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B737-800 flight crew has a slow hydraulic fluid loss from 'a' system. Calls dispatch and maintenance coordination, makes an equipment adjustment during a precautionary diversion to ord.
| Attributes | |
| ACN | 638434 |
| Time | |
| Date | 200411 |
| Day | Mon |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : mht.vor |
| State Reference | NH |
| Altitude | msl single value : 35000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zbw.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| ASRS Report | 638434 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | aircraft equipment problem : critical |
| Independent Detector | aircraft equipment other aircraft equipment : hyd quant gauge other flight crewa other flight crewb |
| Resolutory Action | controller : issued new clearance flight crew : diverted to another airport flight crew : landed as precaution other |
| Consequence | other other |
| Supplementary | |
| Problem Areas | Aircraft |
| Primary Problem | Aircraft |
Narrative:
After reaching our cruise altitude, a routine monitoring of the hydraulic display screen showed a loss of left hydraulic quantity from the preflight value of 96% to 78%. After that, periodic re-checks showed a continued decrease in left hydraulic system quantity to 60% at a drop rate of approximately 1% every 10 mins. Reference to the QRH did not include any procedure for hydraulic quantity loss, only a loss of pressure. Because of the consequences of the failure of hydraulic system 'a' which included a manual gear extension, loss of normal brakes, and stopping on the runway to pin the gear, we contacted maintenance coordination for additional insight. Their suggestion to isolate the leak source by turning off flight control switch 'a' was successful in stopping further system 'a' fluid loss. Dispatch was advised that we wished to divert to ord where an uneventful landing on runway 14R was made.
Original NASA ASRS Text
Title: B737-800 FLT CREW HAS A SLOW HYD FLUID LOSS FROM 'A' SYS. CALLS DISPATCH AND MAINT COORD, MAKES AN EQUIP ADJUSTMENT DURING A PRECAUTIONARY DIVERSION TO ORD.
Narrative: AFTER REACHING OUR CRUISE ALT, A ROUTINE MONITORING OF THE HYD DISPLAY SCREEN SHOWED A LOSS OF L HYD QUANTITY FROM THE PREFLT VALUE OF 96% TO 78%. AFTER THAT, PERIODIC RE-CHKS SHOWED A CONTINUED DECREASE IN L HYD SYS QUANTITY TO 60% AT A DROP RATE OF APPROX 1% EVERY 10 MINS. REF TO THE QRH DID NOT INCLUDE ANY PROC FOR HYD QUANTITY LOSS, ONLY A LOSS OF PRESSURE. BECAUSE OF THE CONSEQUENCES OF THE FAILURE OF HYD SYS 'A' WHICH INCLUDED A MANUAL GEAR EXTENSION, LOSS OF NORMAL BRAKES, AND STOPPING ON THE RWY TO PIN THE GEAR, WE CONTACTED MAINT COORD FOR ADDITIONAL INSIGHT. THEIR SUGGESTION TO ISOLATE THE LEAK SOURCE BY TURNING OFF FLT CTL SWITCH 'A' WAS SUCCESSFUL IN STOPPING FURTHER SYS 'A' FLUID LOSS. DISPATCH WAS ADVISED THAT WE WISHED TO DIVERT TO ORD WHERE AN UNEVENTFUL LNDG ON RWY 14R WAS MADE.
Data retrieved from NASA's ASRS site as of July 2007 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.