LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
I've decided to make my own fluid hoses to get a better fit and have more
options than ordering the stock hoses Van's sells (which usually don't fit right
for me) or spend the $ on custom hoses that aren't returnable.

This is an area I don't to scrimp. What is absolutely THE best fluid hose?
 
hose knows?

not to hijack this inquiry, but I also want to know if something like a manifold pressure line must be built with threaded fittings and braided hose, or are typical 'soft' rubber hose and barb fittings ok?

thx
 
Bob Collins said:
I've decided to make my own fluid hoses to get a better fit and have more
options than ordering the stock hoses Van's sells (which usually don't fit right
for me) or spend the $ on custom hoses that aren't returnable.

This is an area I don't to scrimp. What is absolutely THE best fluid hose?
Click to expand...

Bob,

*The* best is pretty hard to quantify. Personally, I've been very satisified with the hoses I made up from steel braded teflon hose and ends from Summit Racing. They didn't require special tools, and pressure tested to several times the normal range for Lycomings. The hoses spec'd at much higher pressures than I tested at.

You might check the RV list archives for some of my old posts on the subject or for some posts from Mark Friedricks, who posted under "[email protected]" in that forum, back in the day...
 
I like the steel braided teflon hoses (I can't remember the code). If you make your own, it would be wise to either set up your own pressure tester or take them somewhere where they can be tested. Just a little extra cheap insurance. I might also recommend steel fittings firewall forward.

On my Rocket, I went ahead and paid the price for professional built hoses. We lost a Rocket here due to a homemade oil cooler hose fitting failure.
 
flyboy1963 said:
not to hijack this inquiry, but I also want to know if something like a manifold pressure line must be built with threaded fittings and braided hose, or are typical 'soft' rubber hose and barb fittings ok?
Click to expand...

I can see no reason that you couldn't use a hose barb fitting, clamps and suitable hose for a manifold pressure sense line.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully
helpful to you. Please use the information provided responsibly and at your own
risk."
 
best hoses

Steel braid teflon hoses are the obvious best choice. Aerospace teflon hose and fittings can get expensive, but "good quality" industrial teflon from a known supplier works very well. Use the conductive (black liner) with properly installed fittings. I crimp all of my assemblies, and test them to 3000 psi. Reusable ends are fine, if properly installed. I'd be cautious of the "look alike" 701 (rubber) hose. Firewall forward assemblies get firesleeve, no matter if it is oil, or fuel. If you were to have a fire or a heat related problem, the teflon liner would begin to melt and fail. Firesleeveing can get alittle pricey, but well worth the insurance. Don't use a "push lock" barbed hose fitting for anything under pressure. Yes, there have been several in-flight failures, like the one that Randy is refering to. You have a big investment in your RV--don"t chance it.
Tom




UOTE=mahlon_r;430204]I can see no reason that you couldn't use a hose barb fitting, clamps and suitable hose for a manifold pressure sense line.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully
helpful to you. Please use the information provided responsibly and at your own
risk."[/QUOTE]
 
Also be very careful if you are running the Christen (or Raven) inverted systems that employ "suction" hosees feeding the oil pump. I had a brand new hose collapse on my initial flight home with a new airplane. It took me forever to finally figure out that the inner liner had sucked (mostly) closed.
 
hose

What hose were you using that collapsed?
Tom

Toobuilder said:
Also be very careful if you are running the Christen (or Raven) inverted systems that employ "suction" hosees feeding the oil pump. I had a brand new hose collapse on my initial flight home with a new airplane. It took me forever to finally figure out that the inner liner had sucked (mostly) closed.
Click to expand...
 
I agree, since the same guy made the hose that was on it for many years prior. The "original" hose was slightly chaffed, so it was replaced at annual. The "new" hose failed after about 2 hrs into the flight home. I still have it around so I'll see if I can post a picture. It looks like a clogged artery.
 
This thread got hijacked so I've waited a few months to revisit it and now I'm ready to order the hoses. Am I correct, then, that everyone agrees a steel braided Teflon hose is the way to go? Because there were two different conversations going on here, it's difficult to know whether the recommendation to test to 3,000 psi was referring to the fuel line hoses.

