Evaluation and comparison of triple and quadruple flight control architectures

Fault tolerances of a triple flight control architecture are defined and compared to that of a quadrupole type, and the impact of worst case failures on the transient response of an aircraft is investigated. Insights in computing fault coverage are discussed. Two coverage models have been used to compute the probability of loss of control (PLOC) and the probability of mission abort (PMA) for candidate architectures. Results indicate that both triple and quadruple architectures can meet the fault tolerance requirements with an acceptable level of transients upon first and second failures. Triple architectures will require a higher level of fault detection, isolation, and accommodation coverage than quadruple architectures and produce substantially larger transients upon second failure.<>