Narrative:

An engine hydraulic pump valve was placed on the MEL by maintenance and two flts were flown in that condition. The engine hydraulic pump valve was inoperative in the open position. We subsequently determined that this specific pump valve should not have been operated inoperative under the MEL and it had been confused with another hydraulic valve with a similar sounding nomenclature. Contributing factors - pressure to maintain schedule, minimize delays, not questioning a maintenance decision, pilot fatigue, 4-DAY trip with long duty days, many flts and minimum rest overnight periods.

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Original NASA ASRS Text

Title: MINIMUM EQUIPMENT LIST REQUIREMENT MISINTERPRETED.

Narrative: AN ENG HYD PUMP VALVE WAS PLACED ON THE MEL BY MAINT AND TWO FLTS WERE FLOWN IN THAT CONDITION. THE ENG HYD PUMP VALVE WAS INOPERATIVE IN THE OPEN POS. WE SUBSEQUENTLY DETERMINED THAT THIS SPECIFIC PUMP VALVE SHOULD NOT HAVE BEEN OPERATED INOPERATIVE UNDER THE MEL AND IT HAD BEEN CONFUSED WITH ANOTHER HYD VALVE WITH A SIMILAR SOUNDING NOMENCLATURE. CONTRIBUTING FACTORS - PRESSURE TO MAINTAIN SCHEDULE, MINIMIZE DELAYS, NOT QUESTIONING A MAINT DECISION, PLT FATIGUE, 4-DAY TRIP WITH LONG DUTY DAYS, MANY FLTS AND MINIMUM REST OVERNIGHT PERIODS.

Data retrieved from NASA's ASRS site as of August 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.