A319
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors; Procedure
I was called at home and told that company Maintenance had disclosed that our flight had its oxygen shut off internally by Maintenance. So I can tell you that on my usual pre-flight; I turned on the [Crew oxygen] O2 with the cockpit switch. Pressed the 'Push to Test switch' on my mask and Jump-seat mask next to mine; and both tested O.K. Having not needed to go the Lavatory in flight; I could not tell that the O2 system wasn't working correctly. I have caught bad mask before; not working properly and had them replaced. Having been recently sick with the Flu; I am reluctant to put a mask on to test it during these epidemic times.
Have been told that the Oxygen on our aircraft may have been in the 'Off' or 'Close' position; possibly prior to our two legs with this aircraft. Per our FOM; Volume Two; Preflight procedures; I properly tested my oxygen mask and speaker before flight. It tested with the three test spurts of air and I observed the Oxygen Blinker show in its window. I always perform this test. Sounds like Maintenance had the oxygen system partially turned 'Off'; or it was completely 'On' during our legs of flight; because it worked normally for us.
Four pilots were informed the Crew Oxygen (O2) supply bottle handle on their A319 aircraft was found in the closed position by Maintenance.  Flight crews did not notice any oxygen supply discrepancies after two days of flying.