Braided Fuel and Oil Lines

[airhound]

AS Flightlines, 

Hi, I enjoyed your RV12 kits. Have you produced a fuel line kit for a FD CTLSI yet?

[Roger Lee]

8 hours ago, Madhatter said:

Roger

No certified aircraft use the rubber hoses we use on lsa or experimental. Even low pressure approved rubber hoses are not used. I don't even use them on j3's or Aeronca's. We don't use barb fittings for fuel, ever, maybe on a Wright Flyer

You said it. No Certified. We aren't certified and neither are tens of thousands of other aircraft in the world that use rubber hoses. Plus you're comparing the US to other countries in the world that use rubber hose. Everyone should stop comparing our engines and aircraft to certified, Continental and Lycoming. We aren't them. Aircraft has been using rubber hoses since the begining of flying and they still are today. Plus you would have to include coolant, fuel and oil rubber hoses to your argument.

No What? They aren't falling out of the sky just because they use rubber hoses.

[Madhatter]

There are good reasons not to use rubber hose with barbed fittings. I'm not against good quality rubber hose, my main issue for my engine is to be able to use AN fittings and get rid of banjo fittings. Teflon hoses just happen to be available for the 912. I have been doing this for 50 yrs and have seen terrible accidents with fuel issues. Some time back a Cessna 310 went down in flames and the suspected cause was 306 rubber hose failure in the engine compartment for the fuel pressure guage. I changed mine to teflon in my 310. I have been working with certified stuff for a long time and there are good reasons for it. This is what I am comfortable with and as an aeronautical engineer it is hard for me change. What you consider acceptable is fine, but I live in a different world of aircraft maintenance than most lsa individuals. I know there are others on this forum that understand what I talking about.

 

[AS Flightlines]

On 10/25/2022 at 5:26 PM, airhound said:

AS Flightlines, 

Hi, I enjoyed your RV12 kits. Have you produced a fuel line kit for a FD CTLSI yet?

We don't have any specific kits for the Flight Designs aircraft...but we have plumbed hundreds of 912 engines.  It is no issue at all to do a custom package for anyone who wants one.

 

Steve

[AS Flightlines]

On 10/25/2022 at 5:27 PM, Roger Lee said:

You said it. No Certified. We aren't certified and neither are tens of thousands of other aircraft in the world that use rubber hoses. Plus you're comparing the US to other countries in the world that use rubber hose. Everyone should stop comparing our engines and aircraft to certified, Continental and Lycoming. We aren't them. Aircraft has been using rubber hoses since the begining of flying and they still are today. Plus you would have to include coolant, fuel and oil rubber hoses to your argument.

No What? They aren't falling out of the sky just because they use rubber hoses.

Respectfully, this mindset isn't prevalent in the experimental world either.

The largest and most successful experimental aircraft manufacturer in the world moved over to Teflon hoses years ago.  The truth is that it is safer, stronger and lasts much longer than rubber.   Rotax uses Teflon as standard on their new engines.

I've seen garden hose being utilized as an oil line on an experimental aircraft (I kid you not)..... it didn't turn out very well.  I have also seen rubber hose failures in a variety of forms that are an unacceptable risk in my opinion.  Each builder/owner needs to do their own analysis on this.

There are very real monetary costs associated with having to change out rubber hose assemblies on a "regular" basis.  There are also very real safety implications for using inadequate materials in an aircraft.  An experimental aircraft doesn't know that it is experimental.  As such, I personally won't use anything that is of inferior quality in order to save a few dollars.  If you utilize hardware store bolts to hold on the wings, you can't expect the same level of performance as a true AN bolt. 

With this in mind.... I am fully in agreement that you don't need to utilize "certified" priced hoses in experimental aircraft.  However, I also wouldn't skimp on quality just because it is allowed.  There is a middle ground between treating an aircraft like a John Deere Tractor and paying thousands of dollars for what should be a $200 part.  This is the beauty of the experimental aircraft sandbox so many like to play in.

 

[Towner]

I’m pretty ignorant to this stuff, but you have my attention. Is there a life limit to the Teflon hoses? Everyone is mentioning “expensive “, but any idea how much extra I’d be spending to swap to Teflon vs a regular hose change? 

