Electrical connections

[Huitt3106]

When splicing wiring in any aircraft is there a particular spec that must be used for electrical connectors such as butt splice connectors? Basically what I’m asking is there an aviation grade connector required like there are marine grade connections or is it just advisable to use high quality connectors?

 

 

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[Steve W]

For splices there are Raychem Solder sleeves that some swear by. There are also environmentally sealed splices that cost a fortune but have a nice shrink tube you seal over them. But generally I've found the 'PIDG' from TE / AMP seem to be most commonly used in the high quality arena for common type splices and connectors. You'll also find that the electronics shops(Mouser, DigiKey) tend to have a much better selection than the aviation shops. Sometimes even too much of a selection.

The harder part is finding a good crimper, you don't want to use an automotive style connector masher on these types of connections. I have a Greenlee Crimp Handle and use various dies depending on what's being crimped. The official crimpers are far more expensive.

Edited February 17, 2020 by Steve W

[Bob Weber]

2 hours ago, Huitt3106 said:

 

When splicing wiring in any aircraft is there a particular spec that must be used for electrical connectors such as butt splice connectors? Basically what I’m asking is there an aviation grade connector required like there are marine grade connections or is it just advisable to use high quality connectors?

 

 

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The best first question here would be what are you splicing. If you can solder proficiently, I would recommend it. There are crimp connectors that are sufficient, I always attempted to stagger them in order to minimize the "wad" that always seemed to be where the problems were.

[Huitt3106]

Fair question, this is the ground to one of the magnetos. It has rubbed against the vacuum pump and almost worn in two. I discovered it while looking at something else.


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[Steve W]

1 hour ago, Huitt3106 said:

Fair question, this is the ground to one of the magnetos. It has rubbed against the vacuum pump and almost worn in two. I discovered it while looking at something else.
 

Ok, ignore what I said then. I'm just barely qualified to talk about wires in the panel. 

 

[Huitt3106]

Ok, ignore what I said then. I'm just barely qualified to talk about wires in the panel. 
 

You were helpful in me learning about that aspect of the wiring. I’ve unsuccessfully tried to get in touch with my A&P but he’s apparently just began a new job and will only be doing the work part-time now. I may be looking for a new mechanic...


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[EricJ]

5 hours ago, Huitt3106 said:

When splicing wiring in any aircraft is there a particular spec that must be used for electrical connectors such as butt splice connectors? Basically what I’m asking is there an aviation grade connector required like there are marine grade connections or is it just advisable to use high quality connectors?

The short answer is no, but AC 43.13 Chapt. 11 deals with wiring stuff, and Par 11-167 gives a little bit about splicing.   The section after describes terminals.   Par 11-178 says to use a ratcheting crimper (example link below).   To just make a splice a typical decent-quality butt connector can be used, just use a ratcheting crimper.   There is guidance in AC 43-13 to not make a splice within 12" of a terminal, so if the wire is shorter than that just put a new terminal on it, and terminals need to be ring-type.   Some foks may have preferences or references to best practices beyond what's in 43.13, but so far in my limited experience I've seen a wide variety of inexpensive connectors used, plus some expensive ones...on the same aircraft. 

Example crimping tool:  https://www.amazon.com/Hilitchi-Professional-Insulated-Connectors-Ratcheting/dp/B01IQIALJC/      You can get different types of jaws for them to do all kinds of different connectors.  

I can also say that in the A&P school that I'm attending it is taught that soldering should be avoided due to cracking under vibration, and crimped solderless connectors are preferred.

[carusoam]

@Huitt3106,

For some wires that are important for safety... like the mag ground wire...

It may be possible to find a proper replacement without too much trouble... and getting it installed, not much more difficult...

The added challenge of the environment that wire is in... hot, and vibrating....

Probably makes more sense to start with a new wire than ‘experiment’ with splicing.
 

Read up on broken mag grounds to see why we are looking for them, and why the ignition key is left on the glare shield in plain sight...

PP thoughts only, pass this question back to your mechanic...

Best regards,

-a-

[Bob Weber]

13 hours ago, Huitt3106 said:

Fair question, this is the ground to one of the magnetos. It has rubbed against the vacuum pump and almost worn in two. I discovered it while looking at something else.


