Yellow fuel in sump

Discussion in 'Maintenance Bay' started by AuntPeggy, Aug 7, 2013.

  1. AuntPeggy

    AuntPeggy Final Approach

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    The C-172 has not been getting enough exercise lately. The other night, Hubby took it up for its first launch since the annual in May. The fuel tests for both wings looked normal and blue, but the one under the belly returned what looked like yellow fuel. A second sample was the same. He eventually removed about a pint of the wrong colored stuff before getting blue fuel.

    Any idea what turns the fuel (100LL) yellow?

    Interesting side note: He was there with an old friend who is in the habit of simply pulling the knob and discharging some fuel from the gascolator without capturing it into a jar to test. If it had been his airplane, he would not have known that it was the wrong color.
     
  2. SCCutler

    SCCutler Administrator Management Council Member PoA Supporter

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    Did someone pee in your gas tank?
     
  3. AuntPeggy

    AuntPeggy Final Approach

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    Wow. Never thought of that. I can think of a few in SZ who might want to.
     
  4. douglas393

    douglas393 Pattern Altitude

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    Did you save it to see if it is even fuel. 100LL evaporates without a residue, while water would not evaporate quickly. I use a GATTS and this supposedly will allow the fuel to pass throught the filter, but not water, but to be perfectly honest, if I got a pint of something out of my gas tank that I could not identify and assure it was safe to fly I would scrub the flight until I had a mechanic check it out.
     
  5. SkyHog

    SkyHog Touchdown! Greaser!

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    Isn't diesel fuel from a car gas station yellow? Or maybe E85? I know I've seen yellow fuel somewhere before...
     
  6. Brad Z

    Brad Z En-Route

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    Whatever it is, it is contamination if all you burn is 100LL.
     
  7. Chip Sylverne

    Chip Sylverne En-Route PoA Supporter

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    Fear is the poison of our lives.
    Yep, yellow for road diesel. Off- road diesel is red.
     
  8. NineThreeKilo

    NineThreeKilo Ejection Handle Pulled

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    Sometimes old auto fuel can look kinda yellow? What did it smell and feel like?
     
  9. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser! PoA Supporter

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    Could it have picked up a little color from rubber hoses attached to the gascolator?
     
  10. Archammer

    Archammer Cleared for Takeoff

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    JetA is also yellow or straw color.

    Did someone put a little JetA in your tank and not tell you. Since it's heavier, it would sink to the lowest point. I have seen that happen more times than I'd like to admit.
     
  11. Norman

    Norman En-Route Gone West

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    Jet-A is yellow(ish). I'm thinking that is what it is. Can't find the specific gravity of 100LL, but I think Jet-A is heavier. A sniff test would have been of value. Jet-A has a distinct odor even when mixed with 100ll. It would also have a more "oily" feel than straight 100LL. How it got there I wouldn't want to guess, but I've seen the mixture ruin engines.
     
  12. Norman

    Norman En-Route Gone West

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    Shane and I were typing at the same time. LOL.
     
  13. dell30rb

    dell30rb Final Approach PoA Supporter

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    Sounds reasonable to me.
     
  14. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser! PoA Supporter

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    I'm surprised that it doesn't just mix in - like oil added to gas for a two stroke.
     
  15. weirdjim

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    SG:

    Gasoline: 0.73
    Jet-a (Kerosene): 0.82

    www.engineeringtoolbox.com is your friend.

    Jim
     
  16. Geico266

    Geico266 Touchdown! Greaser!

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    :rolleyes:
     
  17. Jim_R

    Jim_R Cleared for Takeoff PoA Supporter

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    Carnac the Magnificent says:

    You replaced a fuel line during your annual.

    Is he correct?

    If so, that's what's turning your fuel a funny color. Give it some time for whatever causes the color change to leach out of the hose, and you'll get your normal blue back.

    No impact to engine ops or safety.

    (Happened to me this year after adding a fuel flow sensor and replacing the line it spliced into. Spooked me a little until I remembered reading messages on other forums before about folks who had replaced fuel lines and were similarly surprised.)

    Edit: See attached file for more info on this phenomenon.
     

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  18. Skylane81E

    Skylane81E Final Approach

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    Water in the gas tanks often takes on a yellow tint...
     
  19. Jim Logajan

    Jim Logajan En-Route

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    Maybe. Maybe not. Just a few weeks ago I was reviewing the chapter on properties of solutions in Pauling's descriptive "Chemistry" text and he states:
    "Substance vary greatly in their solubilities in various solvents. There are a few general rules about solubility, which, however, apply in the main to organic compounds.

