The paper presents a model-based approach to the optimal
design of diagnosis system architectures for complex high lift
actuation systems. The overall approach consists of two steps.
In the first step, safety and reliability related requirements are
introduced. These focus on the detectability and isolability
of faults. Symptoms are used therefore. These are separated
into safety and reliability related symptoms. In the second
step, different alternatives to provide the symptoms are drawn
and evaluated in order to gain an optimal design solution. A
two stage analysis process is used therefore. The first stage
focuses on the fulfillment of the safety related requirements
whereas the second stage concentrates on the reliability re-
lated requirements. All aspects of the analysis are depicted
exemplary and formalized theoretically. The results of the ap-
plication to the high lift actuation system of an Airbus A340-
600 aircraft are presented afterwards and discussed in the end.