The A320 is normally powered by the two engine generators during flight. When the engines are not running an Auxiliary Power Unit (APU) in the rear of the aircraft can be used to provide power. On the ground when the aircraft is parked we can also connect an external power generator to the power inlet on the outside. If all generators fail during flight a ram air turbine (RAT) automatically deploys and is driven by the airstream to provide essential power. Lastly the A320 has two batteries that provide DC power for APU start.
Upon entering the flight deck:
- Check that the wipers and weather radar are turned off
- Check that the landing gear lever is down, engine master switches are off and engine mode selector is normal
- Check Battery Voltage greater than 25.5V
- Push BAT 1 and BAT 2 pushbuttons to turn both batteries on which will give us basic DC power
- When the EXT PWR pushbutton shows a green AVAIL text push it to use the external AC power for the flight deck screens