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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Fuel Line Breaking Down??
09-04-2006 02:24 PM  14 years ago
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DWS6

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Newark,DE

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Fuel Line Breaking Down??
What causes the fuel line to break down, the fuel? I don't think so and heres why.

We were checking the clunk line in a buddys heli the other day and found the main tank fuel line in very bad condition and splitting, nothing new here it happens after 6-7 gallons of fuel.

Next we checked the header tank and that fuel line was in near perfect condition and older (had been in the tank longer) than the main tank line. I thought this was wierd because I figured it should be the same if not worse because it is submerged in fuel nearly 100% of the time. Even after flight (I usually don't drain my header).

Next I checked my fuel jug were the line is submerged 100% of the time and is very old and been through countless gallons of fuel. Again in near perfect condition. It can't be the fuel, so what is it???

I beleive it is one of two things causing this.
1. The exhaust gases or temp. This pressurizes the main tank but not the header or your field box obviously.
Maybe someone that uses a pumped engine can chime in and verify this seeing as they don't use exhaust pressure. Although they do use crankcase pressure and is that the same? I don't know.

2. Air getting to the lines after the fuel causing some sort of a reaction. Maybe a chemical engineer can chime in on this one.

This is something I never really payed attention to and was wondering if anyone else had any thoughts on it. Sorry if this topic has beened discused before.
Dave Williams
Team Align
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09-04-2006 02:27 PM  14 years ago
BarracudaHockey

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Jacksonville FL

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Exhaust gasses.Andy
AMA 77227
http://www.jaxrc.com
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09-04-2006 02:42 PM  14 years ago
DWS6

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Newark,DE

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Exhaust gasses
Do guys with pumped engines not have this problem?
Dave Williams
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09-04-2006 02:44 PM  14 years ago
George Matthews

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N.W. Ohio

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Yep I agree the breaking down of the fuel line has mostly to do with exhaust gases and it seems that 30% fuel is worst than 15%.
I have had a couple crashes due to bad cluck lines that was until I discovered the Hayes medium black neoprene fuel tubing. Trust me on this the hayes will last much longer that any silicone fuel line.
Just make sure you cut it about 1/8 inch shorter than normal as it will swell slightly during the first couple tanks. After that you will have a clunk line that will outlast any silicone.
George Matthews
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09-04-2006 02:48 PM  14 years ago
Mike557

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Northumberland England

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The problem is accepted as being caused by the line sitting in fuel ( the higher the nitro content the quicker it goes) and has been exhaustally debated both here and on other forums.
I have just had the same problem this week on my R50. I usually change my lines 3or4 times a year.

Regards
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09-04-2006 02:53 PM  14 years ago
z11355

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New England

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The problem is accepted as being caused by the line sitting in fuel ( the higher the nitro content the quicker it goes)
Thats a contributing factor certainly but it is the combustion
byproducts that are sent into the tank via muffler pressure
tha is the greater factor.

When was the last time the fuel jug line quickly failed? Ditto
YS engine users?
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09-04-2006 03:24 PM  14 years ago
da_man

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Central NC

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I bought the hayes stuff tubing for my main tank and it didn't last very long. Like within 2-3 gallons. The stuff in the header tank seems to last forever.

I got this ksj kinkless line from helikraft and so far it is good. I used it just for the season on my raptor 50 and a half season on a stratus. Its not silicon, but a rigid plastic molded like a bent straw. Its very flexable and seems to last. So far I think its good stuff.
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09-04-2006 03:27 PM  14 years ago
George Matthews

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N.W. Ohio

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I find it hard to believe that the hayes lasted only 2 or 3 gallons.
It may depend on how long it took you to burn those two or three gallons and did you leave fuel in the tank between flying sessions.
George Matthews
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09-04-2006 04:55 PM  14 years ago
sharam

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Northern California - Fly at Morgan Hill Field

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The clunk line sitting in my gallon fuel jug has been the same clunk line now for four years. It sits in 30% fuel 24/7. The line is still as supple as it was the first day. The problem is not the 30% fuel.

As others mentioned, it's the exhaust gases. The answer is simple - just air out your tank at the end of the day. This will make your clunk like last a lot longer.

Crankcase pressurized engines like the YS don't use the exhaust gases so they won't have the same problem.

The Hayes line is pretty good altho I have used regular fuel tubing as a clunk line before and it works just fine.
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09-04-2006 05:43 PM  14 years ago
dkshema

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Cedar Rapids, IA

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Fuel line doesn't last forever. With most kits, the stuff they put in for the tanks is very flexible, but also very short lived. Apparently the amount of nitro you're burning, plus the fact that you're putting burnt fuel back into the tank via the exhaust tap, are the two main factors involved in fuel line deterioration.

Just get a routine of changing out your tubing at least once a season. It's a maintenance item.

Prior to the introduction of silicone tubing for fuel line, we used surgical rbber tubing. This stuff was very flexible, worked great, but would eventually turn into a big sticky blob of snot on the bottom of the tank. The stuff that was exposed would turn brittle and crack.

Prior to surgical rubber tubing, we used a clear plastic tubing. It was stiff, and over time would simply harden. The stuff was similar to Tygon tubing in appearance. Clear, fairly thick walled.

Tank manufacturers have gone through just about every kind of tubing imaginable over the years to find a suitable product. So far, the search is still on.

Dave
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09-04-2006 08:17 PM  14 years ago
Mike557

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Northumberland England

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I stand corrected. My apologies
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