A320 Passenger Oxygen System

Dear All,

The A320 has a very nice safe system controlling the passenger oxygen masks. But always please note that we are dealing with machines that you will never get a 100 % efficiency of any machine.

I will brief you little bit about the passenger oxygen masks operation and when they are going to be deployed.

The passenger oxygen masks are installed in PSU - Passenger Service Unit - above each group of seats. This PSU has a door (Panel Which cover the masks container). This door is stay locked electrically by solenoid.

When the solenoid is energized, the door will open and the masks will drop by gravitydown infront of the passenger. The door solenoid is energized by two means.

Either 1) automatically and this is controlled by relays connected to cabin pressure sensor that when heavy drop of pressure is measured at above certain altitude (on A320 above 14000 cabin altitude then this electrical "AND GATE" will make the door solenoid to be energized automatically causing the masks to drop.

2) Manually by the pilot, using a switch that when switched will cause the doors solenoids to be energized so the door will open and the masks will drop.

B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer