The New Wiring Diagram

I have posted it in PDF over here.

Wire length / drop / load calculations are in the Excel spreadhseet over here.

• The design is based on Figure Z-11 from AeroElectric Connection by Bob Nuckolls, with the following tweaks:
  • I'm using the B&C LR3C Voltage Regulator, so it's wiring has been incorporated
  • I dropped the Endurance and Main Battery busses
  • I have tweaked the starting switches circuit, main buss feeder, and how ammeter is hooked up - see below for discussion
• The diagram is laid out to generally clump the components together as they would be on the airplane. It initially might seem convoluted - but it has a certain flow to it matching the locations of components. Start in bottom right corner for battery/starter/alternator circuitry and go counter clockwise - this will effectively take you "thru the airplane" as the components will be laid out; roughly

Review Items and Commentary on Specifics

Starter Circuitry

My current take on my Starter and Mags circuitry is this:

Starting and Mags Circuit

This is a deviation from Z-11, with both switches having to be in the momentary up position for starter to engage. I like this better for two reasons:

• It makes the act of starting the motor more explicit
• It returns back to correct "running" position automatically

I need to test the ergonomics of pressing up a couple switches together. If I don't like it, another alternative would be to replace the "Right Mag" switch circuitry from -5 to -1: making the top position on it non-momentary (as noted on the diagram). This will reduce the "user-friendliness" but will still keep the explicitness, especially with my using pull-to-unlock switches from Honeywell.

Main Power Distribution

The Charging and Buss circuitry excerpt below:

Power Distribution

Note that:

Shunt is set up to be in the "battery" lead. I like "battery lead" style ammeters, showing charge current on the 12-o-clock-plus segment, and discharge current on the 12-o-clock-minus segment.

Note that the buss feeder wire is protected by a slow-burn 35A current limiter. In Z-11, that wire is not protected at all. My reasoning for this decision is that this wire is relatively long on my plane (around 4 feet), since fuse block is near the rear cockpit. I wanted to protect it.

One area of concern here is that in the event of alternator short, the Ammeter Shunt will be a part of the alternator circuit that will see a lot of current while the 40A slow burn opens up. My gutfeel says it should be able to handle it, but I am not sure. At any rate, figure Z-11 has the same setup with shunt on the alternator's B-Lead.

Voltage Regulator Field Supply Circuit

The circuit looks like this:

Field Supply Circuit

I copied the AeroElectric's figure Z-11 wire gauges here. In Z-11, everything upstream of Breaker is 18 AWG, and everything downstream is 20 AWG, but it's not explained why.

Is this driven by a requirement to ensure that fuselink survives the short in the circuit in case of crowbaring, and the breaker pops first, w/o endangering the fuselink much (18 AWG allows for 22 AWG fuselink instead of 24 AWG)?

Components Location and Main Connector

Here's a relative diagram of components location, that is necessary for explaining what Main Connector is. Click it for larger version.

Key component locations

Note that logically, the way one would wire this airplane would be to pre-wire switches and other items that go into the pilot's (back) instrument panel with long pigtails, then install the switches, and tie down wiring behind the panel. Then, the pigtails can be connected to fuse block and loads.

Some of the load wires already exist (lighting for example), and they will have to be spliced to wires coming from switches.

I have decided instead to locate a kind of "Main Connector" right there near the Fuse Block. A wire comes off of the Fuse Block, goes to the switch on the panel, then switched power is returned to the "Main Connector". Load is on the other side of Main Connector.

This serves a couple purposes:

• Create a logical "access point" into the main wire bundle, for reading labels, tracing wires later, and such
• Simplify installation process
• Connect to existing load wires that are not being replaced

For now, I am thinking about using Molex 0.093 pins in two housings (I have 13 circuits total to connect via this thing, and want to have room for further expansion). I would love suggestions here. One of the requirements is that it should be easily workable with a multimeter for tracing / testing purposes (I technically could've used D-Sub here , but am not due to this precise reason).

Wire Marking

I like marked wires. I used to be a networking guy, and I was very meticulous about marking every single wire in my cabinets, so that I knew exactly what was plugged in where.

It took a bit of upfront time, but saved a bunch of it later on.

So naturally, I was planning to do the same on the Charger, and, more importantly, make it look professional.

Thanks to living in this day and age, that is simple. No, I'm not gonna pay someone to laser etch my wires - that's a cop out :). It's like paying someone to paint your plane.

