What was found
(CAN) INVESTIGATION OF A TREND SHIFT OF NR 2 ENGINE IN WHICH ALL PARAMETERS HAD DROPPED FOLLOWING AN ENGINE ELECTRONIC CONTROL (EEC) CHANGE, REVEALED THAT THE CHARACTERIZATION PLUG FOR THE TSOU (TORQUE SIGNAL CONDITIONING UNIT) HAD FAILED INTERNALLY. AS THE CHARACTERIZATION PLUG IS MATCHED TO THE ENGINE AND A REPLACEMENT WAS NOT READILY AVAILABLE. THE ENGINE WAS REPLACED AND THE AIRCRAFT WAS RETURNED TO SERVICE.