STC'd Fuel Tanks, etc.

[MikeB]

Looks like my faithful old Cherokee will probably be sold within the next few weeks so I'm "thinking" about installing extra fuel capacity in my Champ (hate it when the needle bounces around the 1/4-E mark) I guess my preference would be 5 or 6 gallon wing tanks. I may have one located, depending on whether or not the owner decides to install 13 gallon wing tanks in his Champ that's currently in the rebuild stage.
Questions (1) Does anyone on this site have a set for sale? Price? etc.
(2) What's involved with installing the two tank setup? I assume pull the wings, etc. but are there any pitfalls, I should be aware of? The wings on my Champ were covered with the 7600 BR process several years ago which is still good, but most likely I will do a wing recovery anyway as the stuff is pretty hard to work with when trying to patch and I'd like a good look inside the wings since they're the only thing I didn't cover myself.

Finally, does anyone have a 337 for installing a Brackett air cleaner on a Champ?

You can contact me off list on the "membership list".

Thanks,
Mike

[Ron Babos]

Mike: Whatever tanks you install in the wing or wings, put a nice big blast tube in the cap and cap off the original vent. My experience has been without it, the dam thing will vapour lock and not transfer fuel when you need it . How the original set-up ever got certified is beyond me. The L-16 beside me which has two wing tanks, and mine which has one 5 gal in the right wing have had problems until the pressure tube was added. I found even the 100ll vapour locked. The main design flaw here is the fuel transfer should be at the top of the tank , and not the bottom, where vapour pressure in the transfer tube is high enough to keep fuel from flowing from the wing tank. The only way that I could make it work some times is pull some Gs or throw the plane around the sky until it started to flow. This erratic flying behaviour is no longer needed with the pressured fill cap. Just something to think about.
Ron

[Dennis]

I am in the process of installing two of Wag's wing tanks into my Champ. I welded a bushing with an internal tube into both sides of the bottom of the header tank. This way, the fuel enters the header tank by exiting the tube near the top of the tank without restriction and does not "compete" against the pressure in the header tank. An additional plus is in the event the line from the wing tank leaks, the fuel below the tube inside the header tank is not affected.

Dennis

[MikeB]

Dennis,
What you're doing makes sense, although you must have the tank out to be able to weld on it. In my case, that's not an option without pulling the boot cowl, windshield, etc. How do the tanks fit into the wing cavities? and how does the plumbing normally go? Did they send fairly detailed directions. Sorry for all the questions, but just trying to get a feel for what I might be letting myself in for (I've done enough of these jobs to know that something which should be simple, often isn't). If you have a direction sheet, is it possible to fax me a copy? 715 878 4482 Thanks, Mike Berg, Wisconsin.

[Dennis]

Mike,

The tanks fit into the first bay cavity with "lips" on the top front and back of the tank designed to fit over the spars. There are a couple of "L" bracket supports. There is a plywood floor for the bottom. Since the edge of the main rib (not the wing root rib) is used to support the outside of the plywood floor, one side must have an "L" member riveted to it to support the plywood. Pretty straight forward. The tanks are designed to set between the drag wires. Nothing to move. The plumbing exits the wing root at the rear plus the drain on the bottom of the wing. The wing is presently on the table going back together. The kit is pretty complete. The directions are pretty good except for where the fuel lines enter the fuselage. According to the instructions, as best as I can make out, they enter through the windscreen??????? Since I am not that far along, I have not taken the time to reread or research the instructions. Will let you know how it goes.

Dennis

[Dennis]

Mike,

Several interesting points concerning the Wag wing tanks. The first point concerns running the fuel line from the shutoff valve inside the aircraft to the wing tanks. According to the STC:

"Complete the installation by making up the other fuel lines from the fuel shut off valves to the tank, .......run this line upward along the inside of windshield and out the through the side opening near the top. Be sure that the bend in the fuel line is made so that it will be lower than the tank fitting when the aircraft is in level flight position. It will be necessary to drill a 11/32" hole in the left window sill approximately 1-5/8" to the rear of forward edge and and 1/4" inboard of the edge of the window sill. Install into this hole the AN 911 grommet and run the fuel line through it to prevent vibtration and chaffing."

The first sentence sounds as if the fuel line exits at the wing root opening in the windscreen and is so indicated on the drawing as the fuel line installation for the right side. I am sure you know, however, that there are no wing root openings on a Champ windscreen. The last two sentences indicate that the left side fuel line runs up through the left window sill adjacent to the sliding window and is so indicated on the drawing. Quite frankly, if you have the Citabria windscreen, you could run both fuel lines through the wing root openings. I do not think it would be wise to notch the Champ windscreen for the fuel lines for obvious reasons. Nor do I want to "drill" the window sill. I think the installation on the right side can be duplicated on the left side without drilling the window sill. I plan to run the fuel lines up the inside edge of the windscreen, circle around the post at the top and through the headliner and farbic.

If you got a better idea, let me know.

