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Captain reports finding the standby hydraulic system pump indicating normal operation; but the standby low pressure light remained illuminated when he performed an optional preflight check on a B737-900 aircraft. Maintenance found hydraulic supply line to standby pump partially disconnected. Unknown how long aircraft had been flying without a functional standby hydraulic system.
| Attributes | |
| ACN | 1131958 |
| Time | |
| Date | 201311 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B737-900 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Other Parked Pre-Departure |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Hydraulic System Pump |
| Person 1 | |
| Function | Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
During preflight I performed an optional check (per our flight manual) of the standby hydraulic system. I found the standby pump indicating normal operation; but the standby low pressure light remained illuminated. Maintenance was called and they confirmed the low pressure indication and began troubleshooting. What we had was a pump running; but not putting out any pressure. After various tests and about 45 minutes; our mechanics informed us they had fixed the problem. The maintenance logbook [indicated that maintenance] found the hydraulic supply line to standby pump partially disconnected at the standby reservoir. Reconnected same. Verified proper operation of standby rudder and alternate flaps. Verified quick disconnect at reservoir is secure; ok to continue. There is no way to know how long this aircraft had been flying without a standby hydraulic system.
Original NASA ASRS Text
Title: Captain reports finding the Standby Hydraulic System Pump indicating normal operation; but the Standby Low Pressure Light remained illuminated when he performed an Optional Preflight Check on a B737-900 aircraft. Maintenance found Hydraulic Supply Line to Standby Pump partially disconnected. Unknown how long aircraft had been flying without a functional Standby Hydraulic System.
Narrative: During preflight I performed an Optional Check (per our Flight Manual) of the Standby Hydraulic System. I found the Standby Pump indicating normal operation; but the Standby Low Pressure Light remained illuminated. Maintenance was called and they confirmed the low pressure indication and began troubleshooting. What we had was a pump running; but not putting out any pressure. After various tests and about 45 minutes; our mechanics informed us they had fixed the problem. The Maintenance Logbook [indicated that Maintenance] found the Hydraulic Supply line to Standby Pump partially disconnected at the Standby Reservoir. Reconnected same. Verified proper operation of Standby Rudder and Alternate Flaps. Verified Quick Disconnect at reservoir is secure; OK to continue. There is no way to know how long this aircraft had been flying without a Standby Hydraulic System.
Data retrieved from NASA's ASRS site as of July 2013 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.