Joseph Frost

Not so long ago I have published an article in numerous online and print magazines about crumbling fuel lines in turbine powered jets if not replaced on regular basis.
Currently transforming one of my EDF jets to kero power and while pulling the engine in & out few times during install the main in-line snapped off again at its sharp curve via
rubber grummet. It is actually less than 2 years since my full replacement of the tygon lines inside-out the engine cover!'

After removal of the broken line today I have noticed the dramatic difference in fuel line colour, inside the cover still in its original state, but past the grummet on the outside
total change of the colour due to the sunlight deterioration, also more brittle.

Keep an eye on those lines!

Sunlight fuel line deterioration on the outside of the engine cover.

joeflyer

My Feedback: (48)

If it lasted only 2 years you're not using real Tygon.
Tygon gets a bad rap because a lot of places sell cheap yellow vinyl tubing and call it Tygon. If it doesn't have "F-4040" printed on it it's not real Tygon.
I've had real Tygon last 10 years in some of my planes.

Furthermore you should not be using Tygon on your engine. In case you haven't noticed all turbine manufacturers plumb their engines with polyurethane when new.

If you want something that will last indefinitely use Viton (fluorelastomer). The only downside is that it's not transparent.

I typically use Viton inside fuel tanks, Tygon from the tanks to the fuel pump, and polyurethane from the pump to engine.

highhorse

My Feedback: (2)

While the admonition to check fuel lines regularly seems like good advice for a variety of reasons, are you certain that it was Tygon, and not a knockoff? I have some ancient (installed) Tygon which is still plyable, and have seen brand new knockoff deteriorate whilst sitting in the drawer.

Dave Wilshere

What is in the picture is not tygon. You can see the wall thickness too.

Len Todd

What is in the picture does not look like real tygon. If it did not last at least 5 years and snapped off proves it.

I have used typgon for 5+ years w/o any issues other than a slight discoloration and it gets slightly stiff. I do inspect and sometimes replace clunk lines every couple years though. I also use Festo type tubing too. But for both types, I stick to suppliers who I know will send me quality products speced for our specific use.

Kind of a side thought: As I understand it, plastic wire ties are not all that great around the barbed fittings either. A couple wraps of safety wire is the only way to go to prevent fuel leakage on the pressure side or air in-leakage on the suction side. Most of the wire ties, I have seen, do NOT make a complete circle and are difficult to get tight enough. Also, unless your get a high quality grade wire tie, they are highly susceptible to UV. Most of them out there are NOT of high quality. Just a thought.

Joseph Frost

The regular check, maintenance and replacement is the key to the reliability of the fuel system no matter what brand modelers use. In today's world of knock-offs it's always hard to know what's the real thing no matter who you buy it from.
I have ones bought a fully assembled header fuel tank from 'so called' the 'elite' distr. of jet turbine parts in Austr. the tank was so badly put together it flooded internals of my model with 2 liters of kero. LOL.

F900

My Feedback: (2)

Any suggestions online that sells real Tygon?

Joseph Frost

I normally buy mine in all sort of diameter from specialist lawn mower outlets, it is pretty expensive stuff, no matter what outlet I got it from, so who the hell would know what's real thing or knock off?

joeflyer

My Feedback: (48)

Dubro gasoline fuel tubing is real Tygon.
Most hobby shops carry it.

joeflyer

My Feedback: (48)

Read post #2

olnico

Dupont changed the chemical formulation of Tygon years ago. It is not what it used to be.
The latest tygon smells like rotten fish and exudes silicon oils relatively fast if kept on storage ( it becomes "oily".
We stopped using this product in UAVs years ago due to fuel injection needle carbonation because of this silicons sweating.

We now exclusively use high quality push-to-conect Pisco fittings on high quality 95A shore hardness lines that are certified to 28 in Hg vacuum.

https://www.ultimate-jets.net/collec...ct-fuel-tubing

F900

My Feedback: (2)

Thanks, bought Ultimate jets fuel line and fittings.

Joseph Frost

Reply- I have installed today the broken 'Taygon' fuel line, less than 2 years after it was last time replaced! I always purchased my Taygons from lawn mower outlets, believing it is kero compatible, and so it is, a genuine one I bought again this morn after looking closer at it, and all my remining stock with very small white print, only readable with strong magnifier "Saint Goban Taygon (R) F-44 49 A".
I'm also very well aware of genuine Polyutherine Festo tubing that from my experience deteriorate the same way, you can always ask me how I know that, LOL.
Also, as someone suggested not to use cable ties, I find them more practical, and just as reliable, as I'm paying lot more attention to my fuel system last few years after 17 years of pretty good experience with it.
I only recommend to pilots to check all their fuel system on very regular basis, at least every 6 month. "Prevention is better than cure!" Anything like, JetA, Kero or Diesel is a horrible stuff doing terrible things to our fuel system, just as well as to our lungs when inhaled! LOL. Carcinogenic!
BTW, after buying more of "Tygon" today, the girl behind counter charge me 20 cents per one centimeter, after getting 200 cm you can work out the cost.

Genuine (R) Taygon stuff.

All fixed.

Good for at least 6 month.

Joseph Frost

Q-Furthermore you should not be using Tygon on your engine. In case you haven't noticed all turbine manufacturers plumb their engines with polyurethane when new.

