AC 20-152

{{Infobox technology standard

| title = Development Assurance for Airborne Electronic Hardware

| image = US-FederalAviationAdmin-Seal.svg

| caption = FAA Publication

| status =

| year_started = 2005

| version = A

| versionDate = {{Start date|df=yes|2022}}

| organization = Federal Aviation Administration

| abbreviation = AC 20-152

| domain = Aviation safety

| website = [https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-152A.pdf FAA]

}}

The Advisory Circular AC 20-152A, Development Assurance for Airborne Electronic Hardware, identifies the RTCA-published standard DO-254 as defining "an acceptable means, but not the only means" to secure FAA approval of electronic hardware for use within the airspace subject to FAA authority. With the 2022 release of Revision A (effectively a complete rewrite and remarkable expansion) this Advisory Circular becomes a very important instrument for completing and updating some DO-245 guidance and providing applicants with clarifications and additional information on that standard.{{cite web |title= Order 8110.105B (and the Evolution of Guidance Surrounding DO-254) |website= Airworthiness Certification Services |author= Tammy Reeve |date= May 14, 2024 |access-date= 2024-10-23

|url=https://airworthinesscert.com/order-8110-105b-and-the-evolution-of-guidance-surrounding-do-254/

|quote= Then on 10/7/2022, the FAA set forth two new and very important documents: AC 20-152A and AC 00-72. These documents helped to close some of the most important gaps and make a number of much-needed clarifications. }}

Initially, the DO-254 was commonly interpreted as applying only to complex custom micro-coded components within aircraft systems with Item Design Assurance Levels (IDAL) of A, B, or C.[https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-152.pdf AC 20-152], FAA, Office AIR-100, 2007.{{cite book |editor=Cary Spitzer |editor2=Uma Ferrell |editor3=Thomas Ferrell |title= Digital Avionics Handbook, Avionics, Development and Implementation |edition= 3rd |publisher= CRC Press |location= Boca Raton, FL |year= 2015 |page= 14-6 |isbn=978-1138076983 |quote= DAL D electronic hardware may use DO-254 or applicable in-house design assurance processes. }} DO-254 guidance on simple electronic hardware and other topics needed some clarification. However, Revision A of this AC clarifies that AC 20-152() and DO-254 apply to the type certification of all electronic hardware aspects of airborne systems, including all simple electronic hardware, although at greatly reduced effort.

Revision A also defines 29 objectives additional to those identified in DO-254. Applicants choosing to follow DO-254 under the authority of AC 20-152A must also accomplish all of these additional objectives that apply to their particular hardware.{{cite web |title= Order 8110.105B (and the Evolution of Guidance Surrounding DO-254) |website= Airworthiness Certification Services |author= Tammy Reeve |date= May 14, 2024 |access-date= 2024-10-23

|url=https://airworthinesscert.com/order-8110-105b-and-the-evolution-of-guidance-surrounding-do-254/

|quote= AC 20-152A did such things as clarify the classification of Simple vs. Complex, the difference between the validation and verification processes, what was expected with respect to robustness, HDL code coverage, tool assessment, and previously developed hardware. In this context, it created 12 new objectives that applicants needed to address. It also covered the larger topics of the use of COTS IP and COTS devices, creating 7 and 8 new objectives, for each respectively. It also tackled the issue of applying DO-254 at the board level, since previously DO-254 was almost exclusively applied at the chip level. }}

Specifically excluding COTS microcontrollers[https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-152.pdf AC 20-152], FAA, Office AIR-100, page 2, 2007. (see AC 20-115()/DO-178C), complex custom micro-coded components include field programmable gate arrays (FPGA), programmable logic devices (PLD), and application-specific integrated circuits (ASIC), particularly in cases where correctness and safety can not be verified through testing alone, necessitating methodical design assurance.{{cite journal |title= Simple Electronic Hardware and RTCA Document DO-254 and EUROCAE Document ED-80, Design Assurance Guidance for Airborne Electronic Hardware |journal= Certification Authorities Software Team Position |issue= CAST-30|publisher= FAA |url=https://www.faa.gov/aircraft/air_cert/design_approvals/air_software/cast/cast_papers/media/cast-30.pdf |access-date= 2019-09-30 |date= August 2007}} Simple devices are those that are verifiable with testing alone, such that the FAA may agree that methodical design assurance is unnecessary.

For DAL D hardware, as long as the applicant follows DO-254, the applicant does not need to apply this advisory circular since the FAA does not expect to examine the life cycle data. However, if the applicant chooses to follow other design practices for DAL D hardware (as permitted by this AC) the FAA will review the data.ORDER 8110.105A {{cite web |title= Simple and Complex Electronic Hardware Approval Guidance |publisher= FAA |url= https://www.faa.gov/documentLibrary/media/Order/FAA_Order_8110_105A.pdf |page= 1-1 }}

Cetain of the new objectives in AC 20-152A explicitly state DO-254's application to circuit board assemblies (CBA).{{cite web |title= Order 8110.105B (and the Evolution of Guidance Surrounding DO-254) |website= Airworthiness Certification Services |author= Tammy Reeve |date= May 14, 2024 |access-date= 2024-10-23

|url=https://airworthinesscert.com/order-8110-105b-and-the-evolution-of-guidance-surrounding-do-254/

|quote= It also tackled the issue of applying DO-254 at the board level, since previously DO-254 was almost exclusively applied at the chip level. }}

; Relationship to FAA Order 8110.105

With the release of the expanded AC 20-152A and its companion AC 00-72, Best Practices for Airborne Electronic Hardware Design Assurance Using EUROCAE ED-80() and RTCA DO-254(), chapters 3 through 6 of FAA Order 8110.105A were removed in a Revision B released in 2024 to eliminate any duplication or conflict with the new ACs. The removed sections had been published as an expedient solution the concerns of authorities and applicants, but the FAA wished ultimately to not provide applicants with guidance and clarifications in its orders to certification workers. Where this pair of new ACs replace material in Order 8110.105, AC 20-152A provides new guidance to close gaps in DO-254 and AC 00-72 provides "additional information" on some of the new objectives in AC 20-152A.{{cite web |title= Order 8110.105B (and the Evolution of Guidance Surrounding DO-254) |website= Airworthiness Certification Services |author= Tammy Reeve |date= May 14, 2024 |access-date= 2024-10-23

|url=https://airworthinesscert.com/order-8110-105b-and-the-evolution-of-guidance-surrounding-do-254/

|quote= Order 8110.105A added a number of topics that needed some urgent clarifications. Order 8110.105B replaces Order 8110.105A, which had some conflicts with the newer documents AC 20-152A and AC 00-72, that covered and expanded upon much of the content of 8110.105A with more informed and thorough approaches. }}