PA-12 Fuel System Questions..

[Mikey]

Hope somebody can give me some insights, in process of recovering (read restoring...) my PA-12 after 30yrs of faithful service. My question is regarding the standard 18 gal wing tanks. There is what appears to be a "vent" port at the upper fwd. corner of each tank, the 2 ports are interconnected by a tee in the headliner, piped down the window post and run into a fitting at the top of the gascolator on the firewall. What is the purpose of these lines? In that it bypasses the L & R fuel shutoff valves, it would appear that in event of a nose-over accident, there would be fuel to the firewall that cannot be shut off. Any thoughts on this?
Thanks
Chris Duros
N3719M

[Fortysix12]

Look in the part manual. CAll Clyde Smith JR.

[Fortysix12]

Look in the part manual. CAll Clyde Smith JR.

[PA12driver]

Mikey,

What you are looking at is most likely the "stock 12 configuration when a "header" tank is installed with two tanks. When I first got my 12 (and after owning a half dozen supercubs) I thought I had a bad selector valve? Let me explain: the system has a shut off valve for both the left and right tank, there is a "Cross over tube that (is the one you are talking about it goes into both tanks at the upper front corner then there is a Tee that goes down as you described to the (top of the Headertank) that is buried under the boot cowl (outside the fuselage tubing) dumbest damn place I can think of) both tanks feed into the bottom of that tank, and the "head pressure" keeps the engine running if you get the "Nose" down and are extremely low on fuel or in a slip and at the same time and no longer are flowing fuel to the rear (and only outlet of the wing tanks) there should also be a shut off valve that is just in front of the header tank just before the firewall bulkhead?/ gascolator.

Ok enough is enough, If this is what you have it is plumbed according to the factory drawings. I will post a drawing in the Photo section (cub mods) if you need on or if you give me your e-mail by PM I will email you a drawing and photos?

Good luck,

Tim

[PA12driver]

Mikey,

I sent you a drawing of the fuel system (stock configurations) Hope it helps.

Good luck with your project. Post us some pictures?

Tim

[klm_ak]

Hey Tim,
Mine's a late model Pa-12, May '47, after they stopped building them with header tanks and it still had that silly line from the gascolator up to the crossover vent tube (not anymore though!).
KLM

[PA12driver]

KLM< Best I can tell is it will allow for 'expansion to flow to the Gascolator rather then all over the wing?

Tim

[klm_ak]

landesskis,
Just curious, why?
Kenneth

[klm_ak]

Thanks for the info Gary.

I have replaced my tanks with AES tanks, which do appear to drain much better than the stock tanks (something like 1/2 gallon of fuel left out of 48 rather than 1 gallon of 38 ) I hope they sump equally well.

I didn't realize you had a PA-12. I'm surprised you haven't STC'd the belly pods for the PA-12.

Kenneth

[BES]

Please forgive my ignorance, but what are AES tanks?

Bent :o

[djfraudman]

BES, I believe it is Air Energy Supply and the operator is as follows from another post.

Clarence Witt has an STC, and builds 24gal tanks for the PA12/14 and also has an STC for 19 gal tanks


The STC #'s for Clarence Witt's PA12/14 modifications are:

SA01333CH - installation of 24 gallon fuel tanks for the PA12/14. Note that header tanks are not required. In my case, I already installed header tanks before I became aware of this mod, so I intend at this time to leave them in. Both fuel gauge options are available - sight or electrical.

SA00805CH - installation of 19 gallon fuel tanks for the PA12/14.

Give him a call: (309) 594-2280

[BES]

OIC, thanks for the explanation. I did in fact talk to Clarence. I bought a J3 tank from him years ago and was happy with the quality and workmanship. Unfortunately, Clarence has decided to retire and is no longer building or selling fuel tanks.

Bent

[Marc Olson]

Interesting that Gary pointed out problems with water in stock -12 tanks. About a month ago I noticed a line midway down the sight gauge for my left tank. Closer inspection showed water at the bottom of the gauge, which had somehow migrated to the gauge. This after months of sumping with no sign of water at either the tank or gascolator...

[klm_ak]

Mark,
Do you have stock PA-12 under wing sight gauges or supercub style wing root sight gauges?
K