting that ridiculous piece of lead off the flange of the left elevator counterweight rib.

A while back, I’d balanced out my elevators, or so I thought. You’re supposed to put the elevator tips on, then drill holes in the lead weight until the elevator balances. Well, guess what? You’re not supposed to have the elevators connected when you do this. I discovered this, freaked out, then riveted a flat piece of lead (cut from an extra counterweight) to the outboard rib.

When I put that away, thinking I was just about the smartest cat in the whole barn, I started imagining the kind of beating a control surface takes in flight. So what happens to a little piece of lead riveted to this structure with a couple of Cherry countersunk blind rivets? The piece of lead comes off and somehow jams the elevator in the dive position and I go screaming downward like a holed Stuka, straight into a busload of orphans on the 405. This has bothered me for months, but I could never find a good opportunity to fix it until Saturday. I drilled out the rivets and put the lead back in a drawer. I also read about a neat trick you can do when balancing your elevators: Pour some lead shot into the tip through the tooling hole in the rib until th elevator balances out, then stick it in place with epoxy resin. Even if it’s not perfect, bias it a little heavy, because paint will change the balance.

I also mounted the MGL GPS antenna on the top side of the glare shield. It works; I get an intermittent GPS position while still inside the guest house.

Oh and one other thing: I dragged the wing cradle over to the shop and tested out the bank servo of the autopilot. Since I actually followed a wiring plan and wired the fuselage-side and the wing side according to it, I was able to test out both servos simultaneously. I do need to make a new ground connection though. The ground from the servo bracket sucks and I was only able to get a good ground by cleco-clamping the ground terminal to a wing rib.

Fiddly bits.

January 14, 2013 / posted in Firewall Forward, plotting/planning/deciding / No Comments

8 hours.

So yesterday, I joined EAA 723 at Camarillo airport. I dunno why, but I’m drawn to Camarillo. Maybe it’s because my cousin finished and flew that little hot-rodded Vari-EZE out of there many years ago, maybe it’s because it was the first place I took passengers when I got my private ticket, who knows? But I like Ventura county, and I like KCMA. It also doesn’t hurt that the EAA hangar is right near the Commemorative Air Force hangar, where there are a multitude of interesting flying machines to gawp at. Everyone seems friendly, and the guest speaker for the meeting was an FAA official, who gave us the rundown on ramp checks and a few FAR’s that are very much misinterpreted by the likes of you and I.

The goal of this is to find a nest for my bird where I can final-assemble, certify, and test fly 313TD. Currently, there isn’t any room in either of the hangars, but one gentleman is 20 hours into phase 1 on an RV7A and another is getting ready to go fly, so maybe a spot will open up soon.

Another benefit to membership is that the chapter has a flatbed trailer suitable for moving a project to the hangar, which I will hopefully need very soon. Yet another is several more sets of eyes looking at workmanship and assembly techniques.

As for actual work on the plane, I got the left intercylinder baffle and the replacement fuel pump installed, which is nice. All the wiring is re-secured where it was, and the fittings on the sensor are properly installed with thread seal.

Today, the morning was spent with my neighbor’s vast crew-cab contractor truck, schlepping stuff to and from two different Ikea stores, one in Carson, one in Costa Mesa. We’re doing this kitchen remodel, and our designer was a complete monkey: he ordered a ton of stuff we can’t/didn’t use and failed to get a bunch of things we need, so Shelley and I had to kill our morning putting everything right in preparation for the final cabinet install tomorrow.

I did get some work in on the plane, but it’s cold in Los Angeles right now, down in the 50’s during the day. You East-coasters, Northerners and Midwesterners chuckle all you want, but the little space heater in my shop wasn’t able to take the edge off, so it kind of sucked to be out there today. Cold hands bashing on metal structures when wrenches slip reminds me way too much of college street surgery, changing out a part lying on my back under a car in an icy parking lot. One of the many reasons I moved out here and stayed.

So no, it didn’t go well. First event of the day was an oh-shit moment, when I snapped the head off one of the bolts holding the throttle bracket on. That was a study in anger manangement, and I had the presence of mind to self-soothe through the initial impulses of throwing the torque wrench through the sliding glass door. Tantrums do not fix airplanes.

Fortunately, there’s an O’Reilly Auto store not a city block from my house, so I picked up an EZ-Out (sorry, screw extractor- generic) and through some miracle, managed to get the offending bolt out of the sump. I guess I’m now 1 for 5 using those things. At least I didn’t snap the drill off inside the broken bolt like I did with the wing attach adventure from a couple of years ago.

I installed the breather tube and safety-wired the mixture bracket bolts after torquing them with a different torque wrench (A Snap-On dial-type I bought used) and those are fine. I’m hoping I’m nearly done messing around with Adel clamps. Space is getting tight.

More firewall forward progress… And regress.

January 7, 2013 / posted in Firewall Forward / No Comments

5 hours.

The latest load from ACS allowed me to finish a couple of things. I got the oil pressure line/oil line adel clamp securing done, I finished the purge valve bracket assembly, I got the fittings installed on the oil cooler, and I actually got the prop governor installed, and the front center baffle reinstalled. I painted the throttle and mixture brackets and put them back on, and I re-secured the current sensor to the alternator wire. This is where it all went south.

