What was found
(CAN) IN PREPARATION OF THE ENGINE SHUTDOWN, ENGINES THROTTLES WERE BROUGHT DOWN TO FLIGHT IDLE, APPROXIMATELY 80 PERCENT NR, ALLOWING FOR COOLING PERIOD. ALL OF A SUDDEN AND COMPLETELY UNEXPECTED, THERE WAS AN OVERSPEED OF THE ENGINE NP 1 NR AND N2 OF UP TO 126.7 PERCENT. ENGINES WERE SHUTDOWN UNEVENTFUL. ENGINES ARE BEING REMOVED AND RETURNED TO O/H FACILITY.