What was found
(CAN) DEPARTING, WHILE CRUISING AT 31 000 FT, LOUD BANG COMING FROM LT ENGINE WITH DECREASING EPR , INCREASING EGT UP TO 575 C. DID NOT HAVE A RE-LIGHT WITH IGNITER ON INCREASING POWER WAS NOT RESPONDING, SO WE TREATED THAT AS A SEVERE DAMAGE OR SEPARATION AND THE ENGINE WAS SHUT DOWN. AIRCRAFT WAS DIVERTED.