Template:Effectiveness factor crow extended

Effectiveness Factor

When a delayed corrective action is implemented for a Type B failure mode, in other words a BD mode, the failure intensity for that mode is reduced if the corrective action is effective. Once a BD mode failure mode is discovered, it is rarely totally eliminated by a corrective action. After a BD mode has been found and fixed, a certain percentage of the failure intensity will be removed, but a certain percentage of the failure intensity will generally remain. The fraction decrease in the BD mode failure intensity due to corrective actions, [math]\displaystyle{ d }[/math] , [math]\displaystyle{ \left( 0\lt d\lt 1 \right), }[/math] is called the effectiveness factor. A study on EFs showed that an average EF, [math]\displaystyle{ d, }[/math] was about 70%. Therefore, typically about 30%, i.e. [math]\displaystyle{ 100(1-d)% }[/math] , of the BD mode failure intensity will remain in the system after all of the corrective actions have been implemented. However, individual EFs for the failure modes may be larger or smaller than the average. This average value of 70% can be used for planning purposes, or if such information is recorded, an average effectiveness factor from a previous reliability growth program can be used.