As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT RETURNED TO RAMP DUE TO "HYDRAULIC LOW LEVEL CAS MESSAGE" (COMBINED SYSTEM), INITIAL INSPECTION SHOWS HYDRAULIC LEAK ON NOSE WHEEL STEERING UNIT (NWSU), (ATL SEQ. #12574). MAINTENANCE REMOVED AND REPLACED NOSE WHEEL STEERING UNIT (NWSU) IAW AMM 32-05-00. OPERATION AND LEAK CHECK, SATISFACTORY. (ATL SEQ. #12574) (SN ON: 1719, SN OFF: 1475).