Development of Redundant Protection Device for the Civil Aircraft Electrical Power System using FTA Method

Airborne equipment must meet the safety requirements for the aircraft. In order to meet the certification requirements, development procedure of the device must follow the process defined in SAE ARP 4751, and the safety assessment must follow the methods commended by SAE ARP 4761. Through this process, design changes in different stage may be required to achieve specific safety targets. Implementing safety assessment in early stage of the design can effectively minimizes rework. In order to optimize circuit design, improve design efficiency, the safety assessment process SAE ARP4761 for the civil aircraft, particularly the Fault Tree Analysis (FTA) was implemented in this study. Safety requirements are allocated to the redundant protection device to achieve the system level safety targets. Based on the functional modules of the device, a civil aircraft power system redundant protection device was developed and verified by simulation using Simulink. Through the FTA method, safety analysis of the device was conducted by allocating preliminary equipment failure rate as its safety requirements for each functional module's design. Based on the detailed design, CFMEA based on industry standard is also performed to verify its safety target. A whole device level develop cycle which will be able to support the certification has been established here.