combined with contaminant identification technology and  microorganism detection, chances of delivering clean fuel  to the aircraft engines are good.  [Figure 14-101] Bug test kits test fuel specifically for bacteria and fungus.  While other types of microorganisms may exist, this semi- quantitative test is quick and easy to perform. Treat a fuel  sample with the product and match the color of the sample  to the chart for an indication of the level of bacteria and  fungus present. These are some of the most common types  of microorganisms that grow in fuel; if growth levels of  fungus and bacteria are acceptable, the fuel could be usable.  [Figure 14-100] Fuel trucks and fuel farms may make use of laser contaminant  identification technology. All fuel exiting the storage tank  going into the servicing hose is passed through the analyzer  unit. Laser sensing technology determines the difference  between water and solid particle contaminants. When an  excessive level of either is detected, the unit automatically  shuts off flow to the fueling nozzle. Thus, aircraft are  fueled only with clean dry fuel. When surfactant filters are  Before various test kits were developed for use in the field  by nonscientific personnel, laboratories provided complete  fuel composition analysis to aviators. These services are still  available. A sample is sent in a sterilized container to the  lab. It can be tested for numerous factors including water,  microbial growth, flash point, specific gravity, cetane index  (a measure of combustibility and burning characteristics),  and more. Tests for microbes involve growing cultures of  whatever organisms are present in the fuel.  [Figure 15-102]  A continuous effort must be put forth by all those in the  aviation industry to ensure that each aircraft is fueled only  Fuel Contamination Control Figure 14-101.  This contaminant analyzer is used on fuel supply  source outflow, such as that on a refueling truck. Water and  solid contaminant levels are detected using laser identification  technology. The valve to the fill hose is automatically closed when  levels of either are elevated beyond acceptable limits. Figure 14-100.  Fuel bug test kits identify the level of bacteria and  fungus present in a fuel load by comparing the color of a treated  sample with a color chart.  14-55