Fabbing Lines with AN Fittings? Good -- Read This
 

I'm installing an oil cooler and plan to use a combination of hard (5052-0 Aluminum) and flexible plumbing with AN fittings. AN (Army/Navy) fittings date from the 1930s and helped firmly establish the USA as the goto country for anything that flies (Dreamliner teething issues notwhithstanding). In the ~80 years since their invention, they've made their way onto all sorts of devices where high-reliability, lightweight fluid connections are needed (like my turbocharged Miata).

To make sure that I get the most out of my AN connections, I decided to brush up on fabrication, assembly and inspection techniques. To do this, I went right to the source -- FAA. They publish a great how-to with lots of pictures and easy step-by-steps. Without further ado . . . here's the link:

http://www.faa.gov/library/manuals/a...83-30_Ch07.pdf

Happy wrenching.

Wow lots of neat info there! Saved this in my bookmarks!

That's awesome info. Especially cause I have a single and double flare tool wasting space and my Artech water fittings are looking iffy.

BTW, in the discussion on rigid line materials, 3003 Aluminum is discussed. Versatube (the aluminum tubing that comes in rolls) is 3003. When you buy aluminum tubing from most online retailers, this is what you are buying and those retailers gladly recommend it for fuel and oil lines.

According to FAA, 3003 should be used for:

"General purpose lines of low or negligible fluid pressures, such as instrument lines and ventilating conduits."

FAA specifies 2024-T3, 5052-O or 6061-T6 for fuel and oil lines. I got my 5052-O from Aircraft Spruce and Specialty.

Food for thought if you're doing rigid lines for something critical.

good shit !

Interesting document.

Dovetailing onto what Hornetball posted, perhaps this quote, which follows it, will provide some context:If 1,500 PSI is "medium pressure," then I think I'm OK with tubing rated only for low pressure. :)

An exercise in "FAA speak." The 1000 to 1500 psi recommendation applies to "hydraulic and pneumatic" systems.

The recommendation on fuel and oil lines (lines containing combustibles) is actually based upon strength and fatigue resistance where the specified alloys are far superior to 3003 (which is almost 100% aluminum). Oil and fuel systems on piston (and even turbine) aircraft generally have similar pressures to what we see on our cars -- far below 1000psi.

Nice link, adding to bookmarks. Thanks

Yeah F-15 structures and tubing craftsman here.

The important thing to remember about this, yeah it is over kill for the pressure inside trying to get out, but it also prevents any dings and wear from the outside getting in too. Don’t want any crush damage or even sand grains getting between it and a clip and vibrating itself a nice hole in the line. Some of the tubes I have seen, you can dent it with your fingernail.

We don’t use anything but steel in the wheel well on aircraft simply due to debris that can be kicked up. I do not have any 3003 on hand here at work (as it is almost pure aluminum I don’t see using it on these aircraft) It is probably softer then the copper tubing that everyone seems to bend that goes thru the firewall to the heater core. That stuff is soft.
And just checked, we only have 5052-O and 6061-T6, ¼ hard steel and titanium here, so I can’t get any to show the difference

We do use something that might be really close to it thou for one fluid and application. Fire retardant lines that go around the engines of a C-130, they had holes drilled every 12-18 inches to disperse the fire retardant and was super soft, so could be bent very easily. Always had to tweak it back after people stepped on it. By tweak i meanjut grab it and move it back.. it was almost like a what you would expect solder to feel like it if was a 1/2" around.

Might have that on other side of base, but I don’t have any reason to go over there. Will have to ask tomorrow.