What was found
CLE - FLT 4227 - CREW REPORTED WHILE EN ROUTE FROM EWR, THEY RECEIVED A HYDRAULIC LOW QUANTITY SYSTEM 1 INDICATION FOLLOWED BY PRESSURE LOSS AND THE FAILURE OF THE SYSTEM. AIRCRAFT DIVERTED TO CLE AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED A FAILED O-RING AT THE NR 1 HYDRAULIC SYSTEM PRIORITY VALVE IAW EMB-1465 MM 29-10-13. THE NR 1 ENGINE DRIVEN HYDRAULIC PUMP WAS ALSO REMOVED AND REPLACED IAW EMB-145 MM 29-10-03 AS A PRECAUTION. OPERATIONAL AND LEAK CHECKS WERE SATISFACTORY. AIRCRAFT RELEASED FOR SERVICE. (X)