Instead, I have researched and found a perfect label maker - Brady BMP21 (not including a link here because it will probably go dead after some time... just search for it). This thing has 3:1 heatshrink tube cartridges.

The proverbial coupon

Prior to shrinking

Shrunk!

Fusible Links

Every wire must be fused at the source. Well, almost every :). We don't fuse a couple wires like battery - master contactor: but this is an exception rather than the rule.

Most wires are fused on the fuse block at the main buss. But some wires are impractical or impossible to have hooked up to that. Think ammeter shunt wires as a classic example.

For those, most people use bulky, ugly, and generally eww-y inline fuses. But there's a better option! Enter fusible links.

The idea is simple: use a short length of wire 4 gauges smaller the wire to be fused. So if your wire to be fused is 20AWG, you would do:

Source -> 24AWG -> 20AWG where the 24AWG segment acts as a fuse. The idea is, in case of a short, that piece will burn first.

So, I wanted to convince myself that that will work fine for me.

Initially, me and my ham neighbor tried to use his ~30 amp power supply to do it. No joy. The best we could do is 22 amps, and (imagine that!) 24 gauge we were trying to burn held up to the abuse with no sweat at all! I could even hold it in my fingers. Yay, milspec wire!

So I decided to go rough. I do have a discarded old battery, after all. It was time to burn some wires with it.

Here, the red wire is 20AWG, and the black wire is 24AWG. Using crimps for quick setup.

The link

The hookup

Boom!

It burnt real quick, in less than a second, and the protected (red) wire barely got hot (I was holding it - that was a part of the test). Yes, say that I am unscientific all you want - milspec wire holds up to 150C, and I can't hold up to 150C. The 20GA wire got barely warm - which means it won't cause any problems in a bundle.

It worked!

Now, it was time to set up a real one - to make sure that when the "fuse" wire burns, it doesn't damage anything.

B&C sells very nice fiberglass tubing covered in silicone for exactly this purpose.

I also soldered the fuselink in this time - I wanted to see how well will the solder splices hold to the temps.

Soon to be splice

24AWG spliced into 20AWG

Note here: I know that in reality, the thin 24AWG wire will be the first in chain; here I'm just splicing it in the middle of 20AWG segment so that I can cover both ends. In "production" fuse links, the "source" end will be a ring terminal, and the fiberglass sleeve will go over it.

Sleeve on

With heatshrink

Ready to go!

Boom! Or not? I thought it didn't work, frankly. I didn't hear anything. I didn't smell anything. I actually took my multimeter to make sure the continuity wasn't there - it wasn't!!! Wow. The fiberglass sleeve contained the micro-explosion really well.

I took it off to inspect.

All burnt up wire

The fiberglass sleeve showed no signs of damage.

Great success!

I will need to play with different sizes of heatshrink and probably will use the glue lined strain relief kind just to support everything well, but hey - this worked very well indeed!

Load Measurements

Prior to ripping the old wiring out, I wanted to take some real life load measurements with various things turned on, so that I don't get any nasty surprises.

But this plane has no ammeter... damn. I searched around, and found this little doodad:

Hall Effect ammeter

Very nice. It basically measures current on the wire passing thru this big white ring using Hall effect. Very cool! No need to splice into the battery leads and install a temp shunt.

So, I rigged it up and took some numbers.

Rigged up

• Master On: 1.5 amps
  • Includes: Master Solenoid, and a couple of gauges
• Fuel Pump: 0.2 amps
• "Radios" switch (turns on engine monitor, and power to radios: turning backlighting on them): 0.8 amps
• I-Com Radio, Transmit: 2.6 amps
• Intercom: 0.1 amps
• Transponder: 1.1 amps
• Smoke Oil pump: 2.2 - 2.6 amps (high on startup)

So couple interesting things here. I think the x-der number is too low, but it wasn't being interrogated, and I can't make it be interrogated without flying the plane or using a transponder tester which I don't have. Also, Master On is too high seemingly... Will need to double check later and isolate things (master solenoid, hobbs, voltmeter, voltage regulator, fuel gauge) if I care enough - I don't think I do. Also, fuel pump is too low seemingly. Need to double-check the spec.

And then, I could not turn on the Turn-Slip Indicator...

Turn-Slip Indicator

Sad, sad indicator... see, it's long. And it's wire connector is sticking out. And it's right behind the front seat's headrest, and there's just not enough room for it, and the connector.

