What was found
(CAN) FLIGHT CREW REPORTED THAT DURING TAKEOFF THE NR 1 ENG HAD TORQUE & PROP FLUCTUATIONS & AS A RESULT THEY DID A PRECAUTIONARY SHUTDOWN OF THE NR 1 ENG. THE ACFT RETURNED TO THE DEPARTURE AIRPORT. TROUBLESHOOTING DETERMINED THAT THE ENG PARAMETER FLUCTUATION WAS A RESULT OF A FAILED & INTERNALLY SHORTED BETA BACKUP SWITCH 6141-S3, PN V3-19, LOCATED IN THE CTR CONSOLE. THE SWITCH WAS REPLACED IAW THE APPROVED REFERENCES & THE AC RETURNED TO SERVICE.