How to preflight oxygen mask
• Select the status display.• Oxygen mask – Stowed and doors closed• RESET/TEST switch – Push and hold– Verify that the yellow cross shows momentarily in the flowindicator.• EMERGENCY/TEST selector – Push and hold– Continue to hold the RESET/TEST switch and push theEMERGENCY/TEST selector for 10 seconds. Verify that theyellow cross shows continuously in the flow indicator.• Verify that the crew oxygen pressure does not decrease more than100 psig.• If the oxygen cylinder valve is not in the full open position, pressurecan:• decrease rapidly, or• decrease more than 100 psig, or• increase slowly back to normal• Release the RESET/TEST switch and the EMERGENCY/TESTselector. Verify that the yellow cross does not show in the flowindicator.• Normal/100% selector – 100%• Crew oxygen pressure – Check EICAS– Verify that the pressure is sufficient for dispatch.