As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DUCT PRESSURE DIFFERENTIAL GREATER THAN 20 PSI (APPROX 22). LT PACK LOWER THAN RIGHT PACK. LT 23PSI. RIGHT 45PSI. PERFORMED ENGINE BLEED AIR SYSTEM HEALTH CHECK ON NR 1 ENGINE, NO FAULTS FOUND, LEAK CHECKED OK. NR 1 ENGINE HAD BLEED TRIP. PRECOOLER CONTROL VALVE AND PRECOOLER CONTROL VALVE SENSOR WERE REPLACED WITH REPAIR CONFIRMATION AND FVR FLIGHT CONFIRMING NORMAL BLEED AIR OPERATION.