[AS Flightlines]

17 minutes ago, Towner said:

I’m pretty ignorant to this stuff, but you have my attention. Is there a life limit to the Teflon hoses? Everyone is mentioning “expensive “, but any idea how much extra I’d be spending to swap to Teflon vs a regular hose change? 

There is no defined lift limit on Teflon hoses.  We have a 10 year warranty on all assemblies that we sell.  They are "on condition" replacement.  However, engine overhaul is always a good time to refresh everything.

Most of the 912 installations that we do are $1,000 or less for the fuel hose portion of the setup.  This is assuming a standard hose from the gascolator to the mechanical fuel  pump, hose from mechanical fuel pump to rotax fuel block and hoses from the rotax fuel block to each carb.  Additionally, this includes a fuel return hose and a fuel pressure hose.  This is what we would consider a "standard" Rotax 912 ULS setup.  Also, most are choosing to utilize the premium integral firesleeve hose which is included in the cost above.

Each engine is a case by case basis.....you can also go to a standard firesleeve which is still very nice and will save about $150 over the premium integral hose.

Depending on the vintage of the engine, some hoses may already be teflon from Rotax and don't require replacement.  Some installs don't have a fuel pressure gauge.  This can all help lower the cost.

Steve

 

P.S. The most expensive Rotax engine fuel setup we have done was around $1700 but that one had bypass valves and tees and y connections and inline filters and all sorts of things we rarely see on the 912 engines FWF.  It was actually a ridiculously complex setup.  I believe it was somewhere around 14 hoses.

 

 

[Madhatter]

I purchased my hoses from Aircraft Specialties which I had mentioned earlier.  They made it easy to order and I no longer have to change them on the 5 year rubber change. The AN fittings are much better especially on the carbs. 

[AS Flightlines]

12 minutes ago, Madhatter said:

I purchased my hoses from Aircraft Specialties which I had mentioned earlier.  They made it easy to order and I no longer have to change them on the 5 year rubber change. The AN fittings are much better especially on the carbs. 

We are in the process of rebranding everything to Aircraft Specialty Flightlines.  http://www.asflightlines.com or http://www.aircraftspecialty.com

Also... we are working on a Rotax 912 specific section that will detail the systems and make custom ordering of hoses specifically for the 912 configurations extremely easy, including directions for how to measure for a variety of configurations we have seen.  But for now, reach out to us and we will be happy to work with 912 owners on custom setups for their aircraft.

 

Steve

[airhound]

4 hours ago, Madhatter said:

I purchased my hoses from Aircraft Specialties which I had mentioned earlier.  They made it easy to order and I no longer have to change them on the 5 year rubber change. The AN fittings are much better especially on the carbs. 

Hi Madhatter, 

Do you know if an MRA is required to put AS gas hoses and fittings on a CTLSI?

[Jim Meade]

10 hours ago, AS Flightlines said:

There is a middle ground between treating an aircraft like a John Deere Tractor and paying thousands of dollars for what should be a $200 part.  This is the beauty of the experimental aircraft sandbox so many like to play in.

 

I don't follow you here.  These days, John Deere tractors are for the most part programmed so that the owner can do very little maintenance.  That's the subject of a suit that I think is being considered by the Supreme Court.  I am sure it is being discussed in Congress.  You are required to use a John Deere dealer and the shop rate on our local dealer is $120/hour.  Parts make aircraft prices look tame.  Oh.  Maybe you're talking about the old 2-cylinder classics?  Those prices are high, too.  Anyway, I am confused about what your message is.

[FlyingMonkey]

Madhatter, thanks for the heads up.  I called Steve at Aircraft Specialty and we had a very detailed conversation.  It looks like I’ll be going in this direction.  Steve confirmed that the conductive teflon in these hoses has no defined life limit.  He guessed maybe 20-30 years, essentially a lifetime hose for most of us.  The cost blew me away…my CT is pretty simple, and he quoted $2000-2500 for all oil & fuel lines, fittings, and integrated firesleeve.  That to me is a great deal, less than a single hose change if you pay somebody.

