turbine d, thanks, cfm 56
old boeing...I understand exactly what you are getting at.
another poster, yaw string, indicated he checked his oxygen in havana after the inbound crew HAD NOT and found the valve OFF.
I've seen this too, esp after servicing. I am of the habit to make DARN SURE the oxygen system will work at 100 percent EMERGENCY and blow my lungs up and sound like the movie 2001 space odyssey .
this might have been part of the problem and I hope the oxygen service records will be released soon.