Downloaded from https://www.everyspec.com MIL-STD-810D 19 July 1983 I-3.2 .~ O ,..’ 1-3.2.1 Procedure I -.. development test I-3.2.1.1 Use the analysis outlined in paragraph I-3.2.2, flight ,or operational support test; to determine realiatic environmentalstress .levela, durations and rates of change. The more benigtiportions of the test”profile can be eliminated for an engineering development test. Likewise the amplitude of environmental stresses can be increaeed to accelerate the occurrence of Pailures. Depending upon available facilities, environmental stresses may be teated in combination or singly.
s I-3.2.1.2 It ie reconunendedthat a Procedure 11 test of short duration be done when the test item is fairly mature and its design stable. This would teat the accuracy of the prejudgments made as to which environmental atresaea are benign. I-3.2.2 e II - Flight OL)erat~ort test. The combined environment test combines the environmental,stresses of temperature, vibration, humidity, and, if required, altitude and cooling airflow in a manner occurring in actual deployment. Mission profilee are used as the basis for formulating the environmental atreases.
The failure data obtained from this teat will help determine the corrective actiona to be performed on the item to prevent failure in the operational environment. Generally, the combined environment test simulates those environmental effects that occur for the majority of the deployment life. 1-3.2.2.1 ~ for test. . . This seotion describes,the step-by-step approach in the measurement, prediction, and choice of forcing functions for a combined environment test. Figure 520.0-1 is a flow diagram for generating a test profile, as described throughout this section. I-3.2.2.2 ~.
A‘test ‘cyclei’sdefined as a unit of time where several mission profiles are simulated under different atmospheric conditions. A teat cycle shall consist of at least three atmospheric ?egments of the sequence, composed as follows: cold and dry, warm and moist, and hot and dry. Within each atmospheric segment of the test cycle, several different miaaion profiles may be simulated. A miesion ‘profileis defined as a Mach number-altitude-time history that.an aircraft oan fly. For example, a fighter aircraft may predominantly fly three different miesions: air auperiority, ground support, and interdiction; therefore, this aircraft has three mission profiles.
Each mission profile is divided into flight phaeea, such aa takeoff,, Cruise, combat, low-level penetration, etc. (figure 52o.o-2). During a teat cycle, temperature, vibration, humidity, altitude, and cooling airflow shall be varied. Altitude simulation may be considered for a test item that ie hermetically sealed,.usea pressurized cooling paths to tranafer heat, has components that contain a va”cuum,haa ,voltagesof sufficient potential to arc in the presence of rarefied air, long range missions, or for other appropriate caaes. Cooling airflow is required for all test items that use supplementary airflow in the aircraft.. ~THOD 520.0 19 July 1983 520.0-3