What was found
(CAN) PILOT REPORTED THAT #2 ENGINE STARTED SURGING IMMEDIATELY AFTER THE AIRCRAFT WAS AIRBORNE AND WITH THE GEAR SELECTED UP. PILOT INITIALLY HEARD THE CYCLING CHANGE IN ENGINE SOUND, AND FELT THE YAW. #2 ENGINE TORQUE WAS OBSERVED TO BE FLUCTUATING BETWEEN 80 AND 120%. THEY DID NOT LOOK AT THE PROPELLER RPM GAUGE, BUT BASED ON THE TORQUE INDICATIONS DETERMINED THAT THE #2 ENGINE WAS OPERATING ABNORMALLY. THE ENGINE WAS SHUT DOWN AS A PRE-CAUTIONARY MEASURE AND THE AIRCRAFT LANDED SAFELY WITHOUT ANY INCIDENT. AFTER THEY HAD SHUT DOWN THE ENGINE, IT WAS NOTICED THAT THE ENGINE MANUAL CAUTION LIGHT HAD ILLUMINATED. TROUBLESHOOTING IS GOING ON. (TC# 20190704001)