Downloaded from https://www.everyspec.com MIL-STD-81OD 19 July1983 1-3.2.3.5 ~. The item shall be operated throughout each test except when being exposed to maximum and minimum temperatures that occur in equipment bays or the cockpit. If separate tests are conducted, the test item shall be turned on and off using the same schedule as if the test environments were all combined. 1-3.3 ~ a. lc~ re . The test should be conducted so that the test item experiences 300 to 600 mission hours of stress exposure. The rate of occurrence of defects in conjunction with schedule and”coat generally determines the duration of an engineering development test.
If few or no failures are occurring, littlenew information is being generated ss to how or where to improve the test item and the test should be terminated. ,,& b. J’rocedureu: Test duration shall be sufficient either (1,)to give the tester confidence that environmental factors will not cause significant problems during the flight test program or (2) to resolve a problem that arisea during flight or operational testing. c. f’rocedureu. Procedure III shall be conducted for ten test cycles per figure 520.0-5, or ita equivalent (40 environmental stress hours with 30 hours of equipment turned on).
This is somewhat arbitrary, but reflects the duration of previous temperature-altitude-humidity teats. ~-~ ~ I-4.’1 Mt interruot~. In the event of an unplanned teat stoppage due to an event such as a facility failure, the following is recommended. If the item has not failed and there is no apparent damage ,tothe teat item, the test continues. If the test item was damaged when the unplanned event occurred, testing should not be resumed until it can be determined whether the stress combinations during the unplanned event are likely to occur in the deployment environment.
Testing gbould be resumed at the point of interruption and fsiled teat article(s) remove’dbefore beginning the next phase, unless the nature of the failure precludes any useful equipment operation. I-4.2 Mlure orlt~. . . All incidents where the test item does not meet equipment operating requirements shall be analyzsd to determine the cause and impact of such occurrences. Corrective actions shall be proposed or implemented as required to meet equipment performance requirements. .- .,. 1-4.3 ~- The accuracy required in General Requirements of MIL-STD-81O appliea for each stress measurement system.
The ability of a given test chamber to control,to tbe specified atress conditions ia a function of the chamber’a design and appropriate placement of tranaducera. Thus, in evaluating tbe teat tolerances for any given combined environment teat, the test plan should clearly identify the placement of the atress measurement transducer relative to the teat item. I-U.4 mt Drofile tolerancex. The tolerances for each stress in each phase of procedure II can be derived from design specifications. For examplm, the design specification may call for a phase of cruise between 20,000 and 30,000 feet.
For the test mission, this can be translated into an altitude of 25,000 feet with a tolerance of s ,000 feet. 520.0-23 METHOD 520..0 19 July 1983