What was found
(CAN) AIRCRAFT HAD 2 AIR TURNBACKS DUE TO NR 2 PITCH TRIM LEVER DISENGAGING DURING CLIMB. THE NR 1 PITCH TRIM SYSTEM WAS ON MEL, AT THIS TIME. AFTER THE FIRST TURNBACK, THE NR 2 FLIGHT AUGMENTATION COMPUTER WAS REPLACED. THE NR 2 FAC TESTED SERVICEABLE. NR 1 SYSTEM REMAINED ON MEL. AIRCRAFT DEPARTED, DURING CLIMB NR 2 PITCH TRIM DISCONNECTED WITH ANOTHER NR 2 FAC FAULT. AIRCRAFT RETURNED TO BASE. THE TORQUE LIMIT SWITCH WAS REPLACED AS PER AMM 22-13-24 PAGE 401, FOR THE NR 1 SYSTEM. THE NR 2 FAC REPLACED AS PER AMM 22-26-34. OFF PART NUMBERS 2-2221-9-0001.