As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - DURING SCHEDULED BORESCOPE INSPECTION FOUND TOP ONE THIRD OF THREE TURBINE BLADES IN THE HPT DISK MISSING. REPLACED ENGINE. REPLACED ENGINE. OPERATIONAL OF AIRCRAFT CHECK GOOD. AIRCRAFT RETURNED TO SERVICE. ENGINE UNDER INVESTIGATION AT GE. INVESTIGATION BY THE ENGINE MANUFACTURER (GE) HAS BEEN COMPLETED. IT HAS BEEN CONCLUDED THAT MODIFICATION TO THE HPT1 DAMPNER (ALONG WITH RE-WORK OF THE ACCELERATOR) IS THE CORRECTIVE ACTION FOR THE REMOVED ENGINE. A PLAN HAS BEEN DEVISED TO INCORPORATE THIS MOD IN THE NEXT FEW QUARTERS.