So whomever put it in... did this:

Sad, sad wiring

It's hard to see; but basically, those wires are bent "down" at a very sharp 90 degrees angle. Notice how he just used pins without the actual connector. The distance between them is tiny! I am surprised they haven't shorted over all these years. I really am.

Initially, I thought the gauge didn't turn on because that wiring was all bust up, so to test it, I decided to pull it out.

On the bench

I cut off the wires with those pins on them to hook it up to my testing battery... hmm.. but I needed some leads! Well, I was gonna make a bunch of various test leads - so this is as good a time as any! Man, I love soldering...

I long decided to make a bunch of leads with "passthru" banana plugs on one end, and something (a crocodile clamp, a battery clamp, a ring terminal) on the other. This way, I could mix and match, and plug them into my multimeter; daisy chain, and have multiples depending on what and how I needed to hook up. I had all the bits (clamps, crocodiles, banana plugs), and even got a roll of very nice super flexible silicone coated probe wire.

Components, and the battery clamp crimped on

Release the Soldering Kraken!

The banana plug pin

All hooked up

The gyro in the gauge didn't start. Damn.

But I had resistance between + and -. And I had voltage! Hmmm..

Second time I hooked it up, I saw a bit of a spark when I put the positive clamp to the battery, and heard something.

I spun the gyro with my finger.... it spun up!

Well, well. So that gyro "froze" in a bit... Yep, it was hard to turn over with a finger - no doubt a small motor in there had a hard time!

I probably "cleared it up" a bit when turning it over with my fingers - but that won't last long... damn.

Are we looking at the overhaul for this thing too now? Sigh.... Maybe I can find parts to do that myself, but not so sure about that.... It's not common for owners to overhaul their instruments - they're precision clockwork, after all...

Oh well.

And I will have to figure out how to solve that wiring problem with no space to hook up the right type connector. I am thinking along the lines of maybe routing a wire from inside of the gauge down thru a hole I'd drill, a grommet it it, and covering the whole business with with some sealant or something, so that the dust doesn't get in. we'll see. Need to ponder this a bit more.

PS

... and here's what happens to airplanes that aren't flown enough...

Dinner for someone...

Easy Route

I didn't have anything in the hangar besides a couple of old bookshelves, a couple of small tables, a few filing cabinets I have inherited from my good friend Pete, and a cart. Not very nicely set up for working on airplanes, and everything was overflowing with parts, tools, and hardware even after just a bit of disassembly I have done for the annual.

I needed a lot of shelf space, and a lot of bench space.

I decided to take an easy route this time, and instead of building everything, just bought a bunch of shelves at Costco, and benches and a tool cart at ... Harbor Freight. Yep, I know. Throw a rotten egg in my face next time you see me.

The First Shelf

The Light

I work evenings a lot, and the only light source there was there was a four T8 tube fixture in the back of the hangar. But the most interesting stuff is on the front of it (engine, yep :) ). So I added some lights around the front.

Lights

The Benches

Next, came the benches from Harbor Freight. Don't buy them. They're built like crap, and, frankly, I think I could've built better ones out of 2x4s in about the same amount of time it took me to put these together... But hey, I already bought them, and disassembling the first one (I got three total) rather than putting the other two together... I didn't want to...

Benches

You might notice the pegboard at the back "wall" of those benches. Well, they attach it every about 12 inches around the perimeter with machine screws and nuts. Guess what happened to the first pegboard after a humidity cycled high, and then low? Yep; it all warped!

Ended up resorting to straightening it out with shelves that acted as "stiffeners", and putting the warped pegboard bench as far away from the "main" bench as possible).

On the other two I actually made the pegboard "floating" - re-drilled the mounting holes to be large, and used large washers and just enough small washers underneath to MacGyver me a "bushing". That worked, and the other two benches' pegboard is straight after quite a few large humidity changes now.

And then, the sink.

The Sink

I long had a large 7 gallon jug with a tap. When I was doing a lot of work, I'd drag it out of the hangar, put it on a small folding table, and use it to wash my hands. Very nice to be able to do that when your hands are covered in oil and crud, and you need to climb into the airplane or grab something generally clean. I also like clean hands when doing detail work like soldering, painting, etc.

The Jug

But dragging out a 7 gallon jug every time I got into the hangar got very old very fast, and I ended up typically resorting to rags and not so clean hands, or "washing" them with mineral spirits... ugh.

But hey, we're cleaning up! So I decided to put in...

The Sink!

But a sink needs a drain!

No problem.

The Drain.

