What was found
(CAN) #2 ENGINE EXPERIENCED SUDDEN VIBRATIONS THROUGH FL270. ALL ENGINE PARAMETERS WERE FINE BUT VIBRATIONS COULD BE FELT THROUGH THE AIRCRAFT AND POWER LEVERS. ENGINE WAS SHUTDOWN AND THE AIRCRAFT RETURNED TO ITS POINT OF DEPARTURE. POST FLIGHT INSPECTION FOUND A BLADE MISSING FROM THE AFT TURBINE WHEEL. THE ENGINE WAS REPLACED, THE AIRCRAFT GROUND RUN SERVICEABLE AND THE AIRCRAFT RETURNED TO SERVICE. THE FAILED ENGINE WAS SENT TO ROLLS ROYCE FOR INVESTIGATION, FURTHER REPORT TO FOLLOW.