The Supplemental Type Certificates process, regulations, and policies are the same for small airplanes, transport category airplanes, and rotorcraft.
FAA Order 8900.1, Flight Standards Information Management System (FSIMS) identifies types of alterations:
A field approval may require coordination or technical assistance from the Aircraft Certification Engineering Division or other technical personnel. Ask your Flight Standards Aviation Safety Inspector (ASI) to coordinate with the Aircraft Certification Office (ACO) for needed technical assistance for a field approval.
Page Last Modified: 09/02/08 10:17 EDT
This page can be viewed online at: http://www.faa.gov/aircraft/air_cert/design_approvals/small_airplanes/stc_field-approval/