AC 21-46A

U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Technical Standard Order Program Date: 02/23/2017 Initiated By: AIR-100 AC No: 21-46A

This advisory circular (AC) explains the Technical Standard Order (TSO) process outlined in Title 14 of the Code of Federal Regulations (14 CFR) part 21, subpart O, for manufacturers producing articles under a TSO authorization (TSOA) or letter of design approval (LODA).

Susan J. M. Cabler Acting Manager, Design, Manufacturing, & Airworthiness Division Aircraft Certification Service

TABLE OF CONTENTS Paragraph Page ii

Chapter 1. General Information1-1

1.1 Purpose1-1

1.2 Audience1-1

1.3 Where to Find This AC1-1

1.4 Cancellation1-1

1.5 Explanation of Changes1-1

Chapter 2. The TSO Program2-1

2.1 Technical Standard Order (TSO) Definition2-1

2.2 TSO Authorization and Letter of Design Approval2-1

2.3 Limitations of a TSO Authorization2-2

2.4 Deviation Definition2-3

2.5 TSOA or LODA Are Not Mandatory2-3

2.6 TSO Markings2-3

Chapter 3. TSOA and LODA Applicant Responsibilities3-1

3.1 Certify That Your Article Complies With the Applicable TSO Standard3-1

3.2 Compliance Matrix3-1

3.3 Control the Design and Quality of Your Article3-2

3.4 Set Up and Maintain a Quality System (QS)3-2

3.5 TSOA Application Requirements3-2

3.6 LODA Application Requirements3-4

3.7 Use of Subject Matter Experts in the TSOA Process3-4

3.8 Provide Installation Instructions and Limitations3-4

3.9 Provide Maintenance Instructions for the Article3-6

3.10 Submit Open Problem Reports (OPR)3-7

3.11 Requesting Approval to Deviate From a TSO (§ 21.618)3-7

3.12 Roles of the FAA and Applicant3-9

Chapter 4. TSOA and LODA Holder Responsibilities4-1

4.1 Continue to Meet the Requirements of the TSO4-1

4.2 How to Mark Each Article4-1

TABLE OF CONTENTS (CONTINUED) Paragraph Page iii

4.3 Report Service Difficulties Pursuant to § 21.34-2

4.4 Design Changes4-3

4.5 Transferability4-6

Chapter 5. Additional TSO Topics5-1

5.1 Receiving a Parts Manufacturer Approval (PMA) to Modify a TSOA Article5-1

5.2 Shipping a Subcomponent of an Article Independent of the Complete Article5-1

5.3 Incomplete TSO Article5-1

5.4 Multiple TSO Authorizations for the Same Article5-2

5.5 Non-TSO Functions (NTF)5-3

Appendix A. List of AcronymsA-1

Appendix B. Sample Compliance MatrixB-1

Appendix C. Advisory Circular FeedbackC-1

1-1 CHAPTER 1. GENERAL INFORMATION

1.1 Purpose.

This advisory circular (AC) explains the Technical Standard Order (TSO) process. It 1.1.1 also explains the responsibilities of the TSO authorization (TSOA) applicant, the letter of TSO design approval (LODA) applicant, holders of TSO production and design approvals (TSOA holders), and TSO design approval holders (LODA holders).

This AC is not mandatory and does not constitute a regulation. It describes an 1.1.2 acceptable means, but not the only means, to comply with the requirements of Title 14 of the Code of Federal Regulations part 21, subpart O. However, if you use the means described in this AC, you must follow it in all important respects.

1.2 Audience.

We wrote this AC for manufacturers of articles who are applying for a TSOA or a LODA, and for manufacturers of articles who are already approved by a TSOA or a LODA.

1.3 Where to Find This AC.

You can find this AC on the Federal Aviation Administration (FAA) website at http://www.faa.gov/regulations_policies/advisory_circulars/.

1.4 Cancellation.

This AC cancels AC 21-46 dated 09/30/2010.

1.5 Explanation of Changes.

This revision:

General: change numbering system within the document to comply with Order 1.5.1 1320.46D (FAA Advisory Circular System).

Revised paragraph 1.1 for a clearer purpose. 1.5.2 Added a paragraph to explain the changes in this revision. 1.5.3 Reworded paragraph 2.1 in defining TSO and TSOA. 1.5.4 Changed wording in paragraph 2.2 to the language used in FAA Order 8150.1D, 1.5.5 Technical Standard Order Program.

