What was found
PILOT REPORT: WHEN DEPARTING PN44 IN 431MK WITH TWO PAX ONBOARD, WE EXPERIENCED A MOMENTARY LOSS OF POWER WITH ENGINE OSCILLATIONS. ON TAKEOFF WE PULLED APPROXIMATELY 95% TQ, AFTER ABOUT 5 SECONDS THE LEFT ENGINE ROLLED BACK TO ABOUT 70% TQ AND THE RIGHT SPIKED TO 108% TQ. ALL INDICATIONS RETURNED TO NORMAL AFTER MOVING THE COLLECTIVE SLIGHTLY. WE WERE DISCUSSING WHAT TO DO NEXT WHEN THE SAME THING HAPPENED AGAIN IN CRUISE EXCEPT AT A LOWER POWER SETTING. IN CRUISE WE WERE PULLING ABOUT 75% TQ WHEN THE LEFT ENGINE DROPPED TO ABOUT 50% AND THE RIGHT ENGINE ROSE TO COMPENSATE. CREW ELECTED TO RETURN TO TTN WHERE PASSENGERS TRANSFERRED TO ANOTHER HELICOPTER TO CONTINUE THE TRIP. THIS COLLECTIVE STICK TRANSDUCER HAS BEEN CHANGED MULTIPLE TIMES SINCE THE FIRST OF THE YEAR. S/N: 0454 REPLACED AFTER 47.8 HOURS, FAILED INSPECTION; S/N:0485 FAILED AFTER 25.2 HOURS. ALL THE FAILURES HAVE BEEN AN INFLIGHT TORQUE OSCILLATION OR MOMENTARY LOSS OF TORQUE.