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Fuel System Mod

Taledrger

Taledrger

SPONSOR
SW Michigan
Decide to redo the interior on the L21 and install the CC fuel STC to get rid of the header tanks. She's all tore apart and ready to start reassembly as soon as I get the right tank back from doing the fitting mod.
Any advise on the install? Do's don'ts, etc.
Any examples of how to run the lines with L21 glass would also be appreciated.
 
airframesalaska.com. look at the fuselage mods pictures for the L-21 glass.....
 
Well....

Jason G. talked me out of this mod. He did some test flying for Dakota, and said that if you fly with low fuel in steep angles it will cough on you.

Example: put 5 gals. in to fly to that steep approach gravel bar or mountain top and back.

I am leaving headers in.
 
I put the mod in my -12. I thought the instructions/STC was straight forward. I had to call CC once during the whole thing to ask them about a question. I did some research on here before I bought the STC. I learned that if you are parking on a slope, you could transfer fuel from one tank to another, even if the valve is off. To prevent this, people say to move the valve to the Left or Right tank. I haven't flown mine yet so I can't tell you how it operates but I know others here who have them on their -18 and -12 and like them. Hope this helps.
 
I've heard of low-fuel continuous-banking engine-coughing on the headerless systems. Never experienced it, though.

I also don't want to run those snorkel gas caps (icing, bug problems??), so I'll keep my headers on this next one I build. DAVE
 
I have done some aggressive angles of attack and banks with 1/4 fuel and can't say I ever had one cough or sputter with headerless. More tanks mean more weight to everyone who is sensitive about weight. One less thing to catch on fire (corrected remarks from napalm) ;)
 
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It does require thought on part of the pilot..... If you small quanity of fuel is only in lower wings tank... It's gonna get quiet...
 
I doubt many have flown there headerless system as low on gas as I have and continued 60 degree banks.
It has never stumbled once in 1200 hrs.
Somethings not right if it does.

Brad
 
Have two with ,and one with out. always run right dry on every flight, so if you have 2or 3 gallons it's best to be in one tank,and of corse header planes left tank highest header. don't tell but remove cross over tube on penn yenn or CC , then no cross over so you can time out tanks, our burn can very from 11/hr to 5/hr
 
Attlee makes a nice SS header tank. I replaced my aluminum header 15 years ago....the forward one...the one that is always above the carburetor, providing a positive head...That's a good thing in a gravity flow system.....
 
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Never had a problem, unless it was my fault for running low on fuel,, very low... But it dosent matter which angle, you always have fuel flowing to the carb... The Dakota tanks have outlets front and rear and running the valve on both, you have fuel flowing out of any corner you need...... Never had a problem with the snorkel caps either...
 
The CC AFC has a Left---Right----BOTH----OFF select valve. The left and right wing tanks are bunged/ported fore and aft and there is a cross over feed tube.

If you have three cups of fuel remaining and are in a seventy degree bank I could foresee the engine stumbling for fuel starvation-----otherwise I have never had a problem.

The "snorkel" fuel caps pressurize the system to 1-2 psi--if memory serves.
 
I know a few guys who have crashed Cubs and been splashed with fuel. Without exception it's been from the wing tanks, not headers. If you're building a Cub from the ground up (like CC does) it probably makes good sense to eliminate expensive outsourced parts. Duh. In my plane? I have headers and a L/R/Both fuel valve. I didn't ask for it. When I took my airframe to the recognized PA-12 expert for the fuel system installation that's what he put it. With Atlee headers, too. I have no reason to think my fuel system is superior to anyone else's. I'm comfortable that it isn't inferior, either. It's proven airworthy. That's satisfactory for me and my family. If you're one of those guys who flies with minimum fuel in order to allow you to get into short places in the mountains to chase sheep, you're bucking the winds while you work your way under the clouds to the only notch that will let you get to the other side, you line up to fly through only to be met with turbulence that hurts, the only option to escape is to do a high power 60* plus face bender right at the granite wall that's filling your windscreen, and the very last thing you want is to hear your engine stumble? Your decision to remove your headers might be different than the other 99% of Cub owners who will never push themselves or their planes to that extreme. You know what? If it doesn't apply to my capabilities, performance potential doesn't matter. I could get along with or without headers. It sure as hell isn't worth arguing about.

My Atlee HD header tanks are aluminum.

SB
 
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I am putting together a PA-18 frame right now for a customer and it has a headerless fuel system. I got this project after another mechanic in the area had already started on it. Most of the fuel system was already installed. All I did was finish installing the right tank fuel lines. Here are some pictures I took the other day after I finished it.

IMG_0198.JPG

Here is the fuel valve. It has been modified to L/R/Both positions as per the STC. I deviated from the STC a little bit by installing the tee for the Right fuel tank lines right at the valve. I did this because the position that the instructions refer too interferes with the cabin heat/carb heat controls that are mounted on the interior panel.

IMG_0199.JPG

Here is a view of the forward fuel lines. You can see the right tank fuel line running down the windshield post, across the firewall and into the rear tee on the valve.

IMG_0200.JPG

Here is a view of the rear fuel lines. If you look closely you can see the right tank line running basically in the same location as the original except the header tank is removed. This cub had L-21 glass in it at one time and the lines ran right in the same spot as a standard cub. It is being put back together with D windows and a metal Atlee Dodge head liner.

