TSO and ETSO — Technical Standard Orders
TSO/ETSOSection 13: Jurisdiction Mapping Sets
Definition
A Technical Standard Order (TSO) is a minimum performance standard issued by the certification authority that an article (equipment or appliance) must meet in order to receive a TSO Authorization (TSOA). A TSOA certifies that the article meets the applicable TSO performance standard and may be installed on any applicable aircraft. The FAA issues TSOs under 14 CFR Part 21 Subpart O. EASA issues European Technical Standard Orders (ETSOs) under Part 21 Subpart O. TCCA issues Canadian Technical Standard Orders (CAN-TSOs).
Where This Shows Up
The TSO system enables the certification of equipment independently of a specific aircraft installation. A TSOA demonstrates that the article meets the minimum performance standard (which typically references an RTCA/EUROCAE document as the technical standard), but it does not by itself constitute installation approval: the article must still be shown to be compatible with the specific aircraft installation. TSO/ETSO numbers reference the applicable performance standard (e.g., TSO-C151c references DO-260B for ADS-B Out equipment). The TSO application process requires the submission of a Declaration of Design and Performance (DDP), test reports, and software/hardware assurance data as applicable.
Primary Sources
Technical Standard Order Approvals — FAA regulations governing the TSO application, approval, and production processes.
European Technical Standard Order Authorisations — EASA framework for ETSO approvals.
Across Jurisdictions
14 CFR Part 21 Subpart O
Issued by the FAA under 14 CFR Part 21 Subpart O. The applicant submits a TSOA application to the responsible ACO with a Declaration of Design and Performance (DDP) and supporting data. The TSOA letter authorizes production under the TSO marking (TSO-CXXXx). The manufacturer must hold a production approval (Part 21 Subpart K or accepted equivalent) to produce TSO articles.
EASA Part 21 Subpart O
Issued by EASA under Part 21 Subpart O. ETSOs largely mirror FAA TSOs in numbering and referenced standards. The ETSO applicant must have a DOA or work with EASA directly. EASA ETSOAs are recognized within all EASA member states and may be accepted by other authorities under bilateral agreements.
ETSOs often reference the same RTCA/EUROCAE documents as the corresponding FAA TSO. However, differences may exist in administrative requirements, environmental qualification expectations, and the specific referenced document revision.
CAR Part V, AWM Chapter 537
TCCA issues CAN-TSOs referencing the same technical standards as FAA TSOs. Many CAN-TSOs directly adopt FAA TSO standards. TCCA also accepts FAA TSOAs under the bilateral agreement for articles imported into Canada.
Related Terms
Need help navigating certification?
Understanding the terminology is the first step. If you need expert guidance on DO-178C, DO-254, ARP4754B, or any aspect of FAA, EASA, or TCCA certification, our team is here to help.