14 C.F.R. § 47.69
A Dealer's Aircraft Registration Certificate is valid only in connection with use of aircraft—
(d) On a flight that is—
(2) Necessary for, or incident to, sale of the aircraft.
However, a prospective buyer may operate an aircraft for demonstration purposes only while he is under the direct supervision of the holder of the Dealer's Aircraft Registration Certificate or his agent.
[Doc. No. 7190, 31 FR 4495, Mar. 17, 1966; 31 FR 5483, Apr. 7, 1966, as amended by Amdt. 47-4, 32 FR 12556, Aug. 30, 1967; Amdt. 47-29, 75 FR 41983, July 20, 2010; Docket No. FAA-2024-2765, Amdt. No. 47-36, 90 FR 5572, Jan. 17, 2025]