What was found
(CAN) ON DESCENT AS POWER WAS REDUCED, A-SYSTEM PRESSURE FLICKERED THEN WENT TO ZERO, LOW PRESSURE LIGHTS ON. EMERGENCY DECLARED. LEFT ENGINE A-HYDRAULIC PUMP PRESSURIZED SYSTEM. LANDED OK. AFTER SHUT DOWN, AIRCRAFT TOWED TO GATE. FOUND HYDRAULIC TANK PRESSURE LINE FROM PRESSURE REGULATOR TO A-SYSTEM RESERVOIR ADRIFT. LINE SECURED ENG 1 AND 2 FILTER DRAINED, REPLACED. PRESSURE FILTERS REPLACED, LEAK CHECK CARRIED OUT.