As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL180 E1 SURGED REPEATEDLY. ENGINE 1 CONTROL FAULT CAME ON EICAS. FOLLOWED QRH AND THRUST WAS UNSTABLE. PERFORMED INFLIGHT SHUTDOWN OF ENGINE 1 AND RETURNED TO DTW. DECLARED EMERGENCY, LANDED WITHOUT INCIDENT. MTX PERFORMED BOROSCOPE OF ENG 1 IAW GE MM 72-00-00-220-802, FOUND EXTENSIVE DAMAGE TO COMPRESSOR SECTION. 865RW REMOVED AND REPLACED E1 ENGINE IAW JOB CARD.