As mentioned above, the test articles should represent a "mature" design. No further engineering changes should be pending prior to the RDT. The RDT supplements the design reliability effort but does not take its place. Similarly, it is too expensive to be a quality screen. Therefore, the test articles should be constructed with quality parts (rescreened for 100 ppm or less defect rate). The equipment should be subjected to environmental stress screening, when appropriate, prior to the RDT to find and eliminate workmanship defects.
The conduct of the RDT is defined in Task 202 of MIL-STD-781D. This task in turn identifies Task 102, Task 103 and Task 104 of MIL-STD-785 as essential elements. Other essentials listed include specification of the required value for each reliability parameter to be measured, specification of the combination of environmental test conditions and levels, and specification of performance parameters to be measured and frequency of measurement.
1. Test Reviews
a. Test Readiness Review. A test readiness review should be held approximately one week prior to the start of the RDT to assure that all test items and supporting elements are ready to begin the test. This review should include the following, as a minimum:
(1) Results of latest reliability predictions.
(2) Status of design
(3) Results of previous tests
(4) Review of all open problems and failures
(5) Availability of approved test procedures
(6) Readiness status of test equipment and test chambers.
b. Monthly Status Reviews. After the start of the RDT, monthly tracking meetings should be held to review test progress. These reviews should address the following, as a minimum:
(1) Current reliability growth assessments and projections based on test results and illustrated by reliability growth plots.
(2) Open failures and schedule for correction.
(3) Results of failure analyses and corrective action recommendations.
(4) Effectiveness of previously implemented corrective actions.
(5) Results of other tests which might affect RDT test hardware.
c. Other Reviews
(1) Weekly Status Reviews. After the start of the RDT, test progress should be briefed at weekly Program Managers meetings. Test progress should be shown through the use of RDT growth plots and any ongoing or anticipated problems should be discussed.
(2) Special Status Reviews. When the reliability growth plot shows a growth rate less than the minimum required, special reviews should be held to discuss options for correcting this situation. Such options might include more aggressive failure analysis and corrective action activity by the contractor, or suspension of the RDT and a major redesign effort.
2. Failure Actions
Upon the occurrence of a failure, the equipment under test should be repaired and placed back on test. The failed parts, circuit card, etc., can then be analyzed off-line, without adversely impacting the test schedule. Otherwise, the RDT could be stopped for weeks or months while corrective actions were being developed and implemented. When corrective actions are ready for implementation they should be installed in all equipments under test as logical block changes. These changes must then be tested adequately to ensure the original failure mode has been corrected and no new failure modes introduced