Not enough dye in the 100LL?

Daleandee

Daleandee

Final Approach
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Mar 4, 2020
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Dale Andee
During the last couple of fuel stops I have made it appears the 100LL has hardly any color in it when I check the sump after fueling. I've noticed this at two different airports.

From reading another, older thread here I understand some of the reasons why this happens:

Just curious if anyone else has noticed any changes in the 100LL they are buying.

TIA
 
I noticed some blue goo dripping from the underside of my Arrow on a hot day once. I was baffled at first but I finally figured it was concentrated dye leaking from the intake plenum.
 
put a gallon or two in a white bucket, how blue does it look then?
 
Wagondriver said:
put a gallon or two in a white bucket, how blue does it look then?
Click to expand...
Interesting you mentioned that.

Just the other day I was with a rusty pilot who had never guses a Gats jar. He drained about the amount that would fit in one of those old test tube types. I could barely see the color at all until he added more.
 
Daleandee said:
During the last couple of fuel stops I have made it appears the 100LL has hardly any color in it when I check the sump after fueling. I've noticed this at two different airports.
Click to expand...
You'll find there is no minimum dye ratio requirement for avgas, however, there is a "color intensity" range with a minimum value. And given that range is rather wide it is not uncommon to see color intensity varinces for several reasons. Unfortunately it requires a specialized tester to measure the dye color intensity, but if there is ever any doubt with the fuel color a quick call to the fuel provider or distributer should answer any questions you may have.
 
I've experienced the opposite lately especially at my home airport - there is so much dye in the fuel, it looks like the Caribbean Sea on a sunny day.
 
If I saw that, I'd check a drop or two on a sheet of paper to make sure it wasn't diluted with Jet-A. The gasoline will evaporate but the Jet-A will leave an oily residue.
 
I learned using the test-tube type, not the GATS jar, partially because dumping that volume of expelled fuel on the ground was acceptable, vice recycling expelled fuel through a GATS strainer back into your tank. I was advised to choose a white background (like the aircraft) and not the sky for comparison because of the color subtlety. The main point was to recognize the separation where the water failed to mix with the gasoline, which was clear enough regardless of color.
 
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