Knowledge of ground fuel characteristics and significance of Existent Gum, Corrosion effects, Oxidation effects, Particulate Matter, Additive content, Water Index, Commingling of Fuels, Adverse and benign sediment sources and types, Free Water & Dissolved Water. Knowledge of sampling techniques and uses of, to include all level, average, spot, upper, lower, middle, top, bottom, composite, siphon, drain, filter effectiveness, nozzle, contamination analysis unit, nozzle and free water.