What was found
(CAN) DURING CLIMB AND PASSING THROUGH FL80, THE FLIGHT CREW WITNESSED TORQUE ON THE LEFT-HAND ENGINE EXHIBITING AN UN-COMMANDED ROLL BACK. AT FL100, LEFT-HAND ENGINE TORQUE DECREASED TO A LEVEL THAT WAS 20% LESS THAN RIGHT-HAND ENGINE TORQUE. UPON ATTAINING CRUISE ALTITUDE AT FL140, THROTTLING BACK ON THE RIGHT-HAND ENGINE RESULTED IN THE TORQUE DIFFERENCE BETWEEN THE TWO ENGINES NARROWING DOWN TO 5%. AFTER CONSULTATION WITH MAINTENANCE CONTROL, A DECISION WAS MADE FOR THE FLIGHT CREW TO DIVERT. TORQUE SPLIT RE-ASSERTED ITSELF DURING SUBSEQUENT FLIGHTS ON 13-MAR-2019 AND 16-MAR-2019. NO DIVERSION WAS REPORTED ON THESE TWO OCCASIONS.