As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON INITIAL CLIMB, CREW RECEIVED EICAS MESSAGE "L HYD QTY" AND "RSVR" LIGHT ON LEFT SYSTEM. QUANTITY WAS VERIFIED AS DECREASING. LATER, "L HYD SYS PRESS" EICAS MESSAGE APPEARED AND CONFIRMED. CREW FOLLOWED ALL CHECKLISTS AND DECLARED AN EMERGENCY. FLIGHT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE RIGHT GEAR ACTUATOR LINE LEAKING. REPLACED THE LINE. LEAK AND OPERATIONAL CHECK OK.