Big Tex follow up

[kennyd]

Ok, stayed out of it until now. If you ever get a chance to look into a commercial airliner with its guts out you will see 1000's of butt splices. I guess the difference is they are in a sealed environment where as a trailer is out in the muck.

I agree soldering is a much better way. Just kind of scary to think the butt splices are used in aviation. I have been flying commercially as my primary job since 1996 and have accrued about 7,000 hours in the air. 5,500 of these hours are in jet aircraft. I am sure many of the squawks I have given to the mechanics were due to the butt spice failures but can only think of one that was serious and lead to me shutting down the left engine. Anyway got feed back it was a bad connection in a wiring loom and the direct cause was a bad butt splice.

Chris

I believe everything you say is 100% true...BUT I am sure they are not the same ones that Wally World and AutoZone sells


Also, When using heat shrink-don't use the thin-walled cheap stuff.. use what is called "double walled" or "Heavy Walled" adhesive lined shrink for use outdoors.

 

[jinman]

Ok, stayed out of it until now. If you ever get a chance to look into a commercial airliner with its guts out you will see 1000's of butt splices. I guess the difference is they are in a sealed environment where as a trailer is out in the muck.

I agree soldering is a much better way. Just kind of scary to think the butt splices are used in aviation. I have been flying commercially as my primary job since 1996 and have accrued about 7,000 hours in the air. 5,500 of these hours are in jet aircraft. I am sure many of the squawks I have given to the mechanics were due to the butt spice failures but can only think of one that was serious and lead to me shutting down the left engine. Anyway got feed back it was a bad connection in a wiring loom and the direct cause was a bad butt splice.

Chris

Back in the late 80s, I was an instructor teaching high-reliability soldering, hot-air sleeve soldering, and contact crimping for wiring harness manufacturing on the F-16. Of particular interest was the Cannon plug type crimp contacts used by the millions in aircraft manufacturing. These type connections and properly crimped butt-splice connections will be airtight and watertight at the crimp point. The operative words here are "properly crimped." These type connections and the crimped connections shown in the original post are so different as to be impossible to compare except that they are both meant to carry electricity. Proper crimp tools have calibrated "indenters" and a ratchet mechanism that will not release until the crimp is fully made. The terminal lug type crimps are normally done with an Amp brand cutter/stripper/crimper that is no better than the user and provides no consistency of finished product (or perhaps, consistently bad).

With the thousands of solder joints, crimp connections, and connector pin insertions in a modern commercial aircraft, it is almost impossible to completely ensure there will not be some failures. That's why critical flight controls often have multiple redundancy built into their design. That's hardly what you would expect on a trailer that can be pulled over to the side of the road and parked if something fails. Finding a parking spot at 40k ft is a little more difficult.

 

[wushaw]

Enviromental splices are used in the open areas exposure to possible weather. Tyco Electronics Unveils Sealed Splices for High-Temperature Applications
Clear butt splices are used in areas where there is no water exposure.
Peerless Electronics: Tyco Electronics Aircraft Splices

There are many different kinds of crimpers used for aviation wiring, AMP is a popular brand for butt splices.
I use the enviromental splices on my trailer wiring, they work on airplanes why won't they work on a trailer.

There are some stuff solidered, not much though, vibration is the reason.

 

[Soundguy]

At very least.. grease filled splices would be better'n nuttin!

soundguy

 

[wushaw]

Maybe but not used per Boeing standard wiring practices manual. The splices are sealed by the heat shrink.

 

[CurlyDave]

I use the enviromental splices on my trailer wiring, they work on airplanes why won't they work on a trailer.

The splices probably do work, but I know for a fact aircraft wire does not. I used to work at a place that made aircraft wire, and one of the guys "liberated" enough to re-wire a log dolly. 6 months later the wire insulation had chaffed through in many places.

Airplanes travel a lot of miles and vibrate some, but trucks and trailers get driven through mud, sand, dirt, etc. none of which gets into aircraft wiring bundles. For some applications a lot of cheap thick insulation beats expensive very thin and light weight insulation.

 

[MikeD74T]

All my trailers get used year 'round. In New Hampshire that means they see more salt than a tuna boat. Without a doubt soldered splices have been the most reliable for me but I don't always have solder & heat availible. I prefill my crimp splices with RTV sealant before inserting the wire & crimping. I've never had one fail due to corrosion.
Where ever wires pass thru frame hole I "secure" them with a gob of RTV sealant. It makes a custom bushing that holds wires & prevents chafing. This works even where wires just lay on the frame.
MikeD74T

 

[Soundguy]

For some applications a lot of cheap thick insulation beats expensive very thin and light weight insulation.

ditto that... I like dual insulated wires.. IE. the ones with a clear pvc sheath over their rated insulation.. gives them superior abrasion resistance..

soundguy

 

[wushaw]

Curly, the insulation is teflon and it is not as flexible as the standard trailer wiring.
No, aircraft wiring does not see what trailer wiring sees, alot of it sees hydraulic fluid (Skydrol) engine oil and heat. The anti-skid harness on the main gears is covered in a stainless sheath so no damage comes from snow,water..etc.