This came out very nice, and I love that I can now just wash my hands whenever, no jug dragging required.

The best part? The hangar door slides, so I can have it closed and then slide it a bit past it's "closed" position, so that there's a gap between the hangar divider wall and the outside for the drain to be put out.

But how do I close the door?

Retractable!

Do I need a Complex endorsement to operate in my hangar now? ;)

The Wiring

Before you wire your plane, wire your hangar, says a proverb. Or something like that.

Well, my hangar floods. And it's not my hangar, so I can't quite make holes in the walls and run wiring and conduit. And I only have one outlet. Yep.

So it was all to be a bunch of extension cords, making sure that all connections are suspended a few inches above the floor, hooked to something (previous tenant of my hangar had some holes in the walls drilled, so I reused his, or hooked them up to legs of whatever was there, etc).

I ended up making a bunch of splices on extension cords. Hey, I love soldering!

Almost a splice

And now, with liquid metal!

Air and Shelves

I had a compressor. I moved it to the back corner of the hanger, and hooked up a reel in the front, so that I can have my hoses neat... Not much more.

The back wall of the hangar got lined with the big shelves, too... Mostly, to stack the parts I take off the plane and need to keep off.

The first one up is there on the right, near the yellow barrel.

The First Shelf

Some child labor might have been involved in cleaning this hangar

The Shrine

... and since the Charger is a Grand Champion, I needed a shrine in the "mancave corner" of the hangar. Every hangar must have a corner with a couch, a fridge and what-not, to relax and ponder and procrastinate. And that's where all the artifacts need to go.

The Shrine

And I didn't drill a single hole! All those rails and shelf are re-using the screws that are holding the hangar walls together :).

The Bench

I needed at least one good bench for grinders, bandsaw, and aluminum work; and there was a perfect spot for it. Didn't have my wood tools though, so had to use 2x4s straight out of the store... Normally, I mill them down :).

The top and the frame to be

Legs

All together...

... and then, you flip it, add the bottom shelf, attach the leg stands, and voila:

The bench

Even though it's not very flat, it's perfectly fine for anything but being a reference flat surface for assemblies...

Set up

The End

Well, and I guess, that was it. I spent a few more days and evenings cleaning up, and putting everything in place. And I guess, we're due for some "before" and "after" pics :).

Lighting: before

Lighting: after

The mancave: before

The mancave: after

The back: before

The back: after

The main work area: before

The main work area: after

Benches' closeup

So, there. Took me a month with the breaks for fixing HVAC wiring on a Subaru (funny how that happened in anticipation for rewiring the plane, eh? and I really started to dig Molex connectors doing the fix - but we'll talk about Molex when the time comes), and a bunch of other stuff.

But hey, I can work on things comfortably now. And, wash my hands whenever I want!

Fuel / Intakes

So first, it was to be intakes.

RTV where there should be none

Somebody put RTV to "seal" the intake gasket. Oh well.

Did you know that those 1 1/2 inch rubber hoses that go on intake tubes are much easier with very thin coat of oil?

Oiling the hoses

And then, it was the TBI.

Recall that when I was putting her apart, I found pipe dope on the TBI inlet port?

Let me explain.

Fuel goes into gascolator. Then it branches: one branch goes to the engine driven pump, the other goes to the electric pump. Then, they go to the regulator on the TBI. Then, a couple of 90 degree fittings feed it into the TBI's inlet port, which has the "last chance" screen in it.

That's the port here, right above the airflow straightener:

TBI from the down low

See that white gunk? That's Teflon dope. "Aircraft grade"; whatever.

Here's the problem.

TBI inlet hole

Fuel has to go there, into that inlet hole. That's what the screen fitting screws into. Right past that, inside the TBI itself, there's a turn, another turn, and a spray bar that sprays gas into the intake, injection-style, thru a tube with a bunch of tiny holes. That's why there are screens in the fuel system: to prevent gunk from clogging up those tiny holes.

So now, what happens when you take a male fitting out of a female threaded hole, and the fitting was doped? Some of that stuff ends up on the female portion. Next time the fitting is put in, dope remnants will be pushed in past the engaged threads, and possibly clog up the works.

Not. Good. At. All.

That's why there is the copper crush gasket behind that screen fitting - to seal it to the TBI body w/o requiring anything extra. You can kinda see that gasket all smudged around with that dope on the first picture.

So I had to deal with it.. Clean it out somehow.

It was crumbly, but sticky enough to not want to come out.

