As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING TAXI FOR FLIGHT, THE CREW NOTICED LOSS OF BRAKES, RECEIVED NR 1 ISO VALVE AND ROLL SPOILER INBD CAUTION LIGHTS. ADDITIONALLY, THE NR 1 HYDRAULICS WERE DOWN TO 1 QUART. ACFT RETURNED TO GATE AND UPON SHUTDOWN, IT WAS VIEWED THAT THE INBD SIDE OF THE NR 1 NACELLE WAS DRIPPING WITH HYDRAULIC FLUID. MAINTENANCE INSPECTION FOUND THAT THE BRAKE QTY LIMITING VALVE CASING WAS FRACTURED/BROKEN. VALVE WAS REPLACED.