fuel lines

[mclayton]

I am getting ready to install the fuel lines in my project, a rebuilt Kitfox II. I started with a lot of parts, as it was badly damaged in an accident before I acquired it. The only evidence I have of the original setup is a short piece of flexible rubber fuel line coming from one of the wing tanks.

I installed a header tank kit, from John McBean, behind the seat. I will need to run flexible fuel line from the wing tanks to the header tank. Indeed the fittings supplied in the kit have barbed connectors for the lines. From the header tank, I want to go to a Facet fuel pump, then to a shutoff valve, then to a gascolator, a pulse pump, and the carburetors. Alternatively, I could locate the Facet pump on the engine side of the firewall.

Recognizing that certified aircraft utilize solid fuel lines before the firewall, I would like to use a flexible fuel line for ease of installation, and the ability to see the fuel flowing. I would like to use the Bing fuel line, which is alcohol resistant, and rated for temperatures of -65F to 220F, pressures of 50 psi, and a tensile strength of 8000 psi. Since the maximum pressure in my system will be on the order of 2-3psi, this should be more than adequate.

It seems that it would be a good choice, with the only risk being the line getting pinched somewhere in the cockpit. I will have to be careful how I route it, and so on.

I would like thoughts and opinions on this type of installation before I get going. Any and all thoughts are welcome.

Thanks.

[Dick B in KY]

Don't know how this will translate to your II, as I am building a SS7. From the header tank aluminum line to the fuel shut off valve, then to a Facet electric fuel pump in console area, on to the firewall bulkhead fitting. After firewall fitting, aluminum to the Rotax supplied firesleeve enclosed rubber fuel line to the fuel filter and on to the engine driven fuel pump. Hope this helps.

Dick B

[DBVZ]

I looked at this:

http://74.63.161.211/downloads/BarricadeBrochure.pdf

But you can not see the fuel flowing. I have not used it. Just looking at fuel line that would resist any ethanol blend. Any comments on this choice also appreciated.

[Geowitz]

Looks nice to me. Also, because of the very low permeability it would keep most or all of a gas smell out of the cockpit. A lot of fuel lines will let fumes seep out and make things stinky at least when you first open the doors after letting it sit for a while.

[HighWing]

Mike,
I am not sure if this is absolutely true, but I have heard that the Facet pump doesn't pull as will as it pushes the fuel. In the typical early installations the fuel lines are run near the floor to then go back up to the valve and through the firewall. With this in mind, I opted to put the Facet pump immediately after the header tank in the lowest part of the run - mounted to the bungee bulkhead, the closest to the header tank I could fit it in.
Lowell

[cap01]

i used this parker hose from the wings to the header . i had originally installed some other hose that wasnt low permeation and had a faint gas smell in the plane . i replaced that hose with this and it eliminated the smell . figure that out .

[mclayton]

Thanks for all the ideas! I will include some pics, showing the header tank location, and state again where the Facet pump will likely go, and where the shutoff valve will be.

My original idea was to use the blue Bing fuel line that ACS sells. . The specs are comparable to other fuel lines, plus you can see if air is trapped in the line.

The routing will have to be directly from the two wing tanks to the header tank, located behind the seat. I then plan to install the Facet pump between the header tank output and the main shutoff valve, which I would like to locate near the instrument panel, at the front of the cockpit. I am debating whether or not to install shutoffs for each tank, to make it easier to service things associated with the fuel system. I would not expect that the shutoff would be used very often.

The view in the pic is from the rear of the aircraft, looking towards the cockpit.

[rogerh12]

Having had 7 planes now, I say always install shut off valves at the wing tanks. Sooner or later you will want to drain the tanks and that's the easiest way. After they are mostly drainged, back flow the fuel lines to clean the finger strainer. Then use a syringe to suck out what’s left in the wing tanks. You might be surprised at what’s stuck to your finger strainer !!!
Roger

[cap01]

when i installed the header tank , i installed a s/o valve between the header outlet and the electric pump for maintenance only . also after flying the plane for a while i installed another s/o valve in the line from the left tank . the tank valve comes in handy when parking on uneven surfaces and prevents transfer and if you stay too long , fuel running off the lower wing . normal local flying , i only carry around 15 gal of gas, so ill use the left tank as a reserve and keep the valve closed

[Dave S]

There is another option for the frugal in lieu of shutoff valves between the wing tanks and header tank.

If the system needs to be opened up for maintenance, a clever mechanic can always shut off a flexible line by clamping the hose with a small C clamp and two small blocks of wood over the flex hose.

