What was found
ACFT HAD AN AIR-TURNBACK DUE TO RIGHT ENGINE N1 ERRATIC JUMPIMG BETWEEN 88.2 - 82.0 N2 JUMPING BETWEEN 94.3 - 94.9 STBY ENGINE INDICATOR MATCHED EICAS DISPLAY. REMOVED AND REPLACED N1 SPEED SENSOR AS PER MM 77-12-01 OPS CHECK AND LEAK CHECK GOOD, REMOVED AND REPLACED N2 SPEED SENSOR AS PER MM 77-12-02 REMOVED AND REPLACED CIT SENSOR AS PER MM 73-21-02 ALL OPS CHECK AND LEAKS CHECK GOOD