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 Is this a P lead? That's safety related and needs to be right. Unlike what they seem to be teaching the kids at school today, a properly executed solder joint will go a lot further, be less bulk, and consequentially more trouble free. Granted, they're not child proof, I routinely revisit installations and repairs I have accomplished over the last 5 decades now, and see the durability of the different methods.

[Huitt3106]

[mention=17950]Huitt3106[/mention],
For some wires that are important for safety... like the mag ground wire...
It may be possible to find a proper replacement without too much trouble... and getting it installed, not much more difficult...
The added challenge of the environment that wire is in... hot, and vibrating....
Probably makes more sense to start with a new wire than ‘experiment’ with splicing.
 
Read up on broken mag grounds to see why we are looking for them, and why the ignition key is left on the glare shield in plain sight...
PP thoughts only, pass this question back to your mechanic...
Best regards,
-a-

That’s why I’m asking the question, to determine what the common practice is. I could have worded my question better I suppose.


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[Huitt3106]

 Is this a P lead? That's safety related and needs to be right. Unlike what they seem to be teaching the kids at school today, a properly executed solder joint will go a lot further, be less bulk, and consequentially more trouble free. Granted, they're not child proof, I routinely revisit installations and repairs I have accomplished over the last 5 decades now, and see the durability of the different methods.

No, it’s the ground wire. It wasn’t secured far enough away from a friction point and has rubbed about 30% through the wire.


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[Bob Weber]

12 minutes ago, Huitt3106 said:

No, it’s the ground wire. It wasn’t secured far enough away from a friction point and has rubbed about 30% through the wire.


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30% is beyond acceptance, I would still treat it as a safety issue. If I were standing there I would cut it at the abrasion sight, clean and strip the wire to expose an 1/8th of an inch of clean copper, quickly "tin" each one with a good, hot, clean soldering iron. at this point I would slide an appropriately sized length of shrink tubing on one of the wires, then, with a fresh ball of solder on a clean iron, I would make the connection waving the iron in order to create the connection and carry off any excess solder to make the joint as small as you can with a good shiny connection.

[Huitt3106]

Just now, Bob Weber said:

30% is beyond acceptance, I would still treat it as a safety issue. If I were standing there I would cut it at the abrasion sight, clean and strip the wire to expose an 1/8th of an inch of clean copper, quickly "tin" each one with a good, hot, clean soldering iron. at this point I would slide an appropriately sized length of shrink tubing on one of the wires, then, with a fresh ball of solder on a clean iron, I would make the connection waving the iron in order to create the connection and carry off any excess solder to make the joint as small as you can with a good shiny connection.

Definitely, I had no intention of not repairing it before flying again.  Plus, I'd have to take all of the cowling off again to reach it.  Would soldering like this be a permanent repair?  I'm very comfortable soldering like you've shown in a photo (everything would be inspected and signed off by my A&P).  

[Yetti]

58 minutes ago, Huitt3106 said:

No, it’s the ground wire. It wasn’t secured far enough away from a friction point and has rubbed about 30% through the wire.


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Why not solder all new wire onto the p leads.   Will be good for another 20 years

[Bob Weber]

Just now, Huitt3106 said:

Definitely, I had no intention of not repairing it before flying again.  Plus, I'd have to take all of the cowling off again to reach it.  Would soldering like this be a permanent repair?  I'm very comfortable soldering like you've shown in a photo (everything would be inspected and signed off by my A&P).  

If this a simple length of wire to replace, by all means replace it. If not this would be a repair I would consider permanent. That being said I would like to see the joint you end up with.

[Huitt3106]

2 minutes ago, Yetti said:

Why not solder all new wire onto the p leads.   Will be good for another 20 years

The wiring was all very recently replaced.  The installer didn't have the ground pulled far enough away from the vacuum pump so its been rubbing.  Its the only needed repair.  

[Huitt3106]

2 minutes ago, Bob Weber said:

If this a simple length of wire to replace, by all means replace it. If not this would be a repair I would consider permanent. That being said I would like to see the joint you end up with.

