What is an STC - Supplemental Type Certificate ?
A Supplemental Type Certificate (STC) is a document issued by the Federal Aviation Administration (FAA) or European Aviation Safety Agency (EASA) approving a product (aircraft, engine, or propeller) modification. The STC defines the product design change, states how the modification affects the existing type design, and lists serial number affectivity. An STC is typically owned by a FAR 21/Part 21 Design organisation who remains responsible for the “Continuing Airworthiness” of the Product. It also identifies the certification basis listing specific regulatory compliance for the design change.

Information contained in the certification basis is helpful for those applicants proposing subsequent product modifications and evaluating certification basis compatibility with other STC modifications.

What is a C of C?
Certificate of Conformity. Affirmations that the supplier has complied with your purchase order.

Is a Purchase Order a contract?
Yes it is. If you have not accurately fulfilled the PO, you have not fulfilled a contract. So to consider the C of C as a supporting document only!

What is the AMP – Aircraft Maintenance Program
The AMP is the operators approved maintenance program, typically based on the MPD (Maintenance Planning Document). Note the Aircraft Maintenance Program includes Operator additional requirements over the AMS.