MIL-DTL-25971C
4.4.2 Operation. The light shall be operated to determine that all controls work properly
and the color filters and color indicator are positioned correctly.
4.4.3 Sights. The accuracy of the sighting device of each light shall be checked by
centering the light beam upon a 3 by 3 foot target not less than 400 feet from the light, or any
other combination of target and distance which presents the same angular relationship between
the target and the light, and observing the alignment of the sights.
4.4.4 Focus. Each light shall be tested to determine the accuracy of the focusing of the
parabolic and spherical reflectors. A plate with four holes, as shown on figure 1, shall be placed
over the end of the light, and a blank screen shall be placed 4-1/2 feet from the plate. If the
focusing is correct, the images as shown on figure 1 shall have the same spacing as the holes in
the plate. At each point on the screen, two images shall be superimposed, one of which is caused
by the spherical reflector and the other by the parabolic reflector. If the two sets of images are
not superimposed with the correct spacing, the focusing is incorrect and the light shall be
rejected.
4.4.5 Photometry. The light shall be operated to determine photometric compliance with
4.4.6 Environmental. The light will be subjected to tests in accordance with the
following specified procedures of MIL-STD-810 to determine proper operation and freedom
from adverse effects resulting from environmental exposure.
4.4.6.1 High temperatures. The light shall be subjected to high temperature test Method
501, Procedure II, except at a temperature of 55 șC ± 2 șC for 4 hours. Controls shall be
operated at this temperature to determine that there is no binding of parts or other
malfunctioning.
4.4.6.2 Low temperature. The light shall be subjected to low temperature test Method
502, Procedure I, for 12 hours, followed immediately by operation of controls.
4.4.6.3 Humidity. The light shall be subjected to humidity test Method 507, Procedure I,
except that the 6-hour high temperature phase shall be conducted at 40 șC and the relative
humidity shall be held at 100 percent during the 6 hour period.
4.4.6.4 Sand and dust. The light shall be subjected to sand and dust test Method 510,
Procedure I.
4.4.7 Transformer temperature rise. When subjected to a heat rise test, conducted by
connecting the primary to a 120-volt, 60-cps power source and loading the secondary with a
resistive load drawing 7.0 ± 0.1 amperes current, the temperature rise after 1 hour continuous
operation, determined by the resistance method, shall not exceed the requirement as specified in
10
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business