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After a quality assurance audit indicated the flight crew oxygen bottle pressure was below 1;750 psi; minimum on a B777-200. Mechanic reports he may have miscalculated the temperature difference and expected pressure readings.
| Attributes | |
| ACN | 825311 |
| Time | |
| Date | 200902 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B777-200 |
| Flight Phase | Parked |
| Component | |
| Aircraft Component | Oxygen System/Crew |
| Person 1 | |
| Function | Technician |
| Person 2 | |
| Function | Lead Technician |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Procedural FAR Deviation - Procedural Maintenance Deviation - Procedural Published Material / Policy |
Narrative:
Myself and another mechanic were assigned a 3 service check on aircraft. I looked at CRT display; oxygen pressure read 1;630 psi with that in mind and the fact that it was approximately 50-55 degrees and knowing that it is not abnormal for the bottle pressure to be approximately 50 psi or more greater than CRT pressure. I calculated that pressure would be at or above 3 service minutes of 1;750 psi at 70 degrees. I was informed by my lead of findings of quality assurance audit team; which was CRT oxygen pressure at 1;540 psi; at which time I proceeded to service oxygen per MM.
Original NASA ASRS Text
Title: After a Quality Assurance audit indicated the flight crew oxygen bottle pressure was below 1;750 PSI; minimum on a B777-200. Mechanic reports he may have miscalculated the temperature difference and expected pressure readings.
Narrative: Myself and another Mechanic were assigned a 3 service check on aircraft. I looked at CRT display; oxygen pressure read 1;630 PSI with that in mind and the fact that it was approximately 50-55 degrees and knowing that it is not abnormal for the bottle pressure to be approximately 50 psi or more greater than CRT pressure. I calculated that pressure would be at or above 3 service minutes of 1;750 PSI at 70 degrees. I was informed by my Lead of findings of Quality Assurance Audit Team; which was CRT oxygen pressure at 1;540 PSI; at which time I proceeded to service oxygen per MM.
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.