What was found
(CAN) AFTER TAKE OFF, THE NR 3 THROTTLE WAS RETARDED, THE ENGINE WAS SHUT DOWN DUE TO HIGH VIBRATIONS (2.5 2.7 UNITS) , CHANNEL A&B FROM LOW CHANNEL. THE AIRCRAFT RETURNED TO BASE (YYZ). MAINTENANCE C/OUT A BOROSCOPE AND THE FINDINGS WERE, HP COMPRESSOR STAGE 1, DAMAGE TO MOST OF THE BLADESAND ONE BLADE WAS DAMAGED BEYOUND LIMITS I.A.W. 72-00-00 P.629, THE ENGINE WAS REJECTED. MAINTENANC E WILL REPLACE THE ENGINE