Narrative:

In cruise flight, the master caution annunciator illuminated for system 'a' hydraulic low pressure for the #1 engine driven pump. We followed the procedures in the pilot's handbook and turned the system 'a' pump switch to off. The hydraulic fluid quantity gauge indicated full. Upon descent, the master caution annunciated again showing low hydraulic pressure on the #2 engine driven pump for the 'a' hydraulic system. We followed the same procedure as above, declared an emergency, and checked the system 'a' hydraulic gauge which still indicated full. We proceeded with the loss of system 'a' hydraulic procedure in the pilot's handbook. As we extended the flaps and gear by alternate means, the master caution annunciated again for system hydraulics and we noticed erratic N1 and fuel flow on the #2 engine. At this time we requested a shorter final. On final, the captain said the airplane felt as though it wanted to roll to the right at vref 15, so we increased airspeed. We felt the tendency to roll might be caused by a spoiler flutter. Landing was uneventful with the speed brake and reversers deploying as expected. After landing, we noticed a low quantity light for the standby hydraulic system which would explain the third illumination of the master caution light. The aircraft was towed to the gate. At the gate, it was discovered that the system 'a' hydraulic quantity gauge was faulty and the #2 hydraulic pump was leaking fluid.

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Original NASA ASRS Text

Title: AN ACR MLG LOST MOST OF ITS HYD SYS.

Narrative: IN CRUISE FLT, THE MASTER CAUTION ANNUNCIATOR ILLUMINATED FOR SYS 'A' HYD LOW PRESSURE FOR THE #1 ENG DRIVEN PUMP. WE FOLLOWED THE PROCS IN THE PLT'S HANDBOOK AND TURNED THE SYS 'A' PUMP SWITCH TO OFF. THE HYD FLUID QUANTITY GAUGE INDICATED FULL. UPON DSCNT, THE MASTER CAUTION ANNUNCIATED AGAIN SHOWING LOW HYD PRESSURE ON THE #2 ENG DRIVEN PUMP FOR THE 'A' HYD SYS. WE FOLLOWED THE SAME PROC AS ABOVE, DECLARED AN EMER, AND CHKED THE SYS 'A' HYD GAUGE WHICH STILL INDICATED FULL. WE PROCEEDED WITH THE LOSS OF SYS 'A' HYD PROC IN THE PLT'S HANDBOOK. AS WE EXTENDED THE FLAPS AND GEAR BY ALTERNATE MEANS, THE MASTER CAUTION ANNUNCIATED AGAIN FOR SYS HYDS AND WE NOTICED ERRATIC N1 AND FUEL FLOW ON THE #2 ENG. AT THIS TIME WE REQUESTED A SHORTER FINAL. ON FINAL, THE CAPT SAID THE AIRPLANE FELT AS THOUGH IT WANTED TO ROLL TO THE R AT VREF 15, SO WE INCREASED AIRSPD. WE FELT THE TENDENCY TO ROLL MIGHT BE CAUSED BY A SPOILER FLUTTER. LNDG WAS UNEVENTFUL WITH THE SPD BRAKE AND REVERSERS DEPLOYING AS EXPECTED. AFTER LNDG, WE NOTICED A LOW QUANTITY LIGHT FOR THE STANDBY HYD SYS WHICH WOULD EXPLAIN THE THIRD ILLUMINATION OF THE MASTER CAUTION LIGHT. THE ACFT WAS TOWED TO THE GATE. AT THE GATE, IT WAS DISCOVERED THAT THE SYS 'A' HYD QUANTITY GAUGE WAS FAULTY AND THE #2 HYD PUMP WAS LEAKING FLUID.

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.