What was found
(CAN) DURING MAINTENANCE RUN-UP, THE NR 1 ENGINE VIBRATION BEGAN TO INCREASE. THE NR 1 ENGINE WAS SHUTDOWN. INSPECTION FOUND A HOLE IN THE LOWER TURBINE CASE, WHICH INDICATED A TURBINE BLADE, OR BLADES, HAD FAILED AND EXITED THROUGH THE CASE. THERE WAS NO AIRFRAME DAMAGE. THE ENGINE HAS BEEN REMOVED AND IS BEING SENT FOR INVESTIGATION AND REPAIR. PART TC: 21,407.