What was found
(CAN) NR 1 ENGINE WAS VIBRATING AT TAKEOFF POWER WHILE TAXIING. THE AIRCRAFT RETURNED TO THE GATE WHERE THE ENGINE WAS INSPECTED AND THE LP COMPRESSOR WAS LUBRICATED. DURING SUBSEQUENT RUN-UP, ALL ENGINE PARAMETERS WERE NORMAL, BUT WHEN TAKEOFF POWER WAS APPLIED, THE ENGINE BEGAN TO VIBRATE VIOLENTLY. INSPECTION FOUND A MISSING TURBINE BLADE AND SOME METAL IN THE TAILPIPE. THE ENGINE WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE. ENGINE RETURNED TO R & O, FURTHER REPORT TO FOLLOW.