What was found
(CAN) DURING A ROUTINE FLIGHT THE PILOT REPORTED A TORQUE DROP TWICE ON RT ENGINE. THE FIRST WAS A SUDDEN TORQUE DROP FROM 90 PERCENT TO 0 PERCENT. THE PILOT MANAGED TO BRING THE TORQUE BACK TO 90 PERCENT FOR A WHILE BEFORE IT DROPPED AGAIN TO 20 PERCENT IN 2 SECONDS. THE TORQUE WAS BROUGHT BACK UP AGAIN TO 90 PERCENT WHERE THEY ELECTED TO GO BACK TO AIRPORT OF ORIGIN WHERE THEY SAFELY LANDED WITH THE 2 ENGINES RUNNING. TROUBLESHOOTING ONGOING.