What is TSO (Technical Standard Order) in Aviation?

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If you spend enough time in or around the aviation sector, you will inevitably hear the term TSO used. In an industry with so many highly-specialized parts and practices, the many acronyms and abbreviations can become hard to remember. This blog will cover the technical standard order, or TSO, one of the more important acronyms in the industry.

TSO refers to the minimum performance standards put forth by the United States Federal Aviation Administration (FAA) for specified materials, parts, processes, and appliances found throughout civil aircraft. Any part of an aircraft, regardless of size or importance to the aircraft’s function, must have authorization that it meets the minimum standards necessary for operation. The most basic authorization is called a Type Certificate (TC). This is issued to the manufacturer of an aircraft or part once the FAA judges that the part has satisfactorily adhered to performance criteria. Another authorization, the Supplementary Type Certificate (STC), is given when an aircraft undergoes significant modification, addition, or repair. For instance, if a passenger aircraft is converted into a freight aircraft, an STC must be issued before it is able to fly.

The Technical Standard Order is the highest level of authorization and serves as a method for manufacturers of all types of parts to meet a single, standardized criteria. There are countless TSOs issued for many different part types both simple and complex, making them a critical part of the aviation industry as a whole. For most TSOs, the FAA employs SAE International, formerly known as the Society of Automotive Engineers, to provide consultation in the establishment and implementation of their stringent standards. SAE International is made of many different groups with expertise in varying areas such as airlines and manufacturing to create transparent and easily-understood standards. One thing to note is that, despite a part receiving TSO approval, the way it is utilized or implemented on an aircraft is subject to the operating requirements of the individual aircraft.

For a part or aircraft to be TSO approved, it must adhere to certain criteria. Some of the criteria include electrical, safety, and environmental standards. The electrical factors taken into consideration include capacity and power ratings at different temperatures, charge and discharge characteristics, life cycle testing, charge acceptance, shelf life, and more. Safety considerations include short circuits, insulation resistance, dielectric strength, explosion containment, and general strength of parts. The item must also be environmentally efficient at different altitudes, humidities, and be resistant to fluid and fungal contamination.

It’s fair to say that the TSO system is an international system. The governing body of European aviation, EASA, issues ETSOs, China’s CAAC releases CTSOs, and many other countries issue their own technical standard orders. Despite being issued by different governing bodies, all TSOs are essentially the exact same, and are widely accepted as global standards. Additionally, there is a process called validation wherein arrangements are made so that the TSO of one authority is approved for use by another country. This is sometimes called a bilateral agreement.

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1. kenneth lewis
2. Posted on February 19, 2020
aviation

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