Narrative:

On maintenance walkaround found excessive hydraulic fluid coming from wheel well area. Operated hydraulics system and found B system hydraulic pump leaking from the pump and B system check valve cracked. I removed and replaced the B system pump and performed an operations and leak check of pump. It functioned properly with no leaks. The B system check valve was changed later in the morning by next shift when the part arrived. Callback conversation with reporter revealed the following information: reporter noticed lots of fluid on the lower belly of the B737-700 running all the way to the APU. Fluid seemed to be coming from the electric 'B' system hydraulic pump. He ran the 'B' pump and saw the pump leaking at the case drain and the check valve. He removed and replaced the 'B' pump. Next shift replaced the check valve. After departure; the aircraft lost all 'B' system hydraulic fluid. Flight did not divert and continued to original destination. Contract maintenance provider said the new hydraulic 'B' system pump was leaking. No indication where; on the pump; the leak was found. His company maintenance was dispatched to replace the new leaking pump. Unit was changed; pressure run and aircraft released without any further reports.

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Original NASA ASRS Text

Title: A B737-700 ACFT NEW ELECTRIC HYD 'B' PUMP FAILED ENROUTE AFTER BEING REPLACED FOR THE PREVIOUS HYD PUMP LEAKING.

Narrative: ON MAINT WALKAROUND FOUND EXCESSIVE HYD FLUID COMING FROM WHEEL WELL AREA. OPERATED HYDS SYS AND FOUND B SYS HYD PUMP LEAKING FROM THE PUMP AND B SYS CHK VALVE CRACKED. I REMOVED AND REPLACED THE B SYS PUMP AND PERFORMED AN OPS AND LEAK CHK OF PUMP. IT FUNCTIONED PROPERLY WITH NO LEAKS. THE B SYS CHK VALVE WAS CHANGED LATER IN THE MORNING BY NEXT SHIFT WHEN THE PART ARRIVED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR NOTICED LOTS OF FLUID ON THE LOWER BELLY OF THE B737-700 RUNNING ALL THE WAY TO THE APU. FLUID SEEMED TO BE COMING FROM THE ELECTRIC 'B' SYSTEM HYD PUMP. HE RAN THE 'B' PUMP AND SAW THE PUMP LEAKING AT THE CASE DRAIN AND THE CHECK VALVE. HE REMOVED AND REPLACED THE 'B' PUMP. NEXT SHIFT REPLACED THE CHECK VALVE. AFTER DEPARTURE; THE ACFT LOST ALL 'B' SYSTEM HYD FLUID. FLIGHT DID NOT DIVERT AND CONTINUED TO ORIGINAL DESTINATION. CONTRACT MAINT PROVIDER SAID THE NEW HYD 'B' SYSTEM PUMP WAS LEAKING. NO INDICATION WHERE; ON THE PUMP; THE LEAK WAS FOUND. HIS COMPANY MAINT WAS DISPATCHED TO REPLACE THE NEW LEAKING PUMP. UNIT WAS CHANGED; PRESSURE RUN AND ACFT RELEASED WITHOUT ANY FURTHER REPORTS.

Data retrieved from NASA's ASRS site as of January 2009 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.