Cessna Citation Sovereign (C680)
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors; Procedure
Picked up [the aircraft]. Had a few write-ups for Maintenance including oxygen level low. I wrote it up and it was serviced to the max level. Then 2 days later (they were working other maintenance issues) we went to go fly it and the oxygen was low again. Wrote it up again. The mechanic discovered 7 of the 10 passenger masks were not attached properly.Reporting this event in the hopes that this type of discovery won't happen again. This could have had a very bad outcome.
CE-680 Captain reported maintenance found 7 of 10 passenger oxygen masks were not attached properly; causing a loss of oxygen pressure.