For the purpose of standardization and valid testing, and unless otherwise specified in the individual methods, apply the following procedures when a test is interrupted. Explain test interruptions in the test report, and any deviation from the following information. Due to the nature of testing, any observation that may indicate a safety issue should be immediately addressed.
5.11.1 In-Tolerance Interruptions
Interruption periods during which the prescribed test conditions remain in tolerance (e.g., power interruptions that do not affect chamber temperature) do not constitute a test interruption. Therefore, do not modify the test duration if exposure to proper test levels was maintained during the ancillary interruption.
5.11.2 Out-of-Tolerance Interruptions
A logic diagram for these methods is on Figure 1-5.
- a. Undertest. If test condition tolerances fall below the minimum tolerance value (i.e., environmental stress less severe than specified) resulting in an undertest condition, the test may be resumed (after reestablishing prescribed conditions, except as noted in the individual methods) from the point at which the test condition fell below the lower tolerance level. Extend the test to achieve the prescribed test cycle duration.
- b. Overtest. If an overtest condition occurs, the preferable course of action is to stop the test and start over with a new test item. If it can be shown that the overtest condition had no detectable effect on the test item, continue the test. Overtest conditions can damage the test item and cause subsequent failures that may not have occurred otherwise, thus failing a test item because of an invalid test. However, if damage resulting directly from an overtest occurs to a test item component that has absolutely no impact on the data being collected, and it is known that such damage is the only damage caused by the overtest (e.g., rubber feet on bottom of a test item melted by high temperature where those feet have no impact on the performance of the test item), the test item can be repaired and the test resumed and extended as in the undertest condition. Coordinate with the customer before repairing and continuing to test an item after it has been overtested. This coordination is aimed at preventing customer objections if the test item fails during the remainder of the test program (claims that the test was invalid past the point of the overtest because the overtest caused undiscovered damage to a critical component).
5.11.3 Interruption Due to Test Item Operation Failure
Each Method contains information for handling interruptions due to test item failure. Analyze any such interruption carefully. The failure of the item may be due to accumulative stress of several tests in sequence and not just the final test where the item failed.
5.11.4 Scheduled Interruptions
It is highly recommended to perform a continuous test(s) without interruptions, however there may be situations in which test interruptions are necessary. This may be to conduct maintenance to the test item or perform an inspection. Such interruptions must be scheduled prior to the start of test so as to minimize the disruption to the test. These interruptions cannot be allowed to affect the result of the test. Additionally, they should not be so frequent that the test conditions cannot stabilize between interruptions. All scheduled interruptions should be documented in the test plan prior to the start of testing. The rationale for any deviation or unscheduled interruption shall be documented as they occur and included in the test report.