As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER TAKEOFF, NR 1 HYD SYS WAS LOST, AIR CREEBEC FLIGHT 921 DECLARED AN EMERGENCY AND TURN BACK TO YUL AIRPORT ACFT LANDED SAFELY AND WAS TOWED TO GATE FOR PASSENGER OFFLOAD. AFTER MAINTENANCE INSPECTION THEY FOUND THE NR 1 ENG DRIVEN PUMP CASE DRAIN LINE RUPTURE AT THE FILTER AREA IN THE LT WHEEL WELL LINE AND PUMP WAS REPLACED AND THE ACFT WAS BACK IN SERVICE AROUND 11:00 AM.