What was found
DURING CRUISE RECEIVED A "HYD 1 LOW QTY" EICAS MESSAGE, FOLLOWED A FEW MINUTES LATER BY A "HYD E1 PUMP FAIL" EICAS MESSAGE. HYD SYS 1 PRESSURE AT 2900 PSI INDICATED THAT E1 ENGINE DRIVEN PUMP HAD FAILED. A FEW MINUTES LATER HYD PRESSURE DROPPED BELOW 2900 PSI ACCOMPANIED BY NOISE REPORTED BY THE F/A INDICATING THE ELECTRICAL PUMP WAS CAVITATING. ELECTRICAL HYD PUMP WAS TURNED OFF TO PREVENT FURTHER DAMAGE. FOLLOWED AOM 1 PROCEDURES AND DECLARED AN EMERGENCY. LANDED WITHOUT INCIDENT. ACFT REMOVED FROM SERVICE. REMOVED AND REPLACED THE #1 ELECTRIC MOTOR-DRIVEN PUMP IAW AMM 29-10-04.THE OPERATIONAL AND LEAK CHECK WAS GOOD THE AIRCRAFT WAS RETURNED TO SERVICE.