Narrative:

About 3.5 hours into the flight; I was called back to the cockpit from break by the first officers. They indicated that there was an overheat condition of the center hydraulic system C2 demand pump; and that they had run the appropriate checklists and secured the pump per checklist. The pump however; had continued to run with the overheat condition still present and possibly worsening. They were involved with an ACARS datalink discussion with dispatch and maintenance; and the possibility of a divert was being discussed. Once up to speed on what actions had been taken; and what were ongoing; I placed a satcom call to dispatch/maintenance. Another snapshot was taken of the system for maintenance; to help them in understanding of the problem. Earlier; maintenance had indicated that the pump could be secured by pulling circuit breakers in the lower equipment bay. I was reluctant to have this done in flight; and suggested isolating the C2 pump by turning of bleed air to it via the right and center bleed air isolation valves. Maintenance concurred with this 'under captain's emergency authority'; so respective isolation valves were closed. The pump depressurized; and temperature began to decrease. Another snapshot was sent to maintenance and the maintenance controller made appropriate write-ups. I also requested and reviewed the MEL language for C2 pump deferral; even though this was not an inflight failure; and review flight handbook procedures and system discussions. No other systems were effected by bleed air isolation; and a normal approach and landing were anticipated with the remaining operational systems. Flight continued on to destination without further event.

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Original NASA ASRS Text

Title: An Air Carrier Captain on an oceanic flight reported that the aircraft's Hydraulic Demand Pump would not shutdown automatically and so was overheating. The Captain closed the bleed air supply to the pump; it stopped and cooled down.

Narrative: About 3.5 hours into the flight; I was called back to the cockpit from break by the First Officers. They indicated that there was an overheat condition of the center hydraulic system C2 demand pump; and that they had run the appropriate checklists and secured the pump per checklist. The pump however; had continued to run with the overheat condition still present and possibly worsening. They were involved with an ACARS datalink discussion with Dispatch and Maintenance; and the possibility of a divert was being discussed. Once up to speed on what actions had been taken; and what were ongoing; I placed a SATCOM call to Dispatch/Maintenance. Another snapshot was taken of the system for Maintenance; to help them in understanding of the problem. Earlier; Maintenance had indicated that the pump could be secured by pulling circuit breakers in the lower equipment bay. I was reluctant to have this done in flight; and suggested isolating the C2 pump by turning of bleed air to it via the right and center bleed air isolation valves. Maintenance concurred with this 'under Captain's emergency authority'; so respective isolation valves were closed. The pump depressurized; and temperature began to decrease. Another snapshot was sent to Maintenance and the Maintenance Controller made appropriate write-ups. I also requested and reviewed the MEL language for C2 pump deferral; even though this was not an inflight failure; and review flight handbook procedures and system discussions. No other systems were effected by bleed air isolation; and a normal approach and landing were anticipated with the remaining operational systems. Flight continued on to destination without further event.

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.