MIL-DTL-55425E
4.3.3.2 Group C failures. Actions required relative to group C failures shall be as specified in the contract.
4.4 Inspection covered by subsidiary documents. The following shall be inspected under the applicable subsidiary
documents as part of the inspection required by this specification, and the inspection requirement specified in the
contract.
Item
Requirement paragraph
Strands
Insulating compound
Code marker threads
4.5 Inspection of preparation for delivery. Refer to section 5 for packaging requirements, including any special
packaging inspections prior to delivery.
4.6 Physical tests.
4.6.1 Tubing (heat shock). The specimen (insulated pair) shall be looped back and wound tightly on itself for five
close turns. The ends shall be securely taped, and the specimen shall be placed in an air oven maintained at a
temperature of 121±1 °C for 24 hours, plus 5, minus 0 minutes. The specimen shall then be removed from the oven
and the insulation examined for strains and cracks under a magnification of at least three diameters (focal distance of
8 centimeters) and meet the requirements of 3.4.1.
4.6.2 Thermal stress cracking. The test of 4.6.1 shall be performed except that the specimen shall be placed in an
air oven for 14 days at 100±1 °C. The specimen shall then meet the requirements of 3.4.2.
4.6.3 Cold bend. The specimen of insulated pair and a mandrel of 0.125±.003 inch (.3.17± .08 mm) diameter shall
be placed in a cold chamber maintained at a temperature of -55±1 °C for a period of 24 hours. At the end of this
time, while still in the cold chamber, the specimen shall be wound around the mandrel for five close turns at a rate of
approximately one turn per second. During this processing, no object having a temperature higher than -55±1 °C
shall come within twelve inches of the point of the specimen being wound. After the test, the specimen shall be
examined under a magnification glass with at least three diameters magnification for visible evidence of cracking of
the insulation and meet the requirements of 3.4.3.
4.6.3.1 Cold bend after aging. A specimen of insulated pair shall be placed in an oxygen bomb containing an
atmosphere of oxygen at 300+10 pounds per square inch at a temperature of 70+1 °C, and held there for a period of
96 hours, plus 2, minus 0 hours. At the end of this period, the specimen shall be tested as specified in 4.6.3, except
the temperature shall be -40+1 °C. The specimen shall then meet the requirements of 3.4.3.
4.6.4 Elongation. A specimen of a full cross-section of conductor pair insulation shall be tested in accordance with
4.6.4.1 Elongation after aging. A specimen of a full cross-section of conductor pair insulation shall be placed in an
air oven conforming to the requirements of ASTM D573 and maintained at a temperature of 100±1 °C for a period of
seven days. After a cooling period of at least 24 hours at room temperature, the specimen shall be tested as
4.6.5 Cutting. A specimen of insulated pair shall be cut in half and the insulation stripped from one end of each
piece. One piece shall be formed in a loop, the ends of which shall be tightly clamped in one of the grips of a tensile
tester. The second piece shall be passed through the loop and its ends shall be tightly clamped in the other grip of
the tensile tester. The two bared conductors of a pair shall be connected together. These bared ends shall be
connected in series with an electrical alarm circuit and a load shall be applied to the looped conductors by separation
of the tensile tester grips at a rate of two inches per minute until they cut through the insulation, thus making electrical
contact as indicated by the alarm circuit. If metal grips are used, one of them must be insulated from the rest of the
machine to avoid false indications. The specimen shall then meet the requirements of 3.4.5.
4.6.6 Breaking load. The breaking load of an insulated pair shall be determined using the apparatus and method
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