As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, THE AIRCRAFT LOST THE NBR 4 HYDRAULIC SYSTEM FLUID QUANTITY AND PRESSURE. CREW DECLARED AN EMERGENCY AND RETURNED TO MNL AND LANDED WITHOUT INCIDENT. REPLACED THE HYDRAULIC RETURN LINE BETWEEN THE CASE DRAIN MODULE AND HEAT EXCHANGER, CASE DRAIN MODULE, ENGINE DRIVEN HYDRAULIC PUMP, AND AIR DRIVEN HYDRAULIC PUMP. OPERATIONAL CHECK GOOD.