As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED A NR ONE BLEED SYS FAIL. ACFT RETURNED TO DEPARTURE WHERE IT LANDED WITHOUT INCIDENT. MX REMOVED AND REPLACED THE NR 1 FAN AIR VALVE FILTER, OPS AND LEAK CHECKED WITH NO DEFECTS, AND THE ACFT WAS APPROVED FOR RETURN TO SERVICE.