A Structured Assurance Case for Commercial Off-The-Shelf (COTS) Airborne Electronic Hardware (AEH) 2018-01-1939
One particular issue with the use of Commercial Off-The-Shelf (COTS) components in Airborne Electronic Hardware (AEH) is that they have not been developed to the applicable avionics industry standards such as ED-80/DO-254 [DO-254] and their development and design data generally remain proprietary, hence not available for review to the levels expected by those standards for certification.
A previous (2016-2017) research sponsored by the Federal Aviation Administration (FAA) Software and Digital Systems (SDS) program on assurance for AEH was intended to assess the feasibility of COTS AEH assurance possibly achieved at system level, i.e. going beyond or beside ED-80/DO-254, and/or using the current practices of ED-79A/ARP-4754A [ARP4754] for systems.
A main conclusion of that research [TC-AEH] was that, on one hand, one cannot fully get rid of ED-80/DO-254, which already provides clues on how to handle assurance for COTS AEH, and on the other hand, ED-79A/ARP-4754A, though well suited for a system-level approach, neither targets COTS, nor provides evidence to COTS assurance whatever their level of integration, inherent complexity, or allocated Development Assurance Level (DAL).
The research then recommended a more system-wide approach rather than a standard process for system-level assurance. This approach, now cited as a Characteristics-Attributes-Properties (CAP) approach, was later on elaborated into a so-called “Structured Assurance Case”, which seemed well suited to provide COTS AEH assurance. This approach is further discussed and elicited in the present paper. Its future use for components other than COTS AEH is also considered.