A CRJ700 ACFT #3 BRAKE HYD LINE QUICK DISCONNECT COUPLING SEPARATED FROM BRAKE ASSEMBLY AFTER FIVE FLIGHTS SINCE RE-INSTALLATION.

Narrative

ON ACFT X I REINSTALLED THE #4 BRAKE PER THE WORK CARD AND THE AMM. ON THE #3 BRAKE THE QUICK DISCONNECT FITTING ON THE BRAKE SIDE OF THE ASSEMBLY WAS FOUND TO BE LEAKING AND I CHANGED THAT FITTING. ON THE LEAK CHK FOR THAT FITTING I PRESSURIZED THE #2 AND #3 HYD SYS AND NO LEAKS WERE NOTED ON THE #3 OR #4 BRAKE. I CLEANED ALL THE QUICK DISCONNECT FITTINGS ON THE ACFT BEFORE ASSEMBLY BECAUSE THE GEAR HAD NOT BEEN WASHED PRIOR TO THE C-CHK. NO LEAKS OR OP PROBS WERE NOTED DURING THE REST OF THE C-CHK OR DURING MAINT GND ENG RUNS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THIS CRJ-700 ACFT WAS IN FOR A LANDING GEAR AXLE REPAIR AND INSPECTION. THE #3 AND #4 BRAKES WERE REMOVED FOR THIS PROCEDURE AND REINSTALLED. THE HYD BRAKE LINE'S QUICK DISCONNECT COUPLINGS WERE RE-ATTACHED AND THREADED DOWN. ON LANDING; THE FIFTH FLIGHT SINCE THE BRAKES WERE RE-INSTALLED; THE ACFT EXPERIENCED A #3 BRAKE OVERHEAT CONDITION. HOWEVER; NO ANTI-SKID WARNING INDICATION APPEARED IN THE COCKPIT. REPORTER ALSO STATED THE BRAKE QUICK DISCONNECT COUPLINGS ON THESE CRJ'S (700) WITH THE LARGE THREADED SCREW DOWN AND SERRATED LOCKING TEETH ARE IDENTICAL TO THE MD80 ACFT BRAKE QUICK DISCONNECTS. THE MD80'S HAD THE SAME PROBLEM WITH THE QUICK DISCONNECTS SEPARATING AFTER BEING RE-ATTACHED. HIS CARRIER; FOR SOME TIME HAS REQUIRED THE DISCONNECT COUPLING BE SAFETY WIRED AFTER THE COUPLING IS ATTACHED. REPORTER ADDED; HE DOES NOT KNOW WHY; OR WHERE; THE RESISTANCE TO INCORPORATING THE SAFETY WIRE PROCEDURE COMES FROM: THE ACFT MFG; THE CARRIER OR BOTH.