I tried every solvent on hand. Nope.

I tried carefully scraping it out with a dental probe. Yeah, kinda worked, but I wasn't satisfied.

I tried every solvent in my buddy Dick's hangar. Nope.

In desperation, I drove to the local Home.. strike that, Aerospace, Depot, thinking about picking up every kind of solvent they had and I didn't.

And then, I remembered this:

Goof-OFF!

I don't know what kind of concoction that is; but it worked! The hole was clean. Next time was a couple days after, and when I got back to the hangar, I discovered that it has turned into a lake :(

Lake in my hangar

Grading's all screwed up around our hangars, and when we get lots and lots of rain, they flood. Not too much though, luckily. This was the second time in the past few weeks - first time, I had my tools scattered around the floor. This time, I was smarter...

Anyway, back to the TBI. The rest of it went together quite nicely. I discovered that there was TorqueSeal put on the idle mixture screw.

Why? No idea. That screw is spring loaded. Should stay put.

Torque Seal where there should be none

I wanted to flush the lines and then the TBI to make absolutely sure none of that dope went it. The best way to do that would be with the electrical pump; but I'm a one man show.... and the switch for it is 5 feet away from the firewall.

So, I had to rig me up a little doodad.

The simple click switch

.. with ring terminals

The ring terminals were hooked up to the Master Solenoid in such a way that when the button was clicked on, the Solenoid would close.

The pump was turned on.

This way, I could click my button, Master Solenoid would close, and the pump would start running. Neat-o! I'll need it later, too.

Flushing - braided hose provides nice bond to the airframe

The Pickling

I borescoped the engine (looked alright - I'll post a report about this later, maybe...); and it was time to fill'er up with oil.

Pickling oil was mixed up next, and into the engine it went.

A pitcher of pickling oil

A recipe for a mess...

After filling the sump up, it was time to check for oil pressure. Lycoming tells you in SB1241C to pre-oil your engine by cranking with the starter in 10-30 second bursts until oil pressure comes up to 20 PSI.

Well, oil pressure gauge on the Charger is finicky, so I wanted it to at least move.

Oh wait. She has an ignition/start switch. No way I can use that to crank and not have a hot mag w/o messing with P-Leads.

Crap.

Also, I might want to crank from around the firewall (the prop was still off).

But I had my pushbutton doodad!

So I rigged it up to the starter solenoid this time.

Of course I misunderstood the way the starter solenoid was wired.

It had two terminals.

I thought one of them was ground; with the wire going to the firewall. The other then was supposed to be positive.

That didn't work.

I measured it - between those terminals - nothing. "Dead starter solenoid", I though. Crap! It was 8pm. Auto parts stores were closing soon.

I rushed to a nearby O'Reilly. Picked up a starter solenoid. Went back.

Measured it too. NOTHING? How come? Something was amiss.

Only then I started suspecting that something was off. That other terminal on the original starter solenoid I was hooking my positive wire to was all corroded and looked like it never had a nut.

OH! The way it's supposed to be wired is that positive goes to the same terminal where that wire I thought to have been ground was. It wasn't a ground wire - it was a diode. And the ground was off of the case of the solenoid.

Okay.

So, we're cranking now.

30 seconds. No pressure. 30 more. No pressure. Crap!

I unhooked the oil pressure sending hose (the one that hooks up to the line that goes to the gauge).

Crank. No oil. A couple bubbles is all I got.

CRAP!

The oil pump de-primed itself?

Kinda makes sense I guess? The plane was sitting for way too long :(

So, I took off the oil cooler return line. Dumped another quart of oil in there.

I had this hose fitting that goes on top of an oil bottle that was very neatly set up to mate with the engine oil hose's flare: so I could squeeze the bottle and push the oil in.

After the whole quart, I re-hooked the line back onto the oil cooler, and tried again.

Success! Now, I saw oil coming out of the oil pressure sending hose.

Hooked it up to the gauge line, and saw the gauge move, finally. Good.

Damn, with all that cranking I ran out my old battery I had put in there.

Now, have to flip the battery (to put in the good one - the flying one - I always use my old battery from the Cheetah when I mess with electrical, not to abuse the actual "production" battery).

Now, the top spark plugs go back in, the ignition wires get hooked up.

Prop time!

Bolt one - start it in. Bolt two. Bolt three.

Bolt 4. Doesn't go in? Not even a chance? What the hell?

I pulled the prop back off and laid it down. Put the front crush plate on top (that one positions the bolts).

