What was found
(CAN) PILOT REPORTED THAT DURING THE DESCENT, WHEN PASSING FL250, THEY HEARD A NOISE ON THE ENGINE NR 2, WHILE BOTH ENGINES WHERE BELOW CRUISE POWER. THE AIRCRAFT DIVERTED. DURING THE TROUBLESHOOTING, BOTH ENGINE SPOOLS (LOW AND HIGH POWER) ROTATED NORMALLY. A DCU DOWNLOAD WAS RECEIVED FOR ANALYSIS.