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Thread: Concerned about some corrosion on tubes

  1. #1

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    Concerned about some corrosion on tubes

    I recently bought this cub and noticed some corrosion on the X brace and a couple other tubes in the cockpit. Everything else looks fairly clean but these spots are showing some clear signs of corrosion. It kind of looks like some of the rust was painted over at one point as well. It's going in for its first annual next week and I'm a little worried about what might come of this. Just trying to budget for the annual bill, anyone have any idea if this is something that can be cleaned and protected or am I looking at a major repair with replacing these tubes?

    In one of the pictures you can see I cleaned a small spot of the rust off, it wasn't deep but the tubes definitely have some minor pitting left behind from the rust. :/
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  2. #2
    mvivion's Avatar
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    That does NOT look like "Minor" rust to me. A little hard to tell for sure from photos, but that would spook me. And, in any case, I'd REALLY want to know what the rest of the frame looks like.

    Where was this plane before you bought it? High humidity/coastal area? Do the logs offer insights? Do you know who rebuilt it last? Etc.

    MTV

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    All I know is it was hangared in northeastern Pennsylvania. Logs don't offer any insights. :/

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    RCharles's Avatar
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    When was it built and is there rust showing on the fuselage lower tubes any where?Check the tail group carefully.If you see any brown stains on the fabric inside the fuselage along the longerons then I would say find yourself another plane! That is from personal experience...

  5. #5
    Charlie Longley's Avatar
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    Rust never sleeps. You own the airplane so keep after it. A little elbow grease, primer and paint goes a long way. The lower longerons are critical to inspect.

  6. #6
    aktango58's Avatar
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    Hard to tell, but looks like some of the gingerbread also has corrosion.

    Not that hard to deal with that area, though you might end up pulling the skylight to really get it Clean.

    What I would be concerned with is having that much corrosion up high where it doesn't get wet, and wondering how much corrosion is on the lower part of the plane where it really gets wet?

    As your mechanic though. Let him guide you as it is his signature on the line. Also, he can touch it, and inspect it, and make a determination.
    I don't know where you've been me lad, but I see you won first Prize!

  7. #7
    TurboBeaver's Avatar
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    A prick punch and small hammer spent tapping every, 6/8" up "every one of the lower longeron's"; will tell you awful fast, spend extra time around gear fittings. It ring right out
    if it's solid. If they are half rotten thru they will sound flat and punky................ If they are 80% or more corroded from inside the punch will go right thru or dent the tube. This was standard procedure 30 years and NO ONE would have
    purchased without doing this test on any rag/tube airplane
    Some modern day mechanics will talk about the tiny spot
    the prick punch leaves......... Say a .030 spot. Could start coroding after the test. So simply take a small brush and put one tiny drop of paint/dope on the spots. Done.
    If it has longeron's that are rusted better plan on $20k to
    Replace em in today's market. Your surface rust on the overhead stuff will seam pretty minor if your longeron's are shot!
    Good Luck
    E
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  8. #8

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    Concur with the posts above especially #6, was that aircraft ever a banner tow? Or live outside in Florida? Corrosion up high like that is a tell tale sign it flew in humid salt air.

  9. #9
    jrussl's Avatar
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    Make sure to check behind the channel on the rear door post.

    Everything looked good on this one until the channel was cut off.

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  10. #10
    behindpropellers's Avatar
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    Are those LED lights glued to your tubing?

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    To my eye, those pictures show the tubes were repainted over existing rust and other crap. I would hate to see what is back there the fabric wraps the tubes.
    Regards, Charlie
    Super Coupe E-AB build in process

  12. #12
    Steve Pierce's Avatar
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    What does the tail look like? Remove the battery cover or baggage aft panel and look. Seen corrosion on the cockpit tubes from people grabbing the tubes and over time rubbing the paint off.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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    Quote Originally Posted by Steve Pierce View Post
    What does the tail look like? Remove the battery cover or baggage aft panel and look. Seen corrosion on the cockpit tubes from people grabbing the tubes and over time rubbing the paint off.
    Combined with salt from sweat on ones hands.


    Sent from my iPad using Tapatalk
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    Quote Originally Posted by behindpropellers View Post
    Are those LED lights glued to your tubing?
    Yeah the previous owner put them on. It's an E/AB cub and that was his solution to night cockpit lights.

