System Dependency Analysis as a Common Cause Search Engine for Complex Aircraft Systems 2009-01-3105
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 other, related requirements. 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.
This paper describes additional steps to enable the search for potential common cause failure conditions for the system of interest or airplane level systems based on the system model. Common cause analysis (CCA) procedures using the system dependency analysis rely on a systematic and checklist-based approach to determine potential common cause failure conditions. The model-based approach of the system dependency analysis can be converted to search for critical functional failure combinations and therefore for sensitive installation areas and potential common mode failure conditions.
This paper is based on the system dependency analysis described in the SAE papers 2007-01-3852 and 2009-01-3107 which provide the modeling approach and the analysis of system dependencies to support the aircraft and system safety analyses including examples for the common cause analyses. An example of a quad-redundant flight controls system for a regional jet aircraft serves to show the system model and the analysis.