I ask b/c the Aeroquip 666 hose, which seems to be the only Teflon steel hose I can find on Aircraft Spruce, has a max psi of 1,500.

Any guidance here would be appreciated. I've read Bingelis' thoughts on the subject but he mostly relates to the 301 hoses.
 
Bob,

I know this isn't a direct answer to your question, but here's my personal experience. I, like you, wanted to get an exact fit, learn how to make hoses, and save some money. I went with Aeroquip fittings, 601 hose and firesleeve from Spruce. The process was easy, but there was a bit of waste due to the learning curve. When done, the fit was spot on. I then read on here about how to pressure test them with a grease gun. I proceeded to throw away a bit of money and a lot of time trying to make this work. After MUCH frustration I found a hydraulics place to test them for me while I waited. This cost a whopping $20. Shoulda gone that route from the start.

Now having said all that, if I did it again I would probably just buy the premade stuff with the integral firesleeve. It looks way nicer and lasts a real long time. It does cost more, but it is way nicer stuff. As for the fit, go to Home Depot and buy a few feet of vinyl tubing and mock up the hoses until they're perfect.
 
Bob Collins said:
I ask b/c the Aeroquip 666 hose, which seems to be the only Teflon steel hose I can find on Aircraft Spruce, has a max psi of 1,500.

Any guidance here would be appreciated. I've read Bingelis' thoughts on the subject but he mostly relates to the 301 hoses.
Click to expand...

Think about this Bob - your fuel lines will see maybe 50 psi at a maximum (if you are fuel injected). Oil lines will see maybe 100 psi on a very cold day of the oil pump runs away and is very well built. DO you think that a safety factor of 15 is good enough? Your wing spas are good to 6 G's with a safety factor of 1.5. I think folks can get a little carried away with "I have to have the best available, no matter what". "Better" is frequently the enemy of "good", and projects stall when folks can't decide if they should exceed the requirements by an excessive amount or a ludicrously excessive amount...;)

Aerospace works because we have learned how to build light and not overbuild. Personally, I am probably going to go with -701 from Aeroquip for my oil lines, an industry standard that works pretty well. I haven't picked fuel lines yet, we'll see when I am ready to make them. The Van's hoses in the val came in the FWF kit and are -701. No problems there, and I'll replace them when they reach a reasonable age.

(There is nothing WRONG with going more expensive than you need of course, if cost is not an issue.)

Paul
 
Ironflight said:
Think about this Bob - your fuel lines will see maybe 50 psi at a maximum (if you are fuel injected). Oil lines will see maybe 100 psi on a very cold day of the oil pump runs away and is very well built. DO you think that a safety factor of 15 is good enough?
Click to expand...

Right. I get that. But the reason I noted the psi is because upstream someone wrote the hoses should be tested to 3,000 psi so I wondered if I was looking at the wrong hose type to accomplish that, since the hose I was looking at topped at 1,500.
 
I agree with Paul on maybe getting a little carried away with the 'best'. The teflon hoses are said to last practically forever. The rubber and synthetic rubber hoses work just fine, are rated to 1500psi with their appropriate fittings, and are less expensive than teflon, but should be replaced after a few years - like five years depending on condition. Building teflon hoses is a little more difficult in my opinion than standard hose ends on rubber/synthetic hoses because you deal with the teflon liner in a different way. Care should also be exercised if you remove and then reinstall a teflon hose. Teflon tends to take a shape after heating and are pretty stiff at that point. When reinstalling, if not put back in the same orientation, they can be damaged if bent the wrong way. I've purchased Aeroquip hose at a local speed shop and perform-o-flex hose and hose ends from Earl's. These hose/hose ends are steel braided, flexible, very easy to assemble, and are rated for 1500 psi - 10 times over what they'll likely ever see. Fire sleeve is available at both of those places too and should be used. I had mine pressure tested on my first airplane, but after making a few and seeing how easy they go together, I'm not sure it's necessary. I also wonder about testing a 1500 psi hose assembly (or 2000 psi in the case of a teflon assembly), to 3000 psi. If it didn't blow apart - that's good I guess, but I wonder if it could have been damaged or stressed under a pressure that is way over anything it was designed to take??? Did this test have negative effect on it's ability to perform after the test? Personally, I'll use steel braided synthetic rubber hoses, and replace the hoses after about five years. The hose ends can be reused if not damaged during assembly or installation.
 
