[Ref. Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 7-27, 7-28]

Accidents attributed to powerplant (engine) failure from fuel contamination have often been traced to :

1. Inadequate preflight inspection by the pilot
2. Servicing aircraft with improperly filtered fuel from small tanks or drums
3. Storing aircraft with partially filled fuel tanks
4. Lack of proper maintenance

Water is the principal fuel contaminant

Suspended water droplets in the fuel can be identified by a cloudy appearance of the fuel – they cannot be mixed with fuel, so the clear separation of water from the colored fuel is a good indicator of water contamination.

To prevent fuel contamination :

1. Preflight inspection – fuel should be drained from the fuel strainer quick drain and from each fuel tank sump into a transparent container and then checked for dirt and water
   (Notes: If water or other contaminants are found in the first sample, drain further samples until no trace appears.)
2. Avoid refueling from cans and drums
   (Notes: In remote areas or in emergency situations, there may be no alternative to refueling from sources with inadequate anti-contamination systems, a chamois skin and funnel may be the only possible means of filtering fuel)
3. Fuel tanks should be filled after each flight or after the last flight of the day to prevent moisture condensation within the tank
4. Proper maintenance