FAULT TREE CONSTRUCTION RULES

(a)  Define the  undesired  fault  condition  as the  "Top"  event. The  fault  event describes the state of either the system or a component. (b) Fault events should be indicated in rectangle boxes.

(c)  Identify the possible Fault events that may individually or collectively cause the Top- undesired fault condition. These may be any one of the following type:

Primary       - failure with normal parameters,

Secondary - failure due to excessive stress,

Command  - failure due to a command event.

(d) The fault events should be linked to the higher event through the OR, AND, INHIBIT or NOT gates.

(e)   Gate to gate connections are not allowed.

(f)    Only normal fault state events are to be considered.