Over the last 6 months, when I sump fuel out of my 1976 Aztec, I see white stringy stuff floating in the fuel. The fuel supplier at KDPA (Phillips) upon looking at a sample couldn't explain what it was. I asked maintenance to investigate. Tanks were drained in order to access the bladders. The fuel cells were coated at the bottom with a brown sooty slime. Bladders were replaced in 2012. Maintenance contacted the fuel bladder supplier who stated that this could be a result of different fuel suppliers haven't different fuel formulations, and the brown soot may be the result. The fuel filters were coated with this soot. Has anyone ever heard of this or experienced this?
I've attached a few photos, along with one photo of a special surprise in the left tank.
Pete N21NC !