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Planning the fuel system

rotoiti

Well Known Member
I deleted the standard fuel valve from my fuse kit (want to get the Andair one, there seems to be a consensus that they are better). I see a lot of people replace aluminum fuel lines with flexible ones. Is that better? Easier to install? Less maintenance?

Also, which Andair fuel valve should I order? The website lists a myriad possible combinations for the 90 degree, two tank, no "both" one. And, if I order it, would I be able to reuse the blue connectors that came with the kit?
 
I have the Andair valve in my 10, and it is a nice setup.

I did not buy or install it, but bought a project with it installed already.

The Andair requires a different mount in the tunnel, but it is pretty simple to accomplish------by the time you get to this step you should have the needed skills to just take care of it without breaking a sweat.

There is a lot of tubing in a close space when plumbing the fuel valve, and I suspect the reason for flex lines being used is to simplify the installation. But, they will add cost, and probably more connections/possible leak sources. No free lunch..............

Another thing to keep in mind is the type of fuel injection you plan to use, and if there is the need of a return line. You can get an Andair valve that will switch a return line as well as the supply line.
 
A little uneasiness here

This is of course a critical part of the airplane and the possible implementations are many. I did not build an RV-10 so I don't know the context you are working in.

Valves - I used the standard issue valves and they are stiff - I get mildly tense every time I switch tanks but I have had no trouble with them in 1000+ hours of flight operations. I personally would NEVER have a fuel system where when the engine stops from fuel starvation I have no switch option - no "BOTH" fuel valves in my cockpit.

Fuel Lines - I used aluminum everywhere except across the interface between the rigid airframe and the vibrating engine and inside the console where my replaceable fuel filters (4 for 4 tanks) are located - there I used hoses. Hoses are limited life items and will have to be replaced eventually. Aluminum tubing is subject to cracking in certain applications over time - strain relief and motion tolerant routing is important.

Bob Axsom
 
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Andair

Hello

I did the same thing that you are asking. Ordered directly from Andair and this is what they recommended.

Valve FS20x7-T
Pump PZ375-TC
Filter FX375-MK

One thing to keep in mind, If you are using Aerosport lower panel and middle console, you may want to add the extension with the u-joint so that you can move the valve back a bit on the console. I did not and it makes it quite hard to get the console on and off.

As for the brake and fuel lines. I used Bonaco, he has a set up just for the RV10. The kit replaces all tubing line with braided hose that is plastic coated. The reason I did it is because of ease of installation and also do not like the alum tubing. Does not seem as strong to me, IMHO.

TS Flightlines also has braided lines but not sure about ones for fuel. Heard good things about these as well.
 
I have the TS Flightlines braided lines for brakes and fuel lines along with all the Andair stuff listed above, I wouldn't do it any different very high quality .
 
I have the TS Flightlines braided lines for brakes and fuel lines along with all the Andair stuff listed above, I wouldn't do it any different very high quality .

Me too! In my opinion this is the best option.

Actually I purchased Bonaco brake lines, but if I was doing it again, I would purchase them from TS Flightlines. I've seen Tom go above the call of duty with more than one RV'er. I walked in on one session in which he had a web cam in the tunnel helping to figure out an issue. For those that are concerned about limited life, give Tom a call. He can explain the limitations.

Bob
 
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I went with 5052 (vs 3003 supplied with the kit) hard lines and the stock valve and an aftermarket handle.

Having said that, personally I think most of the aftermarket upgrades while nice, really aren't as necessary as some would have you believe. Again I've got a number of upgrades so I'm as guilty as the next guy in splurging for stuff, some are IMO important (MATCO front wheel and axle, PlaneAround door latch), others not so much (titanium door pin guide blocks). I guess what I'm trying to say is build the plane you want, not the one others want. There's nothing wrong will going with every mod/aftermarket item out there, just understand the difference between a "want" vs. a "need". Sometimes perfection is the enemy of good enough, just saying....
 
I went with 5052 (vs 3003 supplied with the kit) hard lines and the stock valve and an aftermarket handle.

Having said that, personally I think most of the aftermarket upgrades while nice, really aren't as necessary as some would have you believe. Again I've got a number of upgrades so I'm as guilty as the next guy in splurging for stuff, some are IMO important (MATCO front wheel and axle, PlaneAround door latch), others not so much (titanium door pin guide blocks). I guess what I'm trying to say is build the plane you want, not the one others want. There's nothing wrong will going with every mod/aftermarket item out there, just understand the difference between a "want" vs. a "need". Sometimes perfection is the enemy of good enough, just saying....

