Replies to This Discussion

Permalink Reply by Bob Pustell on May 7, 2010 at 10:01am

If I read your description correctly, Jimmy, the RV10 builder used solid line all the way to the carburetor. Is that what you describe? In most installations there is flexible hose going from the firewall to the engine even if the rest of the plumbing is solid tube. That is a very vibration prone crossing, going from the fixed airframe to the vibrating engine. There should be flex lines crossing that area for all plumbing, with the possible exception of very small diameter tubes such as primer line or mechanical oil temp or oil pressure gage sensing line. Those should have a several turn spiral in them to absorb vibration if they are not flex line in the firewall to engine section.

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Permalink Reply by Mike Armstead on May 13, 2010 at 1:14pm

I purchased a new 601 from an insurance company that had been involved in a nose gear collapse on it's first flight. The fuel line was rubber with barb connectors and the oil lines were AN fittings and stainless braid. The rubber fuel line stretched about 5 inches and was very tight, but did not break or leak. Both the AN fittings broke in the center of the aluminum elbo. They did not stretch, they broke.

For some situations the rubber is better, others the AN hardware is better.

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Permalink Reply by Jonathan Porter on May 13, 2010 at 1:36pm

Interesting and useful. I have considered alu and steel lines, but I like the rubber lines, they seem to accept better the vibrations and, I like to change them every 5 years - it is a nice opportunity to look around and you do spot little leaks and insect nests that you might other wise miss.

I think that we should all have inspection covers that allow for change of the lines - regardless of the type installed - and that really is the bottom line. Install what you like - but do not be so short sighted as to imagine that you can avoid changing them or inspecting from time to time!!!

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Permalink Reply by Christopher Nail on August 27, 2010 at 1:41pm

So what hoses did y'all use? I've been looking at using a hose but I just cant decide between the Aeroquip 303/601/666. 303 is rubber lined, 601 is synthetic rubber (difference??), and 666 is the teflon. Price varies accordingly and I guess so does quality.

Price is a secondary concern; I am more concerned about lifetime and ease of adding the fittings.

Anyone want to go into detail on which ones they went with? Did anyone use hoses from the wing (I've got a 650, or at least parts of one) and then tubing to the firewall? It seems like anyone who's done this can just drag and drop what they did (lengths, #of fittings, etc) onto this page.

Thanks!

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Permalink Reply by Chris Aysen on August 30, 2010 at 7:14am

I had some fuel smell in the cabin until I installed some Parker "Stratoflex" I highly recommend it. All in all rubber tubing or some kind of flexible tubing would probably work best on the 912 series of engines. Periodic replacement is always a must you can't escape it. Solid lines have also work in aircraft and will continue to be used in certified aircraft. However, using it requires a well layed out schematic plan with vibration considerations at all times. Solid lines are usually run in solid lengthes up to connection points where flex hose is used to make the connection. A long solid run with a solid fitting splice in it is asking for trouble on a 912 series engine. I recommend flexible hose with firesleeve.

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Permalink Reply by Dale Medendorp on August 31, 2010 at 8:37pm

If I want to use AN fittings and Aluminum tubing, what adapter do I use at the finger screen on the outlet of the fuel tank (in place of the barbed fitting)?

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Permalink Reply by Chris Aysen on September 1, 2010 at 7:03am

Word search "AN Fittings" on the Aircraft Spruce home page you will see a selection of fittings. The screen fitting in the tank is 1/4" pipe (was on mine anyway) so you would need either a 4-4 fitting or a 6 fitting (choice of steel or aluminum) depending on the OD of the tubing you are using. Don't forget a shut off valve some where close in that area. Also use fairly thick grommets to run the tubing through the root rib if you have to go through the rib. I ran everything through a lightening hole.

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Permalink Reply by Dale Medendorp on September 1, 2010 at 3:32pm

That's what I thought I bought (1/4" NPT Pipe), but they don't fit. I guess I better look at this a little closer.

Thanks!

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Permalink Reply by Robert E Pickens on September 1, 2010 at 5:39pm

Dale, I think you would need to use an "AN816-4D" nipple which is a 1/4" NPT pipe thread on one end and a 1/4", 37 degree flared tubing on the other. Bob Pickens, Troy Mo.

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Permalink Reply by Robert E Pickens on September 1, 2010 at 10:42pm

correction, should be AN816-4-4D. Bob P.

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Permalink Reply by Jorge Fernandez on September 7, 2021 at 9:46am

Old thread but I can't decide between stainless steel or nylon braided PTFE fuel lines. Any opinions?

I was looking at these.

https://hotrodfuelhose.com/products/an6-ptfe-lined-nylon-braided-ho...

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Permalink Reply by John Austin on September 7, 2021 at 12:49pm

In the fuel lines you reference, there is no mention that they are carbon impregnated/electrically conductive.  In the picture on the website, the PTFE liner appears to be white, which means they are probably not conductive (conductive lines usually have a gray or black liner).  If the liner is conductive, it reduces the possibility of a static build-up and a spark. This is one area where you want the best quality available - period!

I'd recommend using braided stainless steel lines - almost indestructible and permanent. If you're going to fabricate them yourself (I did!), get some quality lines and fittings such as Earl's "Speed-

flex" at ANPlumbing.com or you can have them made-to-order by various vendors such as Aircraft Specialty.

John

N750A

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