14 CFR § 61.321

If you hold a sport pilot or higher grade certificate and seek to operate an additional category or class of aircraft meeting the performance limits and design requirements of § 61.316 under this subpart, other than an airplane single-engine land or sea or a rotorcraft-helicopter, you must—

Receive a logbook endorsement from the authorized instructor who trained you on the applicable aeronautical knowledge areas specified in § 61.309 and areas of operation specified in § 61.311. The endorsement certifies you have met the aeronautical knowledge and flight proficiency requirements for the additional aircraft privilege you seek;

Successfully complete a proficiency check from an authorized instructor, other than the instructor who trained you, consisting of the tasks in the appropriate areas of operation contained in the applicable Practical Test Standards or Airman Certification Standards (incorporated by reference, see § 61.14) as listed in appendix A of this part for the additional sport pilot privilege you seek;

Complete an application for those privileges on a form and in a manner acceptable to the FAA and present this application to the authorized instructor who conducted the proficiency check specified in paragraph (a)(2) of this section; and

Receive a logbook endorsement from the authorized instructor who conducted the proficiency check specified in paragraph (a)(2) of this section certifying you are proficient in the applicable areas of operation and aeronautical knowledge areas, and that you are authorized for the additional category and class aircraft privilege.

If you hold a sport pilot or higher grade certificate and seek to operate an airplane single-engine land or sea or a rotorcraft-helicopter meeting the performance limits and design requirements of § 61.316, you must successfully accomplish a practical test for that category and class privilege as specified in § 61.307(b).