    One of these rules is that a substance tends to dissolve in solvents that are chemically similar to it. For example, the hydrocarbon naphthalene, C[sub]10[/sub]H[sub]8[/sub], has a high solubility in gasoline, which is a mixture of hydrocarbons; it has a somewhat smaller solubility in ethyl alcohol, C[sub]2[/sub]H[sub]5[/sub]OH, whose molecules consist of short hydrocarbon chains with hydroxide groups attached, and a very small solubility in water, which is much different from a hydrocarbon."
     
  20. Dan Thomas

    Dan Thomas Final Approach

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    That's what I would expect, and have seen happen with gasoline and diesel fuel. It mixes and stays mixed.

    The Jet-A I'm familiar with is clear, not yellow.

    Dan
     
  21. Graueradler

    Graueradler Pattern Altitude

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    Jet A ranges from nearly clear to straw colored.
     
  22. weirdjim

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    There is no "maybe, maybe not" THe OP asked what the specfic gravity of two substances were and I posted them. Whether or not they are miscible is a totally different question.

    And whether or not they STAY miscible over hours, days, weeks, or months is another totally different question.

    Jim
     
  23. Cap'n Jack

    Cap'n Jack Final Approach

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    They are miscible and will stay miscible. It's possible they weren't well mixed allowing the heavier jet-a to be removed before the two fuels diffused into one another.
     
  24. Jim Logajan

    Jim Logajan En-Route

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    Sorry, I incorrectly quoted your post when I should have quoted post 10 in my "maybe, maybe not" reply. I quoted your post only because it appeared to be the most recent in the subthread about Jet-A and 100LL mixing vs separating. Your post was of course a proper answer to the question.
     
  25. Z06_Mir

    Z06_Mir Pattern Altitude

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    Jet wouldn't evaporate either once it was sumped. And it's clear, at least if it's proper JetA it's clear. If you touch JetA it's very oily and you won't be able to get dry whatever you touched it with, your shirt/gloves/pants will stay damp from it. It's nothing like 100LL where it evaporates and you don't notice it. The stuff will stink up a whole load of clothes if you wash them together.
    No, it wouldn't. JetA is kerosene based and it weighs 6.7 pounds (on average) per gallon compared to 100LL's 6 pounds per gallon. They're very different fuels and I really don't think they'd ever blend together.
     
  26. AuntPeggy

    AuntPeggy Final Approach

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    It seems to have been water.
     
  27. Cap'n Jack

    Cap'n Jack Final Approach

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    If not caught, they could blend together given time or mixing such as in turbulence. Both are hydrocarbon based fuels and are fully soluble in each other. As you note, jet A does evaporate more slowly and one can place a drop on a piece of paper ans see if it evaporates or stays oily.

    Glad the water was found on the ground.
     
  28. Skylane81E

    Skylane81E Final Approach

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    :wink2:
     
  29. Dan Thomas

    Dan Thomas Final Approach

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    Someone needs to try it. They're both hydrocarbon liquids, like gasoline and two-stroke oil, which blend just fine and stay that way despite having different specific gravities. We're not talking hydrocarbon liquids and water here.

    Dan
     
  30. Tony_Scarpelli

    Tony_Scarpelli Pattern Altitude

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    We have had a lot of rain this year. Maybe its time for new gas cap seals.
     
  31. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    I guess no one remembers the mis-fueling that occurred in So-Cal a few years back.

    5% Jet "A" in 100LL caused many engines to get overhauled on the truck companies dime.
    there is an AD on it.
     
  32. Norman

    Norman En-Route Gone West

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    I've seen the results of someone misfueling a Navajo many years ago. The Jet-A destroyed the engines. The feds brought some of the parts to a meeting. They were a total mess. Oh, and the Navajo was also destroyed in an emergency landing. Pilot survived.
     
  33. Bob Noel

    Bob Noel Touchdown! Greaser!

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    I'd be mighty tempted to drain the tank, toss the fuel (at my club, they'd probably burn it in the snowblower or the tugs), and fuel with known good fuel (partially fill, wouldn't fill it until satisified it was the fuel and not something else).

    I hope it's just water, like you suspect.
     
  34. Jim_R

    Jim_R Cleared for Takeoff PoA Supporter

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    Interesting that it happened right after annual. You sure there were no fuel hoses replaced?
     
  35. AuntPeggy

    AuntPeggy Final Approach

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    Yes. Pretty benign annual. Hubby always assists, so we know what goes in/out.