testing to 3000psi

I get asked about this quite a bit. Pressure testing to 3000 psi is basically 2 times the rated working pressure of teflon hoses. Yes, it is probably way overkill (pressure wise) for fuel and oil systems. Teflon has its place in the experimental aircraft industry. But, it is not easy to assemble, unless you are using reusable fittings. Crimped fittings are less expensive, but need to have an accurate hose crimper to do a proper job. And, just because you may use reusable fittings on teflon hose or 701 hose, pressure testing should be done. What you choose as that test pressure is up to you. Leak testing at 150 psi with your shop air compressor is inexpensive insurance.
By comparison, 303 or 111 hose is rated at 3000 working pressure, so 2 times is 6000psi for pressure testing. So, you can see where some of this comes from. Just because that mainly applies to hydraulic applications, may not matter.
And, pressure testing to 2 times the rated working pressure of the hose doesnt damage the hose.
Tom
 
Permanent never lasts forever...

I Notice over the years that 'PERMANENT' new products - like teflon hose - are only permanent until problems start to show up.
I doubt teflon hoses are going to last forever. I don't mean this disrespectfully, just, how long would you trust a dirty hard old fuel or oil hose near the exhaust pipe?
So maybe it's a 10 year hose instead of a 5 year hose. That's still really good.
I'm with Scott Hersha, I use speed shop hose and fittings; Earl's and Russell, I also use their stainless steel braided Proflex hose. However, I don't trust the aluminum long sweep swivel tube end fittings smaller than -6. They failed my "Abuse test'.
 
Last edited:
ANPlumbing.com

All the fittings and teflon hose can be bought at: www.anplumbing.com

They also have Tech Help videos that guide you through the fabrication process. I tested mine to 1000 psi. Easy to make the fit perfect.
 
I Notice over the years that 'PERMANENT' new products - like teflon hose - are only permanent until problems start to show up.
Click to expand...
I've seen 3 teflon hoses go bad so far. All fuel lines. I don't know why, but when they go, they weep fuel all through the braid. Not saying they're bad hoses, just that I've seen them fail also.
 
conductive hose?

Was this conductive teflon?
Tom




aerhed said:
I've seen 3 teflon hoses go bad so far. All fuel lines. I don't know why, but when they go, they weep fuel all through the braid. Not saying they're bad hoses, just that I've seen them fail also.
Click to expand...
 
Pressure Testing Hose Assemblies

Be very careful pressure testing hose assemblies at high pressure, it is possible to damage the hose assembly if the test pressure is too high. Consult the manufacturer's data sheets which will show the maximum working pressure, the proof pressure and the minimum burst pressure. Parker Stratoflex hose assembly instruction say to pressure test to proof pressure after assembly.
Here are some numbers for 111 medium pressure rubber hose general purpose
Size------Work Press.-----Proof Press.-----Burst Press.
111-3-----3000-----------6000------------12000
111-6-----2000-----------4500------------9000
111-12----1500-----------3000------------6000

And some numbers for 124 teflon hose general purpose
Size------Work Press.--Burst Press.@70degF--Burst Press.@450degF
124-3----1500---------12000----------------7500
124-6----1500---------9000-----------------6500
124-12---1000---------5000-----------------3500
And the assembly instructions say proof pressure as 2x rated working pressure.

This source, which references AC43.13 among others:
http://aviationinspection.com/syste...exible-hose-assemblies-maintenance-practices/

says "Hoses should be hydraulic pressure tested at 1.5 times the maximum system pressure without leakage."

That is if a fuel system maximum pressure is 50 psi then (50 x 1.5=) 75 psi is adequate for a pressure test.
 