Okay,  when I go back to the airport I'll take a look at the difficulty of replacing the whole wire and see how that'll work instead of making the repair.  I'll take a picture if I solder instead of replacing.  

[Bob Weber]

1 minute ago, Huitt3106 said:

The wiring was all very recently replaced.  The installer didn't have the ground pulled far enough away from the vacuum pump so its been rubbing.  Its the only needed repair.  

You might want to have a chat with your mechanic, he can replace the wire, route it where it won't get damaged, and learn from the experience. Under warranty.

[RLCarter]

By ground wire are you talking about the braided shield around the P-lead wire?

[Huitt3106]

3 minutes ago, RLCarter said:

By ground wire are you talking about the braided shield around the P-lead wire?

I need to take a picture of it.  From memory, there are two separate wires going to each of my slick mags.  They are independent wires coming out of the firewall and labeled.  The one that is worn is labeled mag ground and I think the other may be labeled either mag power or p lead (I can't remember exactly).  

[JimB]

25 minutes ago, Bob Weber said:

30% is beyond acceptance, I would still treat it as a safety issue. If I were standing there I would cut it at the abrasion sight, clean and strip the wire to expose an 1/8th of an inch of clean copper, quickly "tin" each one with a good, hot, clean soldering iron. at this point I would slide an appropriately sized length of shrink tubing on one of the wires, then, with a fresh ball of solder on a clean iron, I would make the connection waving the iron in order to create the connection and carry off any excess solder to make the joint as small as you can with a good shiny connection.

Looks good Bob. I am also a fan of soldering permanent connections but rather than tin them first (aviation wire is already tinned copper strands), I prefer to separate the strands of each wire, slide them in to each other and twist them together. Then solder them together with heat shrink covering. Inexpensive, quick and very secure. Similar to below. 

 

[Bob Weber]

Just now, JimB said:

Looks good Bob. I am also a fan of soldering permanent connections but rather than tin them first (aviation wire is already tinned copper strands), I prefer to separate the strands of each wire, slide them in to each other and twist them together. Then solder them together with heat shrink covering. Inexpensive, quick and very secure. Similar to below. 

 

After 50+ years of soldering I can assure you this is really a waste of time, no more conductivity, no more structural integrity, just more work initially and even more if you need to service the repair.

[Bob Weber]

Very early in my aviation career I was "educated" about this, I have been fighting it ever since. In college, in a shop processes class, the "professor" showed us a soldering course film from the military in the fifties. I quickly went to a friend and got a bunch of cull electrical equipment, brought it to class, and showed the class real life.

https://www.google.com/search?q=western+union+splice&client=firefox-b-1-d&sxsrf=ACYBGNR6BgK01AwA8G0IzJALCRMFg0OQ6g:1582039203731&tbm=isch&source=iu&ictx=1&fir=PiXVPFBnMdOLrM%3A%2CzKQGGCVxPzvR9M%2C_&vet=1&usg=AI4_-kTBSKgdk7nqJiRKl8u3ore0-5VLZg&sa=X&ved=2ahUKEwjPhomms9vnAhX2Ap0JHQo2DUwQ_h0wHHoECAoQCw#imgrc=PiXVPFBnMdOLrM:

[Andy95W]

Well, I've only been soldering for 45+ years which takes me back to the old Heathkit days.

I'm with JimB and the guy in the video.  I don't think I would ever trust a 1/8" solder connection in a high vibration environment as much as I would the traditional methods.

But I will keep your technique in mind for tight situations where it might be needed.

[PT20J]

I believe the Western Union splice was designed back in the telegraph days as a means to splice solid connector wires without solder. For small gauge wires that are soldered, the technique that Bob showed earlier would be better. You want a soldered splice to be as small as possible because makes a stiff place in the wire that can lead to stress fractures when the wire flexes. The shorter the stiff section, the better. A butt splice adds mass and can cause failure if it vibrates, so butt splices are best used where they can be supported, for instance, in a bundle of wires.

I don't understand the description of the mag ground wire. Mag P-lead wire should be a single conductor with a braided shield (the shield is for radio interference). A shield should not conduct current and thus should be grounded at only one end. I believe that Slick recommends grounding the shield at the ignition switch end rather than the magneto end.

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