As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT AROUND 9,000 FEET AT NORMAL EPR CLIMB LIMIT. THE LEFT ENGINE DEVELOPED STRONG SURGES. RETURN TO LAX WITH ENGINE AT IDLE. PERFORMED BORESCOPE OF THE NR 1 (LEFT) ENGINE. FOUND NUMEROUS 13TH STAGE BLADES DAMAGED BEYOND LIMITS. PER MM 72-00-00. R&R NR 1 ENGINE.