pierre smith

pierre smith

Well Known Member
Yesterday at Ridgeland, S.C., Tom Swearingen, hose builder, sliced and sectioned my scorched fuel line and the teflon held up amazingly well! Much better than rubber would have fared:

firesleevedamageinside.jpg


This shows the scorched firesleeve and here you can see the discoloration of the stainless braid:

Hoseheatdamage.jpg


Last of all, Tom removed a section of the hose, centered on the heated area:
Damagedhosecomponents.jpg


To our mutual amazement, the teflon wasn't blistered inside and no signs of failure were seen or evident. I am now a strong believer in the value of teflon over rubber hoses, anywhere near a heat source. He and I both realized that we could have been toast, had I had rubber-lined hoses under the circumstance. Probably the higher fuel flow rate of my IO-540 helped cool the inside of the line and the fact that thin-walled stainless steel exhaust cools fairly quickly, keeping much of the heat away from the inner teflon liner. Tom was as relieved as I was, seeing first hand, the fruits of his labor and the fact that nobody has been BS'ing anybody about the merits of teflon-lined firesleeved hose!

Guys, don't fiddle around and penny-pinch when it comes to your oil and fuel lines...call Tom or email him for quick, experienced service and the peace of mind that a properly done fuel and oil system can bring...from one who has just "been-there-done-that!" We very simply, lucked out!


Best,
 
My fuel line came in the Vans Firewall forward kit. It is firesleeved but does anyone know what the inside is made from? I would hope it is teflon.
 
Curious - does anyone here know what the actual "teflon" liner is? It has to be some sort of blend, as teflon alone would not be flexible enough to act as a hose wall. I did some searching, but can't find just what it is.

Also, as has been stated elsewhere, a rubber lined hose (like 701) would have done fine, as long as there was some fuel flowing in it. A styrofoam cup with water in it will survive when placed directly into a fire, I've done it. The top burns off, but the cup only partially melts where the water is. Has to be seen to be believed.
 
What is the construction of this hose. I see the exterior steel braid then something that appears black. Is the black material teflon or rubber with teflon inside?
 
Thanks Tom. I was talking earlier today about this with my IA and he showed me some smallish hose that was steel braid exterior and white teflon inside.
 
pierre smith said:
To our mutual amazement, the teflon wasn't blistered inside and no signs of failure were seen or evident. I am now a strong believer in the value of teflon over rubber hoses, anywhere near a heat source.
Click to expand...

Maybe so, but hardly a fair test since there was no test of rubber hose under the same circumstances. I dont recall seeing any claims of better heat resistance from Teflon hoses, but wouldnt go so far as to deny it either. The cooling effect of the fuel going through the hose helps a lot, as scary as that sounds.

Regardless, glad you caught the problem in time. Neither Teflon nor rubber would have protected you in the long term with things left alone.

best regards
erich
 
Interesting comment Erich. My mechanic showed me a rubber/steel braid (?)/ rubber hose (Aeroquip 303 ?) which he asserts is just as good.
 
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I seem to recall that the selling point for Teflon vs rubber hoses was life expectancy. Rubber have a definite usable life and need to be replaced every so often (the interval escapes me at the moment) but Teflon can last much longer IIRC, perhaps indefinitely. Of course, that doesn't mean they are install and forget as Pierre's experience clearly shows.
 
Teflon

Pierre,
In my experience with teflon, it usually doesn't start to melt under 700Deg F.
I do remember a problem with "cold flow" a property which under pressure from say a too tight hose clamp actually causes the teflon to flow away from the clamping pressure. Typically, it's not an issue when proper clamps and pressure are used. I used Summit Racing stainless braided, teflon lined brake hoses throughout for the reasons of extra fire resistance over other materials. I was careful to not to use too small a clamp (cushioned) of course. I will report results after flying the plane. Right now I'm in Clearwater building my engine :}

Jerry
 
If there was ever an example of why to install firesleeve, this is it.

I'll venture to say you didn't build it like that, so the fact that it moved some how is proof positive that you just never know what can happen. Thanks for sharing.
 
Teflon vs 303

If you go to Teflon just be careful when you inspect the hoses down the line. Be careful not to change their position.
From AC43.13:
[FONT=Times New Roman, serif]Although Teflon hose has excellent performance qualities, it also has peculiar characteristics that require extra care in handling. It tends to assume a permanent set when exposed to high pressure or temperature. Do not attempt to straighten a hose that has been in service.[/FONT]
 
Sig600 said:
If there was ever an example of why to install firesleeve, this is it.

I'll venture to say you didn't build it like that, so the fact that it moved some how is proof positive that you just never know what can happen. Thanks for sharing.
Click to expand...


Pierre can correct me if Im wrong, but my understanding was that the firesleeve didnt move, it was worn/burnt through from contact with the exhaust. It did its job to the extent it could, but eventually wore through.

erich
 
The firesleeve didn't move.

Tom has band clamps on the ends of his hoses that permanently locate the firesleeve and it can't move.

The story is that I had new hoses made last year, because my IA didn't like the AN fittings and some had broken on other airplanes. Tom made braided, teflon-lined, firesleeved hoses with all stainless ends which replaced the originals.

The fuel supply line to the servo has a straight end and a 90 on the other. The hose was installed with the straight end at the servo, not the 90 as it should have been. The radius the hose has to bend made it lie against the exhaust...a point that was missed until I luckily found it last Monday.

Best,
 
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