What was found
(CAN) DURING CRUISE, NR 1 HYD QTY INDICATED, 0 AND NR 1 ENGINE HYD PUMP, NR 1 HYD ISO VALVE, ROLL SPOILER INBD HYD, CAUTION LIGHTS ILLUMINATED. THE CREW CARRIED OUT NON-NORMAL PROCEDURE AND DECIDED TO DIVERT BASE. DURING APPROACH, NR 1 HYD QTY INDICATED ABOUT 20 PERCENT. ACFT LANDED WITH NO FLAP AND TOWED AFTER SHUTTING DOWN ENGINES AT TAXIWAY. MAINTENANCE FOUND FLUID LEAKAGE FROM THE MATING SURFACE OF THE NR 1 EDP, DPI OF THE CASE DRAIN FILTER ALSO POPPED UP. THE LEAK WAS LATER CONFIRMED DUE TO GASKET FAILURE, PN 51761, CMM 29-11-40, ITEM 265, NR 1 EDP, SPU AND THE FILTER WAS R & R, NR 1 HYD SYSTEM FLUSHING CARRIED OUT FOR THE ACFT.