I tested my Teflon lined (Aeroquip conductive Teflon) hoses to their proof pressure (3000 psi). I did this by using a hand operated hydraulic pump and some hydraulic fittings. Total cost was less than $50.
 
AN vs. JIC fittings

I recently ran across the following:

"What is the difference between aircraft AN and JIC fittings?

One of these fittings is 40% weaker than the other, can you tell which one it is?

"AN flare and 37 degree industrial flare fittings appear to be functionally interchangeable, but they are not" (quote from Parker Aerospace Fitting Solutions Series No.11 )
The most notable difference is in the threads. AN fittings use a increased root radius thread ("J" thread) and a tighter tolerance (Class 3) to achieve a 40% increase in fatigue strength and 10% increase in shear strength.
These two fittings function the same, they look the same, AND the industrial version is much less expensive to manufacturer. The problem is that the industrial version is 40% weaker.
There is a an Airworthiness Directive (90-04-06) involving breaking of the aluminum propeller governor fitting on Lycoming engines. The aluminum AN fitting was used successfully for decades before they started breaking. The justice department brought charges against a company that was selling these fittings as AN when they were in fact industrial. Sometimes the higher strength serves an important purpose."

For the full article see http://weislake.com/sig/mucker/an-vs-jic.pdf

In discussions of hoses and fittings it is sometimes recommended to source these from various racing and industrial suppliers - bu if these are JIC, then are we getting what we think we are? And what we should be using?
What I imagine to be pretty straightforward things on this project - like screwing a fluid fitting into the engine - really isn't. Aluminum or steel, AN or JIC, torque, conductive....

Bill Brooks
Ottawa, Canada
RV-6A finishing
 
Interesting

I have used a few JIC fittings, but these are all steel (FWF). I understand that that from a strength perspective I could use the aluminum AN fittings, but I now I wonder if the added strength the steel brings overcomes the weakness in the fitting type (JIC vs AN).

Anybody know?
 
I hope this offers some clarity?

SMO said:
I have used a few JIC fittings, but these are all steel (FWF). I understand that that from a strength perspective I could use the aluminum AN fittings, but I now I wonder if the added strength the steel brings overcomes the weakness in the fitting type (JIC vs AN).

Anybody know?
Click to expand...

If they are steel and you are installing them on an experimental aircraft such as an RV or similar, I would not worry about the fittings at all, as long as everything is torqued properly.

Be clear I am only talking about the fittings that are NOT hose ends!

I have noticed that most factory Lycoming's use at least some fittings that seam very much like Parker commercial fittings. In these cases it is the entire installation that is approved by the FAA, and that includes the fittings that come with the engine.

We sell a variety of Parker fittings in steel as "Test Fittings" We list them that way, as it is the buyers responsibility to assure there suitability for the intended purpose.

http://www.gen-aircraft-hardware.com/amelia/details.asp?store=&id=517&TName_HID=subcat

I hope this offers some clarity.:rolleyes:
 
I bought fittings, Aeroquip 701, and the assembly tool from Van's. So far very pleased with the results. Now have to figure out how to pressure test. Building RVs is still a blast.
 
Interesting

A number of my RV friends and myself have used Hyrdaulics shoppe industrial teflon hose firwall forward with steel fittings. I did not have to use any such fuel lines but all my oil lines are made this way.


Interesting that it was an Aeroquip hose that collapsed on the suction side of the pump.

Frank
 
To make a pressure test set up, just get two plugs of the appropriate size to plug the hose.
In one, drill and tap for a tire valve stem, or use an AN nipple and what ever adapters you want in order to get a valve stem installed on one end of the hose. (Doing it this way, you can change the nipple and use the set up for different size hoses.) You can get fancy and add a gage and valve, but basically, you can just use your compressor to pump in whatever air pressure you want to test to.
Dunk the hose in water or use soapy water to test for any leaks.
Works fine for the pressures our shop compressors put out.
As Terrye stated, using the rule spelled out by AC43.13-1B, you don't need exotic amounts of pressure to test your hoses.
Good luck.
 
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