We have several of the MS225-48FP in the field and asked about the loud fans. Back then we were told this wasn't a defect. fast forward to a few months ago and the fan recall came out. It's likely that and should be replaced on an RMA. So far we have only had two of them fail and sending high temp alarms. The replacements just recently started shipping out.
The MS225 is a very popular model as its the first entry level model that supports SFP+ I can understand while these are onl constraint, not only do they have to manufacture replacements but also enough sotck for new sales.