Narrative:

During the preflight of the first officer's O2 mask I heard the caution chime. I looked up to see what it was and noticed a oxy low press caution briefly. I asked the first officer to do the test again and we got the caution message and chime again. I noticed the oxygen pressure drop about 200 psi while the test was being performed. I tested my mask and the pressure dropped but did not cause the caution. I called dispatch to begin a write-up. On call maintenance was sent and the observer's mask was swapped with the first officer's mask. The mechanics told us everything was good and we were going to MEL the jumpseat. I had the first officer test the mask again before I agreed to board again and the message continued to show up. The observer's mask was tested and was now also causing the caution message to appear briefly. The mechanic called maintenance control to discuss the problem. They checked the bottle gauge and it was higher than the EICAS gauge pressure. I noticed they had no idea where to go with the problem. As I waited I thought about it. I myself am an a&P and I was guessing there was a restriction in the O2 getting from the bottle to the O2 lines. I asked the mechanic if they checked the bottle valve was open. They had not; and found the bottle valve to be only partially open. When testing the masks after the valve was opened there was no drop in pressure and no caution message.honestly this scares me since I flew the airplane less than a month ago. Crew oxygen not being available when needed could cause the loss of the aircraft. I think the oxygen mask test should be modified to include watching the gauge pressure while the test is performed; and the appropriate pilot training conducted. The first officer had no idea the caution chime was associated with the test he was performing. And I hate to say it but I believe most pilots wouldn't make that association.

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Original NASA ASRS Text

Title: CRJ-200 Captain reported discovering the crew oxygen bottle valve was not fully open during their preflight inspection.

Narrative: During the preflight of the FO's O2 mask I heard the caution chime. I looked up to see what it was and noticed a Oxy Low Press Caution briefly. I asked the FO to do the test again and we got the Caution message and chime again. I noticed the Oxygen Pressure drop about 200 PSI while the test was being performed. I tested my mask and the pressure dropped but did not cause the caution. I called Dispatch to begin a write-up. On Call Maintenance was sent and the Observer's mask was swapped with the FO's mask. The mechanics told us everything was good and we were going to MEL the jumpseat. I had the FO test the mask again before I agreed to board again and the message continued to show up. The observer's mask was tested and was now also causing the caution message to appear briefly. The mechanic called maintenance control to discuss the problem. They checked the bottle gauge and it was higher than the EICAS gauge pressure. I noticed they had no idea where to go with the problem. As I waited I thought about it. I myself am an A&P and I was guessing there was a restriction in the O2 getting from the bottle to the O2 lines. I asked the mechanic if they checked the bottle valve was open. They had not; and found the bottle valve to be only partially open. When testing the masks after the valve was opened there was no drop in pressure and no caution message.Honestly this scares me since I flew the airplane less than a month ago. Crew oxygen not being available when needed could cause the loss of the aircraft. I think the oxygen mask test should be modified to include watching the gauge pressure while the test is performed; and the appropriate pilot training conducted. The FO had no idea the caution chime was associated with the test he was performing. And I hate to say it but I believe most pilots wouldn't make that association.

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.