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    Quote Originally Posted by CharlieN View Post
    To my eye, those pictures show the tubes were repainted over existing rust and other crap. I would hate to see what is back there the fabric wraps the tubes.
    fortunately it's easy to see the tubes in the back, my cub doesn't have a cargo headliner installed so you can see everything back there. I didn't notice it until after I bought it but the tubes are painted two different colors of grey. This dark grey was the paint put over the corrosion and there's a light gray that was the original. Everything in the back is still the light grey and looks pretty good. I found two small spots of concern but the lower longerons look pretty clean and I've combed every inch of the aft structure with no big issues. Which is why I find it odd that this structure up high is what got corroded.

  16. #16

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    Quote Originally Posted by Steve Pierce View Post
    What does the tail look like? Remove the battery cover or baggage aft panel and look. Seen corrosion on the cockpit tubes from people grabbing the tubes and over time rubbing the paint off.
    Steve, aft looks pretty good. I found two spots where paint had chipped off the tubing and started to corrode, but everything looks pretty clean back there. It's all the tubing in the cockpit including places you could never grab that corroded. Seems very counterintuitive that the tubes up high are corroded but not the tubes down low?

  17. #17
    BC12D-4-85's Avatar
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    heated humid air rises - clouds - until it condenses on something cooler like tubing. If the top of the cockpit is somewhat sealed to venting it gets worse. I've seen it in vehicles and airplanes particularly in winter.

    Gary

  18. #18

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    My J3 had pretty good rust on those "handhold" tubes in 1962. Cleaned it up, painted the whole frame in epoxy (cheap back then) and pressed on. No problems since then.

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    Quote Originally Posted by jrussl View Post
    Make sure to check behind the channel on the rear door post.

    Everything looked good on this one until the channel was cut off.

    Click image for larger version. 

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    how does one check this without cutting the channel off. Mine looks good on the aft side but can't see the front side. Would hate to cut that piece off just to inspect there?

    That said, mine is an EAB cub that the builder modified the door so that post slants down and aft to make the door larger. The channel is not welded at the bottom and looks like it allows for moisture to drain out, if I recall from Steve Pierce walking through the annual on the YouTube videos he mentioned this post is a typical corrosion culprit because it's sealed at the bottom and collects moisture?
    Last edited by Globemaster; 11-08-2021 at 01:03 AM.

  20. #20

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    Quote Originally Posted by BC12D-4-85 View Post
    heated humid air rises - clouds - until it condenses on something cooler like tubing. If the top of the cockpit is somewhat sealed to venting it gets worse. I've seen it in vehicles and airplanes particularly in winter.

    Gary
    I discovered the culprit after some more digging in the logs today... can't believe I didn't catch this before I bought it but it did spend six years in Florida on the Gulf coast, and in those six years it was annualed one time. And there were six or seven hurricanes that went through too. God I hope it wasn't just sitting out on the ramp that whole time. Can't believe I never noticed this.

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    Well unfortunately I found this as well. I've inspected the entirety of the lower longerons and everything else still looks decent. There's no evidence of any corrosion on the bottom side, and I went along the length doing a tap test. It all still seems solid except for this one spot. It looks like I'll have to cut the belly open to get to this spot, which I figure if I'm going to do that, I may as well get the metal belly kit from Univair. Anyone have any experience putting one on an already skinned plane? Is that a worthy investment?
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  22. #22
    Steve Pierce's Avatar
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    Steve Pierce

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  23. #23
    behindpropellers's Avatar
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    Quote Originally Posted by Steve Pierce View Post

    I think Steve left this picture out:

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  24. #24
    Steve Pierce's Avatar
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    Actually the last two I drilled, a 1979 and a 1982 were not rusted.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  25. #25
    WhiskeyMike's Avatar
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    Quote Originally Posted by Globemaster View Post
    Well unfortunately I found this as well. I've inspected the entirety of the lower longerons and everything else still looks decent. There's no evidence of any corrosion on the bottom side, and I went along the length doing a tap test. It all still seems solid except for this one spot. It looks like I'll have to cut the belly open to get to this spot, which I figure if I'm going to do that, I may as well get the metal belly kit from Univair. Anyone have any experience putting one on an already skinned plane? Is that a worthy investment?

