Determinations of the Secretary of State under the Foreign Service Pension System which, if made by the Office of Personnel Management under chapter
84 of title
5 or the Director of such Office, would be appealable to the Merit Systems Protection Board shall, instead, be appealable to the Foreign Service Grievance Board, except that determinations of disability for participants shall be based upon the standards in section
4048 of this title (other than the exclusion for vicious habits, intemperance, or willful misconduct) and subject to review in the same manner as under that section.