Downloaded from https://www.everyspec.com MIL-STD-810D 19 July.1983 METHOD 520.0 TEMPERATURE, HUMIDITY, VIBRATION, ALTITUDE SECTION 11 II-1 AUAEANS. The combined environment test chamber(s) shall be capable of producing the required combinations of temperature, altitude, humidity, random vibration, and cooling air.mass flow. All inatrumentation shall be able to meet the accuracy specified in section 4 of General Requirements. . II-2 ~. Select which test procedure shall be implemented. Identify if the test shalI be a combined environment test or a series of single and appropriate environmental combinations tests. Select which of the.
following steps are appropriate for the environmental stresses being included in the test of interest. Step 1. For vibration testing in Procedure I or II, the individual equipment test item(s) should be subjected to random vibration in either the aircraft vertical or lateral axis, whichever seems to offer the greatest potential for defeet disclosure. If neither axis seems to offer a distinct benefit, the test axis may be selected to suit facility convenience.
When practical, diagonal vector vibration (vibration applied diagonally at a test item corner through its center of mass, rather than along a single orthogonal axis) may be applied to provida multi-axis excitation usiriga single test setup. For Procedure 111, conduct vibration test in accordance with method 514.3. 0 Step 2. For tests that do not include vibration, mount test items in their normal orientation with the ground plane when the carrying aircraft is parked on the ground. Step 3. For Procedures I and II, mount at least two vibration pickups to measure the vibration environment for each test item.
Follow practices for the accelerometer mounting, output averaging, and data analyis techniques outlined in method 51Q of this standard. Step 4. For test items that require supplemental cooling air, measure mass flow rate; humidity, and temperature. Mount instrumentation so that these values are known as close as possible to where the air enters the test item(s). Step 5. Bay air conditions around the equipment shall be measured as specified in General Requirements, paragraph 4.6.2. The air temperature around the equipment under test shall be used to control this environmental stress. c. Step 6. Mount humidity sensor to measure bay air humidity.
A single-point measurement is adequate as long as the measurement point is not shielded from the bulk conditions around the test item. & ~THOD 520.0 19 July 1983 520.0-25