As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE, NR 1 ENGINE HAD VIBRATION AND SURGE. AIRCRAFT LANDED BACK TO DEPARTURE AIRPORT WITH ENGINE RUNNING AT IDLE. FOUND SPINNER AND 3 FAN BLADES DAMAGED BY FOD. THERE WAS NO TRACE OF BLUE ICE OR BIRD STRIKE. ENGINE HAS BEEN REPLACED.