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.

For complex design modifications, the Aircraft Certification Office may ask that you follow the Original Design Approval Process.

STC

• Application-to-Issuance
  • Establishment of Certification Basis
  • An STC Will Be Issued
  • An STC Will Not Be Issued
• Installation on the Airplane (STC not your own)
• Regulations & Policies
• STC Holder Responsibilities
• Supplemental Type Certificates & Field Approvals – Guidance for Small Airplanes
• Variants – “One-Only” and “Non-Interference”

Supplemental Type Certificates - database of approved STCs in the FAA's Dynamic Regulatory System (DRS)