Clogged fuel lines

[PropellerHead]

I'd like to begin the process of bringing a 824KF back to life after languishing in my garage for 4 years. I mailed the carbs out for a rebuild and now I need to deal with old congealed fuel in the fuel lines. She has a mix of metal and rubber fuel lines. My first inclination was to pull out and redo all the lines for safety sake. Is this overkill? Is there a safe way to clean it all out?

[rdooley79]

My suggestions is to replace the rubber lines, no matter what.
While you've got them off figure out a way to shoot some carb cleaner or something equally solvent down the metal fuel lines from both ends. That should clean any varnish out and you will know if there is a blockage.
Use a lot of towels and drip trays to protect the finish of your bird.
Get some new fuel filters installed when you're all done and things are nice and clean.

[cap01]

might be a good idea before your replace the the hoses to rinse out the tanks with some fresh alc free gas . also when you replace the rubber hoses be sure to use the low permeation type hose .

[PropellerHead]

My suggestions is to replace the rubber lines, no matter what.


To be clear; Are you suggesting that you don't like rubber lines at all and should be replaced with metal or just that they don't stand up well to old fuel?

[rdooley79]

I'm saying that if you have old gas it's easy and fairly inexpensive to replace your rubber hoses as they can crack over time. It's a good thing to do if you're going to all this effort to make sure the plane has a nice new fuel system. cheap too considering how much aircraft cost. Plus you'll have nice clean hoses.

[Dave S]

Comments offered are right on track.:) The low permeation hoses we can get now are great as they don't smell up the cabin where the hose lines run through the cabin.

FWIW - lacquer thinner makes a really good soak/solvent/flush for the metal parts and metal tubes to dissolve the crud left by the old gas - Acetone is good too. Don't want to have either get on any good rubber parts intended to be used. Both solvents can be inexpensive compared to carb cleaner.

Probably not a bad idea to follow Kitfox's recommendation for flushing new tanks on the ones which have sat with old gas in them. Pretty sure others mignt be able to offere advice on cleanihg up tanks on Series IVs.

Interesting on the rubber hoses - Rotax advises 5 year replacement on these - however, they say nothing about the rubber hoses that are not part of engine - guess they don't give a rat's elbow if any of us has trouble from stuff they might not get sued for:rolleyes:

Sincerely,

Dave S
KF 7 Trigear
912ULS Warp Drive
St Paul, MN

[beeryboats]

I'm waking up my IV after the last owner let her set for 10 years. The rubber hoses are all going to go! The hoses from the tank to the header tank are hard as rocks! My problem is the header tank is half full and there is no low point drain. What the @$%& was the builder thinking? So now I have that to fix as well. My question is, what hose should I use from the tanks to header tank?

[cap01]

Goodyear barricade is talked about a lot on this forum . I used Parker series 39705 super flex which is also low permeation with good results . I'm sure there are other brands also .

[War Eagle]

I have replaced all my black rubber hoses with polyurethane gas lines.

They are see thru and are classically used on motorcycles and hot rods and can be purchased from those types of suppliers. No gas smell in the cabin.

This product can be purchased in clear, blue, red, green and there maybe other colors as well.

Aircraft Spruce handles this but is limited in sizes.

Below is just one site that handles this product in multiple sizes but there are many if you do a search for this product.

http://www.newmotorcycleparts.com/fuel_system_parts/fuel_lines_and_fuel_filters.html

[Timberwolf]

War Eagle,

Just had a buddy make an emergency landing due to fuel in the cockpit. He had the blue poly hoses. They had literally just disintegrated and allowed fuel to spill all over the cabin. I wouldn't have believed it if I didn't see the plane in person. We use to use that fuel line on snowmobiles because it would remain very flexible in cold temps. The strangest thing is the hose was still flexible right around where they broke.

Either way with any fuel system, I don't believe it's bad practice to go through and replace all the hoses like that every few years. Cheap insurance

[kitfox5v]

Shane,
Sounds like ethanol my be the culprit to me. just a thought.

[War Eagle]

War Eagle,

Just had a buddy make an emergency landing due to fuel in the cockpit. He had the blue poly hoses. They had literally just disintegrated and allowed fuel to spill all over the cabin. I wouldn't have believed it if I didn't see the plane in person. We use to use that fuel line on snowmobiles because it would remain very flexible in cold temps. The strangest thing is the hose was still flexible right around where they broke.

Either way with any fuel system, I don't believe it's bad practice to go through and replace all the hoses like that every few years. Cheap insurance

That's correct. Polyurethane is just another option for fuel lines but you always need to use do diligence in managing your maintenance and replacement schedules.

[beeryboats]

I removed my poly header tank tonight and even though it was half full, no fuel came out when I removed all the lines. It has been setting for ten years and all the fittings were plugged solid. That made the tank removal very easy, but I was surprised how much the Mil-6000 hoses had degraded and came apart inside. So now after reading this thread, I don't know what hoses to buy as replacements.

[PropellerHead]

Slightly off topic now but it seems to me that, if you intend to run auto fuel then automotive fuel lines would be a good choice. I replaced my Mil-6000 hoses with automotive fuel lines when I started smelling fuel in the cabin about five years ago. I don't believe that my current problem is related to the fuel lines degrading but rather the fuel itself went bad. I'm personaly leaning towards an all metal solution now (except for those parts that need to flex for wing folding of course). I have no experience with metal fuel lines but it seems like it shouldn't be too difficult...

[Dave S]

PropellerHead,

Your idea is precisely what I followed....since autogas was my fuel of choice, hoses, etc seemed the best bet - afterall, cars have been using SAE hoses and autogas for a while - I never installed the milspec hoses.

If you are looking for some guidance on fabricating metal lines.....there is a huge library of on line videos on the EAA website titled "Tips for homebuilders" I believe metal tubing fabrication for fuel lines is out there. Lots of other good stuff too. :)

The biggest issues with metal fuel lines is bending, including the correct radius; and, most of all, forming the flanges for the 37 degree fittings - takes a bit of practice and a bad one can crack under the fitting. Practice makes perfect.

Sincerely,

Dave S
KF 7 Trigear
912ULS Warp Drive

[Danzer1]

Dave and Luis,

The biggest problem with all metal fuel lines is metal fatigue due to vibration. Do a search on "work hardening". Personally, I wouldn't do it. You really need flex points - particularly before of after bends, hard connections to different parts of the structure, before and after bulkhead through fittings (firewall) and connections to the biggest vibrator of all - the engine. Not to mention the additional fabrication work to make something that will eventually fail over time, if not totally isolated from all vibration.

Good Luck, Greg

[PropellerHead]

Hmm. Sounds like good reason to do the opposite and replace all my lines with automotive fuel line. Especially if it's something that has a high possibility of breaking early because I did it wrong.

[Danzer1]

I suppose you could, but then you need to be careful with attach points and thru bulkhead fittings (firewall) as the vibrations at those points can cause chafing and wear on non-metallic piping. There are good reasons for seeing both used on fuel systems of all machines, not just aircraft.

Greg