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On their preflight test; a B7370-800 flight crew discovered the flow valve on the crew oxygen bottle was insufficiently opened to allow full flow. The initial test by the reporting crew earlier in the day had been successful allegedly because there was sufficient oxygen pressure in the lines to produce an apparently successful test.
| Attributes | |
| ACN | 880249 |
| Time | |
| Date | 201003 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | FO |
| Aircraft 1 | |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Parked |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Oxygen System/Crew |
| Person 1 | |
| Function | Pilot Not Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Person 2 | |
| Function | Pilot Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Procedural Maintenance Deviation - Procedural Published Material / Policy |
Narrative:
After arrival and a crew change; the new crew found that the crew oxygen pressure dropped to zero during [their preflight] flow test. After calling a mechanic; they found that the shutoff valve downstairs was not completely open (it took four full turns to open the valve). The oxygen preflight [prior to our previous departure] that morning was completely normal. Both the pilot not flying and pilot flying held the oxygen switch in test and observed no drop in oxygen pressure. There was enough air in the lines for the first test and one time individual use when a crew-member left the flight deck. In our situation; it appears that we would not have had the volume of oxygen needed for the three people in an emergency situation requiring oxygen. The bottle was changed the night before; and it appears that the valve was only partially open after that.
Original NASA ASRS Text
Title: On their preflight test; a B7370-800 Flight Crew discovered the flow valve on the crew oxygen bottle was insufficiently opened to allow full flow. The initial test by the reporting crew earlier in the day had been successful allegedly because there was sufficient oxygen pressure in the lines to produce an apparently successful test.
Narrative: After arrival and a crew change; the new crew found that the crew oxygen pressure dropped to zero during [their preflight] flow test. After calling a mechanic; they found that the shutoff valve downstairs was not completely open (it took four full turns to open the valve). The oxygen preflight [prior to our previous departure] that morning was completely normal. Both the pilot not flying and pilot flying held the oxygen switch in test and observed no drop in oxygen pressure. There was enough air in the lines for the first test and one time individual use when a crew-member left the flight deck. In our situation; it appears that we would not have had the volume of oxygen needed for the three people in an emergency situation requiring oxygen. The bottle was changed the night before; and it appears that the valve was only partially open after that.
Data retrieved from NASA's ASRS site as of April 2012 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.