As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) OVERWEIGHT LANDING ON ACCOUNT OF AIRBORNE RETURN DUE TO NR 1 PACK FAILURE, APPROXIMATE LANDING WEIGHT 212,000 KGS. PFR SHOWS NO FAULT. PACK 1 OPERATED ON GROUND NO EXHAUST AIR OBSERVED-PACK 1 OVHT WARNING WAS ON AFTER 2 MINUTES. ECS GROUND REPORT SHOW PACK 1, AIR CYCLE MACHINE FAULT. PACK 1 CONSIDERED INOPERATIVE. PACK 2 OPERATED ON GROUND NO ACRID FUMES AND FAULT OBSERVED.