Opinions about solder sleeves

[N96TJ]

Originally Posted by Bill Boyd

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.

[jliltd]

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.

[TJCF16]

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.

[Mike S]

Originally Posted by TJCF16

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.

[jliltd]

Originally Posted by TJCF16

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.

[Walt]

Originally Posted by jliltd

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.

[TASEsq]

Originally Posted by N96TJ

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

[Bill Boyd]

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.