Likes Likes:  0
Page 1 of 2 12 LastLast
Results 1 to 40 of 58

Thread: Fuel System Mod

  1. #1
    Taledrger's Avatar
    Join Date
    Sep 2003
    Location
    SW Michigan
    Posts
    1,012
    Post Thanks / Like

    Fuel System Mod

    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.
    Bob D

  2. #2
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    1,736
    Post Thanks / Like
    airframesalaska.com. look at the fuselage mods pictures for the L-21 glass.....

  3. #3
    aktango58's Avatar
    Join Date
    Aug 2004
    Location
    18AA
    Posts
    9,597
    Post Thanks / Like
    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 don't know where you've been me lad, but I see you won first Prize!

  4. #4

    Join Date
    Apr 2007
    Location
    Kingsburg, CA
    Posts
    1,256
    Post Thanks / Like
    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.

  5. #5
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    1,736
    Post Thanks / Like
    I'm with you on that aktango58.....I'm leaving mine in also.....
    Thanks cubnut thanked for this post

  6. #6
    Dave Calkins's Avatar
    Join Date
    Jul 2002
    Location
    Anchorage, Alaska
    Posts
    5,504
    Post Thanks / Like
    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

  7. #7
    Bugs66's Avatar
    Join Date
    Feb 2004
    Location
    Spokane WA
    Posts
    2,310
    Post Thanks / Like
    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)
    Last edited by Bugs66; 01-31-2011 at 12:00 AM.

  8. #8
    mike mcs repair's Avatar
    Join Date
    Aug 2004
    Location
    chugiak AK
    Posts
    11,773
    Post Thanks / Like
    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...

  9. #9
    Widebody's Avatar
    Join Date
    Oct 2006
    Location
    ND/AZ
    Posts
    747
    Post Thanks / Like
    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

  10. #10
    Widebody's Avatar
    Join Date
    Oct 2006
    Location
    ND/AZ
    Posts
    747
    Post Thanks / Like
    Quote Originally Posted by Dave Calkins View Post

    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
    Not sure why anyone uses them? I never have. Vented cap works just fine.

    Brad

  11. #11

    Join Date
    Jul 2009
    Location
    racine,wi
    Posts
    684
    Post Thanks / Like
    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

  12. #12
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    1,736
    Post Thanks / Like
    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.....
    Last edited by nanook; 01-30-2011 at 09:30 PM.

  13. #13
    SteveE's Avatar
    Join Date
    Feb 2006
    Location
    Jenks, OK
    Posts
    4,264
    Post Thanks / Like
    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...

  14. #14
    Seaworthy's Avatar
    Join Date
    Feb 2005
    Location
    Massachusetts
    Posts
    1,563
    Post Thanks / Like
    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.
    Marine Corps Aviation since 1966

  15. #15

    Join Date
    May 2006
    Posts
    231
    Post Thanks / Like
    If the turn is coordinated the gas does't run "downhill" in the lower wing tank does it?

  16. #16
    StewartB
    Guest
    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
    Last edited by StewartB; 01-30-2011 at 11:30 PM.

  17. #17
    Steve's Aircraft (Brian)'s Avatar
    Join Date
    Aug 2004
    Location
    White City, Oregon
    Posts
    962
    Post Thanks / Like
    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.

    Click image for larger version. 

Name:	IMG_0198.JPG 
Views:	247 
Size:	1.80 MB 
ID:	980

    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.

    Click image for larger version. 

Name:	IMG_0199.JPG 
Views:	179 
Size:	1.72 MB 
ID:	981

    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.

    Click image for larger version. 

Name:	IMG_0200.JPG 
Views:	232 
Size:	1.67 MB 
ID:	982

    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.

  18. #18
    aktango58's Avatar
    Join Date
    Aug 2004
    Location
    18AA
    Posts
    9,597
    Post Thanks / Like
    Quote Originally Posted by StewartB View Post
    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
    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.
    I don't know where you've been me lad, but I see you won first Prize!

  19. #19
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    1,736
    Post Thanks / Like
    Flying in the mountains, sheep hunting, turbulence, minimum fuel for some high short place where you shouldn't be landing.....What could go wrong?

  20. #20
    aktango58's Avatar
    Join Date
    Aug 2004
    Location
    18AA
    Posts
    9,597
    Post Thanks / Like
    Quote Originally Posted by nanook View Post
    Flying in the mountains, sheep hunting, turbulence, minimum fuel for some high short place where you shouldn't be landing.....What could go wrong?
    What could be better? (besides bird hunting up there)
    I don't know where you've been me lad, but I see you won first Prize!