No matter what I did, there'd be at least 3 out of 6 bolts that won't go in. This time, it was a few dry days, and I guess the prop moved enough to have the "top" and "bottom" holes (if looking at the prop horizontally) move closer together. It was off by almost a 1/16th.

So here I was. With an engine that was cranked for a total of a few minutes, and probably had scraped a lot of oil off of cam lobes and lifters.

With a prop.

I couldn't put on.

Which I needed.

To fire the damn thing up.

It was late. I tidied up, and went home.

The Prop

I wrote a note to Frank Johnson who made the prop that same night, and called him the next day.

He wasn't surprised. "Redrill" is a simple fix.

But I was a bit apprehensive, and this was a nice excuse to meet him. He's 2 hours away from me. We agreed to meet in a few days, at the first time he was available.

So, the engine with oil scraped off the lobes had to sit for another couple days.

Nothing I could do in that short a time...

Interlude

The weekend hit us; and it is a weekend in May, in Texas. Which means...

MUDBUGS!

The annual fit inspection

The setup

The fixings

Prep

Aliens!

The Boil

The Finale

Into the trailer the prop went, and to Frank's we drove.

All tucked in

Of course, it took us 15 minutes out of 3 hours I spent there to fix it. The rest of it? Well, what can two guys who're crazy about airplanes do at one of those guys' shop and hangar? Hmm... What could we do? :)

The weather was swell, and I was in a good mood - and airport was on the way back from Frank's.

So, I went straight to the airport.

The prop went on beautifully.

Finally, on

It was nice, sitting in a running, shivering airplane, to watch the sunset. If you looked up, it almost felt like flying. With the buzz, the shake, the smell and the noise.

The Sunset

A couple days later, I went back to the hangar, sprayed the engine top and replaced spark plugs with desiccant.

Now, I can focus on the electrical mess...

The Muffler plug

Interlude

Battery Contactor is an interesting point here. Normally, one terminal is connected to the "always hot" side of it (basically, directly to the battery) and the other goes to the Master Switch. Master Switch turns the Battery Contactor on by grounding that wire, providing the negative side to the circuit. It's a safety thing. If that wire breaks, it'll either turn the electrical off (open circuit), or it will keep it turned on (short to ground). That's it.

But, one of the terminals on the Battery Contactor was grounded... that means, that the other terminal (the wire coming from the Master Switch) must provide positive side??? Huh? But where does it get it's power from?

Tracing

So to tracing we went. I spend maybe 10 hours trying to find diagrams and understand that alternator and voltage regulator hookups.

And me tracing it spelled my doom.

The Diagram

Now, I didn't trace the rest of it. Just the main distribution system. That was enough.

Shall we?

The current main power system of the Charger

Yep, the diagram is missing the main power buss. It's dangling off of the same spot where everything else that's interesting is - the Battery Contactor (marked MA RELAY) <-> Starter Contactor (marked STARTER REL) link.

So let's see what we have here.

• Lots of unfused wires. Do you see a single fuse here? Nope. That's because there aren't any. All the fuses are further downstream, off of the main buss.
• Voltage Regulator has this extra wire running to / from cockpit that isn't really necessary and could've been kept on the hot side of the firewall (terminal 4 wire)
• Alternator field broken at output (F->ALT) rather than at input (battery -> terminal 3)
• And the best part? Always hot wire that you can't turn off between the battery and the Master Switch to turn the Master Solenoid on.

That last bit bugged me. I couldn't find the damn thing. Even before actually tracing it, I knew that if the Master Solenoid is switched on the "hot" side, it needs to get the power from somewhere, and that only could be battery. But I didn't see any wires on the always hot side of the Master Solenoid. Only when I traced it, I actually traced the physical wire to where it goes, and then found it. It was so tucked behind the battery -> Master Solenoid wire that it was invisible:

This little !@#!S@#....

Oh; and by the way, the Master Switch is the only switch that's soldered in, and w/o any good insulation around the terminals, and over-stripped wires. So that's just waiting to short, and the magic smoke that'll be let out behind the panel when that shorts can't be stopped (always hot wire, remember?)

Master Switch

The Wires

So I kinda went backwards here; but I thought it'd be easier to see the diagram first.

Let's see.

Most of connections are made on this very nicely marked terminal block:

The terminal block

All the switched power comes out there, and every wire is marked. This actually helped a lot in tracing. This block is on the side of the plane, right next to the front hole's backrest.

