ARP4754A Introduction – Avionics Systems

ARP4754A Introduction – Avionics Systems

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ARP4754A is officially titled “Guidelines for Development of Civil Aircraft And Systems”. Rarely can one judge a book by its cover or title; however, in this case, the title literally conveys a powerful message: if you are involved with development of aircraft or systems, you should be well versed in ARP4754A’s ‘guidelines’. Why? There are two key reasons which should be understood before first opening the pages of ARP4754A:
1. ARP4754A’s title states “guidelines”, but failure to understand and apply ARP4754A will greatly reduce safety and your ability to achieve certification.
2. Where its predecessor ARP4754 was largely similar, too many organizations treated it as “optional” befitting its name “Guideline”; but certification organizations worldwide have formally mandated adherence to this latest version, ARP4754A.

For experienced, proficient developers of aircraft and systems, ARP4754A reads like a book for maintaining good personal health: make a plan for health, understand healthy living, be safe, eat well, reduce stress, exercise, sleep, get regular check-ups, and repeat. For aircraft, an analogous synopsis of ARP4754A would state:
1. Plan your aircraft/system’s development lifecycle ecosystem;
2. Implement Safety activities per ARP4761/A;
3. Define and justify Assurance Level;
4. Define System architecture and requirements; Validate.
5. Perform Verification and Configuration Management
6. Implement Quality Assurance and prove Transition Criteria.

The original ARP4754 standard was first published in 1996 with the purpose of assisting avionics development organizations to think beyond mere hardware and software. Remember, DO-178 (and its European equivalent ED-12) was published over a decade prior to provide guidelines for avionics software.  But by the early 90’s it was clear that safe software, and software certification itself, required both knowledge of the system and confirmation of system level safety aspects.  ARP4754 was focused upon aircraft systems whose failure could potentially affect safety of aircraft or occupants.  While there are certainly critical stand-alone components on aircraft which could affect safety, ARP4754 is focused not upon components, but rather systems which have complex interactions with other systems on or off the aircraft.  These systems typically involve multiple knowledge domains and are likely to evolve over time. Thus they are developed by different persons via different disciplines often separated by space and time; the best means to ensure safe implementation is via codified development processes based upon deterministic safety:  ARP4754.

ARP4754A versus ARP4754

With revision “A” of ARP4754, e.g. ARP4754A, several key improvements were made as shown below:

ARP4754A requires ARP4754A Planning, ARP4754A Processes, ARP4754A Reviews, and ARP4754A Process  Assurance (quality assurance) Audits.  Here is an all-too-brief summary of ARP4754A Plans, ARP4754A Procedures, ARP4754A Reviews, and ARP4754A Audits for avionics systems:

  • ✓ ARP4754A “Plans” comply with safety requirements and summarize what you will do, while
  • ✓ ARP4754A “Processes” state how you will implement the Plans, and
  • ✓ ARP4754A “Reviews” (with Checklists advised) denote objective review criteria to determine if Processes were followed, then
  • ✓ ARP4754A “Process Assurance  Audits” assess conformance of engineering/manufacturing activities, including respective transitions to those Processes and Reviews.

The following page is reprinted from AFuzion’s 300-page proprietary ARP4754A Training manual (page 37 of 293 pages):

ARP4754A’s Eight Planning Topics

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