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Type Certificate - Supplemental Type Certificate

Supplemental Type Certificate (STC) vs Type Certificate (TC): UNRAVELING THE AVIATION PUZZLE

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The aviation industry is governed by strict regulations to ensure the safety of passengers, crew, and aircraft. Two important concepts in this context are Type Certificate (TC) and Supplemental Type Certificate (STC). In this blog post, we will explore the differences between TC and STC and understand their significance in the aviation industry.

What is a Type Certificate (TC)?

A Type Certificate (TC) is issued by the Civil Aviation Authority (CAA) to signify the airworthiness of a particular category of aircraft, according to its manufacturing design (type design). Certification confirms that the aircraft of a new type intended for serial production is in compliance with applicable airworthiness requirements established by the national air law.

The TC reflects a determination made by the regulatory authority that the type design is in compliance with airworthiness requirements. Examples of regulatory authorities are the U.S. Federal Aviation Administration (FAA), the European Aviation Safety Agency (EASA), Transport Canada, Brazil’s Agência Nacional de Aviação Civil, and the Administración Nacional de Aviación Civil (ANAC).

When there is a change in the TC, you can see what has been changed indicated by a vertical black line at the end each line of the Type Certificate Data Sheet (TCDS) that accompanies the TC certificate.

The TCDS contains detailed information about the aircraft’s performance, weight, balance, structural integrity, and other vital factors that affect its safety and airworthiness. It also specifies the operating conditions and limitations for the aircraft, such as the maximum speed, altitude, and temperature ranges.

When changes are needed to an airframe or onboard equipment, there are two options. One is to initiate a modification by the type design holder (manufacturer), and the other is to request a third-party Supplemental Type Certificate (STC). The choice is determined by considering whether the change constitutes a new design (i.e., introduces risk not considered in the first type design). If so, the type design holder must develop and approve a modification to the type design. If the regulatory authority agrees that the change does not introduce new risk, the STC option is availabl.

What is a Supplemental Type Certificate (STC)?

A Supplemental Type Certificate (STC) is issued to signify that a modification to an approved aircraft type design complies with airworthiness requirements. The STC defines the product design change, states how the modification affects the existing type design, and lists serial numbers of the aircraft affected. It also identifies the certification basis for regulatory compliance for the design change.

An STC includes details of the modification or addition, including the design, testing, and installation requirements. It also specifies any changes to the aircraft’s operating conditions and limitations that may be required due to the modification.

The STC is less expensive because the design change can be developed by a specialized design organization, a generally more flexible and efficient process than going through the original manufacturer. The STC option is available for changes that do not constitute a new desig.

Key Differences Between STC and TC

The main difference between TC and STC lies in their scope and purpose. A TC is issued for a new aircraft design and signifies that the aircraft meets all airworthiness requirements. In contrast, an STC is issued for a modification to an existing aircraft design and confirms that the modification does not introduce new risk and is compliant with airworthiness requirements.
The TC is a certificate that only the aircraft manufacturer can obtain and modify. The STC, on the other hand, is obtained and modified by others who are not the manufacturer. 

Another key difference is the cost and process of obtaining certification. The TC process is more rigorous, time-consuming, and expensive, as it involves extensive testing and evaluation of the new aircraft design. In contrast, the STC process is less expensive and more flexible, as it involves less stringent testing and evaluation requirements.


In conclusion, Type Certificate (TC) and Supplemental Type Certificate (STC) are two important concepts in the aviation industry that ensure aircraft safety and compliance with airworthiness requirements. TC is issued for a new aircraft design, while STC is issued for a modification to an existing aircraft design.

We hope this blog post has provided valuable insights. If you have any further questions or would like to discuss your specific needs, please contact us. Our team of experts is here to help you navigate the complex world of aviation certifications and ensure that your product meets all safety and regulatory requirements.

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