***Meaning*** :: <u>S</u>upplemental <u>T</u>ype <u>C </u>ertificate ***Definition*** :: A major change in type design not great enough to require a new application for a [[type certificate]] under... part 21. ***Example:*** Installation of a powerplant different from what was included in the original TC. ***Source*** :: [[AC 91-67]] #glossary #acronym