Filler nozzles should be treated as the important tools that  they are. They should not be dropped or dragged across the  apron. Most have attached dust caps that should be removed  only for the actual fueling process and then immediately  replaced. Nozzles should be clean to avoid contamination  of the fuel. They should not leak and should be repaired at  the earliest sign of leak or malfunction. Keep the fueling  nozzle in constant contact with the filler neck spout when  fueling. Never leave the nozzle in the fill spout unattended.  When fueling is complete, always doublecheck the security  of all fuel caps and ensure that bonding wires have been  removed and stowed. Good fuel removed from an aircraft must be handled with all  precautions used when handling any fuel. It must only be put  into clean tanks and efforts must be made to keep it clean.  It may be put back in the aircraft or another aircraft if the  manufacturer allows. Large aircraft can often transfer fuel  from a tank requiring maintenance to another tank to avoid  the defueling process. Removing the fuel contained in aircraft fuel tanks is sometimes  required. This can occur for maintenance, inspection, or due  to contamination. Occasionally, a change in flight plan may  require defueling. Safety procedures for defueling are the same  as those for fueling. Always defuel outside. Fire extinguishers  should be on hand. Bonding cables should be attached to  guard against static electricity buildup. Defueling should  be performed by experienced personnel, and inexperienced  personnel must be checked out before doing so without  assistance.  Due to the combustible nature of AVGAS and turbine engine  fuel, the potential for fire while fueling and defueling aircraft  must be addressed. Always fuel and defuel outside, not in a  hangar that serves as an enclosed area for vapors to build up  to a combustible level. Clothing worn by refueling personnel  should not promote static electricity buildup. Synthetics, such  as nylon, should be avoided. Cotton has proved to be safe  for fuel handling attire. As previously mentioned, the most controllable of the three  ingredients required for fire is the source of ignition. It is  absolutely necessary to prevent a source of ignition anywhere  near the aircraft during fueling or refueling. Any open flame,  such as a lit cigarette, must be extinguished. Operation of any  electrical devices must be avoided. Radio and radar use is  prohibited. It is important to note that fuel vapors proliferate  well beyond the actual fuel tank opening and a simple spark,  even one caused by static electricity, could be enough for  ignition. Any potential for sparks must be nullified. Remember that there may be a sequence in defueling an  aircraft’s fuel tanks just as there is when fueling to avoid  structural damage. Consult the manufacturer’s maintenance/ operations manual(s) if in doubt.  Pressure fueled aircraft normally defuel through the pressure  fueling port. The aircraft’s in-tank boost pumps can be used  to pump the fuel out. The pump on a fuel truck can also be  used to draw fuel out. These tanks can also be drained through  the tank sump drains, but the large size of the tanks usually  makes this impractical. Aircraft fueled over the wing are  normally drained through the tank sump drains. Follow the  manufacturer’s procedure for defueling the aircraft. Spilled fuel poses an additional fire hazard. A thin layer  of fuel vaporizes quickly. Small spills should be wiped up  immediately. Larger spills can be flooded with water to  dissipate the fuel and the potential for ignition. Do not sweep  fuel that has spilled onto the ramp.  Class B fire extinguishers need to be charged and accessible  nearby during the fueling and defueling processes. Fueling  personnel must know exactly where they are and how to  use them. In case of an emergency, the fuel truck, if used,  may need to be quickly driven away from the area. For this  reason alone, it should be positioned correctly on the ramp  relative to the aircraft. What to do with the fuel coming out of a tank depends on  a few factors. First, if the tank is being drained due to fuel  contamination or suspected contamination, it should not be  mixed with any other fuel. It should be stored in a separate  container from good fuel, treated if possible, or disposed of  properly. Take measures to ensure that contaminated fuel is  never placed onboard an aircraft or mixed with good fuel.  Second, the manufacturer may have requirements for good  fuel that has been defueled from an aircraft, specifying  whether it can be reused and the type of storage container  in which it must be stored. Above all, fuel removed from an  aircraft must not be mixed with any other type of fuel. 14-58 Fire Hazards When Fueling or Defueling Defueling