Same here. 5052 tubing, buy extra and no flex lines necessary. Stock valve works fine. I have switched it 240 times so far without a problem. I even bought a spare valve and installed fittings for a quick changeout if needed. Still spent way less. 2 yrs/2000 hrs/1656 lbs.
 
Andair valve for me but Van's supplied tubing for all the rest except engine compartment.
Van installs the same tubing in their demonstrators 3003 and no one has more cummulative hours than Vans fleet. They have not reported any failures in their fuel systems. If 5052 hard tubing makes you feel better it probably is a better choice its something you want not need.
Vans fuel valve is just fine but like others, I had to spend some money on upgrades. As Van says "we'll leave the expensive options up to the builder."
 
Filters

I'm looking at going the Andair route, but my plan is to install a filter or gasalator in each wing root.
Two reasons:
1 it makes the annual service and checking of filters much easier and stops having fuel leak in the fuse when checking the filter. No extra panels in the tunnel etc.
2 it gives me two filters, so if one was ever blocked switching tanks may just keep you going.

Peter
 
No Gascolator!

Unless you are mandated by your rules, I would not install a gascolator.

There is simply no room in the wing roots of the 10 to install a filter.
Under the seats is a very convenient spot and you are guaranteed to spill some fuel when checking the filter element so might as well set up for that scenario.
An absorbent pad "diaper" or something simple will take care of that and you won't have to contort yourself inside the tunnel.
You'll also have a very short run from the inlet of the filter to the fuel pick up
fitting on the wing.

Photo%2520%252033.JPG
 
Sometimes, it isn't always about cost, it's about skill and choosing to whether or not to perform the task yourself or outsource.

Getting the flange right on the tubing is critical to ensure that there aren't any leaks.

I personally couldn't get them to come out to my satisfaction. Obviously, one of the many skills that I'm lacking. To compensate, I went with commercially available hoses.

Yes, there are other comprimises like having to inspect the hoses due to their limited life cycle. They will have to be eventually replaced.

Like most options, each builder is going to have different motivations for their decisions. There are very few wrong decisions, just decisions that are best for each of our projects.
 
Ask 5 builders a question like this and you're just about guaranteed to get 7 different opinions. At the end of the day, go with what makes you the most comfortable within your budget. Like Bob said, there are very few wrong choices to be made.
 
How did you determine the flares were not correct? I am doing mine right now and do not really want to do them again....
 
As mentioned by Bob A. in his reply above, flexible lines should be replaced at some point. I seem to remember the life expectancy to be around 10 years.

Also, those braided stainless lines, brake or fuel, act like a saw so you must support them and keep them away from any structure.

There is nothing wrong with adding bulkhead fittings to simplify running your fuel lines. Of course, this will mean more flairs and the possibility of more leaks but I have found they either leak or they don?t and you will find out very quickly if they leak.

For example, put a bulkhead fitting close to your fuel valve. That way, if you want to start with the Van?s valve and change it later, if there is a problem, then you will only have to bend a short section of line to accommodate a valve from a different manufacture.

For side-by-side builders I recommend putting in a 90 degree bulkhead fitting where the fuel line passes through the side of the fuselage and a straight fitting by the box that holds the valve. That way the fuel line that runs in front of the spar only has to be ?L? shaped.
 
I stayed with Van's parts

I stayed with the Van's aluminum tubing and the standard fuel selector valve.

A question was asked how do you tell of you have the right flare. Make it a tad big so that it is difficult to get the nut over the flare. Use a small file to trim it to fit. If you split it, cut it off and do over.

Also, I built a leak check device that uses air at about 40 psi. If the pressure gauge goes down, I use kiddie bubble blowing compound from the dollar store to brush on all the joints to see which ones make bubbles.

I bought the optional booster pump and filter from Van's.
 
How did you determine the flares were not correct? I am doing mine right now and do not really want to do them again....

For me the easiest way to check is the flare should be the same or slightly larger in diameter of the outer diameter of the AN819 sleeve. Much bigger and the flare wall will be too thin which will more than likely crack when you tighten the nut. Too small and you won't get a proper seal or worse you'll tighten the nut and pull the sleeve over the flare.
 
For me the easiest way to check is the flare should be the same or slightly larger in diameter of the outer diameter of the AN819 sleeve. Much bigger and the flare wall will be too thin which will more than likely crack when you tighten the nut. Too small and you won't get a proper seal or worse you'll tighten the nut and pull the sleeve over the flare.

And no nicks, scratches, gouges, etc........

There are several threads on this subject buried in the archives on both VAF and Matronics.
 
Thanks. I bought a double flare tool and it seems to work great. I think I will make a pressure test fitting as well...
 
