The FAA issued a Safety Alert for Operators (SAFO) that outlines guidance and best practices for Parts 91, 133 and 137 operators that conduct fueling or chemical loading with the engines running–hot fueling or loading. “Hot fueling/loading can be extremely hazardous and is not recommended except when absolutely necessary due to the nature of the operation,” the FAA said. The agency recommends that hot fueling be conducted only by aircraft that use Jet-A, warning that hot fueling of avgas “can be extremely hazardous due to its low flash point.” Aircraft being fueled while an engine is operating should have all potential ignition sources–such as engines, exhausts, APUs–located above the fuel inlet ports and above fuel vent or tank openings. Hot fueling is not permitted if an aircraft flight manual prohibits it. A rated pilot should be at the flight controls during the entire hot fueling/loading process with controls appropriately adjusted to prevent aircraft movement. The pilot should unbuckle all restraints, the FAA said, and be prepared to immediately shut down the engine and egress the aircraft, if necessary. Additionally, only designated and properly trained personnel should operate fueling or chemical loading equipment, according to the FAA. The SAFO also contains several more guidelines.