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Why no Teflon tape used in fluid lines

sounds like

something fishy here. Wonder if it was part of the teflon liner, or possibly a 'plastic' cap piece used to cap off the lines was in the hose. At any rate, bad QA. After pressure testing and cleaning, shine a light in one end of the hose and look through the other. Gee, doesnt everyone do that?
Tom
 
Bob Collins said:
Man, if you ever need it to be reinforced why teflon tape shouldn't be used on fluid fittings, this story out of Madison, Wisconsin should do the trick.

An F-16 -- valued at $25 million -- crashed this summer. Investigators found a "chunk of Teflon" blocking an oil line.

D'oh!
Click to expand...

Another reason for not using Teflon? tape on NTP threads is what I call the "#$%* wont leak on me!" syndrome, people will wrap tape and wrap and wrap and then wrap (one more for good measure right?;)) and then proceed to tighten the fitting in. And what happens? They have just split the part the fitting was being put into.
What some folks tend to forget, is that NTP threads are a tapered and that by using to much tape you have added more material to the surface of the male threads, and as it is tightened (into a female tapered hole).....well something is going to give.
Sometimes you'll actually see the crack but more often than naught there will be a hair line crack that is just waiting to ruin your day.:eek:

So when asked what to use on such threads (and I do get calls just for this alone I tell them to find the following product.
Permatex? Thread Sealant with PTFE item# 80633
 
Teflon tape in fluid lines

Bob Collins said:
...why teflon tape shouldn't be used on fluid fittings...
Click to expand...

Bob, my rivet gun, pneumatic rivet squeezer, die grinder, etc. all totaled don't even come close to 25 million, but I did not put any teflon tape on any air line fittings in my shop. After 15 years of designing and modifying chemical plant piping systems, I was well aware of what those little white teflon slivers can do to little orifices.

Thanks for a more-than-subtle reminder.
 
That funny

Brett

I just call you this morning with that question. Always a pleasure to talk to you and thanks for your help.

Pete
 
I believe the actual issue with the use of teflon tape is the improper installation, which leads to FOD in the fluid/air line. I was trained by both the Air Force and for my A&P on the proper installation of the tape and you were never suppose to have the tape within 1 thread of the end of the fitting. You will have issues whenever you have the tape extending past the end of the fitting which will lead to excess tape being cutoff by the threads and left inside the system.
 
thats odd how you don't mention the report says they found enough beads to be worth mentioning. maybe the gearbox never would have had a problem if there wasn't BOTH materials. hard to tell from the news report. typical news report though, just enough material to leave more questions than answers.

even one of the previous articles on the same subject gets a comment: "this is a useless article"
 
curtis said:
I believe the actual issue with the use of teflon tape is the improper installation, which leads to FOD in the fluid/air line. I was trained by both the Air Force and for my A&P on the proper installation of the tape and you were never suppose to have the tape within 1 thread of the end of the fitting. You will have issues whenever you have the tape extending past the end of the fitting which will lead to excess tape being cutoff by the threads and left inside the system.
Click to expand...

Yes, that. ;)
 
curtis said:
I believe the actual issue with the use of teflon tape is the improper installation, which leads to FOD in the fluid/air line.
Click to expand...

Absolutely agree, but there is still enough of a potential problem to ban it around my airplane. If you ever remove the fitting, you'll find teflon strands remain in the female threads. They get pushed into the system on the next fitting installation.
 
Back in the day when I worked at a well-known manufacturer of welding and cutting equipment and medical gas regulators, there was no teflon tape allowed in the factory. We used the purple low-strength Loctite to seal the gauges (NPT)into the regulator bodies.
And in a very odd coincidence, I just arrived in Madison, WI yesterday on a business visit, and saw some of the F-16s ripping around during the drive to the hotel!
 
Some of you

Air Force guys may correct me, but are they still using NPT in F-16s? The
F-18s here dont that I'm aware of. They use MS and Dynatube ( or a derivitive). It thats right, then how did teflon tape get in the hose?
Tom
 
The remnants of teflon tape would hardly qualify as "a chunk of teflon" and none I ever seen would block an oil line. Plug a very small orifice or bind a shuttle valve maybe. I use teflon paste.

Dave
 
Danny7 said:
thats odd how you don't mention the report says they found enough beads to be worth mentioning
Click to expand...

I'm not following you. You find it ODD that I didn't mention something in the article? Ummmm... I post the link so you'll READ the article, so I don't really get the point that you may be trying to make. Or not.
 
DanH said:
Absolutely agree, but there is still enough of a potential problem to ban it around my airplane. If you ever remove the fitting, you'll find teflon strands remain in the female threads. They get pushed into the system on the next fitting installation.
Click to expand...

It works on house plumbing and that is as close as it should get to an airplane.
 
ThisOne said:
So when asked what to use on such threads (and I do get calls just for this alone I tell them to find the following product.
Permatex? Thread Sealant with PTFE item# 80633
Click to expand...

Brett
Is there a Locktite equivalent to the Permatex 80633 you would recommend? Over here in Australia Locktite stuff seems more available.
John
 
Just reviving an old thread as a reminder.
I tried to tell someone not to use Teflon anywhere on an airplane, but he said he's been building multiple airplanes for years and has always used it on NPT fittings. For the record, I tried. Hope a piece doesn't end up stuck somewhere.
 
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