Online Community of Zenith Builders and Flyers
For those of you who want an alternative to the rubber rotax fuel hoses, here is a picture of an installation we have done on a rotax 912 engine. We replace the standard hoses (shown) with all conductive teflon stainless braid that is NOT life or time limited.(shown also...they are the smaller overall looking package) In addition, they are less bulky, more flexible, and weigh significantly less than the standard rubber.
It seems that every rotax engine is a bit different depending on the installation, so there is no standard package, but we love working with customers to make a solution that is right for you. We can custom make fittings or do whatever it takes to make it work. In doing so, you end up without all the hose clamps and with real AN type fittings. In addition, we pressure test all these hoses. They have a continuous working rated pressure of 3,000 psi and a burst pressure of about 9,000 psi. These things are the latest in technology, and are equal or better in quality than the latest certified hoses that are much much more expensive.
We are currently starting to see a lot of interest in the rotax packages. These are the same hoses we use in the RV series aircraft, but need to be adapted to the rotax engine.
If anyone has any questions, or would like to work on your engine, please contact us at firstname.lastname@example.org
Have a great day,
Are these E10 safe?
Absolutely....... you could run nitro through them if you wanted (Wouldn't recommend it with a 912!!!!) The ethanol has no degrading properties on these fuel lines.
Like I was mentioning earlier..they are not life limited either...they literally will last for the life of the aircraft, unless you do something like have one resting on an exhaust. That's another story......had a customer with one of our hoses 150 hours on a hot exhaust. It burned through the firesleeve.....discolored the stainless braid. When the fuel line was dissected, there was NO damage to the hose itself. That has made a lot of believers out of our customers.
Why are they so much thinner? What is the precise weight difference between the two assemblies shown in the picture?
The hoses are a thinner wall than the rubber hose that is typically used. The ID of the hoses is slightly smaller too, but the specs are as follows.....we use -4 hose for brake lines, fuel pressure gauges, even up to the fuel injection spider on lycoming engines. -6 is used for fuel feed lines. -8 is used for oil lines. Our -6 fuel lines we run on 310HP engines.
Also, the Firesleeve on these hoses is a very tight conforming firesleeve. While it isn't integral to the hose itself, it is about as close as you can get. So, a lot of the thickness of the standard assemblies comes with firesleeve that is a bit too wide. With the stainless braided hose we are able to use a snug fitting firesleeve, because the hose braid is rigid enough to pull it over.
When it comes to published bend radius.....bend radius on a -4 is 2", on a -6 it is 4" and a -8 hose it is 5.25"
As far as weight goes...I don't have the exact weights on that complete assembly. This morning I weighed a customer with a Rans. One specific hose the old way weighed about 13oz, and ours came it at around 8oz. Both were firesleeved and of the same length.
Keep the questions coming.
Thanks for the answers.
Do you use true AN fittings or do you use JIC fittings, which are indistinguishable from AN fittings without special equipment?
The stem/lock is proprietary to the company we have build these fittings. The machining, materials and threads are MilSpec. The main difference between JIC and AN is the tolerances used in the machining process, as well as the threads are manufactured differently. One thing that most people don't know is that a lot of the AN fittings they buy will not spec out as actual AN if you actually measure the thread tolerances exactly. Where one of the issues was is that people used to interchange SAE and JIC fittings, which was a problem as aircraft fittings need to be 37 degree flare to meet up with the AN fittings on the aircraft. In the past, I have seen several aircraft that have had 45 degree flare fittings on them. Typically it works, due to the low pressures involved, but you DO NOT have a good mating surface. If there ever was a problem, people thought it was a bad JIC fitting, which isn't the case. It was not a 37 degree flare and the mating surfaces weren't done properly.
The fittings that we use on our hoses are stainless steel and are designed for a 3,000psi continuous rated pressure. They are supposedly a burst pressure of around 9,000 psi, but we have taken them up to our max of about 9500lbs and left them for an hour to see what would happen, and they hold pressure just fine.
I guess to make a long story short....our fittings are not "True AN", but in many ways they are better. They just don't have the stamp of approval on them. The stainless steel adds tremendous strength and very little weight. Especially since our hose is lighter than let's say Aeroquip, the extra fitting weight isn't a factor. In addition, the stainless also adds a tremendous amount of fire protection to the fitting itself, versus aluminum AN.
