MIL-DTL-83420 Wire Rope, Flexible, For Aircraft Control, General Specification ForThis specification covers the requirements for carbon steel and corrosion resistant steel aircraft control flexible wire rope. Type I wire rope will be capable of operation within a -65 degrees F to +250 degrees F \(-54 degrees C to +121 degrees C\) temperature range in wind, dust, fuel, and oil spills, in wash-down and other environmental stresses and aircraft experiences. Type II wire rope will be capable of operation within a -65 degrees F to +200 degrees F \(-54 degrees C to +94 degrees C\) temperature range in wind, dust, fuel, and oil spills, in wash-down and other environmental stresses and aircraft experiences.

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MIL-DTL-83420M

3.4.1.3.1 Twist-off. When a twist-off (see 6.4.14) occurs during fabrication of the 7-wire

layer of a 19-wire strand (see 3.4.1.3), splices and joints in individual wires may be as close as

18 inches.

3.4.2 Wire rope lengths. The wire rope shall be furnished on reels in lengths specified

by the procuring activity. There will be no more than two pieces of wire rope on the reel. The

shortest piece shall be a minimum of 20 percent of the reel length. The distance to the break

point on the reel shall be marked on the reel and package (see 3.6.3).

3.4.3 Wire rope construction. Flexible steel wire rope shall be 3 x 7, 7 x 7, or 7 x 19

construction and shall be regular lay (see 6.4.10) for the respective diameters, the dimensional

tolerances, and the physical properties as specified in tables I and II.

3.4.3.1 Construction 3 x 7. Wire rope of this construction shall consist of 3 strands of

7 wires each laid together without a core. Each strand shall consist of a layer of 6 wires laid

around a center wire (see 6.4.1) in a left-hand direction. The 3 strands shall be laid together in a

right-hand direction. The length of lay (see 6.4.3 and 6.4.4) of the 6 outer wires in each strand

shall not exceed 70 percent of the lay of the finished rope. The length of lay of the finished wire

rope shall not be more than 7 nor less than 5 times the nominal wire rope diameter (see 6.4.17).

3.4.3.2 Construction 7 x 7. Wire rope of this construction shall consist of 6 outer strands

of 7 wires each laid around a strand core (see 6.4.13) of 7 wires. The 6 outer strands shall

consist of a layer of 6 wires laid around a center wire in a left-hand direction. The strand core

shall consist of a layer of 6 wires laid around a center wire in a right-hand direction. The 6 outer

strands shall be laid around the core in a right-hand direction. The length of lay of the outside

6 wires in each of the 6 outside strands and the outside 6 wires of the strand core shall not exceed

60 percent of the lay of the finished wire rope. The length of the lay of the finished wire rope

shall be not more than 8 nor less than 6 times the nominal rope diameter.

3.4.3.3 Construction 7 x 19. Wire rope of this construction shall consist of 6 outer

strands of 19 wires each laid around a strand core of 19 wires. The 6 outer strands shall each

consist of a layer of 6 wires laid around a center wire in a left-hand direction and a layer of 12

wires laid over the 7-wire strand in a left-hand direction. The strand core shall consist of a layer

of 6 wires laid around a center wire in a right-hand direction and a layer of 12 wires laid around

the 7-wire strand in the right-hand direction. The 6 outer strands shall be laid around the core in

a right-hand direction. The length of lay of the inside layer of 6 wires in each of the 6 outer

strands and the one strand core shall not exceed 60 percent of the outside layer of 12 wires in

each strand. The length of lay of the outside layer of 12 wires in each of the 6 outside strands

and the strand core shall not exceed 50 percent of the lay of the finished wire rope. The length

of the lay of the finished wire rope shall not be more than 8 nor less than 6 times the nominal

rope diameter.