A TSO is a written specification published by the Federal Aviation Administration as a minimum performance standard for specified materials, parts, and appliances used on civil aircraft. It may specify input and output parameters, operating parameters, and other minimum specifications that apply to an article.
The FAA publishes TSOs to set uniform, minimum standards for articles installed an used in aircraft. When authorized to manufacture a material, part, or appliances to a TSO standard, this is referred to as TSO authorization.
Receiving a TSO authorization is both a design and production approval. Receiving a TSO Authorization is not an approval to install and use the article in the aircraft. It means that the article meets the specific TSO, meets a minimum performance requirement and the applicant is authorized to manufacture it.
A separate FAA approval is required to install the article on an aircraft independent of the article’s TSO approval The regulations related to Technical Standard Order’s may be found in 14 CFR 21 Subpart O—Technical Standard Order Authorizations