[AS Flightlines]

29 minutes ago, Jim Meade said:

I don't follow you here.  These days, John Deere tractors are for the most part programmed so that the owner can do very little maintenance.  That's the subject of a suit that I think is being considered by the Supreme Court.  I am sure it is being discussed in Congress.  You are required to use a John Deere dealer and the shop rate on our local dealer is $120/hour.  Parts make aircraft priceslook tame.  Oh.  Maybe you're talking about the old 2-cylinder classics?  Those prices are high, too.  Anyway, I am confused about what your message is.

Definitely referring the the old days.....  rubber hoses....paper filters.  Great on my garden tractor..... not on my airplane.

[Madhatter]

2 hours ago, airhound said:

Hi Madhatter, 

Do you know if an MRA is required to put AS gas hoses and fittings on a CTLSI?

I am ELSA

[Roger Lee]

A different analogy and logical comparison,

I'm not saying Teflon isn't better, it's just too costly. Just like when I used to Mfg diving compressors. One guy ask why not build them out of stainless steel. I said it was possible, but he didn't have enough money to afford it. You'd probably have gone from a $2400 setup to $15K. Would it have been better around salt water...sure, but at what cost.

Quote:

"Rotax uses Teflon as standard on their new engines."..........  For fuel only.

"Most of the 912 installations that we do are $1,000 or less for the fuel hose portion of the setup."

They have been using rubber hoses on millions of aircraft around the world since long before most of us were born and still do.

I pay $1.10 per foot for 5/16" and 1/4" Gates Barricade hose which Rotax used for a a long time and there weren't any issues provided an owner didn't screw it up. At maybe 15' of rubber hose for a rubber fuel line hose replacement then that's $16.50 for one fuel hose change which is a lot cheaper than $1000. If we're talking only fuel hoses you need to consider the instrument panel hoses and even with that I can change all the fuel hoses in about 1.5 hrs. Plus that  means I can purchase 60 hose changes for the fuel alone for vs $1000 for Teflon. You guys offered me fuel hoses a long time ago for $575 and that didn't include behind the instrument panel. If they are that much better and someone is worried about a rubber hose failure then you'd really need to replace all rubber hoses anywhere on the plane because thinking rubber is so inferior then you'd would need to get rid of all rubber fuel hose in an aircraft. This analogy means the fuel system is only as strong as its weakest link and if all you did was the engine compartment then there are lots of weak links with the rubber past where the Teflon ends. 

You still have to do the 5 year rubber change for the coolant and oil hoses plus all other rubber parts. So bottom line you still have to do the 5 year rubber change and you would only remove the fuel hoses at $16.50 and 1.5 hrs. of labor vs $1000+. This doesn't sound like a good trade off. 

 

If you want Teflon then go for it, but weigh the pros and cons first.

[Madhatter]

My engine had the old hard stainless carb lines on it so teflon was worth it.

In 50 years I have never see automotive fuel line on any aircraft except for a few experimental and lately LSA. Most used aeroquip 303 prior to teflon.

[Roger Lee]

18 minutes ago, Madhatter said:

My engine had the old hard stainless carb lines on it so teflon was worth it.

In 50 years I have never see automotive fuel line on any aircraft except for a few experimental and lately LSA. Most used aeroquip 303 prior to teflon.

What do you think they used since the begining before Teflon  or Aeroquip was invented? How long before the first flights until Teflon was around?  

What are all the cars, motorcycles and hundreds of millions of other engines using? They're all running just fine of rubberized fuel hose.

[AS Flightlines]

1 hour ago, Roger Lee said:

What do you think they used since the begining before Teflon  or Aeroquip was invented? How long before the first flights until Teflon was around?  

What are all the cars, motorcycles and hundreds of millions of other engines using? They're all running just fine of rubberized fuel hose.

Roger,

I think you're digging a pretty deep hole for yourself here and trenching yourself in.  Accuracy of information is vital.

1. First off, Rotax has only built about 50,000 912/914 series of aircraft engines.  This is a far cry from the "Millions of aircraft" you talk about in your post above.

