MIL-DTL-48556B
FIGURE 1. Orientation of shock loads.
3.4.4 Vibration "A". The quadrant shall withstand a total of 270 minutes of sweep-
cycle vibration. The vibration shall be applied for 90 minutes along each of the three
mutually perpendicular major axes shown in Figure 1. A complete sweep-cycle shall
consist of vibration from origin (5 Hz at 1 inch double amplitude) to mid-point (5 ± 0.5 g's
at 500 Hz) to origin, and shall have a duration of 15 ± 1 minutes. Double amplitude shall
be constant at 1 inch between 5 Hz and 10 Hz, and varied with frequency to maintain a
constant 5 ± 0.5 g's acceleration between 10 Hz and 500 Hz. Upon completion of
vibration, the quadrant shall exhibit no evidence of damage or physical failure and shall
meet the requirements of 3.5 through 3.14 inclusive.
3.4.5 Vibration "B". The quadrant shall be vibrated in the vertical plane shown in
Figure 1 for a total of 15 ± 1 minutes of sweep cycle vibration. A complete sweep-cycle
shall consist of vibration from origin (5 Hz at 1 inch double amplitude) to mid-point (5 ±
0.5 g's at 500 Hz) to origin, and shall have a duration of 15 ± 1 minutes. Double amplitude
shall be constant at 1 inch between 5 Hz and 10 Hz and varied with frequency to maintain a
constant 5 ± 0.5 g's acceleration between 10 Hz and 500 Hz. Upon completion of
vibration, the quadrant shall exhibit no evidence of damage or physical failure and shall
meet the requirements of 3.5 through 3.14 inclusive.
3.5 Sealing. The quadrant shall be capable of sustaining an internal pressure of 5.0
± 0.10 pounds per square inch gage (psig) for a minimum of one hour with no evidence of
leakage.
3.6 Purging. The interior of the quadrant shall be purged with dry nitrogen supplied
at a pressure of 8.00 ± 0.25 psig until the dew point of the emergent gas is no higher than -
25°F. Purging apparatus shall be removed, and subsequent to the seating of the pressure
relief valve, the quadrant shall be pressured to 1.0 ± 0.1 psig for all testing and delivery.
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