Originally Posted by
yotty
In our airline (UK based) routine maintenance calls for replenishment of the crew oxygen system if the pressure falls below 1600 psi every daily chk. Other jurisdictions require bottle changes with no possibility of recharging in situ. If proper "defect coding" of the tech log entry related to servicing is carried out I'm sure a computer somewhere will flag up any unusual frequency, and alert tech services to investigate!
Thanks yotty.
I am looking at an investigation report that says "
the decay in pressure from the nominal value of 1850 psi [to 1120 psi over 75 flights] was not unusual.". However, it strikes me as highly unusual. By my calculations, pre-flight mask testing and bleed on engine start up should have accounted for no more than a 200 psi drop over 75 flights, nowhere near the 730 psi drop recorded.
I don't have access to the maintenance records so I was hoping a B777 maintainer could say yea or nay, not unusual or unusual.