2. I notice you are only referring to the cost of the rubber hose, and no firesleeve when you discuss replacement costs.  This is something that also needs to be accounted for in an enclosed cowl engine compartment.  Further, sliding a firesleeve over a rubber hose without the proper attachment methods to secure the ends doesn't do anything.  There are very specific reasons fire sleeve is secured in certain ways.  This is necessary to ensure the performance required in the event of an engine fire.

3. A fuel system is only as good as its weakest link.  However, the operating environment and requirements dictate the materials used. Above, you mentioned that if you replace FWF with teflon you would also need to do the firewall aft hoses to have the same level of performance. This is not at all the case.  Non-firesleeved teflon can be utilized as a replacement for rubber hoses aft of the firewall.  Another very common and permanent installation is the utilization of aluminum tubing that is properly flared and supported.  The aircraft cabin is a VERY different operating environment than an enclosed engine cowling.  As such, you should utilize appropriate materials for the task at hand.  In many cases, while conductive teflon firewall aft is a viable choice, it may not be the best choice for that area.  We utilize CNC bent rigid tubes, hose assemblies, and combination assemblies in the aircraft cabin where appropriate.

4. Firewall forward fuel lines are the most critical for a variety of reasons.  In an engine fire scenario, a non fire sleeved, rubber fuel line will create the most amount of havoc in the least amount of time.  This is likely why Rotax has swapped to firesleeved Teflon fuel hoses as OEM.  In contrast to that, the failure of a coolant hose in a fire will not negatively impact the potential outcome of the event.  Oil lines are also a consideration and can be easily replaced if the owner chooses to.  Rotax makes provisions for this with both the AN and Metric ball seat fittings on the oil tank as well as the ability to choose from a variety of different return line fittings on the bottom of the engine case.

Everyone is entitled to their own opinion and the level of risk they are willing to accept.  However, I guaranty that no one who has ever suffered an in flight fire has wished they could go back in time and select an option that afforded them less ability to safely survive the event.

 

P.S. I think you're getting ripped off on your hose.  My hardware store sells blue tinted polyurethane fuel hose for about $.60/foot.  I don't know too much about it.  It's in the small motor section, but says it is safe for fuel.....so must be good to go on an aircraft!

[AS Flightlines]

1 hour ago, Madhatter said:

My engine had the old hard stainless carb lines on it so teflon was worth it.

In 50 years I have never see automotive fuel line on any aircraft except for a few experimental and lately LSA. Most used aeroquip 303 prior to teflon.

Madhatter,

You are 100% correct.  303 was fantastic at the time.  There are just better options available now.  I've also seen the catastrophic results that can occur very quickly in an engine compartment.  The beauty of experimental is that we can don't have to choose between certified and the "Aircraft Aisle" at Home Depot.  There are products in between that offer equivalent or better than certified quality at a large discount to the cost of certified.

[Madhatter]

I want to make one thing very clear on this forum. When it comes to any disagreements on technical issues on LSA aircraft,  there is no intention to disparage anyone for their opinions, especially Roger.  I have a great deal of respect for him and engage in numerous phone conversations over getting his advice on his CT experience. Roger has told me many times that he has no knowledge of certified aircraft maintenance and parts and had no intention to deal with them.

So in conclusion now Roger knows what a PITA it is to deal in the world of the FAA and certified regulations

[AS Flightlines]

1 hour ago, Madhatter said:

I want to make one thing very clear on this forum. When it comes to any disagreements on technical issues on LSA aircraft,  there is no intention to disparage anyone for their opinions, especially Roger.  I have a great deal of respect for him and engage in numerous phone conversations over getting his advice on his CT experience. Roger has told me many times that he has no knowledge of certified aircraft maintenance and parts and had no intention to deal with them.

So in conclusion now Roger knows what a PITA it is to deal in the world of the FAA and certified regulations

VERY WELL SAID.  Also no intent to disparage.  We all have different levels of experience and expertise in different areas.  As a company, we play mostly in the experimental arena for the reasons mentioned above.  I do think that the certified world has imparted a lot of good lessons that can help make the experimental and lsa market safer.  As I mentioned earlier, an aircraft does not know if it is experimental or certified.  So I think it wise to take the best of both worlds and combine them in a cost effective manner.

