Fuel Tank Material ??

I need help to understand the material of my tanks. I am working on a home build PA18. I have almost done every thing my self except fuel Tank. I recently get two (RT LT) from a PA12 or later model of piper dual tank with metal wing.

After check in the north land drawing scan of Piper drawing I have saw that material is alu. After inspection of solder join and all tanks I was 100% that was alu. because it look like alu. I have also reformed the drain that have been hurt and the material "behave" like alu.

BUT

Before welding one crack close to the drain. I make decision to clean fuel cap flange where rust was stuck I assumed from the fuel cap.

I was very surprised to discover that fuel flange is in steel !
Yes, it is magnetic !

But it is welded on the tank !

What does that means ?

ALL help or suggest are welcome !

Thanks !

The PA12 had tanks made out of turnplate steel. They are more square if I remember correctly with all the edges soldered. The PA18 tanks are two halves formed out of aluminum, I believe it is 5052, and welded together in the middle with a tube through the middle of the tank for the drag strut. The neck is steel and it is soldered into the aluminum tank.

The tanks are made from 5052 aluminum.

What is....

What is, "turnplate steel", and is it possible to solder steel to aluminum?

Mike

Terneplate is steel sheet that is coated in lead and other alloys. It was used a lot in the past in aviation for tanks. Henry Ford used it a lot on his cars. It solders well and is easy to bend and form. Terneplate is also heavy and not used anymore unless someone is wanting to make a restoration 100% accurate.

Thanks,

When you said steel coated, does that means that the "aluminum" of the flange was coated with steel after it have been weld on the tank ?

Did they use "brasing" for assembly ?

I have placed a picture of this "famous" tank in my folder (see bellow)

That is an aluminum late model PA18 and PA20/22 fuel tank because of the electric fuel gauge hole. The filler neck is formed into the tank with a sort of rolled bead or something and I was told it was soldered. I also edited my above post, the aluminum tank is made of 5052 H34.

Steve,

That is on this one that the the filler neck is magnetic and behave like steel.

Correct, the filler neck is steel and the tank is aluminum.

'Turnplate Steel"

Steve,
"The PA12 had tanks made out of turnplate steel? - Explain Turnplate Steel (you haven't been drinking?).
P.M. your e-maill address - I've got some good photo's of Lee at N.H.

Hope all's well!
Mark

Cub Junkie explained it the way it has always been explained to me.

Terneplate is steel sheet that is coated in lead and other alloys.

Click to expand...

Going good here. Great weekend.

stevepierce@pierceaero.net

Thanks.

I used .050 5052 for my tanks. Wag-Aero weldable filler necks. Building your own tanks is a very do-able and satisfying when done.

Yes, the original 12 had terneplate steel tanks. The seams were soldered, not welded and once removed, then re-installed, they always seemed (in my airplane at least) to decide to leak somewhere other than where it was just re-soldered. Until I had him replace those tanks with Cub tanks, my mechanic groaned every time he saw me coming.

Terneplate is not the most user friendly tank material, in other words.

MTV

I did a pre-buy inspection on a PA14 a few years ago. Removed the tank lids and inspected the tanks as good as I could without removal. Advised the prospective owner of the concerns with the ternplate tanks. A few months later I was doing some work on the plane when I noticed a puddle of fuel on the floor under the fuel site gauge that screws into the bottom of the tank. I tried to tighten the plug in the bottom of the gauge and it broke apart in my hand due to corrosion. I drained the tank and then tried to remove the gauge. Broke a 3/8" drive crows foot and ended up on the floor. Upon inspection I realized it had broken loose but it was the soldered in fitting that had broken loose rather than the threads on the gauge. I was concerned about soldering the bushing back on. I have soldered lots of copper tubing but was concerned about a fuel tank on an almost 60 year old airplane. We have a very talented guy here in town that has operated a radiator shop almost all his life. I called him for advice and he said bring it down. He cleaned it real good and soldered it back on for $20. Ed took that PA14 to Alaska last summer without a hitch and he flew in Saturday with his son and said hello. I am still keeping my fingers crossed but so far no indication of problems.

I have a Cub Club newsletter from about 1987 that has an article by J.E. Soares( Supercub fuselage guy from Montana). He fixed the oil canning problem with the old 12 tanks by drilling a hole top and bottom in the area between the baffles and then silver soldered stainless steel slugs from a punch press with a hole and inserted a welding rod through the tank and washers. Where the rod came through the slug it was bent flat and soldered also. This would keep the top of the tank from flexing.