DO-254 COSTS vs. BENEFITS
Up until several years ago, avionics hardware was deemed “simple” or “verifiable via systems-level testing”. Hence hardware had relatively easy certification standards. And undoubtedly certain functionality was implemented in hardware instead of software to avoid software’s more rigorous DO-178B certification. Today, most avionics hardware falls under the DO-254 purvey (see ConsuNova’s DO-254 whitepaper for a high-level description, or enroll in our 2-Day DO-254 training for complete details). Today, DO-254 has increasingly evolved into the de-facto standard for commercial avionics hardware, then Military avionics, and now general aerospace electronics. DO-254 requires planning, consistency, determinism, thorough requirements, design, documentation and testing, thorough production assurance, and proof of the preceding attributes. DO-254 relies upon testing to verify and validate avionics quality. But avionics quality comes from a quality process, design, and implementation, not just testing. Recently, DO-254 is being required on virtually all aircraft including civilian and new military aircraft (including the A400M, under flight test/certification now, which the author contributed his skills to in Munich Germany).
The DO-254 standard presumes that hardware and software must operate in harmonic unison, each with proven reliability. Previously, hardware was considered “visible” and tested at the systems level with integrated software; hence hardware was exempt from DO-254 quality attributes. But that exemption resulted in functionality being moved from software to hardware for the purpose of avoiding hardware certification. Also, hardware complexity has evolved such that hardware is often as complex, or more so, than software due to the embedded logic within the PLDs, ASICs and FPGAs. Now, everyone recognizes that hardware and software comprise an inextricable chain with the quality equal to that of the weakest link. Hence the mandate to also apply DO-254 to avionics hardware. And the weak links are continually removed through the avionics certification evolution.