  21. #21
    dalec's Avatar
    Join Date
    Oct 2009
    Location
    Anchorage and beyond
    Posts
    529
    Post Thanks / Like
    Flying in the mountains, sheep hunting, turbulence, minimum fuel for some high short place where you shouldn't be landing.....What could go wrong?
    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..

  22. #22
    Widebody's Avatar
    Join Date
    Oct 2006
    Location
    ND/AZ
    Posts
    747
    Post Thanks / Like
    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

  23. #23
    jjack's Avatar
    Join Date
    Dec 2007
    Location
    coastal n.c.
    Posts
    215
    Post Thanks / Like
    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.
    JohnnyJackson

  24. #24
    Taledrger's Avatar
    Join Date
    Sep 2003
    Location
    SW Michigan
    Posts
    1,012
    Post Thanks / Like
    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??
    Bob D
    Thanks cubnut thanked for this post

  25. #25
    behindpropellers's Avatar
    Join Date
    Feb 2003
    Location
    NE Ohio
    Posts
    6,941
    Post Thanks / Like
    Quote Originally Posted by jjack View Post
    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.
    If your turn was not coordinated.....

    I know my stock system will cough when low and on the right tank when nose down.

  26. #26
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Bozeman,MT
    Posts
    11,705
    Post Thanks / Like
    Quote Originally Posted by jjack View Post
    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.
    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

  27. #27
    jjack's Avatar
    Join Date
    Dec 2007
    Location
    coastal n.c.
    Posts
    215
    Post Thanks / Like
    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
    JohnnyJackson

  28. #28

    Join Date
    Apr 2007
    Location
    Kingsburg, CA
    Posts
    1,256
    Post Thanks / Like
    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.

  29. #29
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like
    Some shots taken during our rebuild of N18SY. Not an L21 but one of the shots shows the 1/4 inch crossover line.
    Darrel
    Click image for larger version. 

Name:	PC110008.JPG 
Views:	212 
Size:	1.06 MB 
ID:	1014
    Click image for larger version. 

Name:	P3260004.JPG 
Views:	177 
Size:	1,007.6 KB 
ID:	1016
    Click image for larger version. 

Name:	P8190004.JPG 
Views:	184 
Size:	1.06 MB 
ID:	1019
    Click image for larger version. 

Name:	P8190021.JPG 
Views:	173 
Size:	1.02 MB 
ID:	1021
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	P6200014.JPG 
Views:	136 
Size:	1.03 MB 
ID:	1020  
    Last edited by Darrel Starr; 02-01-2011 at 02:04 PM.

  30. #30
    twoton's Avatar
    Join Date
    Sep 2007
    Location
    Dassel, MN
    Posts
    95
    Post Thanks / Like
    Did the CC STC apply to a PA-12 I was told it doesn't and is only for a PA-18?

  31. #31

    Join Date
    Sep 2007
    Location
    Fairbanks, Alaska
    Posts
    127
    Post Thanks / Like
    Keep in mind during the installation that any water needs to run down hill to the gascolater. 3" gear and bushwheels may require a T with a drain out the belly from the lowest place in the system.
    Sandy

  32. #32
    behindpropellers's Avatar
    Join Date
    Feb 2003
    Location
    NE Ohio
    Posts
    6,941
    Post Thanks / Like
    Quote Originally Posted by twoton View Post
    Did the CC STC apply to a PA-12 I was told it doesn't and is only for a PA-18?
    You can use it in the PA-12 also. I'm pretty sure it is a different STC # though.

  33. #33

    Join Date
    Apr 2007
    Location
    Kingsburg, CA
    Posts
    1,256
    Post Thanks / Like
    Quote Originally Posted by twoton View Post
    Did the CC STC apply to a PA-12 I was told it doesn't and is only for a PA-18?
    CC STC applies to the PA-12 too.

  34. #34
    AkPA/18's Avatar
    Join Date
    Feb 2003
    Location
    Big Lake Ak
    Posts
    746
    Post Thanks / Like
    If I had the crossover between tanks I think I would crossover in front of the main tube above your headd between the front spar attach points. This way you can install a quarter turn valve that you can easily reach to isolate tanks. Solves the problem of full tanks and an uneven parking spot.

    Mark
    http://thrustline.com/

    Takeoffs are optional--Landings are mandatory

  35. #35
    Steve's Aircraft (Brian)'s Avatar
    Join Date
    Aug 2004
    Location
    White City, Oregon
    Posts
    962
    Post Thanks / Like
    Mark

    The crossover tube that Darrel is referring to is for the vent system. it plugs into the top of the fuel site gauges with a tee. The problem with the full tank/uneven parking has to do with the fuel valve. The STC requires that you install or modify the valve for Left Right and Both positions. When the valve is in the both or off position the tanks are interconnected allowing fuel to transfer between tanks. It is easier to ex-plane with a drawing......I can make one up later if needed.

