100LL was dark blue?

Discussion in 'Flight Following' started by Lawson Laslo, Sep 6, 2019.

  1. Lawson Laslo

    Lawson Laslo Pre-takeoff checklist

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    didnt get a picture but when I sumped the fuel in one tank it was a darker than usual blue? Any idea why?
     
  2. Cap'n Jack

    Cap'n Jack Final Approach

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    Either they added more dye than usual, or the fuel was evaporated and concentrated the dye. Those are my best guesses. How about the other tank(s)? The phrasing makes me think you have more than one tank.
     
  3. Lawson Laslo

    Lawson Laslo Pre-takeoff checklist

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    3 tanks but can only sump 2 only 1 was dark blue, we had drained all the fuel out of the whole plane to weigh it, and just added new fuel and the fuel we had drained yesterday via plastic jugs but the fuel was from airport, and when I went to sump the fuel today it was dark blue in one of the tanks
    Any ideas? Anything to be concerned about?
     
  4. denverpilot

    denverpilot Tied Down

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    When we had dark blue it was from areas where a leak had occurred and the fuel evaporated, leaving behind more dye than usual to be moved by the new fuel to interesting places.

    This was not from a sump; but did you leave that tank fairly empty for a long time? Long enough to evaporate some fuel left in the bottom and then added some more fresh fuel to mix it all up again?
     
  5. Cap'n Jack

    Cap'n Jack Final Approach

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    Still seems there was a bit of fuel left when you emptied the tank, it evaporated, and the dye left behind was dissolved by the gasoline when you refilled the tank. As there is no chemical reaction occurring, the dye had to be there already. I don't see a problem.
     
  6. benyflyguy

    benyflyguy Pattern Altitude

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    That’s the high test. You’ll get +10KIAS
     
  7. overdrive148

    overdrive148 En-Route

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    Not sure in your case but occasionally we would get fuel loads that were noticeably darker than normal once in a while. Our jet fuel loads would be different colors depending on the refinery it came from - between straw and clear. I was told by one of the drivers that it had to do with sulfur levels going into the process.
     
  8. Dan Thomas

    Dan Thomas Final Approach

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    I bet the fuel sump drain valve has a really slow seep that lets the fuel evaporate and leaves the dye inside the valve's outlet, where it mixed with the fuel when you sumped, darkening the sample.
     
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  9. jonvcaples

    jonvcaples Ejection Handle Pulled

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    To me it appears light blue but since we all "see" differently could be it appears dark blue to some. Very remote possibility but maybe somehow some 115/145 got mixed in. The old BIG recips used this, it was purplish in color although I am not sure if is available anywhere. WAY back in the days of being a CAP cadet we used to get rides in C-124's which used this fuel. Once during pre-flight a drain got stuck and there was a big purple puddle until the fire department washed it away. HAZMAT, OSHA et al were not even gleams in some congress persons eyes yet. (We didn't wear helmets riding bicycles and cars might have seat belts.)
     
  10. Bell206

    Bell206 Pattern Altitude

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    Since you got the fuel from the airport perhaps take a good sample in a clean jar and ask the fuel provider for ideas. You might get a free analysis out of the deal??
     
  11. david.h

    david.h Pre-takeoff checklist

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    I've had a slow drip from my sump once, and when checking that one it was very dark blue due to the dye remaining in the sump valve. R&R the valve, no more drip, no more dark blue.
     
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  12. Zeldman

    Zeldman Touchdown! Greaser!

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    The color in gas is from the dye that is added at the end of the production cycle.

    It is possible to get a little too much dye in one batch. It doesn't take much at all to make the color look different. The race gas I used to sell took about 3 drops per 500 gallons to get the color we wanted.

    I used to use undyed race fuel in my car. It was clear and everyone thought I was cheating some how...
     
  13. James331

    James331 Touchdown! Greaser!

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    That.

    I have noticed a few times it was a little more blue, still ran just fine.

    Ofcourse your mileage may vary and err on the side of caution, on that note my lawn equipment and saws seem quite happy with 100ll, also keeps waaay longer than mogas
     
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  14. chemgeek

    chemgeek Cleared for Takeoff

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    ^^^^^^
    This. And it is pretty common. I suspect you have a sump drain leak. Sumped fuel is dissolving the dried up and concentrated dye from the evaporated fuel on and around the outside of the drain valve.

    Two of my sump drains are under fairings, so when they drain dark, I know to remove the fairings and investigate for the leak.
     
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  15. kgruber

    kgruber En-Route

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    Could be darker from the 2 cycle oil, mixed at 1000:1
     
  16. PilotRPI

    PilotRPI Line Up and Wait

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    I had the opposite happen. Could barely tell it was blue. Can change depending on the source of fuel and the amount of dye they use. So color can change and fuel could be just fine.
     
  17. ChopAndDrop

    ChopAndDrop Filing Flight Plan

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    Is this a new trend in the fuel supply? to add more dye? because I noticed the same thing about 2 months ago.
    Buying my 100LL at a Class C airport, I sumped the tanks and the blue was much "stronger" blue coloring.
    as far as I can tell this wasn't a case of old fuel drying or anything like that.