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Thread: Lift Strut Corrosion

  1. #1

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    Lift Strut Corrosion

    Considering purchase of a PA18-95. It was recovered in 2010 but has been on floats since so spent summers outdoors. Fabric is badly oxidised but passed the punch test. I am trying to decide if it is worth investing in a pre-purchase or if I should look elsewhere. I have noticed surface corrosion on all four struts. Is this of serious concern or is it a matter of sanding and repainting? Is it safe to assume they are lifetime struts if the yoke bolt is 5/8”? Logs don’t confirm lifetime struts.


    Thanks for any advice.


    Hugh

  2. #2
    windy's Avatar
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    If the lift struts are corroded, what do you think the corrosion would be like inside, on the structural tubes?


    Sent from my iPhone using SuperCub.Org

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    SJ's Avatar
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    If they are lifetime struts, might not be a big deal, might be a big deal, but I think it would be foolish not to get a good pre-buy on any airplane before you buy it unless you are a super cub expert. Saved my bacon more than once, and ate my bacon when I didn't do it.

    sj
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    cubdriver2's Avatar
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    Quote Originally Posted by windy View Post
    If the lift struts are corroded, what do you think the corrosion would be like inside, on the structural tubes?


    Sent from my iPhone using SuperCub.Org
    Not necessarily. 12 years ago I bought some J4 parts that had been stored in a damp environment for 30 years. Cowls, tail feathers, wings with ailerons and struts. Basically I bought it for the cowling. A few years ago while welding up a non aviation project I needed a little more steel to finish. While digging thru my pile I grabbed one of the J4 wings struts. It had laid on the ground for years when I bought it and was corroded with scales over most of it's surface but had a couple good feet that I cut off to finish my project. The inside was spotless and I got curious about the rest of the inside. I cut up several 2" long peices where the worst outside corrosion was. Every inch of the inside of the strut was like new, even the threaded bottom end

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
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  5. #5
    JWE's Avatar
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    I'm with SJ on this one. Regardless of the corrosion you can see, a prebuy is cheap insurance. What else may be lurking? Have a prebuy done by someone who knows what they're looking for.
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  6. #6
    Steve Pierce's Avatar
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    Find out if they are sealed struts. Atlee Dodge/Jensen sealed existing struts and put the big forks in. Problem was the Feds only let them go 5 yrs before needing a punch test. Sealed struts are sealed and full of oil, no issue with internal rust unless someone has broken the seal. the primer used on the Univair sealed struts is red oxide and starts to bleed through pretty quickly. If everything else checks out I wouldn't let that be a deal killer, sand, prime and paint the struts.
    Steve Pierce

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  7. #7
    behindpropellers's Avatar
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    Changing a strut is like changing a shoe. If you are concerned about the struts...what else is lurking.

    If buying without a prebuy, buy it for the salvage value.

    T
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  8. #8
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Steve Pierce View Post
    Find out if they are sealed struts. Atlee Dodge/Jensen sealed existing struts and put the big forks in. Problem was the Feds only let them go 5 yrs before needing a punch test.
    NO, those are 1 INCH forks

    5/8" should be sealed struts....

    but the external corrosion is still part of the AD.... could fail it..

  9. #9
    Steve Pierce's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    NO, those are 1 INCH forks

    5/8" should be sealed struts....

    but the external corrosion is still part of the AD.... could fail it..
    Big forks, no more recurring inspection of forks.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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  10. #10
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Steve Pierce View Post
    Big forks, no more recurring inspection of forks.
    ????

  11. #11
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Steve Pierce View Post
    Big forks, no more recurring inspection of forks.
    no, ATLEE (USED JENSEN FORKS & barrels) these forks were 1" diameter....

    his 5/8" are either univair or Airframes, hence it has sealed struts....

  12. #12
    Steve Pierce's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    no, ATLEE (USED JENSEN FORKS & barrels) these forks were 1" diameter....

    his 5/8" are either univair or Airframes, hence it has sealed struts....
    Yea, they are all larger than the originals that had to be magnafluxed every 500 hours. Lee Budde's early struts used those huge forks as well.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  13. #13
    Southern Aero's Avatar
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    Ha, I have a set of those Jensens if anyone looking for some!!!
    ......... It doesn't cost any more to go first class! You just can't stay as long.

  14. #14

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    Thanks for everyone's input.

    To clarify, I have no intention of proceeding without a pre-buy inspection. I am only trying to decide if it is even worth investing the cost of an inspection. Far from being an “expert”. I am probably better described as a “green horn”. The big advantage to me for this plane is that it is local.

    I think this is quickly turning into a project rather than a useable, but ugly plane. I am slowly coming to the conclusion that I should look for a better candidate.

    Hugh

  15. #15
    55-PA18A's Avatar
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    Well, beauty is in the eyes of the beholder. Depending upon your mission and the selling price, it might be a good opportunity. Faded paint can be improved with elbow grease. 2010 isn't very old fabric if it was done right. Where are you located? Salt water or freshwater float operations. Is the corrosion on the struts just scratches or large areas bubbling through the paint. Any evidence of other corrosion? Since it is local, do you know local pilots that are familiar with this plane and its operator?

    Many members here say the smaller engine PA-18's are real good fliers. It might be a good plane for you if your mission is to build Cub hours, especially float flying, and you can live with the cosmetic imperfections. Above all, a prebuy inspection with someone knowledgable about Cubs is a good idea. There have been a number of threads about the best way to go about it, with some suggesting to get an annual inspection at that time. Long time Forum member Steve Pierce has a pretty detailed pre-buy checklist that is worth checking out.

    Jim
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  16. #16

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    Lift strut corrosion

    On a side note relating to the rear lift strut, I just changed a rear lift strut (PA-1 because of a large rock dent. I discovered the Airframes replacement is slightly larger, so you need to request a replacement clamp (for the jury strut attachment) that fits the new strut. Old one wasn't big enough.
    Last edited by supercub9675; 11-14-2020 at 02:44 PM. Reason: blooper

  17. #17
    Crash, Jr.'s Avatar
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    Quote Originally Posted by supercub9675 View Post
    On a side note relating to the rear lift strut, I just changed a rear lift strut (PA-1 because of a large rock dent. I discovered the Airframes replacement is slightly larger, so you need to request a replacement clamp (for the jury strut attachment) that fits the new strut. Old one wasn't big enough.
    All Airframes rear lift struts have a new jury strut clamp of the correct size included at no extra charge. PM me or call if yours was missing and I can get you hooked up.
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