MIL-DTL-48556B
4.4.5 Vibration "B". The quadrant shall be mounted utilizing the keyway and four
mounting bolts torqued to 25-30 foot-pounds; fixture 11747195 may be used to adapt the
quadrant to the vibration test equipment. The quadrant shall be subjected to the vibration
requirements in accordance with 3.4.5. Upon completion of this test, the quadrant shall be
removed from the vibration test equipment and shall meet the requirements as specified in
3.5 through 3.14 inclusive.
4.5 Sealing. Prior to the start of the test, secure the poppet valve in a closed
position. Pressurize the quadrant with dry nitrogen to an internal pressure of 5.0 ± 0.10
psig, and then remove the pressure source. After a minimum time of 1 hour, check the
internal pressure of the quadrant. The internal pressure must be within the range specified.
4.6 Purging. Connect the test equipment to the purging valve of the quadrant.
Adjust the dry nitrogen pressure to 8.00 ± 0.25 psig. A dew point tester (standard type
shop equipment) shall be used to measure the nitrogen dew point for conformance with 3.6.
Disconnect the purging apparatus when the relief valve has reseated to maintain the
internal pressure of 1.0 ± 0.1 psig. Purging is to be performed at standard ambient
temperature and prior to performing any temperature test.
4.7 Cleanliness. Visually inspect for defects. Internal inspection shall be made by
viewing through the windows.
4.8 Performance. Verifications 4.8.1 through 4.8.7 shall be done with the starting
position of the quadrant as follows:
a. The flat mounting surface of the quadrant in a vertical plane.
b. The locating keyways in a horizontal plane.
c. The elevation level vial bubble centered within the thickness of a graduation line.
d. The four quadrant mounting bolts torqued to 25 to 30 foot pounds.
e. The correction counter indicating "00 mils."
f. The elevation counter indicating "0000 mils", with backlash removed. To ensure
that the backlash has been removed, turn the knob clockwise to reach the desired elevation
setting; if turning the knob counterclockwise, over travel the desired setting by at least a
half turn of the knob and then come back to it clockwise.
4.8.1 Elevation counter excursion range. Mount the quadrant on a cross level
fixture in the orientation specified in 4.8. Manually rotate the elevation counter knob until
the elevation counter has traveled the minimum elevation and depression specified as read
on the elevation counter.
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