Changed wording in paragraph 2.3 to the language used in FAA Order 8150.1D. 1.5.6

1-2 Added paragraph 2.4, which explains deviations using the language in 1.5.7 FAA Order 8150.1D.

Changes the explanation of TSO marking in paragraph 2.6 to the language in 1.5.8 FAA Order 8150.1D.

Added paragraph 3.2, introducing compliance matrix. 1.5.9 Revised TSOA application requirement, paragraph 3.5, using language in Order 1.5.10 8150.1D.

Added paragraph 3.10 regarding Open Problem Reports (OPR). 1.5.11 Reword paragraph 3.12 to introduce Figure 3-1. 1.5.12 Added Figure 3-1 to summarize the roles of applicant, AIR-100, ACO and MIDO. 1.5.13 Adds paragraphs 4.4.1 and 4.4.2, which contain information about design changes. 1.5.14 Change wording in paragraph 4.4.3, minor change to a design. 1.5.15 Added paragraph 4.4.3.5 regarding marking of changed article. 1.5.16 Added paragraph 4.4.4.2 regarding submitting of application. 1.5.17 Change wording in paragraph 4.4.7 regarding design change. 1.5.18 Corrected typo error in paragraph 4.5.3. 1.5.19 Changes title of paragraph 5.1. 1.5.20 Add detailed information to paragraph 5.5 related to non-TSO functions. 1.5.21 Added Appendix A. - List of Acronyms. 1.5.22 Added Appendix B – Sample of Compliance Matrix. 1.5.23

2-1 CHAPTER 2. THE TSO PROGRAM

2.1 Technical Standard Order (TSO) Definition.

A TSO is a minimum performance standard, defined by the FAA, used to evaluate an article. An article can be a material, part, component, process, or appliance. (Refer to Title 14 of the Code of Federal Regulations (14 CFR) 21.1(b)(2)). Each TSO covers a certain type of article intended for use on civil aviation aircraft and provides a baseline standard intended to support compliance with airworthiness or operational requirements. However, compliance with a TSO or multiple TSO cannot ensure the installation of the article will comply with airworthiness requirements. This determination is made during installation. Refer to Advisory Circular (AC) 21-50, Installation of TSOA Articles and LODA Appliances, for further information.

2.2 TSO Authorization and Letter of Design Approval.

As used in this AC, the abbreviations TSOA and LODA refer to “Technical Standard Order Authorization” and “Letter of Design Approval” respectively.

Definition of TSOA. 2.2.1 A TSOA is an FAA design and production approval issued to the manufacturer of an article that has been found to meet a specific TSO. A manufacturer is the person who controls the design and quality of the article produced to ensure it meets the TSO. The manufacturer also must control all the suppliers it uses for parts or services in the design and production of the TSO article (refer to 14 CFR § 21.601(b)(5)). The FAA issues TSOA only to U.S. manufacturers. When the FAA issues a TSOA, it finds:

The manufacturer’s article design meets the applicable TSO. 2.2.1.1 The manufacturer has a quality system (QS) that will produce every article 2.2.1.2 to conform to the approved design.

The United States is the State of Design (SOD), as defined by the 2.2.1.3 International Civil Aviation Organization (ICAO), for a TSOA.

The United States is the State of Manufacture (SOM), as defined by 2.2.1.4 ICAO, for a TSOA.

Definition of LODA. 2.2.2 A LODA is a finding by the FAA that a foreign manufacturer’s article design meets a specific TSO. The manufacturer’s ability to manufacture articles that conform to the approved design is overseen by a foreign civil aviation authority (CAA) with which the United States has a bilateral agreement. All articles destined for import into the United States must be accompanied by a certificate of airworthiness for export pursuant to 14 CFR § 21.502. The FAA may issue a letter of TSO design approval for these articles when it finds:

2-2 The manufacturer’s article design meets the applicable TSO. 2.2.2.1 A CAA with which the United States has a bilateral agreement addressing 2.2.2.2 TSOs will oversee the manufacturer’s quality system to ensure every article produced will conform to the approved design.

The manufacturer’s country is the SOD, as defined by ICAO, for a LODA. 2.2.2.3 The manufacturer’s country is the SOM, as defined by ICAO, for a 2.2.2.4 LODA.

