What was found
DURING CRUISE, PILOT TURNED ON ENGINE DE-ICING SYS, RT ENGINE EGT EXCEEDED LIMITS & RT ENGINE FUEL BYPASS LIGHT ILLUMINATED. ENGINE REDUCED TO FLIGHT IDLE BUT RT ENGINE EGT NOT RESPONSIVE & RT ENGINE BYPASS LIGHT REMAINED. ENGINE SHUTDOWN, DECLARED AN EMERGENCY, DIVERTED, & LANDED WITHOUT INCIDENT. MANUALLY ROTATED PROP & ENGINE WAS DIFFICULT TO TURN. THE ENGINE SHOWED NO DIRECT CAUSE FOR THE REPORTED HIGH EGT. TEAR DOWN REPORT WAS ICE BUILDUP IN THE ACFT ENGINE INLET BEFORE ANTI-ICE WAS TURNED ON, INITIATION OF THE ANTI-ICE SYS A SINGLE SIZABLE SHEET OF ICE DROPPED IN FRONT OF THE INLET AREA CAUSING THE OVER TEMP CONDITION RESULTING IN THE SHUTDOWN.