This is just an Excerpt from a larger document, click here to view the entire document.Development and Reliability Growth Testing
Ideally, the pure design process would be perfect, with no testing required to improve reliability to meet the requirement. However, analytical tools, models, and engineering judgement are not perfect, so some development testing is always needed to fill in the gaps in our knowledge and understanding. As performance deficiencies are observed and failures are uncovered, design engineers should take two distinct actions:
Examine the models and tools used to revise, refine, or otherwise improve them. The improved tools and models can be used to improve the next design process.
Improve the design based on information gained through the analysis of test data. In the case of failures, each should be thoroughly analyzed.
To properly analyze failures, the following information regarding the failure must be recorded:
The conditions (environmental, operational, etc.) under which failure occurred
How the failure was discovered (what were the symptoms)
The effects of the failure
The probable consequences of the failure in actual use
The analysis itself must provide information on the underlying failure mechanism, the probability of recurrence in actual use, and the corrective actions that can be taken to prevent recurrence or minimize the effects of failure. If design changes are identified as the needed corrective action, reliability growth will occur when and if effective changes are incorporated. Often, improvements in reliability are claimed on the basis of planned changes that have yet to be validated. Making decisions based on planned changes is risky. Changes must be incorporated and the effectiveness of the changes in correcting the problem verified.