Note: More information about bilateral agreements can be found at the following FAA website:

https://www.faa.gov/aircraft/air_cert/international/bilateral_agreements/ Definition of Data. 2.2.3 For the purposes of this document, two types of data are defined:

Descriptive Data. Descriptive data is information used to define the article 2.2.3.1 design, and includes:

2.2.3.1.1 The drawings (or equivalent) and specifications necessary to define the configuration and the design features;

2.2.3.1.2 Information on dimensions, materials, and processes;

2.2.3.1.3 Limitations (if applicable); and,

2.2.3.1.4 Required documents, such as maintenance instructions.

Substantiation Data. Substantiation data is information used to show that 2.2.3.2 the descriptive data meets the applicable requirements. For example, substantiation data may include test plans, test reports, and analysis.

2.3 Limitations of a TSO Authorization.

A TSO authorization does not approve the article to any airworthiness regulations, 2.3.1 requirements, or other standards except the Minimum Performance Standard (MPS) listed in the specific TSO.

A person who wants to install a TSO article in a product must obtain a separate 2.3.2 approval under the type certification process (reference § 21.1(b)(1) and § 21.1(b)(4)) or under part 14 CFR § 43.a(2)) to show the article meets the applicable airworthiness requirements for the product. The person approving the installation of the article in the product must evaluate the TSO performance criteria and article installation instructions to determine if they are adequate for meeting the airworthiness requirements of the product (§ 43.2(a)(2)).

2-3 Pursuant to 14 CFR § 21.1(b)(6), “product” means an aircraft, aircraft engine, Note:

or propeller.

2.4 Deviation Definition.

A deviation is any alternative method used to meet performance criteria specified in the TSO. A deviation must have an equivalent level of safety (ELOS) determination instead of literal compliance with the TSO requirement (§ 21.618(a)).

When Do You Need a Deviation? 2.4.1 The FAA requires you, the applicant, to obtain FAA approval for any deviation from the applicable TSO, regardless of the significance of the TSO criteria from which you want to deviate. For example, the FAA requires you to obtain a deviation approval when you propose to use a more recent version of an industry standard than the one referenced in the specific TSO.

How Do You Obtain Deviation Approval from the FAA? 2.4.2 See paragraph 3.11 for detailed instructions. You must request a deviation from the appropriate ACO, and must show that compensating features or factors create an ELOS to the TSO performance requirement(s) from which you propose to deviate.

2.5 TSOA or LODA Are Not Mandatory.

TSOA and LODA are not mandatory. Per 14 CFR 21.8(b), TSOAs and LODAs are one way to get an article approved. You may also use the other provisions in § 21.8 to have your article approved.

2.6 TSO Markings.

The FAA does not allow anyone to mark an article stating it meets a specific TSO unless the FAA has issued them a TSOA or LODA. The article must be produced pursuant to part 21 subpart O or under the provisions of an agreement between the United States and another country or jurisdiction for the acceptance of products and articles.

A TSO marking on an article made under a TSOA or LODA means: 2.6.1

2.6.2 The article’s design meets the TSO standards for which it is marked. 2.6.2.1 The article was produced under an approved quality system and conforms 2.6.2.2 to the TSO-approved design.

A TSO marking on an article made under a TSOA or LODA does not mean: 2.6.3

2-4 The article’s design meets airworthiness regulations for the product. 2.6.3.1 The article is approved for installation on a product. 2.6.3.2

3-1 CHAPTER 3. TSOA AND LODA APPLICANT RESPONSIBILITIES

3.1 Certify That Your Article Complies With the Applicable TSO Standard.

As an applicant for a TSO authorization, you certify that the design of your article meets all the requirements of the applicable TSO.

If the TSO specifies a method for substantiation, you must use that method to 3.1.1 substantiate your article unless you propose other means of compliance (for example, analysis versus test). Use of a method other than the one specified in the TSO requires a deviation (refer to § 21.618).

All substantiation must be completed (pursuant to § 21.611) before submitting your 3.1.2 application for TSO Authorization unless otherwise agreed to by the responsible Aircraft Certification Office (ACO). You should coordinate with the FAA any potential issues with your article before submitting your application.

You are responsible for a process that documents how you conform to the requirements 3.1.3 of the current TSO, including the use of a compliance matrix or equivalent procedure to verify the conformance to the requirements of the TSO.

3.2 Compliance Matrix To help the FAA process applications more efficiently and effectively, an applicant 3.2.1 should submit a TSO compliance checklist or matrix. The checklist or matrix is simply a list of each TSO requirement and how the applicant has met the requirement (for example, by documentation, analysis, or test). The compliance matrix is not a regulatory requirement but it provides the ACO a standardized summary of how an applicant shows compliance to the applicable regulations.

