4.2 Nonrepairable Hierarchical System
Based on the simple and efficient algorithm (SEA) of [7,8] for addressing the one‐level IPCM, Figure 4.2 illustrates a general solution methodology of analyzing an HS subject to the modular imperfect fault coverage. The HS fault tree (FT) is composed of independent fault subtrees for each layer. The layer subtrees are then solved in a hierarchical and bottom‐up manner, where a subtree is replaced by a single component in its parent layer subtrees whose occurrence probability is the occurrence probability of the corresponding layer subtree.

Figure 4.2 Hierarchical FT solution to consider MIPCM [5] .
The probabilistic functional dependency (PFDEP) gate in Figure 4.2 has a trigger input event (representing the occurrence of an uncovered component fault at layer i), and one or more dependent events (UF events of different layers). When the trigger event happens, the dependent events are then forced to occur with certain (different...