Isolated Failure Probability - For items, the portion of the item'srelative failure probability that has been isolated within a fault group. An item's isolated failure probability can be calculated by adding up the isolated failure probabilities for all functions/failure modes of that item that have been isolated within the given fault group:
The isolated failure probability associated with a given item in a specified fault group can be calculated using the following equation:
where
Ix
=
the item for which the isolated failure probability is to be calculated
FGy
=
the fault group for which the isolated failure probability is to be calculated
N
=
the total number of functions/failure modes associated with Ix
Xi
=
1 ifthe ith function/failure mode of Ix has been isolated withinFGy;
0 otherwise
Ifp(Ix, FGy)
=
the isolated failure probability of the ith function/failure mode of Ix
(defined below)
The isolated failure probability associated with a given function or failure mode in a specified fault group can be calculated as follows:
where
Fx
=
the function/failure mode for which the isolated failure probability is to be calculated
FGy
=
the fault group for which the isolated failure probability is to be calculated
the total number of fault groups in which Fx has been isolated
Note: When calculating the isolated failure probability for fault groups that have been isolated using hybrid diagnostics, the corresponding partial failure probabilities are used for each element (function or failure mode) in the isolated fault group, the failure probabilities for each object having been adjusted based on the selected failure probability calculation method.
