As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE NR 1 ENGINE OIL QUANTITY DROPPED TO ZERO AND THE OIL PRESSURE BEGAN TO DROP AFTER TAKEOFF FROM CLE. THE AIRCRAFT WAS RETURNED TO CLE WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE LINE TO FUEL/OIL COOLER LOOSE AND LEAKING. THE LINE WAS TIGHTENED AND THE NR 1 ENGINE WAS SERVICED WITH OIL. THE ENGINE WAS RUN AT FULL POWER AND NO LEAKS WERE NOTED.