Testing of Oxygen in Boeing aircrafts
 

Hi,

This is mainly for B777 fleet for guess most or all of the Boeing fleet has the same oxygen system.

There are two switches, RESET/TEST and EMERGENCY/TEST buttons. My company policy is to hold on to INT and press RESET/TEST, there should be oxy flow through speaker and yellow cross displayed, after which, release INT and hold on to both RESET/TEST and EMERGENCY/TEST buttons and yellow cross is displayed with PSI not dropping more than 50psi.

My ques is, when you test for oxygen, do you hold onto INT and both RESET/TEST and EMERGENCY/TEST buttons at the same time or just the RESET/TEST button and then as per above?

Thanks

All you're trying to achieve by turning on the intercom while testing the oxygen is to test if the mask microphone is working or not. So once you've established that nobody has turned off the bottles and that the regulator works (hence the pressure drop is below 50 psi) how you test that mike is your call in my opinion... Because I hate having my ear drums blown out by somebody else leaving the intercom on during the oxygen test I open the left flap and knock on the mask to test the microphone. Obviously you have to press the reset switch afterwards to switch back to the headset microphone.

"Watch your ears!".

Friend of mine had his headset (left seat) on when a tarmac man plugged his own headset into the ground connection. For unknown reason there was a terrible loud pitch noise through the captain's headset and he experienced massive loss of hearing. He was medically unfit for flying for next three years when eventually he could pass the hearing medical.

FWIW, in 20 years/10,000 hours I have twice boarded an aircraft with the oxygen bottle switched off. Both times a B757 with the same op. One had done several sectors (3, I think) since it left the hangar.

Reset/Test should give a short burst of oxygen then stop. You are testing on demand flow. Em/Test should give continuous flow you are testing the emergency function. Int to test the mic.