Help me understand Hoses and Fluids

I am sitting around waiting for my wing kit to show up (ordered last November) and decided to start researching hoses for the firewall forward. I could use some help understanding the differences in hose types, fluid compatibility, and fittings.

So far I understand aeroquip and stratoflex are generally available in stainless steel braided hoses and they would be capped with aluminum or SS fittings. Aeroquip 601/701 seems to be the standard with a synthetic rubber core and SS overbraid. However TS Flightlines seems to use Teflon core with SS overbraid. I am currently assuming it is Aeroquip 666 hose. Teflon appears to handle any fluid while the synthetic rubber can't handle hydraulic fluid. So this leads me to believe I should just use Teflon core Aeroquip 666 hose for all flexible fuel, oil, and brake lines. I am still working on which fittings to use with the idea that aluminum are fine behind the firewall while SS should be used firewall forward.

I am also reading that the 5052 aluminum is generally preferred over the softer 3003 aluminum that comes in the kit for the rigid lines, although tougher to work with.

Please correct me if I have stuff wrong, but what I could use some help understanding is the following questions:

What type of hose (core type or brand) is generally in use for the fuel lines, oil lines, and brake lines?

What sizes are these hoses (-4, -6, -8, or ID and OD if known)?

What type of fittings are being used for the respective hoses (aluminum, SS, Brand, etc.)?

I can completely understand why so many people simply pay TS flightlines to send them their hoses pre-fabricated, but I am trying to fully embrace the experimental mindset of learning new skills, understanding what I don't currently know, and building the airplane to the maximum extent possibly myself. Thanks for any light you can shed on the subject.

There is plenty to learn when building, and when it came to fuel/oil/brake lines I made it easy on myself. Tom and Steve (Aircraft Speciality) do a fantastic job on all these lines. It costs a bit more (not that much in comparison to the investment) but it gives me confidence in some of the most critical components of the aircraft.

Tom has worked with me on getting a number of special lines (Beringer brake lines, customized oil lines to fit modifications) just right - we've become good friends despite having never met in person, through our phone conversations and emails working on my project. I wouldn't trade anything for the relationship or the service.

FYI Tom is probably happy to chat about all your questions and give you advice, even if you don't buy anything.

Not so sure about costing more, when you compare apples to apples. I thought I had an advantage because I live about 40 miles from earls of Indy (on gasoline ally). After totaling earls prices for conductive Teflon hoses and fittings (for the 3 cabin side fuel hoses) it was going to cost $50 more than TS and I was going to have to make 2 trips to earls, one to get the material, then measure and make up the hoses then a trip back to get the hoses swaged and pressure tested. Oh yea that was using earls aluminum fittings, not TS?s stainless fittings. So it goes without saying that Tom got an order for a complete RV-9 hose kit...

Firesleeve

I came across a follow on question while reading the Aeroquip hose information manuals. Temperature operating range of Aeroquip 666 hose is -65 to 450F. In the exact same manual their AE466 hose which is the same hose with an integral silicone fire sleeve also has a temperature operating range of -65 to 450F. Here is the real kicker. Their AE102 fire sleeve has a continuous operating range of -65 to 500F. So what is the point of the fire sleeve? Does it have increased flash temperature ranges that aren't listed, or does it simply add a second insulated layer that extends the time before the AE666 hose melts?

Jon,

Good morning. Congrats on getting your project started!!!!!

These are all great questions and make for a very interesting discussion.

Let's start off with the rigid tube question. The stock kit comes with 3003 tubing. This is a soft and easy to form aluminum that comes in a roll. You straighten it out, bend it into final configuration and flare it. 5052 aluminum is a bit harder to work with as it is a bit stronger and harder to bend. We purchase it in straight sticks, cut it to length, and then fabricate lines with it.

