B737-800
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
General Maintenance Action
Aircraft; Procedure; Human Factors
While preflighting my O2 mask I noticed the pressure gauge reading slightly over 2000 psi. The mask checked normal after the 5 second check. I was curious about the gauge reading over 2000 psi. I thought that if we have so much pressure it wouldn't hurt to do a prolonged check to try to get the pressure to read normal. After about a minute the O2 stopped flowing from the mask while the overhead pressure still indicated slightly over 2000 psi. Obviously an empty O2 tank and bad gauge. Maintenance confirmed the O2 bottle was empty and replaced it. Maintenance said the previous installation of the O2 bottle damaged the sensors for the O2 pressure gauge. I'm sure you see the seriousness of this and like me wonder how many other airplanes are showing abnormally high O2 pressure with actually very very little O2.
A 737-800 pilot performed an extended crew oxygen system test due to a high pressure indication; only to discover that the oxygen bottle was near empty.