This is just an Excerpt from a larger document, click here to view the entire document.Reliability Growth Test Planning
RGT requires careful planning to avoid problems when the data are evaluated. Some factors to consider when evaluating a planned growth program using any growth model are:
The literature commonly cites test lengths of between 5 and 25 times the predicted MTBF
Growth rates of 0.5 or higher are rare (very high growth rates indicate that the test planners are either being too optimistic regarding the effectiveness of design changes or expect a lot of failures)
If the initial MTBF is very low, it may be that the equipment is entering growth testing too soon (i.e., the pure design process is being terminated prematurely)
On average, design changes are 70% effective in correcting a problem
The period of time to verify the effectiveness of a design change should be at least 3 times the frequency of the failure mode being corrected (i.e, if the mode occurs every 50 hours, the verification time for the design change should be 150 hours)
The starting point of the growth curve can greatly influence the calculated growth rate during the early phases of the growth analysis
The growth rate experienced is a function of the design team's ability to identify and implement effective corrective actions.