Hope this answers your questions. Also, we do pressure test EVERY hose that comes off our production line. We do this because we use them in our own airplane and know our customers depend on them. We have not yet had a fitting that didn't pass this test, but we still check every hose to be sure.
Another thing that we have had customers ask us is why we pressure test up to 2-3,000 psi (depending on the hose size). They think we are going to damage the hoses. I thought I would address that question here. We only run 25psi or so in a typical aircraft fuel system..potentially a bit more for certain engines. The reason we do this is that these hoses are rated to be used at this high pressure day in and day out with no life limit...so it isn't hurting the hose at all. But, what it allows us to do is to make sure there are no tiny imperfections that you couldn't see with the naked eye. Like you mention, a JIC is indistinguishable from AN with the naked eye. If there was any imperfection in a fitting or hose, taking it to it's working pressure would instantly show it to us. So, if it holds at 3,000 psi (or 9,500 as we have done for fun on scrap test hoses), it will absolutely NEVER fail at 25 psi.
Have a great day and keep asking these questions.
I've been an advocate for stainless braided fuel hoses, but ironically, used fire-sleeved rubber between my firewall-mounted gascolator and my engine-mounted fuel pump because the pump had a ? cast-in?/ pressed-in? nipple requiring a hose clamp. Is there a solution for terminating stainless braided hoses with a clamp (Jab 3300)? I don't want to risk destructively removing the nipple and drilling and tapping the hole, etc.
You can't use the stainless braided hoses with a clamp termination. HOWEVER, I will post something new here in about two days. I have someone working on a special adapter fitting for this exact reason. He is going to fabricate a conversion fitting from the nipple to male AN that acts as a compression type fitting over the nipple. I haven't seen it yet...but this guy is AMAZING and can manufacture pretty much anything oddball like that. Once it is converted, one of our standard hoses would work perfectly.
We are also going to be purchasing a CNC lathe at the beginning of next year (the one we want isn't in final manufacturing yet)......then we will be able to take these one off type fittings and start producing them and hopefully creating complete alternative packages for those who want to use all stainless braid hoses.
I'll keep you updated. Hope you are enjoying the plane!
That's great news - there's definitely a need for a solution to convert nipple fittings! Please do keep us posted!
And yes, I'm having a ball with the 750! 145 hrs since July!
John and everyone.....
Spoke with my guy today...he is hoping to have this new fitting done tomorrow.....I will however be with my daughter at a waterpark for her birthday and won't get a chance to look at it until sometime later this week......So I should have an update by the end of the week on this hopefully.
Have a great day,
I have all the information on the fittings now....
It seems that every rotax/jabiru installation is a little bit different, BUT we have a way of adapting the banjo fittings to a stainless braided fuel hose with either a crimp on braided hose, or via an adapter that turns it from a banjo to an AN male. Or, we can fabricate a fitting that goes over a barbed fitting and turns it into a metric compression fitting and can terminate with an AN male that adapts to one of our fuel hoses.
I've taken a look at the stuff, and it's pretty neat. Effectively, if you have an engine that doesn't have "standard" AN fittings on it and want to use something other than the rubber hoses, please email me at email@example.com. We will be able to come up with a solution for your engine to adapt it to standard AN hardware.
We are going to eventually try to get together some hose/adapter packages...but right now we are so busy that piecing them together hasn't been easy. However, we still will be more than happy to do custom work for anyone that would like it done to your engine. If you know the lengths that you need, we can make it.
Have a great day,
Just wanted to follow up with an update to this thread....
We now have the fittings in stock to do a complete rotax 912 fuel system upgrade. This is applicable to the new style rotax fuel pumps with the threaded in fittings. We offer the retrofit fittings to AN, and do a modified banjo to AN to convert all hoses firewall forward to conductive teflon. We will be getting some more pictures together soon, but right now, there are some available on www.kitplanehoses.com
If anyone has any questions, please email us at firstname.lastname@example.org. A typical complete set of hoses that are firesleeved runs in the range of $550-600.
However, we would like to put together some detailed pictures of an installation on a Zenith in addition to the many RV12s that we are doing. For anyone who is interested, please let us know and we will be happy to extend a discount to the first person who is willing to do an install and take detailed pictures of the whole installation. It has to be a stock 912 setup with no modifications.