What was found
WHILE IN CRUISE FLIGHT, THE EICAS MESSAGE "L HYD QTY" ILLUMINATED SHOWING .49 RF. THE CREW TURNED LT PUMP OFF UNTIL LANDING AND DECLARED AN EMERGENCY WITH ATC. THE AIRCRAFT LANDED WITHOUT INCIDENT. CORRECTIVE ACTION: MAINTENANCE FOUND BOTH LINES ON LT DOWN LOCK ACTUATOR HAD RUPTURED, POSSIBLY CAUSED BY A LOOSE HOLD DOWN BRACKET. BOTH LINES WERE REPLACED AND THE ACTUATOR BRACKET WAS RE-SECURED. LEAK CHECK IS OK.