Rogue wire?

OkieAviator

OkieAviator

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OkieAviator
So today I noticed under my 172N panel a little yellow w/connector hanging out from underneath the panel without a home. I stick my head down there and on top of the parking brake simple wire terminal with a few wires sticking out of it. Here's a picture of a similar part...

$_57.JPG


Tonight I searched around and learned that this is possibly where all the Nav lights connect together. If that's the case and all my External Nav lights are working then could this be for the panel lights maybe?

I've had this other issue I was going to bring up with the A&P but my panel lights (Including the overhead red light) haven't been working since he did some maintenance a month back. To be honest I'm not sure but are the red dome light and panel lights in a Cessna 172N tired to the Nav switch? Would make sense for it to be and would also make since of why it's not working if this wire isn't joined to it's Nav light brothers.
 
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So that is where I left my flux capacitor. Thanks! Just fedex it over night to me.
 
I had a problem with my nav lights intermittently tripping the breaker. We figured that the wire to the stern light was the problem as we could see every place it passed through one of the fuselage bulkheads the rubber grommet had long decomposed. My wife redid the whole thing (she could fit down the tail cone). That still didn't fix it. Finally we figured we'd have to redo the wiring to the wings. Finding the junction in the belly where the wires diverged from the common supply we note that there are TWO wires going into the left wing. Gingerly pulling one yields about four feet of disconnected wire (possibly there is some residue of black tape on the end which is also long gone).

After thinking about it a bit it occurs to me this fed a wing where the flap retracts. Navions have no flap indicator (they were originally all up or all down affairs). When the retrofit to allow you to stop the travel was done, the light was added. Apparently someone removed my light but left the wire flopping around in the wing. Periodically it would touch something conductive.

The thing with the wires coming out of it looks like a power resistor of some sort.

I also found a little blue device about the size of a roll of quarters. It has four wires coming out of it and is labeled "Critical Safety Component" with no other markings. I like to drop it on the ramp underneath aircraft that students are doing preflights on.
 
flyingron said:
It has four wires coming out of it and is labeled "Critical Safety Component" with no other markings. I like to drop it on the ramp underneath aircraft that students are doing preflights on.
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Now that is pretty funny.

I'm guessing the Cessna engineers were rushed on deciding where to terminate these wires. "Just put them on top of the parking brake lever".
 
OkieAviator said:
Now that is pretty funny.

I'm guessing the Cessna engineers were rushed on deciding where to terminate these wires. "Just put them on top of the parking brake lever".
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I don't think Cessna engineers had anything to do with it. Cessna never used metal housing power resistors that I know of. Especially they didn't mount them diagonally on the brake rod housing so that the ears could be bolted to something narrower than the resistor. And why cut wires? And what is the little terminal strip for?

Appears to be some sort of jerry-cobble lashup to limit the power to a circuit, but why and what for I have absolutely no idea.

Insofar as I know, nav light power and dome/panel lights are completely independent of one another except for a possible common tie to a breaker or fuse for power.

Jim
 
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I've run across someting similar in a car. It was a resistor for the "high speed/low speed" blower fan switch. Perhaps this is the same?
 
weirdjim said:
Insofar as I know, nav light power and dome/panel lights are completely independent of one another except for a possible common tie to a breaker or fuse for power.

Jim
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Yup. Panel lights are mostly independent of the nav lights so that you can turn the nav lights off in cloud at night so their reflected glare doesn't distract you.

I have seen that thing in some airplanes. It might be the diode that goes between the landing and taxi light switches so that the landing light switch turns on both lights but not vice versa. Or it might be a newer version of an overvoltage sensor. Two leads, grounded case.

The terminal strip is found in most of these airplanes. It was often used as a ground point for a whole bunch of circuitry.

Dan
 
It's a high watt, low ohm resistor. If you have a 2 intensity panel light switch this resistor is used to dim the lights when on the low setting, and is bypassed when on the high setting. Similar to an old rheostat, which is a high wattage variable resistance resistor which allows infinite adjustment of the lights. If one or both legs of it are not connected, you will not have low intensity panel lights, and depending on how it's wired, you may not have any at all. Don't know if it's stock Cessna, but my spidy sense says 'no'. They would not use a $1.60 part where a $76 part would do.
 
OkieAviator said:
So today I noticed under my 172N panel a little yellow w/connector hanging out from underneath the panel without a home. I stick my head down there and on top of the parking brake simple wire terminal with a few wires sticking out of it. Here's a picture of a similar part...
Click to expand...

Notice that the OP isn't asking about the resistor. He posted the photo to inform about the terminal strip.
 
3393RP said:
Notice that the OP isn't asking about the resistor. He posted the photo to inform about the terminal strip.
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Yes he was. He was talking about the "little yellow thing (gold, actually) with a couple of wires hanging out of it". He mentioned the terminal strip collaterally. The yellow thing, as somebody else said, is a power resistor, probably of low to moderate ohmage, using the parking brake rod guide as a heat sink.

Jim
 
weirdjim said:
Yes he was. He was talking about the "little yellow thing (gold, actually) with a couple of wires hanging out of it". He mentioned the terminal strip collaterally. The yellow thing, as somebody else said, is a power resistor, probably of low to moderate ohmage, using the parking brake rod guide as a heat sink.

Jim
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My bad I can now see how my post was confusing. I was actually talking about the terminal on the left and not the right gold resistor thing. I need to take my plane to the radio shop for a firmware update, I'll ask them to figure out what that extra wire is.
 
That terminal 'block' of what appear to be male spade connectors are typically a ganged ground connection for grounding various radios, instruments, etc to the chassis of the plane. Of course, if properly insulated, it could be a common power buss of 12V or 24V for supplying power to various devices, however the normal way of doing this is with a fuse/breaker panel with a common supply and fuses or breakers for the distribution of voltage.

Anything else?
 
docmirror said:
That terminal 'block' of what appear to be male spade connectors are typically a ganged ground connection for grounding various radios, instruments, etc to the chassis of the plane. Of course, if properly insulated, it could be a common power buss of 12V or 24V for supplying power to various devices, however the normal way of doing this is with a fuse/breaker panel with a common supply and fuses or breakers for the distribution of voltage.

Anything else?
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Thanks, it would make sense that it's for grounding... I need to get the plane over to the radio shop so I'll ask them to take a look at it.
 
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