Fuel Lines / Fuel Questions

This is a mixed bag of fuel line questions so feel free to pick and choose what you want to answer....

When dealing with fuel lines in a 7A, is it common for builders to use flexible hoses instead of the aluminum tubing in the fuel tank to fuel selector valve area? I have a flop tube in one tank and a standard pickup in the other if that matters (length?, etc).

If it is an acceptable solution what are the pros/cons of flexible fuel line vs Aluminum tubing?

I'm getting ready to slap the wings on, but thought I'd get the cabin fuel lines taken care of first. I'm going with the Andair fuel selector and pump. I have the red cube fuel totalizer and am trying to figure out where the best home is for that also. I have a Lycoming IO-360-A1A in hand. Any thoughts on the Red Cube placement?

I have an inline Andair fuel filter just before fuel gets to the Andair pump. Is it advisable to put a gascolator, etc in line before or after the pump?

On a Lycoming fuel injected engine, do I need to run a fuel bypass line back to a fuel tank, and can you direct me to some pics of how that has been done by others?

I'm still a ways from hanging the engine but I need to get my plumbing situated first. )

As always, thanks for the advice!

I'm almost at that same point. What my research has come up with:

FI= no gascolator


I plan on calling Tom at TSflightlines for all my fluid lines.

>The best place I've seen for the red cube is up on top of the engine right in line with the fuel injection spider.

>The best reason I can think of to use aluminum tubing per plans is cost, and long term reliability. Flexible aeroquip type hose is more expensive, and may not last as long.

>I would not install a gascolator in your situation. The fuel filter you mention should be all you need.

>Most mechanical fuel injection systems I've seen on RVs don't have a return-to-tank system, but you should check with Lycoming, or get the manual on whatever fuel injection system you are using to make sure.

Good luck

Have you seen this ?

http://www.andair.co.uk/sport-general-aviation/fuel-systems/

I like the idea of not having a filter in the cabin ... the Gasculator in the wing root - 70mic - now if you clog one filter .. you can switch to the other tank ...

Gascolator or not

Hi,
I will get to the same point in the very near future, also Andair fuel pump and fuel seletor.
I asked Andair about fuel filter or gascolator and they recomend 2 gascolator, one in each wing root and no fuel filter. If no gascolator then fuel filter before the pump.
I'm planning the dual gascolator in the wing roots. There is a nice picture on the Andair website to show the setup :
http://www.andair.co.uk/sport-general-aviation/fuel-systems/
And also a few pictures on some buildre's websites, just do search on the forum.
Alain

I used 5052 tubing for brake and fuel lines. I installed the red cube in the tunnel per Van's. My IO-540 sips 26.5 gph at takeoff with no problems. I usually have .5 tp 1 gallon more fuel in the tanks than what my fuel totalizer says after a 4.5 hr flight.

There is plenty of discussion on this topic.

Is it common to install flex hose in this area? I doubt it. However it is "acceptable", if somewhat contrary to aircraft standard practice. People use it because it is easier to run- while aircraft standard practice reserves hose for installations with relative movement or recurring maintenance issues.

The pros and cons of hose vs. Tube are well documented. In this case, where the primary benefit of hose is absent (no relative movement between components) you are left with:

Con:
Hose is heavier, more expensive, bulky, more damage prone, and usually has a shorter service life.

Pro:
Hose is somewhat easier to install, is less sensitive to correct measurement during fabrication, easier to achieve a leak free seal the first time, and some people think it "looks cool"

Thoughts

Ben--There has been volumes written on VAF and other forums about the use of teflon hose versus aluminum tubing in cabins. YES---aluminum when properly fabricated is great. Light weight, and low overall cost. The reason I worked on developing teflon hose packages for alot of the cabin lines was because the average builder was having problems making proper flares on the tubing, and having them either leak, or break. Many builders were learning as they went, and frankly were having problems. Granted, many builders can properly make aluminum tube assemblies they function just fine for the lifetime of the airframe.
Teflon hose is more expensive. BUT--it is in my opinion--a lighter smaller alternative to 303 hose, and believe it or not, a more reliable alternative to hose clamps and barbed fittings when properly installed.

For injected engines, most builders delete the gascolator. Most of the filters used for injection are very high quality. Yes----alot of builders are now installing filters in the wing roots, in addition the the primary one near the pump. Most are also locating the flow transducer (red cube) under the cowling and not in the tunnel, even in RV10 applications. That location is a matter of builder choice---we;ve seen them ins almost every imaginable place, and I personally havent heard of anyone having eratic readings. Perhaps others can chime in here.
Tom