Ruptured Upper Wing Tanks and AVGAS Effects on Wood Wing Structure

Discussion in 'Marquart Charger' started by VF84Sluggo, Jul 11, 2018.

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  1. Jul 11, 2018 #1

    VF84Sluggo

    VF84Sluggo

    VF84Sluggo

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    Gents,

    A Marquart MA-5 Charger I've been looking at buying had the upper wing tanks rupture due to the installation of motorcycle fuel caps that let air in the tank, but wouldn't let it out (like on my HD, the fuel has an overflow expansion drain line) Thus, after filling the tanks and letting the aircraft sit in the sun, the upper tanks ruptured due to expansion of the fuel inside, letting 10 gallons of AVGAS run back through the upper wing structure and out the trailing edge of the wing, all near the center section, maybe 3 to 4 feet outboard from center (and mostly to the right side, it seems.) Don't know how long it took for the gas to drain, how long the wood was soaked by AVGAS.

    The owner couldn't fully answer if any attacking of the rear spar varnish, wood, and other internal wing parts had happened. Further, it seems no inspection has been done to look and see. Access would certainly be difficult, I agreed. But still...

    I think this happed a couple of years ago, maybe less, but the airplane has been flown regularly since this happened. Anyway, I'm wondering if AVGAS attacks wing spar varnish, and/or the wood itself. Are there structural concerns here that would make a purchase unwise?

    Thanks in advance.
     
  2. Jul 11, 2018 #2

    TFF1

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    I would ask what kind of varnish used. Epoxy or other. Glue to put the wing together too. Most likely its OK. AV gas does evaporate fast if given a chance. How many leaking tanks have flown in other plans over the years. I'm not discounting checking it out though.
     
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  3. Jul 12, 2018 #3

    VF84Sluggo

    VF84Sluggo

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    Good point re. leaking tanks.

    The current owner is not the builder, and I don't think the builder is with us anymore. So, details about the varnish, glues, etc. may be lost.

    Thanks for the info.
     
  4. Jul 12, 2018 #4

    Dennis Flamini

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    Randy,
    Since we are talking experimental i would test it before i bought it.
    If you have a water softener that needs salt or know a pretty girl that has one buy enough 40 lb sacks of salt to make 2 layers over the top wing...that will be
    close to 3 neg. G's. You can figure it out exactly by taking the loaded weight divided by the wing area and then the 40lb sack and it's area.
     
  5. Jul 12, 2018 #5

    VF84Sluggo

    VF84Sluggo

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    Good plan...but, I think I might have trouble convincing the owner to let me pile a bunch of sacks of salt on top of his plane.

    Too bad the plane doesn't have a G-meter. I ask him to go out and pull at least 4 g's, land, check the meter, reset it, have him do it again. Do it 5 times.
     
  6. Jul 12, 2018 #6

    cwilliamrose

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    G-meters are fairly cheap, the GT-50 is well under $200. Cheaper than salt........
     
  7. Jul 12, 2018 #7

    planebuilder

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    If you can't see into the wing to inspect....... cut some fabric and install inspection rings, in the area you expect is most affected. The hardest part of that job is deciding to cut the fabric! Then you can see if there's damage and try to peel some gussets off, if they won't peel, great! It would make the airplane more saleable if nothing is being hidden.
     
  8. Jul 12, 2018 #8

    VF84Sluggo

    VF84Sluggo

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    Hmmm...interesting suggestion. This might be a good plan. I like the idea of trying to peel a gusset.

    I pointed out to the owner an inspection hole that was near the affected area, seemed like one could get a look up inside. He pointed out that that wouldn't allow a view of the back side of the rear spar and the area behind it. Perhaps the solution IS a new inspection hole aft of the aft spar.
     
  9. Jul 12, 2018 #9

    VF84Sluggo

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    Yep...and this might be a good plan, too.
     
  10. Jul 12, 2018 #10

    TFF1

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    There has to be a drain hole, cabane cover, or some spot that can slip a borescope into. Might need some inventiveness. If I owned it I would want to know just because. i hope the fuel caps are marked no fuel just in case.
     
  11. Jul 12, 2018 #11

    planebuilder

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    I have seen fuel soaked wings that were not negatively affected. But we don't know if yours had the same glue & varnish as the ones I inspected, or the same attention to detail when they were applied. Bottom line, if you can't see it, you don't know the condition. I have total respect for the others on this forum, but a "G" test only shows it held together during the test. What if the glue is weakened so that it takes 100 applications of load to cause a failure. Inspections are cheap and give peace of mind, what's your life worth? As a community we have an obligation to encourage safety, for your sake, and to minimize bad publicity.
     
  12. Jul 12, 2018 #12

    marquartflyer

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    If he lands like me that'll set the G meter to 10!
     
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  13. Jul 12, 2018 #13

    VF84Sluggo

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    Yeah, mine too...so that thought DID cross my mind LOLOL
     
  14. Jul 12, 2018 #14

    VF84Sluggo

    VF84Sluggo

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    Excellent reply, thanks. That ALSO crossed my mind: is 5 flights enough? 10? 50?

    Yep, it needs a good look.
     
  15. Jul 12, 2018 #15

    VF84Sluggo

    VF84Sluggo

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    There are...which prompted my borescope question. Why not at least try and snake one up in there and take a peek? Obviously no gusset-peel could be done, but if all looks good and the same as other wood not affected, that would be of some peace-of-mind, I'd think.
     

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