Shutoff valves do have their utility; but, a shutoff valve that doesn't exist is relatively fool-proof and absolutely free.

Dave S
KF7 Trigear
912ULD Warp

[cap01]

correct about the c clamps but hard lines it takes too much to smash them down to where they dont leak .

[t j]

Do you Plan to install a sump? A good location is the low point below the header outlet.

[rogerh12]

"Do you Plan to install a sump?"

What would a sump do for you below the header tank?
I think without a fuel pump of some kind there would not be enough head pressure to run the header tank dry, but a sump is usually associated with keeping sloshing fuel from unporting the the fuel pickup tube, yes?

Roger

[Dorsal]

I tend to view a sump as a place where water and debris gather and can be drained away, in my case the header tank itself. The fuel pump on the Rotax can definitely run the header tank dry. Perhaps he is referring to a gascolator?

[t j]

A sump to drain any water or crap. Roger, do you not sump your tanks?

[rogerh12]

I guess I always relied on a combination of gassolator and lots of disposable fuel filters. Even still, my finger strainer got totally plugged in my model 2, with a total stoppage of fuel from one wing tank (I guess that's why Kitfox gave us two !!!)

Isn't a gasolator at the low point of the fuel system a sump in a way?
I do remember to always drain mine, in fact my model 2 had two of them, one on the firewall but also one behind the seat, and I always drained first, fly second

Roger

[HighWing]

I have fuel shut off valves, but keep them with my tool kit.
Lowell

[mclayton]

I want to thank everyone for the thoughts, opinions, and shared experience. Here is where I think things are coming out:

1. Wing Tanks to Header Tank: Flexible line
2. Header Tank to Electric Pump: Rigid Aluminum line
3. Fuel Pump to Main Shutoff valve: Rigid Aluminum line.
4. Main Shutoff valve to firewall: Rigid Aluminum line
4. Firewall forward: Flexible line ( Rubber with steel braid or Bing)

These seem to be a good mixture of the thoughts everyone has expressed so far. Reactions?

[mclayton]

OOPs!

Forgot to mention that I will be installing a gascolator, forward of the firewall, at the lowest point of the fuel line, when the aircraft is parked on the ground, or in level flight.

BTW, the Bing fuel line is rated to 50psig, -65F to 220F, with an 8000 lb tensile strength. This is comparable to other flexible fuel lines. Maximum pressure in my system will be on the order of 2-3 psig, so there is plenty of margin

[DBVZ]

I want to thank everyone for the thoughts, opinions, and shared experience. Here is where I think things are coming out:

1. Wing Tanks to Header Tank: Flexible line
2. Header Tank to Electric Pump: Rigid Aluminum line
3. Fuel Pump to Main Shutoff valve: Rigid Aluminum line.
4. Main Shutoff valve to firewall: Rigid Aluminum line
4. Firewall forward: Flexible line ( Rubber with steel braid)

These seem to be a good mixture of the thoughts everyone has expressed so far. Reactions?
What did you decide to do about shut off from wing tanks?

Be sure to route fuel line below electrical line and connections.

[t j]

My opinion. The gas colator at the low point on the firewall may not be effective as a sump to trap water. If there is any up slope anywhere in the line from the header to the gas colator, water will be traped behind the high points in that line. Another problem is that water could freeze in flight in the winter.

Some builders have installed a T on the outlet of the header. One line straight down to a sump that has a quick drain under the belly and one straight forward like you plan.

FWIW I have a gascolator at the low point on the fire wall like you plan. I have the old fashoned style panel tank that acts as header, so the fuel lines from the wings are steadly down slope to the gascolator. No high spots in the fuel line.

I would keep the gascolator on the fire wall, but add a sump under the header for water. The gascolator also serves as a filter...you can get different screen sizes to comply with you engine manufactor recomendations on filter micron size.

[mclayton]

Sorry for being away so long...got tied up in family stuff and EAA Chapter activities.

I do plan on putting shutoff valves on wing tanks. I think that is a good idea, and they will be visible from the cockpit, and part of the preflight checklist.

The way I plan to route the fuel lines, the gascolator will be at the lowest level when the aircraft is sitting in its normal position on the ground, by quite a bit. I will take care to make sure that the fuel line goes uphill from there to the header tank. So, it should be OK.

Thanks again for all the help. Some excellent observations and suggestions!

[jtpitkin06]

How do you see fuel flowing through tubing without air bubbles in the line?


A fuel line that is full but plugged looks the same as a fuel line full and flowing.



JP