If you go to the following link and click on "Rigid Tubes", you can see the start to finish process of how we fabricate these. It's a long video, but the 11:30 mark is where we show the actual bending of some RV14 tubes.

http://aircraftspecialty.com/howwemake.html

Next, we move on to hoses. In an aircraft where you have fluid that "flows", you want to utilize a CONDUCTIVE TEFLON hose. This ensures that your hoses will not deteriorate over time due to static discharge to the stainless braid causing pinhole leaks in the hose liner. A google search provides more information on that topic.

The stock Van's kit and FWF hose package utilizes conductive teflon hose assemblies for both the Fuel and Oil lines for the stock configuration engine.

Our FWF packages are similar to the stock Vans package in several ways. There are three main differences.

1. The first is that we utilize conductive teflon lines with Stainless fittings on ALL firewall forward lines. This includes oil pressure, fuel pressure and manifold pressure.

2. Second, we firesleeve all our Firewall forward lines (Manifold pressure is optional). We do NOT exclude firesleeve from Oil lines, fuel pressure, or oil pressure lines)

3. Finally, the third difference is that we build our hoses to the EXACT firewall forward configuration that our customers are utilizing. A Thunderbolt engine with an FM150 servo utilizes a different hose setup than the stock IO-390. If you are using a backup alternator, or an upright oil filter adapter, this necessitates a change to some line lengths. Also, a single or dual pmag setup creates another variable that requires FWF hose changes. Basically, we build everything custom and to order and as such are able to ensure that the hoses for your specific aircraft will be a perfect fit.

For more information on the hoses and how they are fabricated, you can go to the same link.....

http://aircraftspecialty.com/howwemake.html

Click on Conductive Teflon Hoses.

Regarding hose sizes.....

-3 - We utilize these for the cabin and gear brake lines. These are utilized for compact routing and great bend radius flexibility.

-4 - These are utilizes for Fuel and Oil Pressure lines, and well as servo to spider fuel distribution lines

-6 - These are typically the fuel lines for an aircraft

-8 - This is the size of the oil lines utilized

As far as fabricating your own assemblies.......the key is to ensure that you are utilizing a high quality conductive teflon hose assembly. That's very important. Also, if you are able to find someone who can do a hydrostatic pressure test on the hose assemblies once complete, that would give you peace of mind that they are perfectly built.

Please feel free to reach out to Tom or I if you have any questions. If you want to go the "build your own" hose route, we would be more than happy to help point you in the right direction and answer any questions that you have.

Steve

mulde35d said:

I came across a follow on question while reading the Aeroquip hose information manuals. Temperature operating range of Aeroquip 666 hose is -65 to 450F. In the exact same manual their AE466 hose which is the same hose with an integral silicone fire sleeve also has a temperature operating range of -65 to 450F. Here is the real kicker. Their AE102 fire sleeve has a continuous operating range of -65 to 500F. So what is the point of the fire sleeve? Does it have increased flash temperature ranges that aren't listed, or does it simply add a second insulated layer that extends the time before the AE666 hose melts?

Click to expand...

Jon,

That is a continuous temperature range. I don't have the exact specs for the AE466 in front of me. However, a Milspec AS1072 compliant firesleeve (such as the one we utilize) meets very specific FAA requirements for Fire Ratings. The temperatures it can withstand for short periods of time are MUCH higher. This is important because it helps prevent a hose breach in the event of a firewall forward fire event.

Steve

Jon, if you want to call me, I;ll give you a short--well maybe not so short- lesson on hoses---then you can decide what best for you.

Tom

One very good reason to use teflon instead of traditional hose liners is the lifespan of the hose. The traditional hoses have a fairly short life limit, if you follow recommendations.

For hard line: I used the stuff Van's ships with the kit. For me, in most situations, 'Better is the enemy of good enough'.

Charlie

Steve gave a most excellent primer on the whole topic (gee Steve, you know that if you threw in some pictures, that would be a great magazine article....) - the only thing I?d ad from an engineer?s perspective is that you use thing in places where you never expect to have access for the life of the airplane - things and places where you won?t realistically want to do routine maintenance. You use hoses where access is good for inspection or maintenance, or where movement and vibration is likely (FWF).