Brian.
 

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StewartB said:
I know a few guys who have crashed Cubs and been splashed with fuel. Without exception it's been from the wing tanks, not headers. If you're building a Cub from the ground up (like CC does) it probably makes good sense to eliminate expensive outsourced parts. Duh. In my plane? I have headers and a L/R/Both fuel valve. I didn't ask for it. When I took my airframe to the recognized PA-12 expert for the fuel system installation that's what he put it. With Atlee headers, too. I have no reason to think my fuel system is superior to anyone else's. I'm comfortable that it isn't inferior, either. It's proven airworthy. That's satisfactory for me and my family. If you're one of those guys who flies with minimum fuel in order to allow you to get into short places in the mountains to chase sheep, you're bucking the winds while you work your way under the clouds to the only notch that will let you get to the other side, you line up to fly through only to be met with turbulence that hurts, the only option to escape is to do a high power 60* plus face bender right at the granite wall that's filling your windscreen, and the very last thing you want is to hear your engine stumble? Your decision to remove your headers might be different than the other 99% of Cub owners who will never push themselves or their planes to that extreme. You know what? If it doesn't apply to my capabilities, performance potential doesn't matter. I could get along with or without headers. It sure as hell isn't worth arguing about.

My Atlee HD header tanks are aluminum.

SB
Click to expand...

SB,

you took a few steps farther than my statement. There are times that I am flying very short hops, and want the plane as light as possible for these. Five extra gal. of gas is 30 lbs. Will that little bit make a difference? maybe not, but I want that option. When I go bouncing down a strip and have to use some rudder uncoordinated turn on approach, I want to know I have fuel.

But most flying it does not make a difference.
 
Flying in the mountains, sheep hunting, turbulence, minimum fuel for some high short place where you shouldn't be landing.....What could go wrong?
 
Flying in the mountains, sheep hunting, turbulence, minimum fuel for some high short place where you shouldn't be landing.....What could go wrong?
Click to expand...

Tango...

It is fun and challenging and we are blessed with the opportunity to play in some of the best country in the world.

I am with you... stock fuel system... when you are out of gas, you are truly out..
 
I should clarify that the times I've been low on fuel and still working, I had a place to go/land if she quit me.
Best solution on any system is plenty of fuel, easier on your blood pressure too.

Brad
 
I have header tanks. From level flight, made a steep left descending turn yesterday with both tanks half full. Full selector was on Rt. tank. Got to the bottom and she coughed and quit. Switched tanks and she flew off. Learned a valuable lesson ending up several feet above the water before flying off. Thought for a second I had lost her. Don't understand why I lost fuel flow? Was also told to take off and land on left tank only. I clearly need additional explanation on his subject.
 
Brian,
Thanks for the pictures. Our plan is basically the same.

Thanks for all the other comments. Did not really mean for this to turn into a header vs header-less debate. There is plenty of that in previous threads.
Wonder if there would be any adverse effect in a downwind turn??:lol:
 
jjack said:
I have header tanks. From level flight, made a steep left descending turn yesterday with both tanks half full. Full selector was on Rt. tank. Got to the bottom and she coughed and quit. Switched tanks and she flew off. Learned a valuable lesson ending up several feet above the water before flying off. Thought for a second I had lost her. Don't understand why I lost fuel flow? Was also told to take off and land on left tank only. I clearly need additional explanation on his subject.
Click to expand...

If your turn was not coordinated.....

I know my stock system will cough when low and on the right tank when nose down.
 
jjack said:
I have header tanks. From level flight, made a steep left descending turn yesterday with both tanks half full. Full selector was on Rt. tank. Got to the bottom and she coughed and quit. Switched tanks and she flew off. Learned a valuable lesson ending up several feet above the water before flying off. Thought for a second I had lost her. Don't understand why I lost fuel flow? Was also told to take off and land on left tank only. I clearly need additional explanation on his subject.
Click to expand...

The stock Cub fuel system has only an AFT fuel pickup in the right tank. So, circling and descending to the left with the right tank selected, and relatively low fuel, all the gas in that right tank flowed forward, and away from the fuel pickup. The engine continued to run until you ran the remaining gas out of the header tank, then quit.

This is the reason that the admonition for the stock airplane is level flight on right tank. Descents are the worst case scenario if you have low fuel. Many airplanes have been modified with a forward pickup on the right tank as well. Probably a good mod in any case, and as noted above, some aftermarket suppliers are providing that. The stock left tank has both a forward and aft pickup.

MTV
 
Thank You mvivion. The response I was looking for ! This is what makes Supercub.Org so Great! Hope someone else learns from this, the easy way!
John
 
This is one reason why I went this route with the -12. The -12 only has pickups on the rear of the tank only. It could cough on you if you are descending from altitude when low on fuel. I wanted forward pickups for safety but I do not think a 337 field approval would be easy to get...ecspecially pertaining to fuel. The CC STC takes care of that because you need to add forward pickups. for me, it was a no brainer and I'd do it again.
 
Some shots taken during our rebuild of N18SY. Not an L21 but one of the shots shows the 1/4 inch crossover line.
Darrel
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Did the CC STC apply to a PA-12 I was told it doesn't and is only for a PA-18?
 
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