As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JFK INFLIGHT T1812/31JAN - GREEN SYSTEM HYDRAULIC FLUID LOSS IN FLIGHT. QUANTITY INDICATES ZERO. LANDING GEAR MANUALLY EXTENDED. LANDED JFK WITHOUT INCIDENT. REPLACED BOTH ENGINE GREEN HYDRAULIC PUMPS AND FILTERS. SYSTEM GROUND CHECKED NORMAL OPERATION.