In short - use tubing in places like the wings or inside fuel tanks (flop tubes are an exception - a miserable exception....). use hoses where you can get at them every year for the condition inspection.

Paul

Just changing the topic a tad. I'm waiting for my 14 wings to arrive this week. What else you need at this stage in terms of wiring/hoses/ad ons for wing assembly?

The wing tubes to the fuselage--

Tom

Follow Up

Just wanted to close out this thread with what I finally decided. After about a day and a half of reading forums, researching materials, and searching places to buy parts, I have come to the conclusion that without a hose crimping machine at your disposal it is difficult to save money by doing the hoses yourself. The greatest factor is that the re-usable stainless steel hose ends are 3-5 times the cost of the crimp on fittings. That fact makes doing all the fuel, oil, and brake lines in conductive PTFE with SS braiding run somewhere around $1500 whether you have them done or do it yourself. This includes fire-sleeve for the fuel and oil lines along with all SS fittings.

With that being said, for now I have decided to likely have the FWF hoses completed by TS Flightlines / Aircraft Specialty (essentially the same companies for hoses) but still do the brake lines myself. While I don't think I will be saving much or any money by doing it myself, I want the experience along with the skillset so I can be better suited for maintaining the aircraft later in life. From what I can see so far the brake lines will need the following components which I priced out at www.anplumbing.com.

(All sizes are -3 hose and fittings for the brake lines which is all that is listed here)
Earl Speed Flex PTFE hose w/PVC coating - 4.48 x 30' = $134.40
Straight SS Speed Seal hose end - 14.29 x 13 = $185.77
45 Degree SS Speed Seal hose end - 49.82 x 2 = $99.64
90 Degree SS Speed Seal hose end - 47.08 x 1 = $47.01
Straight NPT to AN aluminum adaptor - 2.72 x 2 = $5.44
45 Degree NPT to AN aluminum adaptor - 8.35 x 2 = $16.70
90 Degree NPT to AN aluminum adaptor - 7.95 x 10 = $79.50
AN826-3SS AN-T w/ NPT - 25.95 x 1 = $25.95 (this is the firewall hardware in Stainless Steel)
AN924-3SS Bulkhead Nut - 3.95 x 1 = $3.95
Assorted Clamps, bolts, nuts, and Cable ties ~ $25.00

Total Parts Cost = $623.34

I also considered doing the hose fittings in aluminum, but that is not much cheaper than the SS fittings (only $2-4 difference) and Tom is right that the SS will hold up much better. But overall I am not worried about mixing aluminum AN fittings with SS hardware since it is all on the cool side of the firewall.

Off the www.aircraftspecialty.com website the above setup would be $549.95 for the standard brake line package plus $169.95 for the Gear leg hose kit. Total would be $719.90 plus shipping for materials, assembly, and pressure testing. So the total cost difference for having it done professionally vs do it yourself is only $96.56 plus shipping (for the brake system only of course). The 2 biggest differences would be crimped fittings vs re-usable and line testing. A big thanks though to both Steve and Tom for a good bit of shop knowledge and understanding of the system operation and pressures associated with the hoses.

While I am likely missing some small pieces in my list above (which if someone sees something please let me know) this is pretty comparable to having it manufactured and tested. I may be able to get the hose tested at my workplace, but I figure since it is only the brake system (as opposed to fuel and engine oil) I can likely figure out any problems without a catastrophic failure. Unless the brakes give out at a really inopportune time of course. In my mind this is the best way to get the maximum level of safety while still learning a new skill and maintaining a negligible price difference.

By the way, in reading some of the previous threads on this topic their were some pretty heated discussions on hoses. I guess I am just one of those who is more interested in learning the skills associated with building the airplane than the actual end product itself.