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  #41  
Old 01-18-2022, 08:51 AM
Walt's Avatar
Walt Walt is offline
 
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Quote:
Originally Posted by Bill Boyd View Post
I don't doubt you, Walt. A cold joint is exactly what I'd be concerned about - either from under-heating or from an installer pulling on the splice to test it mechanically before it was cooled down to "warm to the touch." Solder must be allowed to set without being disturbed or a frosted-looking cold joint is assured and it will give trouble at some point. This is also true for a conventional solder joint made with an iron and then covered with shrink wrap, the old-school way of doing what a solder sleeve does more easily with fewer hands.

If any failed specimens were brought forward for analysis, I would expect them to be uniformly of the cold-joint variety, although a few solder-starved joints from Chinese manufacturing tolerances wouldn't surprise me either. I like the way the solder sleeves allow for visualization of the melting and wet-out inside the sleeve as the solder paste reaches its alloying temperature. Very reassuring to see the solder flash outward along the whole length of the exposed strands and coat them with a shiny (not frosted) silvery flow. I have an attachment for my heat gun that wraps around the sleeve and warms all sides at once; I suspect not everyone is doing it that way and that's an exposure to installation error.
The failed joints I have seen have been from respected shops which likely have the right equipment and trained personnel. The problem in my opinion is not actually having a good view of the solder joint while looking through the heat shrink. And yes, not moving the assy until cooled presents another challenge (I always hand solder with the wires in a fixed position for this reason).

When I hand solder, I can control the joint by adding solder/rosin until the joint is thoroughly wetted, not something you can do with a sleeve.

There's likely a good reason environmental crimp splices are used in the toughest conditions in aviation when spicing is allowed/required.
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EXP Aircraft Services LLC
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Last edited by Walt : 01-19-2022 at 05:42 AM.
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  #42  
Old 01-18-2022, 09:03 AM
N96TJ N96TJ is offline
 
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Location: Costa Mesa, CA
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Quote:
Originally Posted by Bill Boyd View Post
I'm going to channel my inner Bob Nuckolls and ask that if anyone has a physical sample of a solder sleeve connection that has failed in service in a properly supported wire bundle after checking out normally in initial service, I would ask that it be sent to me (or better, to Bob) for an autopsy and determination of how this failure occurred.
I have had a short "grow" inside a solder sleeve being used to pick up the shield for a pigtail. I repaired it so there is no sample to show but I will describe what happened.

I originally used the Bob Nuckolls method for attaching a pigtail to a shield wire but when I did my G3X upgrade I decided to get modern and use solder sleeves for this. I ran some tests prior to the actual work and I did notice that it took a long time under the heat gun to get a full solder melt inside the sleeve.

The new harness checked out fine on the bench and worked fine in the airplane for over a year. One day, right after I had done a software update, I started getting a few CAN BUS errors and this quickly progressed to 100% CAN BUS errors. It seemed like it had to be a software issue, but it was not.

What I eventually found (long story omitted) is that a short had developed between the CAN LO signal and the CAN shield ground and that this had occurred inside a solder sleeve. When I dissected the shorted joint I found that the insulation for both CAN signal wires showed signs of heat distress but I could not see any point where the insulation was completely compromised.

This has only happened once and you could argue that it was due to poor technique or workmanship but it did happen to me.
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  #43  
Old 01-18-2022, 09:20 AM
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When I do a shield drain splice with a solder sleeve I use masking tape as a tool to hold the drain bonding wire against the shielded wire a few inches out from the solder sleeve. I do this to keep the ground wire from moving around or even pulling out during the shrink/solder process. The masking tape holds the ground wire like it's a part of the shielded wire so there is no relative movement. This, after having numerous issues with ground wires moving or even falling out during the process.
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Last edited by jliltd : 01-18-2022 at 04:16 PM.
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  #44  
Old 01-18-2022, 04:02 PM
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TJCF16 TJCF16 is offline
 
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Default Solder sleeve’s

I worked 26 years on F-16 electrical system, and at no time are you allowed to butt splice with solder sleeves. LM Aero would only allow raychem crimped splice with heat shrink sealing sleeves. They come in Red,Blue and Yellow. Aircraft Spruce Has them, but they are not cheap! I will say this one more time, solder sleeves are for shield wire grounding! Not for butt splicing! This is not MHO but fact.
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  #45  
Old 01-18-2022, 04:05 PM
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Mike S Mike S is offline
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Quote:
Originally Posted by TJCF16 View Post
I worked 26 years on F-16 electrical system, and at no time are you allowed to butt splice with solder sleeves. LM Aero would only allow raychem crimped splice with heat shrink sealing sleeves. They come in Red,Blue and Yellow. Aircraft Spruce Has them, but they are not cheap! I will say this one more time, solder sleeves are for shield wire grounding! Not for butt splicing! This is not MHO but fact.
You are repeating yourself. See post 35.

Guess I am lucky I dont fly a f16-------I have used many solder splices in my aircraft and have had ZERO problems.
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  #46  
Old 01-18-2022, 04:18 PM
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jliltd jliltd is offline
 
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Quote:
Originally Posted by TJCF16 View Post
I worked 26 years on F-16 electrical system, and at no time are you allowed to butt splice with solder sleeves. LM Aero would only allow raychem crimped splice with heat shrink sealing sleeves. They come in Red,Blue and Yellow. Aircraft Spruce Has them, but they are not cheap! I will say this one more time, solder sleeves are for shield wire grounding! Not for butt splicing! This is not MHO but fact.
NASA uses them as splices. See post # 40.
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  #47  
Old 01-18-2022, 05:18 PM
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Walt Walt is offline
 
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Quote:
Originally Posted by jliltd View Post
NASA uses them as splices. See post # 40.
Just because NASA has a spec doesn’t actually mean they were approved for repairs on a space vehicle which is what that would imply.
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Walt Aronow, DFW, TX (52F)

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 2000+ hrs, New Titan IO-370, Bendix Mags, MTV-9 prop
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154

Last edited by Walt : 01-18-2022 at 05:27 PM.
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  #48  
Old 01-19-2022, 04:20 AM
TASEsq TASEsq is offline
 
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Originally Posted by N96TJ View Post
What I eventually found (long story omitted) is that a short had developed between the CAN LO signal and the CAN shield ground and that this had occurred inside a solder sleeve. When I dissected the shorted joint I found that the insulation for both CAN signal wires showed signs of heat distress but I could not see any point where the insulation was completely compromised.
I think this is why they recommend folding the braid back against the insulation now.
http://www.steinair.com/wp-content/u...STRUCTIONS.pdf
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  #49  
Old 01-19-2022, 11:29 AM
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Bill Boyd Bill Boyd is offline
 
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For a moment I thought this thread was headed into the weeds of the RoHS-induced, "here, have-a-tin-whisker-driven-failure!" syndrome. (Makes you wonder if anything good for aviation ever came out of efforts to protect us from the horrors of environmental Pb). Turns out it's just from overheating insulation inside a multiconductor shielded cable.. That's a known risk of poor practices.

Probably best to stipulate that mechanical twisting followed by hand-soldering and application of shrink wrap is the preferred technique for butt-splicing when access allows. I was being lazy and saving time, and I hope to get away with it.

OTOH, I have zero worry about hardening the wire strands with solder beyond the strain relief boundary of the heat shrink, and having mechanical wire breakage at the edge of the solder penetration zone - which can happen with over-zealous hand soldering of terminals and splices.
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Last edited by Bill Boyd : 01-19-2022 at 11:35 AM.
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