As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OUT AT APPROXIMATELY 18,800 FT, NR 3 ENGINE HAD THREE LOUD BANGS. WHEN THROTTLE WAS RETARDED BANGS STOPPED. THRUST LEVER REMAINED AT IDLE FOR REMAINDER OF THE FLIGHT. THE ONLY INDICATION NOTICED WAS THAT THE N1 WAS AROUND 76 PERCENT AT ONE POINT. CHANGE ENGINE IAW MM. POWERPLANT REMOVAL/INSTALLATION.