Narrative:

Worked aircraft xyz (B777), 'deferred inoperative' for #1 brake assembly found leaking. Hydraulic pressure line disconnected and secured with tie wraps. I replaced the brake assembly per air carrier maintenance manual 32-45-07, removed tie wrap from line and secured on brake assembly with fitting. Pressure leak check and set brakes. Confirm brakes were set and actuation with co-worker. No leaks found on fitting connection. Now, 7 legs later in XXX flight abc, may/fri/00, mechanic found line disconnected. I suspect the spring tension on quick disconnect or 'tangs' (pins) that secure fitting, on brake assembly at fault. Callback conversation with reporter revealed the following information: the reporter stated the quick disconnect fittings on the brake and hydraulic line appeared and acted normal on installation. The reporter said the brake was pressurized and actuated several times for leak checking. The reporter stated no logbook reports were noted in the 7 flts on braking or abnormal temperature indication. The reporter stated it is possible the disconnect could have been struck by some object or the spring tension on the line connector weakened or broke.

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Original NASA ASRS Text

Title: A B777 HAD A #1 FORWARD BRAKE ASSEMBLY REPLACED ON MAY WED 2000. 7 FLTS LATER ON MAY FRI 2000 THE BRAKE HYD LINE WAS FOUND DISCONNECTED.

Narrative: WORKED ACFT XYZ (B777), 'DEFERRED INOP' FOR #1 BRAKE ASSEMBLY FOUND LEAKING. HYD PRESSURE LINE DISCONNECTED AND SECURED WITH TIE WRAPS. I REPLACED THE BRAKE ASSEMBLY PER ACR MAINT MANUAL 32-45-07, REMOVED TIE WRAP FROM LINE AND SECURED ON BRAKE ASSEMBLY WITH FITTING. PRESSURE LEAK CHK AND SET BRAKES. CONFIRM BRAKES WERE SET AND ACTUATION WITH CO-WORKER. NO LEAKS FOUND ON FITTING CONNECTION. NOW, 7 LEGS LATER IN XXX FLT ABC, MAY/FRI/00, MECH FOUND LINE DISCONNECTED. I SUSPECT THE SPRING TENSION ON QUICK DISCONNECT OR 'TANGS' (PINS) THAT SECURE FITTING, ON BRAKE ASSEMBLY AT FAULT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE QUICK DISCONNECT FITTINGS ON THE BRAKE AND HYD LINE APPEARED AND ACTED NORMAL ON INSTALLATION. THE RPTR SAID THE BRAKE WAS PRESSURIZED AND ACTUATED SEVERAL TIMES FOR LEAK CHKING. THE RPTR STATED NO LOGBOOK RPTS WERE NOTED IN THE 7 FLTS ON BRAKING OR ABNORMAL TEMP INDICATION. THE RPTR STATED IT IS POSSIBLE THE DISCONNECT COULD HAVE BEEN STRUCK BY SOME OBJECT OR THE SPRING TENSION ON THE LINE CONNECTOR WEAKENED OR BROKE.

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.