14 C.F.R. § 61.17

Temporary certificate.

        (a) A temporary pilot, flight instructor, or ground instructor certificate or rating is issued for up to 120 days, at which time a permanent certificate will be issued to a person whom the Administrator finds qualified under this part.

        (b) A temporary pilot, flight instructor, or ground instructor certificate or rating expires:

        (1) On the expiration date shown on the certificate;

        (2) Upon receipt of the permanent certificate; or

        (3) Upon receipt of a notice that the certificate or rating sought is denied or revoked.

Official source