(a) This subpart applies to fact-finding investigations in which an order of investigation has been issued under §13.3(c) or §13.5(i) of this part.

(b) This subpart does not limit the authority of duly designated persons to issue subpoenas, administer oaths, examine witnesses and receive evidence in any informal investigation as provided for in sections 313 and 1004(a) of the Federal Aviation Act (49 U.S.C. 1354 and 1484(a)) and section 109(a) of the Hazardous Materials Transportation Act (49 U.S.C. 1808(a)).