A 737-800 pilot performed an extended crew oxygen system test due to a high pressure indication; onl...

Attributes
ACN	1278364
Time
Date	201507
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Indicating and Warning - Oxygen Systems
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy Deviation - Procedural Maintenance

Narrative:

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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.