[JDanno]

One thing that I've noticed is that there has been little to no discussion about using the correct teflon hose. For aircraft you really need to be using something like Aeroquip 666 or Stratoflex 124 as it is rated as "conductive". That means that carbon black has been added as a thin layer so that static type electricity won't buildup and cause minute arcing within the tubing which eventually results in the hose failing. It has to due with the electrons being stripped off as the fuel flows thru the hose and then being discharged similar to the way lightning is formed. It usually takes awhile for failure to occur but "racing hose" will eventually fail. I spent hours online reading about this. There is plenty of info in the literature that describes this if you Google for it. There's even transcripts from a law suit between Aeroquip and Stratoflex that says that this situation was well known as far back as 1960.
What's also scary is that there are companies touting their hoses as okay for aircraft that are NOT using conductive teflon hose. I know of one that even advertises here in this web site. 666 and 124 cost more but i guess there IS a good reason. No racing hose for me! All this talk of aircraft fires has me a bit spooked.
P.S., I had a fuel leak in a Twin Comanche while we were over the ocean and no good place to land for another three hours. Aluminum flare cracked.

 

[scsmith]

Interesting

Thanks for this.

"Racing Hose" is most commonly used for brake lines, where there is little or no actual fluid flow. But they probably do also use it for fuel lines?

Anyway, thanks.

 

[az_gila]

Another reason for using TSO hoses...

The FAA TSO points to a Mil-Spec for performance, and a conductivity test is required.

For us electrical guys, it's 6 microamps at 1000 volts for an 18 inch test sample hose - teflon high temp., medium pressure hose.

 

[Lars]

According to my Aeroquip "Performance Products" catalog, their "Teflon Racing Hose" is rated for offroad brake, transmission, clutch, gauge, nitrogen, power steering and hydraulic applications. All of their fuel-rated hose uses a synthetic rubber liner.

I've never seen fuel-rated teflon-lined hose on the automotive side, though I'm sure it gets used that way. Point being that if someone is using Aeroquip automotive teflon hose for fuel, then they are failing to follow manufacturer's recommendations, be it in a land-bound vehicle or an aircraft.

 

[JDanno]

You are absolutely correct. BUT, you have to be very careful when ordering so as to get the conductive. I'll bet that there are a lot of guys out there running around with non-conductive hose that don't know it.


"A tube of polytetrafluoroethylene and the like for conducting fluids under pressure and including means for discharge of internal static electricity to the ends of the tube and grounding the same from the tube interior at said ends in order to maintain the polytetrafluoroethylene tubing performance characteristics, said tubing having an integral polytetrafluoroethylene wall structure with an interior liner portion of a substantially annular conformation from end to end and having a uniform dispersion of electrically conductive particles embedded therein"

This may be more of a problem with jet fuels than avgas. Somebody with way more scientific knowledge of fuels can answer that.

 

[Lars]

I just rooted around in my automotive stuff. Looks like Earl's now sells a teflon-lined, stainless steel overbraid hose with carbon in the liner, rated for fuel. Summit has the -6 stuff for (gasp) $23.95 a foot in bulk. I think I'll stick with 666 or 124 premade hoses.

 

[JDanno]

l also found this:

An area of concern regarding fluids are fuels. Fuels are usually non-conductive, having an electrical resistivity as high as 108 ohms. Examples include gasoline and white spirits, hydrazine, benzene, diesel oil, etc. Generally these fluids are transferred at low velocities but the potential still exists for an electrostatic discharge due to external environmental factors such as humidity and sometimes temperature. Even at fluid velocities lower than 1 meter/second, all these factors should be considered.


I found aeroflex 666 for $8.78 for the -6 hose at:
http://www.aeroquip.cc/aeroquipaerospacemarinehose.aspx

 

[TS Flightlines]

aeroquip "automotive" hose

Aeroquip "performance" hose is NOT recommended for aircraft use. Quote right out of their Performance Products Catalog. Their "Racing Hose" is not conductive. Yes, 666, and 124 hose is expensive, as are the fittings. But, several manufacturers that are in the aerospace business do make a conductive teflon hose that is great. Parker, Titeflex, Teleflex, and Aeroquip, all make an industrial version that is conductive, and with applicable fittings and assembly works very well.

