Downloaded from https://www.everyspec.com MIL-STD-81OC 3.2 Procedure II. Accelerated cycling temperature and solar radiation test. The test item shall be prepared in accordance with General Requirements, 3.2. Raise the chamber air temperature to 32° C (90”F). The test item shall then be exposed to three continuous 24-hour cycles of controlled simulated solar” radiation and dry bulb temperature as indicated in figure 505.1-1 or as speci- fied in the equipment specification. Tolerances for control of radiation shall be f5 watts/ft2.
Tolerances for air temperature control shall be *2° C (*3.6”F).At the beginning and end of each test cycle, the chamber relative humidity (uncontrolled)shall be less than 40 percent. The air velocity in the chamber shall be maintained within 3 to 6 knots (300 to 600 ft/min). When specified in the equipment specification, at 1,500 hours of the third cycle (or at the approximate point of peak test item temperature), the test item shall be operated for 1 hour and results shall be obtained in:accordance with General Requirements, 3.2.
At the conclusion of the last expbsure, the test item shall be removed from the chamber and operated and inspected and results obtained in accordance with GeneTal Requirements, 3.2. If the test item is operated during the test, it,shall be returned to room ambient before the final operation; otherwise the final operation shall be performed as soon as the test item is removed from the chamber. NOTE: The test item may or may not be operated throughout the test at the option of the equipment specification.
When evaluation of heating effects is certain one-shot items (e.g., rockets) thermocouples affixed to critical por- tions of the test item should be used to determine time and value of peak temperature. The time of operation shall coincide with peak temperature. important, operation at least at peak temperature should be specified. For 4. SUMMARY. The following details shall be as specified in the equipment specification. a. Procedure number b. Pretest data required c. Failure criteria d. Number of cycles if other than three (Procedure II) e. Temperature and solar radiation intensity, if other than given in procedure I or procedure II f.
Indicate the operation and inspection required of the test item or to be performed (if any) on the test item during the test cycles, including the start and duration of each indicated operation or inspection Of the test item. 505.1-3 METHOD 505.1