As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 1 HYDRAULIC SYSTEM LOW LEVEL LIGHT ILLUMINATED IN-FLIGHT. RETURNED TO BASE AND LANDED WITHOUT INCIDENT. SYSTEM HAD LOST FLUID THROUGH NR 1 HYDRAULIC PUMP SEAL DRAIN. MAINTENANCE REPLACED HYDRAULIC PUMP. REF: S-76 IPC, CHAPTER 29-10-01, FIGURE 1, ITEM 12.