What is the Impact of AMC 20-152A on Your DO-254 Project?

Posted on by

I have some exciting news for all the companies, teams and engineers working on airborne electronics products.

On July 29, 2020, EASA released the long-awaited and very important document, AMC 20-152A (which I’ve posted our website so you can easily find it). AMC 20-152A has been in development for four years and represents, at last, harmonization between the FAA and EASA regarding compliance of airborne electronic hardware. In addition to harmonization of the US agencies and industry groups, AMC 20-152A also provides state-of-the-art with regard to electronic hardware embedded in airborne systems and equipment.

Background

On April 19, 2000, the RTCA released the document DO-254, governing the development of airborne electronic hardware. On June 30, 2005, the FAA released Advisory Circular AC 20-152, recognizing RTCA/DO-254 as a means of approval by showing the equipment design of airborne electronic hardware is appropriate for its intended function. This established the use of DO-254 for airborne electronic hardware development for aircraft developers applying for certification through the Federal Aviation Administration (FAA).

The problem was that European Aviation Safety Agency (EASA) never took similar steps to formally recognize RTCA/DO-254. 

This inevitably led to some differences and discrepancies in compliance expectations for those trying to gain aircraft certification across both the FAA and EASA.

Significant Aspects of AMC 20-152A

This AMC is significant in four distinct ways:

  1. Formally Recognizing and Clarifying the use of DO-254
    AMC 20-152A finally recognizes the use of the development assurance standard EUROCAE ED-80/RTCA DO-254. It also clarifies its use on digital and mixed-signal custom devices, simple vs. complex devices, DAL D compliance objectives, and circuit board assemblies (CBAs or PCBs).
  2. Addressing Modern Aspects of Hardware
    It also provides guidance for development assurance when electronics use COTS (Commercial-Off-The-Shelf) and Intellectual Property (IP) components.
  3. Objective Focused
    AMC 20-152A focuses on providing new compliance objectives, offering development teams flexibility to determine the activities to meet these objectives. The format of this AMC provides objectives for each area of concern and leaves it to the applicant to determine the activities they will perform to meet these objectives.
  4. Harmonization
    This document was fully developed with the FAA. Together EASA and the FAA reviewed and processed all comments and additionally performed a joint legal review.  (Note: My contact at the FAA has reaffirmed that the FAA equivalent document, AC 20-152A, will be released soon.)

What Will this Mean for YOUR Project?

If you are currently working on an FAA certification project under the AC20-152 you will notice scope of work impact under the new AC20-152A.  The scope change affects the following:

  1. Compliance to DO-254 will include the circuit board assembly (CBA) when the CBA contains a complex custom device or complex COTS devices.   
  2. Compliance to DO-254 will include use and categorization of COTS devices (complex or simple). The reasoning for including this now as needing to be addressed under DO-254 is due to the increased complexity of embedded functions in a single COTS device.
  3. Validation is clarified to be for all requirements, not just derived.
  4. Simple device definition is different than previous guidance in FAA Order 8110.105
  5. DAL C will need to comply with design standards.  Currently DO-254 does not require design standards for DAL C.
  6. For DAL A and B the elemental analysis code coverage for HDL will need to consider more than just statement coverage.
  7. Errata clarifications for Table A-1 for DO-254 revises some of the HC1 and HC2 data control categories.
  8. More extensive section and objectives for COTS IP.  This is much like what was in CAST 32.
  9. Planning and compliance have added new objectives for the following areas:

Unique Identifiers

A unique identifier for each objective is defined with a prefix and an index number (i) as follows:

— for the development of custom devices, the identifier is ‘CD-i’; (CD-1 to CD 12 objectives)

— for the use of COTS IP in custom devices, the identifier is ‘IP-i’; (IP-1 to IP-7 objectives)

— for the use of COTS devices, the identifier is ‘COTS-i’; (COTS-1 to COTS-8 objectives)

— for the development of CBAs, the identifier is ‘CBA-i’. (CBA-1 objective)

The good news is that my companies, Patmos Engineering Services and Airworthiness Certification Services (ACS), LLC., have already been involved in the early work on this new guidance.   Templates and checklists available from ACS already include these new compliance items and are tailorable by design assurance level.   I understand and can provide guidance on how best to comply and perform a gap analysis on your existing processes if needed, to help your company better understand the new objectives of AMC 20-152A (and harmonized upcoming document AC 20-152A) and how to comply.

Tammy Reeve, FAA DER
President Patmos Engineering Services
President Airworthiness Certification Services