I also finished attaching the fuel hose to the throttle body, and securing it to the intake pipes, but this is where it all went horribly wrong. I had purchased a steel 1/4″NPT-AN6 elbow, but I was using one of the blue aluminum ones to get my fit and mount done. The Floscan is on the firewall, and the elbow points toward the intake pipes on the left hand side of the engine. I had the fuel line connected to this. Somehow, in backing out the AN6-1/4″ NPT elbow on the output side of the Floscan fuel flow sensor, I managed to cross-thread the fitting as I was taking it off. Taking it OFF, not putting it on. So what it did was essentially pull on one side of the threads but not the other, kind of just bending the whole thing. Long story short, I completely destroyed the threads on the Floscan and it will have to be replaced. That was a very expensive ($210 from MGL Avionics) lesson in not connecting loads to dry-fitted NPT fittings loose enough to jam up. I did finally manage to extract the threads left in the Floscan housing and re-tap them, but I don’t trust the connection anymore, especially not with high-pressure fuel running through it. Now would be the time to switch to the Red Cube, except that now I’m reading about failures of these units, plus my firewall mount is drilled specifically for a Floscan. The time for experimentation is pretty much over.

I also got a tube of red RTV for sealing the baffles and putting some blobs wherever things might rub that I didn’t get with Adel clamps.

I still have to track down a hose from PHT (throttle body to fuel spider), but that’ll have to wait until tomorrow. My intercylinder baffles are on their way, and once those get installed I can permanently reattach all the baffles. I can also rivet the firewall to belly skin, because I’m giving up on making an exhaust fairing for now.

Adel clamps, and lots of them.

December 31, 2012 / posted in Firewall Forward / No Comments

5 hours.

Today was another iteration of finding the best way to keep things from rubbing together. I did a lot of hemming and hawing about zip ties, reading the horror stories on the Internet of that one guy who had a zip tie saw through his engine mount, and that you’re never supposed to use them on the engine mount or hard lines, and that’s all fine. Supposedly they’re big time savers, and for wiring, you bet. Lacing cord? No way, I don’t have the patience or the skill and zip ties are easy. Firewall forward though, it’s a different story. Conditions are murderous up there, and the regular Home Depot 500-for-$10 pack ones will go brittle and snap off in the heat and vibration of the engine bay. Still, there are a lot of folks who use zip ties up front with no ill effects, and there are all kinds of cool tricks to make standoffs, joins, and other fastenings, but you need to use a tie gun, and my tie gun is shite. I think I bought it at Fry’s for around five bucks, and it shows. I’m not shelling out three figures for a Panduit tie gun though, that’s just crazy. What I did do instead, is finally master the horror of Adel clamps.

Take a look:

That’s the neat little visegrip hack I bought a while ago, but never quite got the hang of. Now I’ve got the hang of it. The way this thing works is you jam a pointy thing that looks like an icepick through the holes on both the Adel clamps you’re trying to put together. Then you try to get the flanges close enough so you can wrap the forks of this gizmo around the icepick, then squeeze the clamps together as if they had a bolt throug them. You pull the icepick out, and you can put a real bolt through the holes. Problem is, the forks on the visegrip thing are pretty thick, so I ground off a couple of 32nds from each side. This way I could use a shorter bolt and not as many washers. At this point, screw it, washers are cheap and I’m not using more than 3 on a side, so this setup works fine.

I did as much as I could on the right side of the engine, where the 1 and 3 cylinders are. This means the alternator wire, the fuel pump input line, the purge return line, and the oil pressure sensor line, along with some miscellaneous wiring, needed to be isolated from the airframe, the engine, and each other.

Above my head, you can see the throttle and mixture cables, as well as my homemade steel brackets, and on the left, the double Adel-clamp assembly keeping the starter wire from rubbing on the mount.

I didn’t take a lot of pics, because I was too busy fiddling with clamps, and that makes my hands hurt, especially the knuckle on the middle finger of my right hand, where that stupid cow knocked me off my motorcycle with the door of her minivan this summer. I did get some, like this one:

This is the purge line, all secured and isolated.

This one:

shows the fuel pump feed and the purge return, held off from each other and the mount. Also clamped up here is the alternator wire and starter wire.


Gratuitous Adel clamp porn of the alternator wire.

Gonna do the rest of it this week. Happy new year!

FWF Sensor Wiring DONE!

October 29, 2012 / posted in Electrical, Firewall Forward / No Comments

10 hours.

This is yesterday and today. Yesterday started with an epic shop cleaning. I have those every so often, and it’s helpful, extremely good to have a workbench devoid of clutter, if only for a little while. Stuff got put away, stuff got tossed out, floors got swept and vacuumed.

