What was found
AT SLOW TAXI SPEEDS WITH PRESS ON BRAKES, THE BRAKES WILL SLOWLY RELEASE, RESULTING IN, PULSATING BRAKES DURING TAXI. IAW MM 12-15-05, CHECKED BRAKE CONTROL ACCUMULATOR, CHARGE WAS NORMAL. WITH ONLY RT ACMP ON, RT EICAS HYD PRESS IS 3000 PSI, BRAKE PRESS GAUGE INDICATES AROUND 3000 PSI. WHILE DEPRESSING BRAKE PEDALS, BRAKE ACTUATION IS NORMAL. TURN OFF RT ACMP, BLEED RT HYD PRESS & BRAKE PRESS DOWN BY PUMPING BRAKE PEDALS, SELECT ONLY LT ACMP ON, EICAS INDICATES 3000PSI, BUT BRAKE PRESS INDICATOR DOES NOT INDICATE ANY PRESS INCREASE. THE RT SIDE IS OPERATING NORMAL, LT SIDE DOES NOT. IAW FIM 32-41 FT 805 BLOCK 22 SAYS, REPLACE ACCUMULATOR ISOLATION VLV REF MM 32-44-06 401. REPLACED ACCUMULATOR ISOLATION VLV IAW 32-44-06. NO JOY. IAW FIM 32-41 805 THERMAL RELIEF CHECK VLV REQUIRED AMM. TROUBLE SHOT R & R ACCUMULATOR ISOLATION CHECK VLV IAW AMM 32-44-07-4. LEAK CHECKED GOOD. BLED ALL BRAKE ASSEMBLIES IAW AMM 32-41-00-2. PREFORMED TAXI CHECK IAW JRH BRAKES OPERATED NORMAL.