Tom

According to my Aeroquip "Performance Products" catalog, their "Teflon Racing Hose" is rated for offroad brake, transmission, clutch, gauge, nitrogen, power steering and hydraulic applications. All of their fuel-rated hose uses a synthetic rubber liner.

I've never seen fuel-rated teflon-lined hose on the automotive side, though I'm sure it gets used that way. Point being that if someone is using Aeroquip automotive teflon hose for fuel, then they are failing to follow manufacturer's recommendations, be in in a land-bound vehicle or an aircraft.

 

[Phil]

Parker, Titeflex, Teleflex, and Aeroquip, all make an industrial version that is conductive, and with applicable fittings and assembly works very well.

Tom, do you know if these are all milspec TSO'd hoses? Not trying to start a flame war, just trying to gather the information for future use.

Thanks,
Phil

 

[Lars]

Aeroquip "performance" hose is NOT recommended for aircraft use. Quote right out of their Performance Products Catalog. Their "Racing Hose" is not conductive. Yes, 666, and 124 hose is expensive, as are the fittings. But, several manufacturers that are in the aerospace business do make a conductive teflon hose that is great. Parker, Titeflex, Teleflex, and Aeroquip, all make an industrial version that is conductive, and with applicable fittings and assembly works very well.

Tom

Exactly my point, regardiing the Aeroquip product. You shouldn't even use it for fuel in automotive applications.

And in the case of the Earl's product I referenced above, it's more expensive than 666 or 124.

In perusing Bonaco's site (one of the hose vendors that advertises on this site) I noticed that they sell Teleflex hose. Though not mentioned by part number on the site, one of the options is conductive hose, likely 1170, which is similar to 1167 except for the conductive liner (see asterisked hoses in the table): http://www.bonacoinc.com/teflon_brake_lines.htm

How much money is saved by using industrial hose, which I would still want firesleeved, compared to the aviation counterparts?

 

[cln1owner]

Aeroquip Host on Vans Site

Anyone know what the Aeroquip hose on Vans site is? 666?

 

[TS Flightlines]

industrial hose

Industrial hose isn't TSO'd, but manufactured to a SAE spec; generally 100R14minimums. There are some differences in the bore sizes ( some make a "true bore" version), but generally all meet the same spec. Now Titeflex, (which is the hose that I use) is a very good product. Parker, Aeroquip, Teleflex, all make a good product, some maybe having a post-sintered conductive liner, where others may not. The .030 conductive lined hose works well for experimentals, with proper assembly and pressure testing to 3000psi.

The money saved is probably 1/2 the cost of TSO'd hoses, even with firesleeve. But, make sure that the liner is conductive, and the hose pressure tests. Even 666, and 124 hose will fail under the wrong conditions.
Tom

Exactly my point, regardiing the Aeroquip product. You shouldn't even use it for fuel in automotive applications.

And in the case of the Earl's product I referenced above, it's more expensive than 666 or 124.

In perusing Bonaco's site (one of the hose vendors that advertises on this site) I noticed that they sell Teleflex hose. Though not mentioned by part number on the site, one of the options is conductive hose, likely 1170, which is similar to 1167 except for the conductive liner (see asterisked hoses in the table): http://www.bonacoinc.com/teflon_brake_lines.htm

How much money is saved by using industrial hose, which I would still want firesleeved, compared to the aviation counterparts?

 

[TS Flightlines]

vans hose

I think it is Aeroquip AE701, which is a neoprene liner, unless Vans has changed things. By the pictures it is anyway. Some that Ive seen on older RV6's were AE701. Changed to teflon with firesleeve!
Tom

Anyone know what the Aeroquip hose on Vans site is? 666?

 

[TS Flightlines]

automotive use for teflon

There are actually alot of vehicles (cars, trucks, etc) that use steel braid teflon for fuel. All of the BIG 3 at some point use it. Some have now gone to a thermoplastic or nylon hose for fuel.
Tom

According to my Aeroquip "Performance Products" catalog, their "Teflon Racing Hose" is rated for offroad brake, transmission, clutch, gauge, nitrogen, power steering and hydraulic applications. All of their fuel-rated hose uses a synthetic rubber liner.

I've never seen fuel-rated teflon-lined hose on the automotive side, though I'm sure it gets used that way. Point being that if someone is using Aeroquip automotive teflon hose for fuel, then they are failing to follow manufacturer's recommendations, be it in a land-bound vehicle or an aircraft.