The fiddling with the FWF stuff has been progressing as well as I can make it, and the wiring has been a bit of a challenge, especially since the K-Type wires on 2 of the sensors were too short to make it all the way to the RDAC engine monitor module. Then there’s the business of where to actually run things so they don’t rub on other bits or get roasted alive by the exhaust pipes. I got the current sensor done, although I suspect I’ll have to flip it over, I got all the temperature sensor wires run, wrapped, and grounded. About the only thing that didn’t happen is the MAP sensor, which needs a 1/8″ to 1/8″ barbed elbow fitting. Searches have turned up no such animal so far. But technically, that’s not wiring, so legally speaking my FWF sensor wiring is done.


Here’s the beginning of the attachment process. The overbraid K-type wires are a ratbastard to work with. They’re a little like shielded cable, but they’ve got an extra woven sheath below the braid that absolutely sucks to try to get off. Maybe there’s a trick to it, but this was by far the worst suckage of this task.


A slightly different angle. On the RDAC (the grey box), the first 4 pairs are exhaust gas temperature thermocouple inputs. Can’t change them, which kind of sucks, because then I wouldn’t have had to extend a couple of TC wires to make them reach the proper input. Oh yeah, splicing TC wire sucks too. The ty-wrapped snarl at the bottom is the FloScan fuel flow sensor wiring. I installed the FloScan months ago, but never got around to properly wiring it until today.


Still a rat’s nest, but there is progress there. This is right after grounding all the things that needed grounding, being the FloScan, the tach sensor, and the RDAC itself. The EGT and CHT probe wires haven’t been cut to length yet, nor have they been secured by Adel clamps to the firewall.


Ahhh, that’s better. Still some wrapping to be done, but all the wiring is secured and attached.


This shows the oil pressure sensor hooked up and run into the bundle. This will benefit from a couple of Adel clamps attaching the main bundle to the engine mount, but we’re in a pretty good place.

Even more fun: Once I got everything wired, I fired up the EFIS and decided to test out whether or not I’d actually inserted the right wires into the right terminals on the RDAC. This was done by means of a heat gun and a blowtorch. The heat gun raised the temperature of the actual cylinder itself so I could check the reading on the EFIS. The blowtorch was for the EGT probes. Suffice it to say that the method of testing was a great success: I found I had miswired the 1 and 3 cylinders for EGT, and the 2 and 4 cylinders for CHT. It is now all fixed.

Some sensor wiring.

October 4, 2012 / posted in Firewall Forward / No Comments

1.5 hours

Tonight I was able to do a little more work on the engine sensor wiring. Mostly it was about figuring out routing and wrapping hi-temp spiral wrap around probe wires, which is such a chore. Not as bad as Adel clamps though. I have to figure out the technique for those, because they’re killing my fingers. Anyway, the major visual effect achieved tonight is now the plug wires don’t hang out the bottom like sword-slashed entrails. I also got started on wrapping/routing the probe wires, but the wrap will have to come off because I forgot about the MGL current sensor that’s supposed to go on the alternator wire. Grmp. I also had to splice one of the EGT wires, because it was too short to make it all the way to the RDAC. I’m a little concerned about that. Oh, and I have no idea what wire goes to which cylinder. Yep. Awesome, that’s me.

I’m sick of this airplane. My wife is REALLY sick of this airplane. I need to get it done, and soon.

[Untitled]

January 4, 2012 / posted in Electrical, Fuselage, Panel / No Comments

Here are some pics from the last couple of weeks.  I’ve recovered my server-side image processing script, so I promise more photos in the future.


This is the mess before I cleaned it all up.


Flap actuator and servo reinstalled (Yay!)


Fuel pump reinstalled, lines secured.


This is me working on the endless process of dressing cables and zip-tying everything.

Avionics Install (almost) DONE!

January 3, 2012 / posted in Electrical, Panel / No Comments

4 hours.

Sweet FA got done over the weekend (New Years, hangover, etc, etc.), but today I finished wrapping and securing various wires, as well as rerouting the starter ground in a bundle instead of floating around all by its lonesome.

Only two things left to do, really, and that’s to install the OAT probe and reconnect the IOX when it comes back from MGL in a couple of weeks.  For now, i’m not sure whether or not to start the baffling or the FWF sensor wiring.

Another productive day.

December 31, 2011 / posted in Fuselage, Panel / No Comments

4 hours.

Bunch of stuff happened today.  Shelley helped me get the fuel lines secured with Adel clamps, and I got the fuel pump reinstalled and wired up.  It works!   I also got the tunnel cover finished, but didn’t get to setting up the cabin heat cable.    The throttle quadrant also went back in.   It’s nice to finally see the ‘damage’ from the avionics install and wiring fiasco put right and parts that were languishing on shelves put back on the airplane.

There is no end to wiring.   I cable-wrapped the antenna  wires and worked on the GS/NAV splitter mounting.  Fortunately, there were two holes ready made for it (not really, they just coincidentally lined up).   But I stopped dead in my tracks when my cable stripper exploded.   I need a new one from Radio Shack ASAP.   But once that’s done, the avionics wiring is just about done.   Finished.  Fin.  The end.

Still have to figure out how to connect the marker beacon antenna.   It comes out of the audio panel as a single shielded wire, but it has to connect to a big, fat length of RG400.   How the hell do I do that?

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