The next point has to do with where the wing tanks feed into the header tank. You do not modify the fuel line from the header tank to the gascolator as I have seen done.

"Remove the primer line 90 degree elbow, from the tank and drill into the small hole, the fitting was removed from, with a 15/32" drill ......., tap this hole with a 1/4" pipe tap. Install nipple............and cross fitting......"

Oh yes, one more thing. Item 1 of the instructions says: "To install this auxiliary fuel tank kit, start by removing all wing fairings, windshield, and metal wrap around cowling that the windshield fits into." Interesting!

Hope this gives you some ideas.

Dennis

[MikeB]

Dennis,
Gives me some ideas that if you follow the directions exactly, you might be letting yourself in for more work than you need to . I looked at a couple of installations at Oshkosh and they pretty much followed the path you are taking. One that I thought was neat, although it might not be 'legal' in the sense of the word, had a shutoff valve on either side up near the headliner and was marked "left tank on/off & Right tank on/off". Thanks for the info and keep me informed.

Mike Berg

[Dennis]

Mike,

The "kit" comes with the shut off valves and the metal placards. I too have seen the valves located near the top. And I think I would like them up high in view. If the fuselage was not covered, painted and the headliner installed, I would weld a plate behind the front post as a mount for the valve. I am just about ready to remove the boot cowling for painting. When it is off, I will look for a place to mount the valves.

Dennis

[MikeB]

Dennis,
I just saw a friend of mine (who seems to be in the know) at a fly in today and were were talking about the aux. fuel tank installation. According to him, the reason for removing the boot cowl, windshield, etc. is to remove the fuel tank and weld in a fitting that will allow the aux. fuel to run into the header tank rather than below the shut off valve (according to STC).
I'm quite sure whatever method is used the fuel will still get to the header tank as everything is gravity flow anyway. I suppose removing the primer line fitting is just another method of accomplishing the same task.

[Ron Babos]

Mike: Adding a fitting is the best way to go. If you don't go this route , add a large blast tube to the filler cap and plug the tank vent , if you go with transfer to the bottom of the tank, otherwize vapour lock will occur and prevent fuel flow. Reliable fuel transfer will not happen if at least one method or other is used. The original factory method will let you down when you need it most.
Ron

[Paul Agaliotis]

Mike,
I have installed two of the Aero Fabricators fuel tank STC. As Dennis has pointed out all of the major components have good installation proceedures. The areas I had concerns with were the fuel lines and valve locations. The lines were installed as Dennis described,drilling a hole in the windshield sounds a bit silly to me. The valves were installed with Adel clamps and are a little strange to operate,being under the panel.
Drilling the fuel tank at the primer tap was not as bad as expected. I drilled and taped the bung with the tank in place. You need to be careful and remove any chips that enter the tank. A little grease on the cutting tools will help hold the chips.
I also have troubleshot some aux tank problems such as slow to transfer as Ron brought up. One had an obstruction (wasps nest) the others were vent problems. The replacement caps that are being used are vented to allow the air in but have some kind of check valve that stops the air from escaping when the aux tanks are selected. As a result the tanks are slow to drain. A quick modification cures this problem.
On a side note the boys at Aircraft Covering Systems are using a modified Ceconite 7600 process that could save you covering your wings. I have used the Blue River process and think it has promise. ACS has smoothed over some of the problem areas and has a good looking product. Being non toxic it doesnt require has-mat shipping. I was going to try Superflight but shipping to Calif. was almost as much as the covering supplies. I hope I have been some help. Paul

[MikeB]

Paul, Ron and Dennis:
Thank you for the useful information. This is a great site to exchange information on. I'm still procrastinating on installing the wing tanks, mostly because I don't want to tie my plane up. So I'm thinking: I'll do it over winter when the weather isn't so nice. But then there's ski flying up here in the frozen north......hmmmm . Thanks for the information regarding Aircraft Covering Systems. I'll have to see if I can find their address on Goggle.

[Eddie Wilson]

Hi,
This subject is just what I have waiting for! I just bought a 7DC project that has two of the STC wing tanks already installed. The both wings are recovered and the fuse was totally diassembled by previous owner. (I mean totally!!!!)I am lost on the fuel system. Each fuel tank have Foward and Aft outlets . Are both used? Does each wing tank have its own dedicated on/off valve or can they be T'ed together? Why would my original on/off valve be relocated ?
I am looking for someone who has already worked this out!

Eddie Wilson

[Paul Agaliotis]

Eddie,
Not knowing all of the information I try to answer your question. If the tanks are 13 gal. in each wing they can be installed per TC information, providing they are installed using Champion kit 192. The plumbing should be covered by this installation kit. I believe the nose tank is removed.
This model should have a 5.5gal wing tank and the 13gal nose tank.
The service and parts books will help you with alot of these questions. I hope I have been some help. Paul

[Eddie Wilson]

I should have specified that my 7DC has the 6 gal aux tanks in both wings. The main tank is original 13 gal.
Thanks
Eddie Wilson