TABLE OF CONTENTS In this chapter a step-by-step method is given for constructing a sequential test plan when the binomial failure frequency distribution describes, or appears to describe, the successes and failures of the device under consideration. The binomial distribution may be applied (1) to hardware which operates in a cyclic fashion, (2) to system evaluation in terms of the probability of S successes in N attempts or trials, or (3) to predict the reliability of go, no-go types of hardware such as squibs, explosive bolts, and others.
The sequential testing analysis technique is applicable when each test of a device will result in either a distinct success or failure. This technique is useful when it is necessary to demonstrate that a device meets a specific reliability requirement. In the case of the binomial, this requirement might be expressed in the customer's specification as the minimum acceptable reliability. Sequential tests developed by contractors in response to military specifications are usually developed to satisfy the reliability demonstration requirements.
The term "sequential" indicates that this type of test is accomplished by conducting a succession, or a "sequence," of runs on one or more devices. Test runs are continued on each device in the test sample until failure occurs, except when an "accept" decision is reached, up to the limit of the operating life specified for the device. When a failure of a device is encountered, either the failed device is repaired or a new device is used to replace the failed...
