14 CFR § 21.55
Responsibility of type certificate holders to provide written licensing agreements
July 13, 2020
A type certificate holder who allows a person to use the type certificate to manufacture a new aircraft, aircraft engine, or propeller must provide that person with a written licensing agreement acceptable to the FAA.
[Doc. No. FAA-2003-14825, 71 FR 52258, Sept. 1, 2006]