System Dependency Analysis Supporting Common Cause Analyses of Complex Aircraft Systems 2009-01-3107

The system dependency analysis for complex aircraft systems is a model-based methodology and tool for analyzing availability and minimum acceptable control requirements for failures or event scenarios to support the aircraft and system safety analyses (SAE ARP4761) required to show compliance to 14CFR/CS §25.1309, §25.671 and others. Aspects of the system such as functional interaction and dependencies to supply systems, physical items (equipment, wiring and tubing) and installation aspects are included in the analysis. The SAE paper “System Dependency Analysis for Complex Aircraft Systems” (2007-01-3852) describes the modeling approach and the analysis of system dependencies supporting the aircraft and system safety analyses.

This paper provides examples for using the system dependency analysis to support the common cause analyses (SAE ARP4761) for complex aircraft systems. Each element of a common cause analysis – the particular risk analysis (PRA), the zonal safety analysis (ZSA) as well as the common mode analysis (CMA) – can gain advantage of the system dependency analysis with the integrated system model to show the failure propagation causing a system and aircraft level effect for various analyses and cases using the same system model and analysis database.

An example of a quad-redundant flight controls system for a regional jet aircraft serves to show the process, the system model, analysis management and the results including the definition of integration and installation requirements.