Mike,
yes 2 fuel valves and a continuous return.
A single valve with these 2 functions is available from Andair but at over $400
I opted to use the kit supplied valve for the return selector and a nice Andair valve for the main.
The system is tolerant of mogas and is vapor lock proof.
Don't want to drift the thread or complicate anyone's decision.
Back to fuel lines and proper flaring.
Flairing a tube to the point where the B nut barely fits over the cone is way too much flair and only adds stress to the work piece.
Look at a blue 37 degree fitting, it has a very narrow contact range and that is all that needs to be covered with the cone of the tube, any more and it simply seals a bit further up the cone and expands the tube further than it needs to be. Or look at the ferrule and anything that protrudes beyond the outer edge of the ferrule is waste and does nothing to seal the connection. A clean debur and a light rubbing with a red abrasive pad is all it needs before you flair the tube and you are done. It really is that simple and most leaking
connection are overtightened B nuts and crushed flaires not improperly fabricated flaires.
I find that excellent flairs can be made with about 2 1/4 turn of the flairing tool. In practice, I count 4 half turns and another quarter turn produces consistently
perfect fitting flaires with enough thickness left to allow for some compression when tightening the nut. Remember, everytime you tighten one of these you compress it just a little more until the piece is work hardened and no longer seals. About 4 or 5 times is all that you can do before having to fabricate new ones.
But 3003 is very cheap and you can practice all you need to get good at it.
 
I've posted many times on flaring, here's a quick pic good vs bad:
Contrary to what the previous poster may have found, I've found numerous bad flares in RV's and have had to remake entire fuel/brake systems.

IMG_6726a.jpg
 
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I like the dual fuel filters. We did the same in our -10. We used the Andair ones however, and also put them under the seat. It is a bit of a pain to clean out the filter however, as you are correct about spilling a little fuel.

No rights or wrong, but we did ours the same way and like it!

Steve
 
As mentioned by Bob A. in his reply above, flexible lines should be replaced at some point. I seem to remember the life expectancy to be around 10 years.

It depends on the flexible lines that are being used. A high quality conductive teflon hose has no "defined" life expectancy. The hose won't deteriorate over time like a rubber lined Aeroquip 303 hose. Basically, a high quality conductive teflon hose is more of an inspect and replace if necessary type hose. However, in the type of installations that we are doing here, a hose like that will pretty much last the life of the aircraft unless you do something to physically damage it. Some people choose to do interval replacements, but it is up to the individual builder.

You are looking at a hose that is made of a material that is impervious to most fluids, and also one with a continuous operating specification of around 3,000 psi. So, the stresses we place on these in our aircraft is minimal.

Have a great evening,
Steve
 
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Filters X2

Andy from Andair has two gasalators, one in each wing root on his rv-7 and there's more room in the rv-10 wing root. So it should be fine.
Another alternative is to use the Andair filters which are quite small.

I just like the idea of a little redundancy.

Peter.
 
2 filters yes, but 2 gascolators???
There is quite a bit of room between the fuselage and the wing on a 10 however, the space accommodates a bell crank assembly. Installing a filter especially a smaller Andair will probably work.
When it comes to the unneeded gascolator and you'll want to install it correctly in the lowest spot of the fuel system, you'd need to have it installed sticking out the bottom of the fuselage.
The fuel pick up is at the very bottom of the tank and trapping additional water that hasn't been drained at the bottom of the tank, you'd have to mount it lower than that spot on the wing. Placing it forward of the bell crank assembly 3 or 4 inches higher than the fuel pick up is defeating the purpose of having a gascolator in the system.
 
It depends on the flexible lines that are being used. A high quality conductive teflon hose has no "defined" life expectancy. The hose won't deteriorate over time like a rubber lined Aeroquip 303 hose. Basically, a high quality conductive teflon hose is more of an inspect and replace if necessary type hose. However, in the type of installations that we are doing here, a hose like that will pretty much last the life of the aircraft unless you do something to physically damage it. Some people choose to do interval replacements, but it is up to the individual builder.

You are looking at a hose that is made of a material that is impervious to most fluids, and also one with a continuous operating specification of around 3,000 psi. So, the stresses we place on these in our aircraft is minimal.

Have a great evening,
Steve
Thanks for the clarification.

Andy from Andair has two gasalators, one in each wing root on his rv-7 and there's more room in the rv-10 wing root. So it should be fine. ...

Peter.
IIRC, that is a requirement in the UK.

Just as a reminder, there are thousands of RV's flying with the "stock" fuel system. Be very careful when making changes to this critical system! A seemingly simple change can have some very drastic and unintended consequences.
 
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