PTFE fuel lines recommended?

Hi Peter,

Zero response's, so thought I would do some speculating:

Know nothing about PTFE fuel hose/lines.

Weight saving? - What do you estimate (grams) compared with the same installation in rubber?

What will the service life of the PTFE be?  Will you still replace at the recommended 5 year rubber replacement?

How does PTFE compare with rubber for abrasion resistance ? movement/vibration tolerance? heat tolerance?

If push fit, unlikly to have any advantage over correctly sized (ID) quality, rubber ones.

Does PTFE require special clamps/connectors (cost? weight? complexity?)

Sounds comparatively (to rubber) expensive. If extended life (longer than 5 years) cost per annum may, or not, be less.

PTFE may be used, as a liner, in some rubber fuel hose (FI hose?)

This video has some thought provoking information:

https://www.youtube.com/watch?v=hNGoeqJDnJg

Hi Sean,

thank you for looking at this post from various perspectives, and for the link to the vid.

I am looking at a non braided type (no metal mesh) and expect approx. 40% weight reduction. Yes, PTFE (Teflon) is pretty dear. However, once it’s done it’s done. They should last a lifetime long. PTFE is very resistant to heat. Ratings go up to 260C.

As per now I was not able to verify if those hoses actually work as push on. With special connectors and fittings the cost side would suffer even more and so would the weight saving.

My research led me to a lad who replaced 8m of rubber fuel hoses in his plane by PA12 hoses. They are very light, too, and far less expensive. For temp rating reasons he stuck to rubber underneath the cowling. I found PA hoses with a temp rating of 130C (some are rated only 80C, some 100C). In my opinion the 130C type should work underneath the cowling, too. With fire sleeves that should be OK anyway.

Regards

Peter

Hi Peter,

I would speculate that PTFE would need to be very carefully supported against vibration/movement and bends quite large radius to prevent kinking.

I am no fan of aluminium fuel lines but at least the equipment is available to make quite tight radius bends.

My preferred system is a combination of "rubber" & aluminium as the installation situation dictates. Aluminium is great for long runs in wings/fuselage. Rubber for short multi bend runs & connecting to fittings such as in line filters, pumps, etc., especially where vibration/movement may need to be accomodated.

I also like the push fit of rubber - done well its absolutely leak free/light weight/ low cost & soooo simple😈.

Peter,

A couple things to consider.  Possibly fuel lines are not the place to save a little weight. Fuel starvation is the number 1 cause of engine failure. I want the most reliable lines possible. All PTFE lines I have seen used in aircraft are either stainless braided or nylon braided, which I believe is appropriate for aircraft use. Also, it’s important that PTFE fuel lines used in aircraft are the conductive type. If conductive PTFE is not used, a charge can build up in the line and it can arc to the metal fitting or jacket and cause a tiny hole in the line where the arc occurs.  

There is some good information at this site.  These folks are very popular with experimental aircraft builders. I have their lightweight stainless braid PTFE lines and they are fantastic. With some of their PTFE hose, the bending radius is similar to rubber hose.  

https://www.aircraftspecialty.com/kitplanehoses/hosevids.html

https://aircraftspecialty.com/index.html

Hi Jeff,

No offence, but the above videos are promoting a product which is completely "over the top" for a non certified, small sport aircraft.

What the owner/maintainer does, regarding hose cost, is entirely at their discretion. If they want to go down the aircraft speciality PTFE hose rout  be sure to have plenty of $$$ on hand.

The result will be aesthetically impressive, will not do much, if anything for your aircrafts performance and arguably will have minimal improvement in safety (in flight fire).

Examples can lead to arguments but I have seen 25 year old Rotax powered aircraft, using good quality automotive fuel hose (rubber), that has been replaced at 5 year intervals, all push on fittings, with not even the hint of a firesleeve, flying quite safely.