You know what threw me off the most with that damned always hot wire (I ended up tracing it physically)? It's how it's hooked up.

Yep, it is hooked up to that terminal block. To the terminal... that is marked.. (drumroll).... "Master Switch".

Wait.. this actually makes sense... But where's the "return" from the switch?

Ah! It's the wire that's marked.... drumroll... "Fuel Gauge"!

So really, let's look at what's going on, shall we? Zoom in the image below, it's annotated.

Untangled

So let's see. We've got this bundle of wires, a lot of which are not fused, and one of which is always hot.

The Main Buss wire is the thickest one (10 gauge maybe?) that's not fused between this buss bar and the source (engine compartment).

Oh, did I mention that this buss bar is on the side of the plane near the rear instrument panel (so that 10 gauge run, and the rest of the harness between firewall and the panel is about 30 inches long)?

What else do we see there? Oh! The two little 1/16inch thick aluminum lines carrying.. fuel pressure (and oil pressure).

Shall I say more?

Shall I say that there's a fuel tank in between the front hole (passenger) and the firewall?

That the wires run along between firewall and rear cockpit along that fuel pressure line (to fuel pressure gauge)?

That if one shorts to this very nearby fuel pressure line, it'll burn a hole straight thru it, and then ignite the gas that'll start coming out?

Yep.

Can I fix all of that?

Sure. But rewiring will be much much easier, because I have to touch pretty much everything. Re-running half of individual wires in a bundle is much harder than re-running them all.

So, I made a decision to rewire the plane... Sigh. Looks like I won't be flying for a looooong time.

Oh, and tell you what. Tracing wires on a biplane is dangerous. I ended up twisting my knee and pulling a muscle while trying to get behind the panel so badly that I couldn't walk (or sit) for 2.5 days :(.

The Nosebowl

One of the things I noticed immediately is that baffle seals were turned the wrong way in the nosebowl area; where the front "air ramp" joins the bottom of the nosebowl.

Here's the nosebowl and the front ramp:

Front ramp

Notice the circled area? Here it is, from the back:

The behinds

That marked rubber seal is in the circled area. Notice it's turned the wrong way; "into" the cowling, rather than away from it? Ram air hitting that front "ramp" will "bend it in", and leak into the underside of the engine compartment - precisely where it's not supposed to go.

Naive me thought that it was just wrongly installed - the rubber needed to have been folded up and out, "into" the lip of the nosebowl.

Correct and current seal orientation

Ha! Well, Remo (the guy who built the Charger) thought different.

There's just not enough room there. Everything is super tight. The seal just won't go there and stay there. There's just no room.

Look at the above two pictures - inside and outside - again. You'll understand why. Use pop rivet line as your reference.

Here's where the problem gets worse. Ramp is really thin - so with just a mild pressure, I can make that gap between the ramp and the bowl 1/4 - 3/8 inches. Guess what happens when ram air hits it... :)

What ram air does...

Okay, so then I went digging.

I thought this was a standard bowl. I was right!

It's an old Comanche single style bowl (I think).

Comanche nose

Looks similar?  I researched further.

Here's a guy making replacement ramps for Comanches, with some good pictures.

Front ramp on a Comanche

Okay; see the difference? Comanche ramps are curved the other way.

Changer vs. the Comanche

This is cross section. Mine's on the left, Comanche's on the right. Red is nosebowl; blue is this ramp, and black is my baffle seal.

Mine is "concave". Comanche is "convex". So if I got my thinking right, this makes the Comanche version more rigid facing the wind.

Drawing from the Comanche's parts' manual confirms this proper curve.

Comanche parts manual on baffles

The parts I'm talking about are numbers 11 and 12, bottom right corner.

But how the heck do they seal them? Notice that the material on the drawing above seemingly has some "dots" on it (as opposed to the rubber material on the side baffles).

Well, back to our "remade Comanche front baffles" guy.

Forward baffles from Comanche Gear guy

Felt strip!

Well, I guess that makes sense. Felt wrapped around the front ramp.

Felt strip

Felt is thick and, contacting the nosebowl, I guess, will create a good enough seal if the ramp is rigid enough. I am guessing that Comanche's ramps are way more rigid than mine due to that opposed curve.

So where are we at with all this?

Remo probably built this noseramp himself. It looks very custom. It's too thin and doesn't have rigidity - ram air will flex bend it "into" the cowling. It's not sealed properly practically along all of that bottom edge between the bowl and the ramp.

