In some applications, a Scully IntelliCheck® onboard control unit is used to control functions such as advanced interface modules, and bottom loading or defueling shutdown controls. Vehicles can be outfitted with an independent dual level system (high & high/high). The high-level sensor is controlled at the fill stand by a Scully control unit. The high/high sensor can be installed as a secondary shut down method controlling the vehicle’s bottom loading valves. If the valve or pump fails to shut down fuel flow at the fill stand, the secondary vehicle system will take over and shut down the vehicle’s bottom loading valve. The U.S. Air Force has standardized on this system.
Vehicle Identification Systems, which communicate via the overfill system plug to the control unit at the fill stand, can also be used to prevent mixing of different fuel grades.
Scully aviation systems have been standard equipment on U.S. Navy refuelers and Air Force R-11 refuelers for many years and are also in use in the commercial aviation market.