Either an appellant or an adverse party may, if he desires a hearing to present evidence on an issue of fact, request that the case be assigned to an administrative law judge for such a hearing. Such a request must be made in writing and filed with the Board within 30 days after answer is due and a copy of the request should be served on the opposing party in the case. The allowance of a request for hearing is within the discretion of the Board, and the Board may, on its own motion, refer any case to an administrative law judge for a hearing on an issue of fact. If a hearing is ordered, the Board will specify the issues upon which the hearing is to be held and the hearing will be held in accordance with sections 4.430 to 4.439, and the general rules in Subpart B of this part.