As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, GEAR RETRACTION NR 1 HYDRAULIC SYSTEM FAILED. CREW RETURNED AND LANDED AIRCRAFT IN HKG WITHOUT INCIDENT. YELLOW EMERGENCY WAS DECLARED. MAINTENANCE FOUND LT AILERON POWER CONTROL UNIT (PCU) FILTER HOUSING CRACKED. MAINTENANCE REMOVED AND REPLACED HOUSING, FILTER, AND ENGINE DRIVEN PUMP (EDP). OPERATIONAL CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.