As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENG HAD AUDIBLE SURGE DURING POWER REDUCTION AT TOP OF DESCENT. THROTTLE REDUCED TO IDLE. NO ENG LIMITS WERE EXCEEDED. WHEN THROTTLE WAS ADVANCED TO 61%, 1 AT FL 230 IT SURGED AGAIN. THROTTLE REDUCED TO IDLE FOR REMAINDER OF FLIGHT. VISUAL CHECKS IAW FIM 71-05 TASK 819 FOUND METAL PARTICLES IN TAIL PIPE. REPLACE ENG IAW MM 71-00-02 PG 401. REPLACED NR 1 ENG IAW MM 71- 00-02 & TOD 71-00-02 UP TO ITEM H NR 18.