Narrative:

Location: 80 mi west of ord. Flight ab, ord-sfo, normal takeoff climbing out of FL280, received an EICAS message, low center system hydraulic quantity. Leveled off and performed checklist, however, hydraulic quantity continued decreasing. We declared an emergency, requested arff and returned to ord. En route we contacted dispatch, briefed flight attendants and performed the required checklists including alternate gear and flap extension. The approach landing and touchdown were normal. After the landing we remained on the taxiway for approximately 30 mins as arff reported some smoke coming off the right main gear. After the smoke dissipated maintenance inspected the wells, pinned the gear and we were towed to the gate. Callback conversation with reporter revealed the following information: the reporter stated the cause of the loss of all center hydraulic system pressure and quantity was a failed hydraulic line or fitting between the input to the right alternate and anti-skid module and the right alternate brake metering valve. The reporter said it was noted the quantity dropped to 70% when the system was shut down but all the fluid was lost. The reporter stated the concern of the loss of the center system is that it is the emergency hydraulic system for the flight controls.

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Original NASA ASRS Text

Title: A B767-300 IN CLB AT FL280 DECLARED AN EMER AND DIVERTED DUE TO LOSS OF CTR HYD SYS.

Narrative: LOCATION: 80 MI W OF ORD. FLT AB, ORD-SFO, NORMAL TKOF CLBING OUT OF FL280, RECEIVED AN EICAS MESSAGE, LOW CTR SYS HYD QUANTITY. LEVELED OFF AND PERFORMED CHKLIST, HOWEVER, HYD QUANTITY CONTINUED DECREASING. WE DECLARED AN EMER, REQUESTED ARFF AND RETURNED TO ORD. ENRTE WE CONTACTED DISPATCH, BRIEFED FLT ATTENDANTS AND PERFORMED THE REQUIRED CHKLISTS INCLUDING ALTERNATE GEAR AND FLAP EXTENSION. THE APCH LNDG AND TOUCHDOWN WERE NORMAL. AFTER THE LNDG WE REMAINED ON THE TXWY FOR APPROX 30 MINS AS ARFF RPTED SOME SMOKE COMING OFF THE R MAIN GEAR. AFTER THE SMOKE DISSIPATED MAINT INSPECTED THE WELLS, PINNED THE GEAR AND WE WERE TOWED TO THE GATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CAUSE OF THE LOSS OF ALL CTR HYD SYS PRESSURE AND QUANTITY WAS A FAILED HYD LINE OR FITTING BTWN THE INPUT TO THE R ALTERNATE AND ANTI-SKID MODULE AND THE R ALTERNATE BRAKE METERING VALVE. THE RPTR SAID IT WAS NOTED THE QUANTITY DROPPED TO 70% WHEN THE SYS WAS SHUT DOWN BUT ALL THE FLUID WAS LOST. THE RPTR STATED THE CONCERN OF THE LOSS OF THE CTR SYS IS THAT IT IS THE EMER HYD SYS FOR THE FLT CTLS.

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.