 

[Lars]

There are actually alot of vehicles (cars, trucks, etc) that use steel braid teflon for fuel. All of the BIG 3 at some point use it. Some have now gone to a thermoplastic or nylon hose for fuel.
Tom

I see now that my comment was ambiguous. I was thinking aftermarket. Now that you mention it I've seen plastic hose with st. steel overbraid on late model Fords, though I don't know what the liner was.

Any thoughts on teflon hose life?

 

[TS Flightlines]

hose life

Mfgs. say teflon has unlimited life. I do know that if it is subjected to heat, not fire, but heat in close proximety to it, the liner will begin to "stretch" and fail. In automotive, we see it in clutch hoses, and fuel hoses routed near exhaust, that are unprotected. Also, anything can rub the steel braid, and eventually break the wire strands, and reduce the working pressure at that area, until it eventually fails. But, like has been stated in this forum, if attention to detail and good practices are used, then there is no reason a teflon hose should not last for many years. But, if you plan on removing it and then reinstalling it after it has taken a "set", dont try to straighten it out, or you will fracture the liner and it will fail.




TE=Lars;432333]I see now that my comment was ambiguous. I was thinking aftermarket. Now that you mention it I've seen plastic hose with st. steel overbraid on late model Fords, though I don't know what the liner was.

Any thoughts on teflon hose life?[/QUOTE]

 

[az_gila]

Stratoflex 124(J)...

Tom, do you know if these are all milspec TSO'd hoses? Not trying to start a flame war, just trying to gather the information for future use.

Thanks,
Phil

...is made into TSO assemblies...

 

[hgerhardt]

Use this stuff

Here's a good conductive ptfe hose: Parker 919B. It's about $5.00/ft and outfits like Controlled Motion Solutions would be more than happy to swage fittings on for you. We use it work for PAO, which is a very light synthetic oil used in military jets for electronics cooling.

I've got non-conductive Parker 919 hose in my -6 for fuel and oil cooler lines, and have been happily using them for 345 hours or so. But after reading about static discharge destroying the hose from the inside, I'm going to replace them soon.

 

[TS Flightlines]

919B

Yes, the 919B is a great hose. All of the Aerospace hose--Aeroquip 666, AE246, Stratoflex 124, 170, etc are TSO'd, Mil-specd. The INDUSTRIAL versions of this hose are not, and differ slightly from their aviation brothers. Usually wall thickness, braid construction & post sintering. BUT---for experimentals use, they work just fine when prepared properly. Conductive hose a must!!!
Tom

Here's a good conductive ptfe hose: Parker 919B. It's about $5.00/ft and outfits like Controlled Motion Solutions would be more than happy to swage fittings on for you. We use it work for PAO, which is a very light synthetic oil used in military jets for electronics cooling.

I've got non-conductive Parker 919 hose in my -6 for fuel and oil cooler lines, and have been happily using them for 345 hours or so. But after reading about static discharge destroying the hose from the inside, I'm going to replace them soon.

 

[rv6ejguy]

It is amazing what you can learn here on VAF. When I read a few years back that a braided hose on Bud Warren's Chevy powered Wheeler had failed in the middle causing an inflight fire and total loss of the aircraft, I didn't see how that was possible- now maybe a possible explanation.

 

[Wayne Gillispie]

5052-O .035"

works fine aft of the firewall with good fabrication techniques, proper clamping and has over twice the fatique strength of 3003-O. It only cost $3.10/ft at AS.

 

[JDanno]

I had a couple of conversations with Bud about his Wheeler Express fire over the last two Oshkosh trips. He was using teflon SS braided hose for a FF fuel line. I didn't ask about whether it was conductive or not as I didn't know that it was an issue. The other possibility is that it might not have been suspended (attached) just right and the vibrations caused an eventual rupture. I've read where there have "been numerous cases" of auto fuel plumbing failing from this problem, usually in the aftermarket crowd doing nitrous. One possibility is a manufacturing defect. And I've seen some pix of alt. engine installations with the fuel line in long droopy unsupported loops between the firewall and the engine. Of course this is all conjecture as nobody knows for sure.
I'll admit I'm somewhat paranoid about fire and that had driven my research into designing a fuel system that minimizes this possibility for my alt. engine installation.
Remember "just because you are paranoid, that doesn't mean somebody isn't following you"!

