Downloaded from https://www.everyspec.com MIL-STD-81OD .;/! 19 JuIY.1983 . METHOD 523.0 VIBRO-ACOtiSTIC,TEilFERATURE ~ SECTION I I-1 PURPOSE . . . . . . . . . . . ., . . . . . . . . . ...523.0-1 I-2 EwIRONMENTAL. . .. . . . . . . . . . . . . .. ... . . . . .523.0-2 I-3 GUIDELINES POR DETERMINING TEST PROCEDURES AND TEST CONDITIONS . . . : . . . . . . . . 523.0-6 I-5 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . 523.0-6 SECTION II 11-1” APPARATUS . . . . . . . . . 11-2 PREPARATION FOR TEST . . . 11-3 PROCEDURES ‘.... . . . . . 11-4 INFORMATION TO BE RECORDED . . . . . . . . . . . . . . . 523.0-.13 . . . . . . . . . . . . . . . 523.0-15 . . . . . . . . . . . . . . . 523.0-18 . . . .
. .. . . . . . . . . .‘“523.0-18 I-1 ~ reproduce the oombined temperature, vibration, and other operating etresses as needed, that an externally-carried aircraft store will experience during in-service flights. 1-1.1 This method seeks to 1-2 ~ I-2.1 Q&&.rvable effe.Q& Possible effects of a combination of vibration, acoustic, and high temperature stresses inolude all those e~fects whioh each of theee factors can cause separately (see method 501, 514, 515). Also; the combined environments may interact to give effects which are not predictable from the results of single-”environmenttests, but which do occur in actual service.use. I-2.2 we ct.meoh~ , ,, 1-2.2.1 e imD~.
All environmental streeaes do not contribute equally to deterioration of.store reliability. Analysis of service failures caused by aircraft environmental stress (reference 2) has identified the four most significant stresses causing aircraft equipment failures. These are operation, temperature, vibration and moisture. Other environmental stresses may produce failure modes in a given type of store and should be investigated for their possible relation to service faiIures. ., I-2.2.2 ~. The source of the heat that causes reliabilityy problems in electronic components of aircraft stores will generslly be an external surface.
This heat in combination with the heat generated within the electronics causes decreased operating life or Mean-Time-To-Failure (MTTF). Another stress aspect of the temperature environment is rapid temperature change (thermal shock). A thermal shock .ortransient registered at the outside surface of the store does not appear as a shock to components somewhat thermally isolated within.. Internal’components experience thermal shock when the unit ie turned on and quickly warms up to operating temperature. MRTHOD 523.0 19 July 1983 523.0-1