What was found
ON FLIGHT 4057 THE CREW REPORTED THEY RECEIVED INITIALLY HYD 1 LOW QTY MESSAGE THEN ROUGHLY FORTY MINUTES LATER HYD SYS 1 FAIL THEN AIL SYS 1 INOPERABLE. THE CREW DECLARED AN EMERGENCY AND DIVERTED TO GRR. THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED NR 1 EDP IAW ERJ 145 29-10-03. RAN NR 1 ENGINE AT TAKEOFF POWER FOR MIN 3 MINUTES. CHECKED FOR LEAKS NONE NOTED AT THIS TIME. THE AIRCRAFT WAS RETURNED TO SERVICE.