Integrated Assurance Assessment of a Reconfigurable Digital Flight Control System.
Final rept. Feb-Oct 82,
LOCKHEED-GEORGIA CO MARIETTA
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FAA Advisory Circular AC 24.1309-1 provides guidance material for demonstrating compliance with the requirements of Part 25 of the Federal Aviation Regulations for flight-essential and flight-critical avionics systems. this advisory circular outlines the use of quantitative safety analyses which may include a Probability analysis b fault tree analysis c failure modes and effects analysis and d other comparable techniques for determining compliance with the requirements of Far 25.1309b. the objective of this study was to explore and demonstrate the integrated application of reliability, failure effects and system simulator methods in establishing the airworthiness of a flight-critical digital flight control system DFCS. The emphasis was on the mutual reinforcement of the methods in demonstrating the system safety. It was concluded from this study that a The integrated approach can be used for the validation of flight-essential and flight critical digital systems b the quantitative assessment of reliability system failure probability can be accurately predicted at less than 1 times 10 to the-9th power by the use of both the fault tree analysis and the analytical reliability prediction analysis c fault tree analysis must be augmented by failure modes and effects analysis which must be used below the circuit card level because of the complexities of the lower level analysis and d system simulation fault insertion confirms the correct implementation of the fault detection and fault tolerance capabilities of the system under study.