 

[Roger Lee]

12 hours ago, AS Flightlines said:

Roger,

I think you're digging a pretty deep hole for yourself here and trenching yourself in.  Accuracy of information is vital.

I still like debate and just a scientific analysis of the debate. I like to let science and proven results lead me in my en devours.   A lot less heart ache, failures and I get to keep more money in my pocket.   For me personally it's just about cost for someone else maybe no big deal. Either hose setup will work just fine as history has proven since 1903.

 

1. First off, Rotax has only built about 50,000 912/914 series of aircraft engines.  This is a far cry from the "Millions of aircraft" you talk about in your post above.

More than 175,000 Rotax aircraft engines have been sold since 1973. Of this number, 50,000 were four-stroke engines from the well-known 912/914 series. It's noy just about Rotax. We are comparing product of rubber vs Teflon world wide on all aircraft and rubber hose isn't limited to Rotax engines.

Rotax has been building engines since 1920 and that's 102 years and all used rubber hose.

2. I notice you are only referring to the cost of the rubber hose, and no firesleeve when you discuss replacement costs.  This is something that also needs to be accounted for in an enclosed cowl engine compartment.  Further, sliding a firesleeve over a rubber hose without the proper attachment methods to secure the ends doesn't do anything.  There are very specific reasons fire sleeve is secured in certain ways.  This is necessary to ensure the performance required in the event of an engine fire.

Fire sleeve doesn't need replacement at the 5 year mark. It is supplied already on the hose from the aircraft MFG  or installed by an owner at the time of the build and is re-usable. Even at $9 ft. the cost of fire sleeve and rubber hose  this is still way cheaper than $1000 over many fuel hose replacements. It's up to the owner and aircraft MFG to apply proper clamps on all hose which is covered in many documents, videos and the FAR's. So this is a non issue because someone can mess up Teflon installation too. I've already seen it on RV12's.  This isn't even a debate, it's either installed properly or not. It isn't a hose failure or hose issue. It's an installer issue. Plus you guys normally only replace what's in the engine compartment and not aircraft wide.

3. A fuel system is only as good as its weakest link.  However, the operating environment and requirements dictate the materials used. Above, you mentioned that if you replace FWF with teflon you would also need to do the firewall aft hoses to have the same level of performance. This is not at all the case.  Non-firesleeved teflon can be utilized as a replacement for rubber hoses aft of the firewall. 

Yes it can, but almost no one does. Whybecause of cost again. They only percieve danger in the engine compartment. They only do the engine compartment. I haven't seen a single Teflon hose installation from the fire wall back.

Another very common and permanent installation is the utilization of aluminum tubing that is properly flared and supported.  The aircraft cabin is a VERY different operating environment than an enclosed engine cowling.

Not really. As a 30 year retired firefighter and HazMat Tech fire will go where the fuel is. Matter of fact the hose inside the cabin is also supposed to be in fire sleeve, but no ones seems to do that either. FD did have an SB out just for that. When you have an 1800F - 2000F degree fire being faned by wind currents all bets are off.

  As such, you should utilize appropriate materials for the task at hand.  In many cases, while conductive teflon firewall aft is a viable choice, it may not be the best choice for that area.  We utilize CNC bent rigid tubes, hose assemblies, and combination assemblies in the aircraft cabin where appropriate.

4. Firewall forward fuel lines are the most critical for a variety of reasons.  In an engine fire scenario, a non fire sleeved, rubber fuel line will create the most amount of havoc in the least amount of time.  This is likely why Rotax has swapped to firesleeved Teflon fuel hoses as OEM. 

Properly installed rubber hose with properly installed fire sleeve will do just as good in a fire scenario. Now you failed to mention the oil hose and it fueling the fire. That's in non Teflon hose and should be fire sleeved. Wait we still have fuel in the carb bowls, fuel pumps and gascolators. Not much will help when you have untrained owners trying to battle a fire. many times they add to the problem.

