Supplemental Type Certificate (STC)
A supplemental type certificate (STC) is a type certificate (TC) issued when an applicant has received FAA approval to modify an aeronautical product from its original design. The STC, which incorporates by reference the related TC, approves not only the modification but also how that modification affects the original design.
STC Holder Responsibilities
Advisory Circular 21-40 and FAA Order 8110.4 identifies the STC applicant’s responsibilities.
In addition, once the STC is approved, the STC holder must:
Report failures, malfunctions and defects (14 CFR § 21.3)
Make the type certificate available to FAA and National Transportation Safety Board, upon request (14 CFR § 21.49)
Make Instructions for Continued Airworthiness available to owner/operator (14 CFR § 21.50)
Make required design changes to address Airworthiness Directives and make them available (14 CFR § 21.99)
Make flight manuals supplements and supplemental flight manuals available with each alteration (14 CFR § 21.5 and § 23.1581)
