Avoiding Misfueling
I picked up an old book published by AOPA from 1978-1986, Defensive Flying by Norbert Slepyan and it has some interesting info on the types of fuel that used to be available. It also has a test, that I’ve verified, for checking whether you have Jet fuel in your tank.
Finally, there is the, pilot, who has the last chance to detect, misfueling. But first the pilot must understand that jet fuel contamination of avgas is dangerous because it damages the combustion chambers of reciprocating engines. Second, he must take the time to supervise the fueling of his aircraft.
The defense begins with checking the labeling on the truck, tank, or pump and asking the lineman to verify the contents.
Next, observe the color of the fuel you drain during the pre-fight. Avgas with an 80-octane rating is reddish; 100-octane agas is a light green; 100LL (low lead) avgas is a light blue; avgas with a 115/130-octane rating is purplish. Jet fuel is color-less. Mixtures containing avgas and jet fuel can be straw-colored or clear. To be safe, you should not operate your plane if your fuel sample is any other color than the one(s) recommended.
Suspect fuel must be drained completely from the airplane’s fuel tanks and lines. Jet fuel also feels greasier than avgas. It evaporates more slowly and has the odor of kerosene, its principal ingredient.
These properties of jet fuel permit a simple test to confirm is presence. Developed by the AOPA Air Safety Foundation, this test requires only a clean sheet of white paper and a medicine dropper. The test will detect fuel contamination levels as low as five percent. To perform the test, fill the dropper with a small quantity of fuel, then place a drop of the fuel on the sheet of paper. Try to make a spot of fuel about the size of a quarter.
As the spot dries, hold the paper up to a light source and observe the perimeter of the spot. Pure avgas will evaporate from the perimeter inward, leaving the outer margin indistinct. After approximately one minute, pure avgas will leave no sign of a spot. Jet fuel, on the other hand, will leave a distinct perimeter, and the spot will evaporate only after several minutes have elapsed.