 

[Lars]

works fine aft of the firewall with good fabrication techniques, proper clamping and has over twice the fatique strength of 3003-O. It only cost $3.10/ft at AS.

Not only that, but in my experience at least, the flares come out automagically looking better than those I've done in 3003

My motivation for participating in this discussion has to do with concerns about the substitution of industrial/automotive hose in aircraft applications, at locations where hoses would be used anyway; for example, firewall to fuel pump. Fuel-rated automotive/industrial hose is attractive because it's less expensive, but I don't need very many, and the money saved is a tiny fraction of the total build cost on my -7.

Lots of great information here!

 

[TS Flightlines]

good point

That is a good point, Lars. We all are spooked by fire, and inflight hose failures. I know of several. I also know of a plane that the builder used clear nylon hose for his cooler hoses. Yep, inflight failure. My point is to try to help guys be safe. The aviation hose market started through the industrial suppliers that saw a need and fulfilled it.
Aeroquip, Stratoflex (Parker), Titeflex (Smiths), Teleflex all make an awesome product, for both aviation and industrial. All adhere to both the SAE specs, and the Mil-Spec/NAS specs. Like I said in an earlier thread, there are differences. Conductive is a must in aircraft. Post-sintered is great. .040 wall is awesome. But, I will say that properly prepared industrial conductive teflon hose is quite sufficient.
Yes, 666, and 124 is the ultimate for our purposes here. Hose isnt that expensive, but the fittings (almost always in CRES) can get expensive, especially if you need to put 45* or 90* hose ends on your assembly. And "most" automotive and industrial teflon hose applications are not for "conductive" operations. But, knowing the product and its parameters, will allow guys to make a decision on what they want. I do know that some go their local parts store, because they make "hydraulic hoses". In most cases, probably a bad choice.
My point is to be safe.

Not only that, but in my experience at least, the flares come out automagically looking better than those I've done in 3003

My motivation for participating in this discussion has to do with concerns about the substitution of industrial/automotive hose in aircraft applications, at locations where hoses would be used anyway; for example, firewall to fuel pump. Fuel-rated automotive/industrial hose is attractive because it's less expensive, but I don't need very many, and the money saved is a tiny fraction of the total build cost on my -7.

Lots of great information here!

 

[vjdslk]

Aeroquip AQP

I'm trying to get a full understanding of the issue. Is it only the teflon lined hoses that have the static issues or is it all lines that don't have carbon black lining?

I have used the Aeroquip AQP hose for years in my race car and now on the plane. It is not teflon lined, it is recommended by Aeroquip for fuels, oils, etc. though they don't specifically recommend it for aircraft. Here are the specs.

Manufacturer's Part Number FCA0620
Part Type Hoses, Miscellaneous
Product Line Aeroquip AQP Stainless Steel Braided Hose
Summit Racing Part Number AER-FCA0620

Hose Size -6 AN
Hose Length (ft) 20 ft.
Teflon? Lined No
Outer Material Braided stainless steel
Hose Color Natural
Hose Inside Diameter (in) 0.343 in.
Hose Outside Diameter (in) 0.550 in.
Maximum Operating Pressure (psi) 1,000 psi
Quantity Sold individually.
Notes Only rated for 750 psi with lightweight crimp fittings.

Any definitive answers one way or the other?

Thanks!

Jon Dembs

 

[TS Flightlines]

aqp

Jon, Aqp is a neoprene/nitril hose, similiar to the AE601/701 certified hose. "Rubber" hoses dont have the static problem like teflon. The 'non conductive teflon-the 'white liner'- picks up static electricity of the fluid as it moves through the liner. Without disappation, the electrons (?) try to seek a ground, and seeks the steel braid. The conductive hose --the black liner--doesnt have this issue. The manufacturers discovered this probably 60 years ago. Some may remember the "sprinkler hose". The conductive hose was devleloped to solve this issue.
The aqp that you buy from Summit, Jegs, or any other "racer hose" source isnt flight rated, even though alot of guys use it. Also, some of the "imported" hose isnt exactly the same liner material as advertised by the larger manufacturers, and may not have the life expectancy. Even Earls has a disclaimer about their Performoflex hose---fuel additives may or may not attack the liner. I will say that several years ago, The Rousch racin gcup cars had an issue with hosein thier fuel systems. I dont know all of the details, but they were on the ground and not flying. Earl's says they if there is a question, use teflon. Just use the right teflon --the conductive liner.