    My guess would be: Hands on the windshield area cabanes leads to minor corrosion. You almost always see that. Upper cockpit, probably had water seep in under the skylight after sitting in the rain. Plane not flown,not dried out. Lower fuselage, water settled in.

    Chances are you can deal with this, but I'd strongly recommend you stay on top of it. It's not just a one time fix. You better have a darn good look at the struts and fork fittings. We used to weld in bushings to add Bradley safety straps between the fuselage fork fitting and the strut before sealed struts became available. On one occasion, we drilled the strut for the bushing near the fork and a quart of water came out. The fuselage probably won't fall apart but if a strut fails, it's all over - and it has happened more times than people generally know about. You should also check the lower tail brace wire fittings at the fuselage. Best of luck, Be careful.

  26. #26

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    Quote Originally Posted by WhiskeyMike View Post
    My guess would be: Hands on the windshield area cabanes leads to minor corrosion. You almost always see that. Upper cockpit, probably had water seep in under the skylight after sitting in the rain. Plane not flown,not dried out. Lower fuselage, water settled in.

    Chances are you can deal with this, but I'd strongly recommend you stay on top of it. It's not just a one time fix. You better have a darn good look at the struts and fork fittings. We used to weld in bushings to add Bradley safety straps between the fuselage fork fitting and the strut before sealed struts became available. On one occasion, we drilled the strut for the bushing near the fork and a quart of water came out. The fuselage probably won't fall apart but if a strut fails, it's all over - and it has happened more times than people generally know about. You should also check the lower tail brace wire fittings at the fuselage. Best of luck, Be careful.

    Yeah I figured I have some consistent work ahead of me. I'll be moving to Alaska in a couple years and when I finally get it up there my plan is to tear it down and build a new so it just has to last me until then haha. I already ordered new sealed struts for it, should be finished up at Airframes this week and I'm planning to buy all four new tailbrace wires as well. They weren't pretty and I noticed someone painted them with silver paint to hide the corrosion.

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    Steve,
    After reading through post #25 and seeing what the channel looks like on other cubs I'm going to remain hopeful. It looks like mine was built to allow it to drain any moisture inside it. (Will post a picture later.) That said I'll probably still have them drill in to it like you did. It's a '98 so hopefully it hasn't had long enough to look as bad as some of the ones you found!

  28. #28
    supercrow's Avatar
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    Hate to be a party pooper, and it is probably just me, but I would tear it down and start over. Not worth the grief, and you "will" find other problems. Sorry, just my 2 cents.

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    Quote Originally Posted by supercrow View Post
    Hate to be a party pooper, and it is probably just me, but I would tear it down and start over. Not worth the grief, and you "will" find other problems. Sorry, just my 2 cents.

    That is the plan, but at the moment I can't afford that, and I'm getting ready to head off to a year and a half of USAF pilot training so I wont have time to work on it that much. After training I'll be moving up to the Anchorage area, once I get there my plan was to tear it down and start over. I just need it to last a couple more years. *fingers crossed*
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  30. #30
    mvivion's Avatar
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    Quote Originally Posted by Globemaster View Post
    Yeah I figured I have some consistent work ahead of me. I'll be moving to Alaska in a couple years and when I finally get it up there my plan is to tear it down and build a new so it just has to last me until then haha. I already ordered new sealed struts for it, should be finished up at Airframes this week and I'm planning to buy all four new tailbrace wires as well. They weren't pretty and I noticed someone painted them with silver paint to hide the corrosion.
    Not to toss even more cold water on your parade, but when you get to Alaska is precisely when you're going to want a flyable airplane, NOT a project. I understand your constraints, as you've explained, but I'd sure try to figure out how to get the thing ready to rock as soon as you arrive in AK. "Project" airplanes can take FOREVER to complete, and while Alaska winters are long, there's still a lot of flying to be done. Trust me, THAT's when you'll want a toy to go play with, as opposed to a "project" to go work on!

