Does anybody have experience with getting complex modules that were designed by others for common use, approved for incorporation in an airborne system that is at DAL A, B, or C and thus requires FAA approval? I am doing research on the topic of how optimal the current approval guidelines are.

The question is of interest for LRU's (Line Replaceable Units), CBA's (Ciruit Board Assemblies, SoC (System on a Chip sunits) and other integrated technology modules.

If anybody out there has interacted with a DER and either found the means of demonstrating compliance to be sensible and practical, or can point out either gaps where potential errors could have snuck through or places where the approval process is impractical, I would appreciate it a lot.

  • 1
    $\begingroup$ You reference the FAA in the body of your question, but you added the easa-regulations tag. Are you asking for both cases, or do you want information for one jurisdiction in particular? $\endgroup$
    – J W
    Commented Mar 17, 2016 at 20:25
  • $\begingroup$ Both or either would be very desirable to learn about. The guidelines are almost identical, but if DERs interpret them differently that would be really excellent to know. $\endgroup$ Commented Mar 17, 2016 at 20:50
  • $\begingroup$ Not sure who voted this "too broad" but to me this question is extremely concise. They are asking about certification viz a vi integration of very particular pieces of hardware. It's a narrow field, and (assuming someone here actually has experience in it), it should be more than answerable. $\endgroup$
    – Jae Carr
    Commented Jun 13, 2016 at 21:33
  • $\begingroup$ @JayCarr I didn't, however I think that this should focus slightly, in that it should ask about either FAA or EASA requirements. In fact, asking two different questions (one for each) would probably be best, because it is very likely that someone will have experience with one or the other, but not both and the answer is likely to be different since it is asking about a very complicated regulatory environment. $\endgroup$
    – Lnafziger
    Commented Nov 10, 2016 at 20:15

2 Answers 2


Yes, I've had some experience in dealing with complex hardware certification both with DERs and with FAA ACOs. For the last 15 years or so, the process has been well defined as both FAA and EASA have adopted RTCA DO-254 Design Assurance Guidelines for Airborne Electronic Hardware.

I haven't run into many cases where there are any meaningful difference in interpretation of the guidelines, especially when discussing internally developed components. There are some differences in what a DER/ACO will accept when you attempt to use commercial off the shelf (COTS) components. DO-254 section 11.2 covers the use of COTS components but as it points out, the issue is lack of design data from the developer/manufacturer. So coming to agreement on what is acceptable for these cases is highly variable depending on the DAL required and the available data.

For higher DAL levels it's getting harder and harder to get approval for COTS. You also have to deal with the fact that COTS parts may go through significant design changes on a regular basis. That will impact your ability to maintain a single configuration. Every part change has to analysed for impact and the configuration and certification updated. That constant churn can quickly overcome any savings in procurement costs.

As to the more generic question of consistency between ACOs and DERs, it's an ongoing discussion within the FAA. They want consistency but they don't want to to be so restrictive that all decisions get made at headquarters. Every DER or ACO I've met has had their individual biases and technical areas where they are comfortable. So in that sense, there's always a bit of luck in getting one that sees things your way. I don't think that will ever change.


The main difference that I am aware of between the FAA and EASA in regards to applying DO-254/ED-80 to Airborne Electronic Hardware is that the FAA applies it to custom micro-coded hardware (FPGAs, ASICs, PLDs, etc.) AC 20-152. EASA looks to also apply it to equipment (LRU, IMA modules) and circuit board assemblies Section 7 of EASA CM_SWCEH-001 Development Assurance of Airborne Electronic Hardware, albeit at DAL D.

Both agencies apply the actual DO-254/ED-80 process in the same manner

As far as COTS components are concerned, it is going to highly depend on a variety of things:

  • The design assurance level of the overall product or main Simple/Complex Electronic Hardware component
  • The functions the COTS components performs in the hardware
  • The available design data (or lack therof) for the COTS component
  • The DER/ACO you are working with

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