Reply- So what you say to this, just another experience in my pocket with pretty new engine? After morning flight, all going good, landed, re-fueled and while ready to go up again the engine just wouldn't spool up to full RPM, (~160K) after hooking up to it my 'goncoolator-LOL' it was reaching only some 110 on full stick.
No more flying for the day, I said what the hell happened?
While still being bit of a green in turbines, my curiosity made me to remove the front cover rather than packing it up to send away for a service to jet tech.
And there it was! The stock 'poly' fuel tubing totally collapsed in curve/bend inside the front engine cover to the point blocking the full fuel flow into the chamber.
Naturally, the heat was part of the problem, that's why I prefer to use Taygon, being more flexible.
Easy fix, and good education in my pocket of experience.

Desertlakesflying

My Feedback: (28)

Why are you using Tygon on anything to do with turbine engines besides maybe fill lines?

Joseph Frost

I use them only in places for more flexibillity, tight places, (if you read my post above), also to minimize use of other fittings like Festos, etc. and find them very practical for the size reductions to fit any other poly lines or what ever fitting. Well experience modelers always adapt things rather than do what's written in the book.
There's nothing wrong with them, if regularly replaced, unfortunately our Austr. sun is lot more potent than in some other parts of the globe, which might be also a cause for quicker deterioration, as mentioned in my first post if you have read it.
BTW, the genuine poly lines crumbled on me in the past to lot worse state over the years I have been dealing with the JetA fuel. They actually become so brittle in tighter curve places they snap off like an 'icicle'!
Just keep an eye on yours, not long ago I have witness as an observer total distraction of well over 20K, 3m turbine model, absolutely nothing left beside few metal shrapenels, most likely cause of internal fire due to the broken fuel lines after closer exams of some left over bits.
Safe flying.

Joseph Frost

While getting ready one of my Delta foamy turbine for a weekend fly I have noticed another fuel line deteriation, by total color change to very dark, also becoming greasy on outiside after being full of kero fuel. While being marked as real Tygon it certainly changed to what I was using over the years.
Regular check, maintenance or replacement is a must! Happy and safe flying.

invertmast

My Feedback: (23)

I dont know what kind of Jet-A you're getting, but for you to be having this many issues with multiple different types of fuel lines, something isn't right. I replace my tygon lines on basically everything on a 1 or 2 year cycle and other than some discoloration and hardening (mostly on gasoline powered models, jets dont seem to have as much of a problem with it) I have never had issues like your stating, even after some models have sat for years without use. When it comes to the polyurethane 3,4 or 6mm lines, i have never had one of those harden and break that wasn't exposed to high heats for a significant amount of time.

highhorse

My Feedback: (2)

I have had supposed Tygon which was brand new get “greasy” just sitting around. I also have 15 year old Tygon which has been flown and exposed to kero stay flexible and not greasy at all. I suppose there’s plenty of counterfeit out there.

Joseph Frost

I don't have any problem with my fuel system thanks to my thoroughly checks and replacements it when needed to, while keeping a detail log book for each model comes also very handy to know when things might need service etc. etc., like this decade plus old turbine powered foamy still going immaculate.
Only sharing my experience to help others to keep an eye on these crucial things, that some may not pay enough attention to.

With out a regular service this beaut wouldn't be still in action after long years of flying.

Keep an eye on those fulel lines!

Where it belongs.

wojtek

My Feedback: (73)

First off, I would not use Tygon with better grade lines available that are les prone to aging and actually kinking/bending. Where I have used tygon however, even after well over a decade, it my be stained, or even hardened a bit , but never have i seen fuel line lose its integrity. Like others have stated, you likely do not have real tygon. Lots of garbage (fake) parts and materials going around these days 🤷‍♂️ ... just my opinion.

Joseph Frost

I found every type of fuel line over the time deteriates, the best example is with the ones fitted by the factory that crambled on me same as anything I used to date. It's quite possibe in EU or US might be more sellection to choose from but down here in this 'asend' of the planet you are lucky to get anything to rely on.
So far no problem with my recent replacement, despite some discoloration, just had few more nice runs today in perfect conditions with the good old Delta foamy. Just love it.

Keep an eye on those fuel lines!

Joseph Frost

Sold as Taygon, didn't take long to get to this state, the colour speaks for itself. Easy fix, I just replace it. (Wren44G Delta outing)

Judging by the colour they must be putting some new additives to these lines coming out of cina, LOL.

joeflyer

My Feedback: (48)

I can tell by looking at the picture that it's not real Tygon. Tygon is a brighter opaque yellow and has F4040 printed on it. If you can get Dubro fuel line it's real Tygon.

You're asking for trouble using Festo connectors with that tubing, they will eventually leak. Also never use nylon tie straps to secure fuel line. They do not apply uniform pressure around the circumference. Use steel wire wrapped around twice.

Joseph Frost

12 years of regular action and service with this bird speaks for itself! LOL. BTW, bought this engine 2nd. hand all those years ago. After check of my service log book I have replaced internal engine fuel/gas lines 3 times, and fuel lines inside the model few more times, no wonder never had any leak so far. It's a scratch Depron build foamy.
My only minor issue is the engine occasionaly flames out at idle's 55K RPM on finals just before or after touch down, caused most likely by the older getting worn out brushed fuel pump, so that will be the next upgrade in this beaut.

Regular check and service of all parts is a must.

Different engine but same principle, regular fuel line replacement, a must!

Just another outing.