Downloaded from https://www.everyspec.com MIL-STD-810D, ~ 19 July 1983 variation, eelect the test temperatures, test durations, teet item configura- tion, and any additional appropriate variablee. Values other than those”sug- geeted may be used if realistic. I-3.2 e of re~ted test o~. After’ohoosing the ‘test expoeure I j! ,.. a. The test temperatures are preferably selected from field data or from the requiiemente documen’ta. If this information is not available, the test temperatures can be determined from the anticipated deployment ,applicationor world areas in which’the teat item will be deployed, or from the most extreme nonoperating temperature requirements. ... ,, (1) ... ~.
.~hethermal stresses that equipment will experience during exposure to this operational environment are dependent upon the ambient conditions; flight”conditions, and performance of the ohboard environmental control syste,ms.– ~ ., ... (a) The ,temperatureand humidity at various altitudea can be found in’MIL-STD-21O. (b) Table 503.2-I,shows temperatures typical at ground level in hot olimates.’ The temperatures ehown are,baaed on frequency of occurrence and correspond to a l-percent frequency of occurrence at or close to the geographical boundary between the category of interest and the next-more- : severe category.
The,probability of.occurrence incrbaa,es, ae the distance,from this line into the category’”area increases. Table 503’.2-11and figure 4 (General Requirements) can be used to determine test temperature? for the anticipated deplp~ent 10cation9. ,. .0 The test conditions for this exposure,are based upon the conditions that will probably exist in the cargo compartment of the aircraft and on the ground at the point of impact. The lower,temperature extreme should assume an unheated, unpressurized aircra’ft‘c’argocompartment with the airoraft at ‘analtitude of 8 kilometers (26,200 ft). This ia the ~‘ :
limiting altitude for cargo aircraft becau.qeof oxygen-preaetirerequirement+ when the aircraft cargo compartment is unpressurized immediately before.airdrop operation. The temperature at this altitude over a desert can be’found in MIL-STD-21O. Thie high temperature eurface extremee ,shouldbe determined according to 1-3.2a, from tables 503.2-I and 503.2-II, or.from method 501.2. ,- (z) ~. (3) /air @JJverv - arctQ. The condition developed for heated inclosurea located in cold regions are 21‘C.(70° F) and 25 per- cent relative humidity. These conditions were selected to roughly corres- . pond to normal heating practices in the Arctic and on”aircraft.
Selection of theouts;de ambient conditions.,should be based upon the climatic categories or .-. areas listed in table 503.2-III. ,, ...:.. ,[ MSTHOD 503.2 19 JUIY 1983 50”3.2-4