Fadec During Descend?

Hi,Recently I bought the Feelthere Legacy which is equiped with FADEC.I have a question about FADEC (in general), specifically during descend below FL100.I descended from FL90 to 4000 with a V/S of 1500ft/min.The FADEC controlled the engine idle thrust, setting it at about 50% N1.This caused the aircraft gradually to speed up again, from 220kts to 250+ kts.Is this normal? I mean normally idle thrust is between 20-25%, but appargantly not for FADEC controlled aircraft.How is speed controlled with such a high idle thrust? Speed brakes, flaps?Most likely I did something wrong (FMC setting, other?) or is this the way it works?EgbertEDIT:OOPS, wrong forum. Please delete will repost in FS2004 forum.Sorry