MIL-S-50725(MU)
not exceed 90% of the prescribed tolerance limit, and permit positive
rejection when non-conforming. Construction shall be such as to favili-
tate routine calibration of test equipment.
4.5.2.2.1 Orientation.- The contractor shall provide special inspec-
tion equipment in accordance with 3.6.1 and 4.6.1.
4.6 Test methods and procedures.
4.6.1 Orientation.- Orientation is accomplished by means of a
special testing device to assure correct orientation in the three posi-
tions indicated on Figure 1. The device shall consist of a slimated
tube, with a base capable of supporting the tube whose axis is inclined
45 degrees plus or minus 20 seconds, above the horizontal. The outside
diameter of the tube shall measure 4.500 inches plus .050 inch and para-
llelism shall be within .003 inch per foot. The surface quality shall
be 63 micro inches RMS.
4.6.2 Collimation.- This test is accomplished by means of two plumb
lines located approximately fifty feet apart, and the tube of the device
positioned midway between the plumb lines so that the axis of the tube
lies in the plane of the plumb lines. This can be checked by locating
a vertical marker on the center line of the tube at each end. By means
of a collimator, located approximately 15 feet from the back of the plumb
line, bring the two plumb lines and the two markers on the tube in aline-
ment with the vertical lines of the collimator. A peep sight placed on
the objective end of the collimator, with a 3/16 inch aperture will en-
able the observer to make an accurate reading. Mount the bare sight on
the tube, as illustrated in (a) of Figure 1$ by means of the strap assembly.
Rotate the bore sight around the outside diameter of the tube until the
cross level bubble is centered, and tighten the clamp screw. Veiw through
the telescope the image of the plumb line. The vertical line of the tele-
scope shall coincide with the plumb line within the tolerance indicated in
3.6.1 as read on a mil chart placed in back of the plumb line. The bore
sight is then reversed on the tube, as illustrated in (c) of Figure 1,
and the same cross level and viewing procedure employed, using the oppos-
ite plumb line.
4.6.3 Plumb travel.- Plumb travel check consists of mounting the bore
sight on the tube by means of the strap assembly as shown in position (a)
of Figure 1. Locate a plumb line as described in 4.6.4. Center cross
level vial bubble within 1/2 the space width between two graduation lines.
The plumb line as viewed through the telescope at the intersection of the
cross lines of the reticle shall not deviate more than the tolerance of
3.6.2 when the telescope is displaced from maximum elevation to maximum
depression. A mil block chart, located at one end of the plumb line,
will indicate the amount of deviation.
4.6.4 Inverted level vial.- Inverted level vial check for accuracy
consists of mounting the bore sight on the tube of the device by means of
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