As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT, THE PILOT REPORTED THAT THE RT BRAKE WAS INEFFECTIVE. THE PILOT USED DIFFERENTIAL ENG CONTROLS & TAXIED BACK TO THE LOADING RAMP WITHOUT INCIDENT. REPLACED THE O RING PACKING’S, PN MS28775-220, IN THE RT BRAKE ASSEMBLY, SERVICED & BLED THE BRAKE SYS. LEAK & OPERATIONS CHECKED GOOD.