    MTV
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    BC12D-4-85's Avatar
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    How about asking around for an A&P that's dealt with corrosion? Ask them to pick and poke the usual suspects for damage. Then you'd know if it's airworthy. Better to know and get it fixed than wait.

    Gary
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    Quote Originally Posted by mvivion View Post
    Not to toss even more cold water on your parade, but when you get to Alaska is precisely when you're going to want a flyable airplane, NOT a project. I understand your constraints, as you've explained, but I'd sure try to figure out how to get the thing ready to rock as soon as you arrive in AK. "Project" airplanes can take FOREVER to complete, and while Alaska winters are long, there's still a lot of flying to be done. Trust me, THAT's when you'll want a toy to go play with, as opposed to a "project" to go work on!

    MTV

    Oh I agree, that's the reason I got the cub in the first place. Unfortunately I just can't take on a restoration project while I'm in pilot training and Alaska is where my buddies are that can help me restore it.
    It's a pickle for sure... At least I have a 10 year contract with the Guard in Anchorage so I've got lots of time once I'm up there haha.

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    Quote Originally Posted by BC12D-4-85 View Post
    How about asking around for an A&P that's dealt with corrosion? Ask them to pick and poke the usual suspects for damage. Then you'd know if it's airworthy. Better to know and get it fixed than wait.

    Gary
    The shop I'm trying to get it in to just got done fixing some corrosion on a Pacer so they are freshly experienced haha. They are going to look at it this week and give me a verdict. That's the worst part of this whole thing is waiting for an answer haha.

  34. #34
    BC12D-4-85's Avatar
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    Good you found a shop with experience. I hope it gets resolved favorably and safely for all. You will enjoy Alaska and have the right plane for exploring.

    Gary

  35. #35
    skywagon8a's Avatar
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    Quote Originally Posted by Globemaster View Post
    Well unfortunately I found this as well. I've inspected the entirety of the lower longerons and everything else still looks decent. There's no evidence of any corrosion on the bottom side, and I went along the length doing a tap test. It all still seems solid except for this one spot. It looks like I'll have to cut the belly open to get to this spot, which I figure if I'm going to do that, I may as well get the metal belly kit from Univair. Anyone have any experience putting one on an already skinned plane? Is that a worthy investment?
    Pictures don't give the full answer. Are those cracks next to the vertical tube on the longeron? Since your plan is to do a major do-over when you get to Alaska, this can just be done with a local repair. Cut open the belly fabric enough to peel the fabric back for access. Fix what needs fixing, patch the belly fabric, reshrink, paint ...done. Forget the metal belly.
    N1PA
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  36. #36

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    Quote Originally Posted by skywagon8a View Post
    Pictures don't give the full answer. Are those cracks next to the vertical tube on the longeron? Since your plan is to do a major do-over when you get to Alaska, this can just be done with a local repair. Cut open the belly fabric enough to peel the fabric back for access. Fix what needs fixing, patch the belly fabric, reshrink, paint ...done. Forget the metal belly.

    Thats fair, maybe the metal belly is a little over doing it at this point. My thought process was to use this as an excuse to inspect the longerons even better than what I've been able to do so far just to be extra sure there are no more corrosion spots I'm missing. I suppose that could be over doing it too... just being a first time owner worry-bee? Haha I will say I thought my cub looked decent compared to a couple Cubs I saw at Airventure this summer. Lol

  37. #37
    Steve Pierce's Avatar
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    Quote Originally Posted by Globemaster View Post
    Steve,
    After reading through post #25 and seeing what the channel looks like on other cubs I'm going to remain hopeful. It looks like mine was built to allow it to drain any moisture inside it. (Will post a picture later.) That said I'll probably still have them drill in to it like you did. It's a '98 so hopefully it hasn't had long enough to look as bad as some of the ones you found!
    This is a 1998 model year Super Cub?
    Steve Pierce

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  38. #38

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    Quote Originally Posted by Steve Pierce View Post
    This is a 1998 model year Super Cub?
    Affirm, it was built new in 1998, from what I can tell it was built to match the standard -150.

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    Here is the after door post, it looks like the bottom is not sealed and allows water to flow out. Not 100% sure though.

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  40. #40
    Charlie Longley's Avatar
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    Pretty rough looking fuselage. Did the builder do it himself or use an old airframe?

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