There shall be no change greater than .25 mil in the azimuth counter
readings and no movement of the line of sight when the 50 mil values are
set into the gunner's aid counters.
3.9 Operability.- The boresight adjustment shaft and the azimuth counter
door and latch shall be operable at the extreme operating temperatures of
3.9.1 Torque.- The running torque required to operate the following
knobs shall be within the values specified for standard ambient temperature
of +60° to +90°F, and shall not exceed the values specified for extreme
operating temperatures. The torque values for the azimuth knob shall be met
with the five mil click lead knob set for "Indirect" fire (out of detent).
AT -40°F AND +150°F
AT +60°F TO +90°F
15 in. lbs. max.
3 to 8 in. lbs.
10 to 45 in. ozs.
5 to 40 in. ozs.
3.9.2 Direct force.- The following operability requirements shall be
met with the force applied horizontally and in the direction of movement.
18.104.22.168 Elbow assembly.- At a standard ambient temperature of +60° to
+90°F, a direct force of 2 to 8 pounds, applied adjacent to the eyelens,
shall be required to rotate the elbow assembly in each direction through
the full extent of travel. The force required at the extreme operating
temperatures of 3.3.2 shall not exceed 15 pounds.
22.214.171.124 Reset counter knob.- At a standard ambient temperature of +60°
to +90°F, a direct force of 11 pounds maximum shall be required to push in
the reset counter knob sufficiently to permit rotation. The force required
at the extreme operating temperatures of 3.3.2 shall not exceed 16 pounds.
3.10.1 Counters.- With the lamp energized, the numerals and markings
of each counter shall be clearly distinguishable when observed in a darkened
3.10.2 Reticle.- With a 28 volts dc, 0.04 amperes light source centrally
positioned 3/8 inch ± 1/32 inch from the illumination slot, the reticle markings
shall be clearly distinguishable when observed in a darkened area. This re-
quirement shall be met through one full revolution of the head and when the
elbow is rotated through its full range of travel.
3.11 Insulation resistance.- Insulation resistance shall not be less
than 10 megohms when a potential of 100 volts direct current is applied
between insulated points and ground.