FFPA is an iterative top-down analysis with a set structure, starting from the PSSA, that identifies the assemblies, components and elements implementing each Level A and B function and the failure modes and effects to analyse, decomposing from system to hardware, circuit, component and elemental FFPs as needed (fault tree analysis, supplemented where useful by functional FMEA, common mode analysis and dependency diagrams). Each Level A and B function is identified, with its level taken from the hardware requirements and system FHA (as subfunctions with derived requirements if needed); its means of implementation is determined and the assurance options analysed, with decomposition stopping once available or expected data is complete and acceptable for the chosen strategy; and the way non-A/B FFPs relate to A/B FFPs is evaluated by functional FMEA, dependency diagrams or common mode analysis to show they cannot adversely affect them. Iterate, or change the architecture, until every Level A and B FFP has an acceptable method and data. Results go back to the aircraft system process to confirm aircraft-level assumptions, notably cross-system use of similar hardware.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.