MIL-DTL-27500H
4.3.6 Cold Bend. The ends of previously untested samples of finished cable shall be secured to a mandrel in a cold chamber.
The other end of each specimen shall be secured to separate load weights sufficient to keep the cable vertical and tangent to the
mandrel during the bending operation. The mandrel size shall be as specified in table IX. The temperature of the chamber shall be
lowered to -550 C ± 50 C at a rate not to exceed 500 C per minute. The specimen and the mandrel shall be conditioned at this
temperature for 4 hours. At the end of this period, and while both mandrel and specimen are still at this low temperatures, the cable
shall be wrapped around the mandrel for 1800 without opening the chamber. The time required for bending around 1800 of the
mandrel shall be one-half minute at a uniform rate of speed. A revolving mandrel operated externally from the chamber shall be
used. The specimens shall then be removed from the mandrel and visually inspected, without magnification, for cracks. Specimens
of shielded and jacketed types of cable with jacket material 01, 02, 05, 06, and 08 through 12, 14 through 18, 20, 22, 23 and 24 and
equivalent double jackets shall be subjected to the voltage withstand test specified in 4.3.6. After being subjected to the cold bend
test or voltage withstand test of the jacket, all specimens shall be dissected. The individual wires shall then be immersed within 3
inches of their ends for 1 hour in a 5 percent salt solution. At the end of this period, a potential of 1000 V rms at commercial
frequency shall be applied for 1 minute from each conductor to the salt solution.
4.3.7 Voltage withstand, jacket. Specimens shall be formed into the shape of a U. All conductors shall be electrically connected
together with the shields (if any) on both ends of the specimen. The specimens shall be tested in accordance with MIL-STD-2223,
method 3005 , except the time of immersion shall be 1 hour minimum. The test voltage shall be 1,000 V rms, and the time of
electrification shall be 1 minute. The test voltage shall be applied between the conductors (plus shield) and the immersion liquid.
4.3.8 Conductor continuity. Each basic wire in 100 percent of all finished cable in shipment reels or coils shall be tested for
conductor continuity with an ohmmeter or other suitable testing device. There shall be no indication of discontinuity.
4.3.9 Thermal shock. Specimens of finished cable with jacket materials listed in table VI shall be wrapped around a mandrel
for at least six close turns with the ends of the specimens tied to the mandrel. The mandrel diameter shall be as specified in table IX.
The specimens on the mandrel shall be subjected to a temperature within ± 50 C of the values specified in table VI for 4 hours,
except for jacket material 02 which will be tested for 30 minutes. At the end of this period, the specimen shall be inspected visually
for cracks, without the aid of magnification (see 3.8.5).
4.3.10 Aging stability. Specimens of finished cable with jacket styles listed in table VI, shall be aged for 96 hours at
temperatures within ± 50 C of the values specified in table VI in a forced draft air oven. These specimens shall then be removed
from the oven, allowed to cool at room temperature for 30 minutes and wrapped at a uniform rate of 15 ± 3 rpm at room temperature
around a mandrel as specified in table IX. At the end of this period, the specimens shall be removed from the mandrel as a helical
coil and be inspected visually for cracks, without the aid of magnification (see 3.8.6).
4.3.11 Crosslinked verification. Twenty-four inch specimens of finished cable with crosslinked jackets (jacket symbols 08, 23,
58, and 73) shall have 1 inch of insulation removed from each end of each conductor. The conductors of each end shall be tied
together and loaded with weights equal to one-half the test load weight specified on the basic wire specification sheet times the
number of conductors. This shall be done at each end of the specimen. The central portion of the specimen shall then be bent over
horizontally positioned smooth stainless steel mandrel of the diameter specified in table IX. To prevent sticking of the wire to the
mandrel, the mandrel may be coated with polytetrafluoroethylene in the form of either enamel or wrapped tape, provided that the
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