As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5998, AMA TO SDF. AFTER TAKEOFF, THE CREW NOTICED THE HYDRAULIC QUANTITY DECREASING. WHILE RETURNING TO AMA, LOW HYDRAULIC 2 WAS DISPLAYED ON EICAS. THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED THE HYDRAULIC SYSTEM AND FOUND THE E2 HYDRAULIC PUMP LEAKING AT THE CASE LINE. THE PUMP WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE.