flexible fuel lines - pro and con

[johncastor]

I am at the point of running fuel and brake lines. I've bought into the braided brake lines but wonder about the fuel lines. Some flex lines are used to connect the return lines to the andain fuel valve. Why or why not use flex lines on all fuel lines? Haven't yet tried to bend the tubing but have the tools.

John
RV-9A fuselage

[Kyle Boatright]

Weight and cost are why most aircraft (certified and non-certified) use aluminum tubing for the fuel and hydraulic lines when there is no requirement for flexibility.

[kevinh]

Originally Posted by Kyle Boatright

Weight and cost are why most aircraft (certified and non-certified) use aluminum tubing for the fuel and hydraulic lines when there is no requirement for flexibility.

Also, the aluminum tubing will likely last the lifetime of the airframe, with no need for the flex line periodic replacement.

I'd say go for the aluminum - at first I found it tricky to get bent to the right shape, but you will quickly learn the skills you need. Even fitting the fuel line through the A style landing gear becomes not that bad.

Learning more skills = a good feeling.

[13brv3]

At one time, I read that Van liked to use aluminum lines going out to the tank, because in the event of a crash, the aluminum tubing tends to pinch closed when bent and broken. Flex will snap right back fully open when ripped in half, and cause more of a fuel leak.

I have to admit that I'm very near the point of having to make some of these myself, and am considering going with flex this time. I will absolutely use flex for the brake lines, as the aluminum cracks under vibration, and there have been a few too many brake fires in RV's for my comfort.

Rusty