As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT, THE NR 1 HYD SYSTEM WENT TO 36 PERCENT AND THE HYD SYSTEM NR 1 LOW LIGHT ILLUMINATED. THE ALTERNATE FLAP AND LANDING GEAR EXTENSION PROCEDURES WAS USED. CREW DECLARED AN EMERGENCY AND LANDED AT YYZ WITHOUT FURTHER INCIDENT. REPLACED THE NR 1 HYD PUMP PRESSURE LINE O-RING. SERVICED WITH HYD FLUID. SYSTEM GROUND CHECKED FOR NORMAL OPERATION. (M)