A U.S. applicant may receive a "one-only STC" for a U.S. State of Design aircraft that is registered outside of the U.S. under the following circumstances:
- If the aircraft is intended for operation by a U.S. operator under lease or charter;
- If safety enhancements such as Traffic Collision Avoidance Systems (TCAS), Enhanced Ground Proximity Warning System (EGPWS), and Reduce Vertical Separation Minimums (RSVM) equipment are mandated;
- If it is involving diplomatic aircraft, or aircraft owned by Heads of State, and production is limited to the U.S.
- If the applicant provides a request letter from the authority of the State of Registry citing the authority's need for FAA support for a U.S. type designed aircraft, e.g. due to the lack of necessary infrastructure to support STC projects on U.S. type designed aircraft.
If one of these conditions is met, normal STC procedures should be followed. FAA Order 8110.4 "Type Certification" contains instructions for issuance of an FAA STC.