The only hope for it is that it's aerodynamic-ish and looks like a "dozer blade" - curved up. Maybe the nosebowl lip deflects the air enough for it not to go under too much:

Airflow diagram

Can I replace the current rubber seal with felt?

Maybe. The front of the engine moves. The ramp's aluminum is very light - I am afraid that if I were to add any reasonable quantity of felt to it to hold the seal tight it will warp the aluminum via relative motion of that ramp (hooked up to the engine) rubbing on the bottom of the nosebowl. Or worse yet, make a hole in the bowl.

Can I replace the ramp? Well, everything's possible; but that's a massive undertaking. That ramp / nose baffle, Comanche-style, has that compound curve, and I don't have time or skill to do it fast. 2 months? Maybe, if I get lucky. BTW this is probably why Remo did it this way - because his is just an aluminum sheet, wrapped around the front of the engine, "neck cone" style, and cut to fit.

So, what do I do?

After discussing this at length with my good friend Ben, we settled on testing this out first to see how bad the air flow going "under" will be. I can mark the bottom of the nosebowl with some tinted oil, and go fly. Oil streaks will tell me if the air is flowing under a lot, or not so much.

I'll also replace all the other baffle seals, which will improve cooling. There's a lot of gaps to RTV, too.

I don't want to replace the bottom nosebowl ones, because actually there the rigidity of old neoprene rubber seals should help...

Annual, Continued

We got together with John, my IA, and continued working on the plane early April.

We pulled the prop, so that I will have access to baffles (I wanted to redo them).

John re-riveted the air takeoff flange back to the front ramp.

Meanwhile, I started disassembling the fuel system to get to the screens, including the oil sump screen, and clean them.

Airbox off

TBI intake airflow straightener

Okay, stop right there. See that fuel inlet, right above the air intake? See the little smudge of dope around the inlet fitting? Yep. Teflon dope. Rotec explicitly tells you not to put ANYTHING on there - there's a copper crush gasket behind that fitting.

TBI screen

TBI crush gasket

See all that dope above? Okay, that thread on the TBI is a female thread. Dope will be all in it, and guess what will happen when I screw the fitting back in? Yep. It'll go into the TBI fuel galleys. Right to where that spray bar is with tiny little holes in it. Not Good (c).

TBI holes plugged

Intakes

I noticed evidence of possible intake leaks, so without "burping" the engine, decided to pull the intakes and replace the gaskets. This is my karma. I did that on the Cheetah just a year ago, and scraping remnants of one of those gaskets and re-chasing the threads took me about 10 hours; maybe more.

Also: interesting note: she has intake tube clamps on studs and not bolts like every other Lycoming I've seen. Old, narrow-deck cylinders :).

Prop

When we pulled it, bolts were in the thru holes on the wooden prop really tight.

Pulling the prop

She has the prop made by Frank Johnson of Performance Propellers fame, and after contacting him, he just suggested to re-drill the holes and re-coat them inside with something.

Well, I got me a 29/64 (1/64 oversize) reamer, and went to town.

But first, I needed a rack.

My prop rack

Built with a 1/2" pipe, some foam, pipe brackets, screws, 2x6s screwed to the table, and my 3/8" drive extension rod. You get the idea :). Redneck engineering galore.

Prop on the rack

This whole thing was happening over a few days by the way; and when I finally got my reamer and had time to deal with it, the holes.. extended. Wood moves!

Hey, we had much rain then, and prop "swelled" a bit methinks.

But I still decided to fill the holes as much as I could.

Even got me some nice scales for mixing System Three ClearCoat.

Mixing

A filled hole

Backside

Interlude

Hey, look, I got a nice neighbor next door!

My new neighbor

Fabric

Fabric on this plane is old. Flyable from what I am being told by experts, but old. Cracking, peeling paint.

Original logs say that she was covered in Polyfiber. But the current finish looks more like Imron and the company - "flexible" automotive poly. It's cracking and peeling around areas of high wear (prop wash, etc).

Sad fabric

Sad, sad fabric

John (my IA) wanted to take a Maule fabric tester to it; but I didn't want holes in my wings.

I discussed this with a few guys that worked with fabric their whole lives, and we came to a consensus that for now this is fine. Will just fill with silver, and keep on flying. Incidentally, that's what Glenn has been doing, too.

Full Stop

I worked on baffles a bit, but then, everything went downhill. We'll talk about baffles in the next post. And the downhill part, afterwards :).