AN EMB145 R ENG HAD ABNORMAL VIBRATION WHEN MOVING THRUST LEVER FROM IDLE STOP. VIBRATION MORE PRONOUNCED ON GND DURING TAXI.

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WE WERE DOING A ZZZ/ZZZ1 TURN WITH ACFT XXX. THE FIRST FLT WAS COMPLETED UNEVENTFULLY. THE RETURN FLT WAS UNEVENTFUL UNTIL THE INITIAL DSCNT INTO ZZZ. THE FO WAS THE PF. AS HE ADDED THRUST AT OUR LEVEL OFF ALT; HE ASKED ME IF I FELT OR HEARD A VIBRATION. I KNOW THAT SOME OF THESE AIRPLANES; PARTICULARLY THE EMB140'S; MAKE A SLIGHT GROWLING NOISE AT IDLE THRUST IN FLT. INITIALLY; I THOUGHT THIS WAS WHAT HE WAS REFERRING TO. HOWEVER; HE CLARIFIED THAT THE NOISE WAS ONLY AUDIBLE DURING THE INITIAL ENG ACCELERATION FROM THE IDLE POS. WE EXPERIMENTED A LITTLE WITH THE THRUST LEVERS AND WERE ABLE TO IDENT THE NOISE AS COMING FROM THE #2 ENG; ONLY WHEN MOVING THE THRUST LEVER FROM THE IDLE POS. AS WE CONTINUED OUR DSCNT AND APCH INTO ZZZ; THE SOUND SEEMED TO BECOME MORE PRONOUNCED. THE ENG VIBRATION GAUGES APPEARED NORMAL; HOWEVER; THE HP VIBRATION FOR ENG #2 WAS SLIGHTLY HIGHER THAN THE OTHERS 'MAYBE HALFWAY BTWN THE BOTTOM OF THE GREEN AND THE AMBER SCALE.' WE DEBATED WHETHER TO EVEN WRITE IT UP; BECAUSE IT WAS SO SUBTLE; BUT DURING TAXI WE NOTICED THE NOISE WAS EVEN MORE PRONOUNCED; PERHAPS DUE TO LESS AMBIENT NOISE; BUT IT WAS DEFINITELY ABNORMAL; SO WE NOTIFIED MAINT. I WAITED FOR THE MECH SO I COULD TALK TO HIM DIRECTLY; AND HE WHEELED UP A LADDER TO LOOK INTO THE ENG TO FIND ANYTHING OBVIOUS. HE LOOKED IN THE FRONT AND BACK OF THE ENG AND DID NOT NOTICE ANYTHING ABNORMAL. HE DID SAY THAT THEY WOULD TAKE THE ACFT TO THE HANGAR AND CHK IT OUT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE AIRPLANE WAS REMOVED FROM SVC FOR INVESTIGATION OF THE ENG VIBRATION AND WAS RETURNED TO SVC THE NEXT DAY. THE RPTR SAID THE AIRPLANE WAS ROUTED S AND INTO A DIFFERENT MAINT SECTOR AND DATA WAS NOT AVAILABLE FROM THE MAINT COMPUTER.