B757 flight crew experienced an engine driven hydraulic pump failure nearing top of climb on an ocea...

Narrative:

Just prior to reaching top of climb; we received a 'left hydraulic pump' EICAS message with associated 'press' light illuminated in the left hyp pump switch. QRH calls for affected pump switch off. We complied and then received a lower EICAS message 'power xfer unit.' we checked MEL and operating manual for explanation of message. Both references stated that the power xfer unit message is a 'failure of circuitry for power transfer unit protection.' we had a three way conversation with the dispatcher and a maintenance person. After a lengthy conversation; it was determined that the ptu (power transfer unit) was not operating properly and given the condition of the engine driven pump; any further degradation of the left hydraulic system would put the aircraft in real jeopardy. I elected to divert and we obtained a clearance and since we were on the edge of making an overweight landing; requested arff to be mobilized and available upon landing.

Original NASA ASRS Text

Title: B757 flight crew experienced an engine driven hydraulic pump failure nearing top of climb on an oceanic flight. An indication of PTU failure was also received; the crew diverted for maintenance.

Narrative: Just prior to reaching top of climb; we received a 'L HYD PUMP' EICAS message with associated 'press' light illuminated in the L HYP PUMP SWITCH. QRH calls for affected pump switch off. We complied and then received a lower EICAS message 'POWER XFER UNIT.' We checked MEL and operating manual for explanation of message. Both references stated that the POWER XFER UNIT message is a 'Failure of circuitry for power transfer unit protection.' We had a three way conversation with the Dispatcher and a maintenance person. After a lengthy conversation; it was determined that the PTU (power transfer unit) was not operating properly and given the condition of the engine driven pump; any further degradation of the left hydraulic system would put the aircraft in real jeopardy. I elected to divert and we obtained a clearance and since we were on the edge of making an overweight landing; requested ARFF to be mobilized and available upon landing.

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.

Attributes
ACN	895650
Time
Date	201006
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Light	Night
Aircraft 1
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Climb
Component
Aircraft Component	Hydraulic System Pump
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Flying
Events
Anomaly	Aircraft Equipment Problem Critical

B757 flight crew experienced an engine driven hydraulic pump failure nearing top of climb on an oceanic flight. An indication of ptu failure was also received; the crew diverted for maintenance.