Appendix B to this AC provides an example of a compliance matrix. If a compliance 3.2.2 matrix is not used, you must have an active system (pursuant to § 21.607, § 21.616) in place that:

Defines all the requirements needed to comply with each TSO and part 21, 3.2.2.1 subpart O requirement.

Ensures each requirement is met before you submit the letter of 3.2.2.2 conformance to the FAA.

Documents the substantiating data for compliance with each requirement. 3.2.2.3

3-2

3.3 Control the Design and Quality of Your Article.

You must control both the design and the quality system (pursuant to § 21.607) for the production of the article. This includes controlling the design and quality of any items you receive from a supplier to the extent necessary to ensure the article meets the TSO.

To control the design of the article means you have the responsibility for the 3.3.1 development and the management of each component, features, and functions regardless of where that process takes place or with whom you have contracted.

Because the FAA issues the TSO authorization to you, we the FAA hold you responsible for ensuring the design met the TSO. This also means each design change to the article or any of its components, features, or functions must also be controlled by you to ensure that, after the change, the article still meets the TSO and all required documentation delivered with each article is updated accordingly (pursuant to § 21.619).

To control the quality of the article means you must build your article in accordance 3.3.2 with the approved design. You are responsible for controlling all your suppliers and all changes they implement in their production line for any part, process, or service they are providing you, as needed.

If you integrate a TSO article from a supplier into your TSO design, you must also 3.3.3 control the TSO article from the supplier to the extent necessary to ensure your article meets the TSO for which you have the authorization (pursuant to § 21.607 and § 21.137(c)).

You are responsible for notifying the FAA of design changes within the time period 3.3.4 agreed to by the ACO at the time of TSOA issuance.

3.4 Set Up and Maintain a Quality System (QS).

If you are a TSOA applicant, you must set up and maintain a QS that meets § 21.607.

Before we can issue a TSOA we must have evidence that you have a quality system pursuant to § 21.607 that meets § 21.137. AC 21-43A, Production Under 14 CFR Part 21, Subparts F, G, K, and O, provides guidance on the type and content of documentation you must submit to allow us to make a determination as to whether you have an acceptable QS.

3.5 TSOA Application Requirements.

You must submit a TSOA application to the ACO in your geographical area, pursuant 3.5.1 to § 21.603. If your facility has multiple locations, the principal manufacturing facility or the associate facility that controls the design and quality of the article(s) submits the TSO authorization application.

3-3 You must use the applicable TSO that is effective on the date of application for that 3.5.2 article, pursuant to § 21.603. Otherwise, you must ask for an exemption to § 21.603, as outlined in 14 CFR part 11.

Pursuant to § 21.601, your TSOA application must include a copy of the technical data 3.5.3 and other documents required by the TSO and QS. This may include:

The TSO number for which the authorization is requested; 3.5.3.1 The manufacturer’s name and physical address of the principal facility that 3.5.3.2 controls the design and quality of the article;

A statement from the manufacturer certifying that it meets the 3.5.3.3 requirements of part 21, subpart O, and the specific requirements of the applicable TSO;

A copy of the technical data required by the TSO; 3.5.3.4 A description of the applicant’s organization as required by § 21.605; and 3.5.3.5 A manual describing the applicant’s quality system that meets the 3.5.3.6 requirements of § 21.607 as required by § 21.608. Applicants who currently hold TSOAs must submit revisions to the existing quality manual as necessary.

Any Non-TSO Functions (NTF) data for which you seek acceptance. 3.5.3.7 The TSOA will be granted for a specific model and specific part number(s) that define 3.5.4 the article configuration. We suggest you include with your application a part numbering methodology pursuant to § 21.603(b) that uses open brackets to define minor changes. The part numbering methodology should include open brackets after the base part numbers to identify specific design configurations as minor changes occur. Refer to the example below for part numbers with open brackets. Refer to paragraph 4.4 of this AC for more information on design changes.

Example:

Initial Part number: 12345[ ] Part number with change 1: 12345[1] It is our experience that applications are processed more efficiently when an applicant 3.5.5 submits to the FAA a TSO compliance checklist or matrix (see Section 3.2 of this AC).

Discuss with the responsible ACO for an FAA recommended means for TSOA 3.5.6 applicant or holder to demonstrate that their organization has and will maintain the capabilities needed to conform to the requirements for each TSO for which they hold an approval.