Tom

I'm trying to get a full understanding of the issue. Is it only the teflon lined hoses that have the static issues or is it all lines that don't have carbon black lining?

I have used the Aeroquip AQP hose for years in my race car and now on the plane. It is not teflon lined, it is recommended by Aeroquip for fuels, oils, etc. though they don't specifically recommend it for aircraft. Here are the specs.

Manufacturer's Part Number FCA0620
Part Type Hoses, Miscellaneous
Product Line Aeroquip AQP Stainless Steel Braided Hose
Summit Racing Part Number AER-FCA0620

Hose Size -6 AN
Hose Length (ft) 20 ft.
Teflon? Lined No
Outer Material Braided stainless steel
Hose Color Natural
Hose Inside Diameter (in) 0.343 in.
Hose Outside Diameter (in) 0.550 in.
Maximum Operating Pressure (psi) 1,000 psi
Quantity Sold individually.
Notes Only rated for 750 psi with lightweight crimp fittings.

Any definitive answers one way or the other?

Thanks!

Jon Dembs

 

[Lars]

yet more AQP

I've used a lot of Aeroquip AQP hose with cloth braid on my truck (an old Bronco, yet another frightfully expensive hobby). It has a finite life, at least when carrying automotive fuel. As an example, I recently removed a length that had been in service for about 5 years, probably 25,000 miles worth of fuel (I don't drive it that much). It was stiff as a board. That piece was in a cool area of the chassis. That was a typical experience for me. I replace it regularly.

 

[TS Flightlines]

more AQP

AQP, like any other hose (teflon included) will "take a set" after some usage. Even Aeroquip 303 hose will. Thats why you should inspect it every chance you get. If it wont flex, pay attention to it. Might look great from the outside, but inside the liner may become erroded, and eventually fail. Even on cars, truck, buses, boats, cruise ships, and yes the Space Shuttle. But, using a good product will obviously help.
Tom

I've used a lot of Aeroquip AQP hose with cloth braid on my truck (an old Bronco, yet another frightfully expensive hobby). It has a finite life, at least when carrying automotive fuel. As an example, I recently removed a length of that had been in service for about 5 years, probably 25,000 miles worth of fuel (I don't drive it that much). It was stiff as a board. That piece was in a cool area of the chassis. That was a typical experience for me. I replace it regularly.

 

[frankh]

Sorry i don't buy it

While you maybe correct in that static charge will build up and over time fail..How long are we talking about here?

I work in an industry that pumps flammable liquids through Teflon hoses that are certainly not listed as conductive.

Has there been documented cases of hoes made in teflon hoses by arching through to the outside?

Not saying its not true but arching usually takes thousands of volts..Does that kind of charge really build up in a 2 foot long fuel hose?

What about oil hoses where the flowrate is much higher and constant..Do they fail??

I'm seriously skeptical on this one..

Frank

 

[TS Flightlines]

Is your pumping operation on the ground or airbourne? I'd guess that its on the ground. Talk to your A&P, DAR, or better yet talk to people in the aircraft hose industry and ask them about the history of teflon hose. They will tell you that the conductive liner was developed because unlike cars, trucks, industrial equipment, race cars, etc, airplanes are generally not on the ground. The teflon hose developed pinholes from the static charge seeking a ground. After the carbon liner was developed, (the carbon allows the charge --however small-- to disapate through the fittings and not through the liner to the steel braid), the problem went away until guys tried to use non-conductive liners in aircraft. That is why there is a mil spec (H25579)for the teflon hoses on aircraft.

Talk to the aerospace people at Aeroquip, Stratoflex, Smiths (Titeflex), Teleflex Aero Hose------I'm sure that they can explain it better that I can.
Just trying to help!
Tom

While you maybe correct in that static charge will build up and over time fail..How long are we talking about here?

I work in an industry that pumps flammable liquids through Teflon hoses that are certainly not listed as conductive.

Has there been documented cases of hoes made in teflon hoses by arching through to the outside?

Not saying its not true but arching usually takes thousands of volts..Does that kind of charge really build up in a 2 foot long fuel hose?

What about oil hoses where the flowrate is much higher and constant..Do they fail??

I'm seriously skeptical on this one..

Frank