What was found
NR 1 HYD QTY LOW, "EMPTY". HYD SYS 1-FAIL AND GEAR ELECTRICAL OVERIDE DID NOT ACTUATE. FREE FALL LEVER WAS USED TO LOWER GEAR IAW AOM-1. DECLARED AN EMERGENCY AND RETURNED TO DEPARTURE. LANDED WITHOUT INCIDENT. ACFT REMOVED FROM SERVICE. R & R NR 1 HYD ENGINE DRIVEN PUMP IAW AMM 29-10-03. OPS AND LEAK CHECKED GOOD. R & R HYD SYS NR 1 EMDP IAW AMM 29-10-04. OPS CHECKED GOOD. R & R HYD FILTERS FOR SYS NR 1 IAW AMM 29-10-08. OPS CHECKED GOOD. ACFT RETURNED TO SERVICE.