VIONICS VENTILATIONThe avionics ventilation system supplies cooling air to the avionicsequipment. This includes the equipment in the avionics compartment,the flight deck instruments and the circuit breaker panels.A blower fan and an extraction fan supply the air through the avionicsequipment.NOTE: Note: These fans operate continuously while the aircraftelectrical system is supplied.The Avionics Equipment Ventilation Computer (AEVC) controls thefans and the configuration of the skin valves in the avionics ventilationsystem based on flight / ground logic and fuselage skin temperature.There are 3 configurations for the skin air inlet and outlet valves:- open circuit: the two valves are open (on ground only),- closed circuit: the two valves are closed (in flight or if there is lowexternal air temperature on ground). The air temperature is decreasedin the skin heater exchanger. The skin heat exchanger is a chamberwhich lets the air be in contact with the fuselage skin during flight,- intermediate circuit: the inlet is closed and the outlet is open, butnot fully.