    Brian.

  36. #36

    Join Date
    May 2006
    Posts
    231
    Post Thanks / Like
    So here is my interest in this thread:

    A couple months ago I came back from a cross country and was doing some touch and goes at the end of the day. Fuel was getting low. On the last one just as I was about to level off and turn downwind the engine coughed. More than coughed it shook pretty good and went quiet. I pushed the throttle in and hit the boost pump and pushed the nose down and landed downwind. The power did come back because I had to pull the power back off. I ran it up as hard as I could on the ground and it ran fine. There was no water in the sumps and I drained the tanks to see how much fuel was in there and there was about 2.5 gallons in each side. This was later and could have ran back across to the other tank though.

    I do have a header tank as well, and fuel pick ups in the front and back of each tank. Only have on or off for fuel selector and it was on! It is a 200HP fuel injected motor so there is a boost pump in there too and I had used it on take off but had turned it off in the climb when I initially reduced my power and prop pitch.

    So far about every theory that I have heard is then dispelled by two other people. Some thought there must be water in the fuel but there wasn't any in the sump and I understand if you get enough water to make the engine stop it doesn't start again. Someone else thought that because I was low and making left turns in the pattern that all the fuel ran to the low tank and away from the pickup on that tank. My brother pointed out that shouldn't happen if you are coordinated. While not perfect I wasn't skidding across the sky. I am thinking to have the mechanical pump checked on the motor and a compression check too.

    I know know the exact amount of fuel in the plane and recalibrated the sight gauge (different on each side) and in the future noise be damned I won't make a power or boost pump change until at pattern altitude.

    I bet there may be some other ideas out there and now I understand those cutsey screen names!
    Thanks Joe I mean AKSOMEWHERE

  37. #37
    AkPA/18's Avatar
    Join Date
    Feb 2003
    Location
    Big Lake Ak
    Posts
    746
    Post Thanks / Like
    Quote Originally Posted by Steve's Aircraft (Brian) View Post
    Mark

    The crossover tube that Darrel is referring to is for the vent system. it plugs into the top of the fuel site gauges with a tee. The problem with the full tank/uneven parking has to do with the fuel valve. The STC requires that you install or modify the valve for Left Right and Both positions. When the valve is in the both or off position the tanks are interconnected allowing fuel to transfer between tanks. It is easier to ex-plane with a drawing......I can make one up later if needed.

    Brian.
    Hi Brian

    The crossover is the problem with full tanks. You can turn the fuel selector to right or left but it will still feed through the crossover to the lowest tank. Put a valve in the crossover and select right or left and the tanks are now isolated.

    Did that explain it better??

    Thanks

    Mark
    http://thrustline.com/

    Takeoffs are optional--Landings are mandatory

  38. #38
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like
    The 1/4 inch diameter crossover tube is connected from the top of one gas gauge to the top of the other one. So except when the tanks are full, fuel doesn't flow through them. They are there in case one of the cap vents plug. The crossover tube in that case gives a second source of air to the tank with a plugged vent.
    Darrel

  39. #39
    Steve's Aircraft (Brian)'s Avatar
    Join Date
    Aug 2004
    Location
    White City, Oregon
    Posts
    962
    Post Thanks / Like
    Mark,

    Yes it did......did not see (or at least comprehend) your reference to the FULL fuel tank...
    In that case you are right, leave the valve in either Left or Right position and shut off the vent crossover to keep tanks from cross feeding while parked on a slope.

    I did a 180HP cub restoration a few years ago with a Penn Yann conversion and it had a vent interconnect running across the front. It is also a shorter run as far as tubing goes. Makes me wonder why CC has it going across the rear....

    Brian.

  40. #40
    SteveE's Avatar
    Join Date
    Feb 2006
    Location
    Jenks, OK
    Posts
    4,264
    Post Thanks / Like
    I have filled my tanks and been on a little of a slope and fuel starts running out the vent.. I reach in and flip the valve to the right tank and the fuel stops dripping... I have the cc fuel system.. now from what you guys are saying is that that shouldnt make a difference on whether or not fuel stops running out.... Dakota tanks with cc crossover fuel system... So what gives.

Similar Threads

  1. cub fuel system
    By petez in forum Tips and Tricks
    Replies: 8
    Last Post: 04-30-2005, 08:05 AM
  2. Fuel System help!
    By Jake in forum Super Cub Sick Bay
    Replies: 9
    Last Post: 01-31-2003, 03:20 AM

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •