What is the purpose of a Supplemental Type Certificate?

A Supplemental Type Certificate (STC) is a regulatory document issued by the Federal Aviation Administration (FAA) that approves a modification to an existing type design of an aircraft or its components. The purpose of the STC is to allow for changes or alterations without requiring a completely new type certificate for the entire aircraft design.

One of the primary functions of an STC is to enable multiple approvals for the same design change across different aircraft models or systems. For example, if a manufacturer develops a new avionics system that can be retrofitted onto various aircraft models, an STC allows multiple aircraft owners to implement that particular modification under the same approval. This streamlines the process for approving alterations that enhance capabilities, safety, or performance without necessitating separate, individual approvals for each aircraft.

In contrast, certifying an entire aircraft design refers to the standard type certificate process that occurs before an aircraft can enter service. The other options, such as providing one-time exemptions from airworthiness requirements or listing aircraft owner responsibilities, do not accurately reflect the purpose of an STC or its role in relation to modifications to aircraft. Overall, an STC is an essential tool in aviation that facilitates improvements and modifications while maintaining compliance with regulatory standards.