As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 1 ENGINE TREND DATA SHOWS A INCREASE IN LOW PRESSURE ROTOR VIBRATION LEVELS. DATA SCATTER INDICATES FAN LUBE REQUIRED. GROUNDED-YES. ACCOMPLISHED STEPS 1, 2 OF TSR710353. REMOVED AND REPLACED ALL FAN BLADE SHIMS 24 QTY, IAW ALASKA AIRLINES MTX TASK CARD 78472010. REMOVED SHIMS ROUTED TO POWERPLANT ENGINEERING FOR EVALUATION.