Minimum 3/8" aluminum fuel line radius

Blain · #1 03-04-2016, 05:45 PM

Using the Andair valve in my -8. Fuel line routing is tight. Left tank line makes a 270 deg loop to find the vavle.

My tubing bender isn't an aircraft tool so I'm not confidant that the radius is correct for aluminum fuel line.

Searched the Forum, FAA AC 43.13 and EAA Hint for Homebuilders. No-joy.

So what is the minimum radius for the aluminum fuel line supplied by Vans?

RVDan · #2 03-04-2016, 07:41 PM

There really is no minimum radius per se'. The minimum radius is determined by the tooling you have and the ability to bend the tube without kinking. There is some very sophisticated tooling with inner mandrels and complex shoes that will bend tube incredibly tight. The common hand benders that we use in the field are a typical radius for general tubing.

Try a bend. If the tube doesn't kink, you are good to go. Vans tubing is soft and will bend fine with just about any hand bender tool.

Toobuilder · #3 03-04-2016, 08:42 PM

I have made some very tight bends with sugar. Get an extra long length of tube flared on both ends with nuts. seal one end with an AN plug of the appropriate size and pack the tube with sugar. Add another plug on the open end and be sure the sugar is tightly packed when the plug tightens down. Now you have a solid "rod" which will not colapse under even a very tight bend. Once to shape, dump out the sugar and wash in hot water. The sugar will not scratch the inside of the tube and hot water will disolve any remaining sugar.

lr172 · #4 03-04-2016, 09:04 PM

Quote:

Originally Posted by Toobuilder

I have made some very tight bends with sugar. Get an extra long length of tube flared on both ends with nuts. seal one end with an AN plug of the appropriate size and pack the tube with sugar. Add another plug on the open end and be sure the sugar is tightly packed when the plug tightens down. Now you have a solid "rod" which will not colapse under even a very tight bend. Once to shape, dump out the sugar and wash in hot water. The sugar will not scratch the inside of the tube and hot water will disolve any remaining sugar.

That is a great idea! A home-made and disposable mandrel.

Larry