Bankerbot,
Welcome to BOL! I presume you have already looked the the NC Administrative Code's
RETENTION: REPRODUCTION AND DISPOSITION OF BANK RECORDS.
You may not find items specifically under the names you are using. I see Powers of Attorney are 5 years. You call yours "POA attorney-in-fact affidavits." I don't know if that is the same.
For affidavits of fraud and forgery, I may take a conservative approach and say at least 5 years. Alternatively a quick call to the NC Banking Commission may yield a more certain answer. They have always been helpful and friendly to me.
MarkB