In contrast to that, the failure of a coolant hose in a fire will not negatively impact the potential outcome of the event.  Oil lines are also a consideration and can be easily replaced if the owner chooses to.  Rotax makes provisions for this with both the AN and Metric ball seat fittings on the oil tank as well as the ability to choose from a variety of different return line fittings on the bottom of the engine case.

Everyone is entitled to their own opinion and the level of risk they are willing to accept.  However, I guaranty that no one who has ever suffered an in flight fire has wished they could go back in time and select an option that afforded them less ability to safely survive the event.

How and why is your Teflon hose better than rubber hose in fire sleeve during a fire? Given enough heat anything can and will fail. Plus what happens if a teflon hose end isn't crimped properly or that batch has a defect in the hose?

P.S. I think you're getting ripped off on your hose.  My hardware store sells blue tinted polyurethane fuel hose for about $.60/foot.  I don't know too much about it.  It's in the small motor section, but says it is safe for fuel.....so must be good to go on an aircraft!

Plus I use only Gates Barricade hose meant to handle ethanol fuels just like all our cars, motorcycles, boats and all other engines. Why don't they all have Teflon hoses especially if rubber hose is dangerous. Anyone still using polyurethane hoses for their fuel system and none being in fire sleeve is foolish.  I buy  in 25' reels because I do so many hose changes. I just completed two of them. One thing I'd like to research is which hose setup insulates from heat better. Since the rubber hose is covered in fire sleeve it would be harder to physically compromise that hose vs an exposed Teflon hose.  See all this depends on the angle you want to approach it at. I prefer all angles because I love to research and not follow down some paths just because others do.

Same hose that Rotax used for many years. If there was a serious issue with this then I'm sure people around the wrold would be complaining and there would be investigations. They use this same hose with 23 % - 25% ethanol.

Gates BARRICADE MPI FUEL Hose

Barricade® fuel injection hose is a low permeation, multi-fuel compatible hose that virtually eliminates fuel vapor loss thanks to our 5-layer GreenShield® barrier technology. Works with multiple fuels (approved for use with leaded and unleaded petrol, diesel, biodiesel up to B-100, E-10, E-15, E-85, 100% methanol, ethanol and gasohol fuels).

• Fuel savings from Barricade's incredibly low permeation rate - the lowest on the market at 1g/m2/day.
• Easily complies with environmental standards, exceeds the requirements of SAE J30R14T2 (except for kink resistance).
•  

 

[FlyingMonkey]

Just to be clear…I have no issues with rubber hoses, they have served me well on my engine.  The only reason I am interested in the fancy hoses is to to make my life easier at hose change time.  If I can leave all the fuel and oil lines alone during the rubber chnage, it will make my life much easier.  I don’t mind paying a little bit for that convenience.

[AS Flightlines]

Roger,

Let's keep this simple.....

1. Why do YOU think that Rotax swapped from Rubber hose to Teflon fuel lines on all new 912 engines? 

2. I don't know how many aircraft you have seen, but there are plenty of aircraft that are utilizing Teflon/Rigid tubes aft of the firewall for their fuel systems.

3. All firewall forward hoses (fuel, oil and pressure) should be fire sleeved appropriately.  This should be done whether it is a teflon hose, or a rubber 303/701 type hose.  This is done to ensure that if a fire occurs the hoses will remain intact and won't add fuel to the fire while it is burning out.  There is a very specific FAA time requirement for this.  If fire has access to the fitting that the hose is attached to, it shouldn't be a barbed brass fitting as that has a much lower melting point than other metals.  Again, the point of this is to keep everything intact long enough to shut the fuel off and let the fire subside while safely getting the aircraft on the ground.

4. The engine compartment is indeed a very different operating environment than the aircraft cabin and is separated by a stainless steel firewall for a reason.

5. If a teflon hose end isn't crimped properly or the hose has a defect in it, this will all be caught during production since all reputable hose manufacturers pressure test and data tag each hose assembly that is built.   The video below shows the process.  Hose assemblies aren't being crimped by a pair of pliers or a vice grip.  It is a highly technical process with very tight tolerances and computerized crimp machines with position and pressure feedback.

 

[Jim Meade]

Time to make popcorn.  Roger with 9,000 posts on here welcomes AS Flightlines who has 12.