As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HAD A LOSS OF THE YELLOW HYD SYS QTY, YELLOW SYS QTY WAS ZERO. FLUID DRAINING FROM THE NR 2 ENGINE. THE AIRCRAFT WAS GROUNDED. MAINTENANCE REMOVED AND REPLACED THE O-RING ON THE NR 2 ENGINE HYDRAULIC FILTER ASSEMBLY IAW AMM 29-13-43. OPS AND LEAK CHECKED GOOD.