What Finishes And Procedures Can Be Applied To Cable Assemblies?


What Finishes And Procedures Can Be Applied To Cable Assemblies?

Wires are installed in bundles for an organized and easy-to-maintain installation. These bundles are often known as cable assemblies or wire harnesses. Aircraft cable assemblies are made in factories or electrical shops on jig boards so that these bundles can be preformed to fit into the aircraft. This is why every cable assembly for a particular aircraft installation is identical in length and shape. Miracle Aerospace is one of the best aircraft cable assembly manufacturers in India, who production processes are certified for quality to ISO 9001, AS9100C; and the quality of the harness are certified and approved by DGAQA and MSQAA for platform specific applications. These cable assemblies could be shielded, grouped, bundled, twisted, spliced, bent, tied, or laced as required. Let us learn all about perfection of cable assemblies here.

Slack in cable assemblies

There must be sufficient slack in the wires so that individual wires as well as the bundles are not under tension. And, the wires at terminal lugs or connectors should have sufficient slack to allow two re-terminations without the need for wire replacement. Sufficient slack should be provided at both ends of the wires to permit replacement of terminals and ease of maintenance, while preventing mechanical strain and permitting free movement of shock-and-vibration-mounted equipment. With sufficient slack, alignment, tuning, servicing, and replacement becomes easier.

Twisting of cables

Certain scenarios call for parallel wires to be twisted together. These conditions may include three-phase distribution wiring, wiring close to a magnetic compass or flux valve, or radio wiring. The twisting should be done so that the cables lie snugly against each other, making the required number of twists per foot. Once twisted, you must check for the wire’s insulation for any kind of damage. If the insulation is frayed or torn, you must replace the wire.

Splicing of cables

Splicing is permitted as long as it does not affect the reliability and electromechanical characteristics of the wiring. There should be an approval of an engineer and also approved data. However, splicing should be kept to the minimum, and must in fact be avoided as much as possible, in areas subject to extreme vibrations. Only one splice in any one wire segment is advisable between any two connectors or other disconnect points. Also remember that splices should not be used within 12 inches of a termination device.

Bending of cables

The minimum radius of bend in a wire should not be less than 10 times the outside diameter of the largest cable. Where appropriate or supported, the radius may be three times the diameter of the cable. RF cables should be bent at a radius of no less than six times the outside diameter of the cable. However, where it isn’t practical to install cables within the radius requirements, the bend should be enclosed in insulating tubing.

Shielding of cables

Wire circuits are generally shielded individually, in pairs, in triples, or in quads, depending on each circuit’s shielding requirement. Generally, wires are shielded when it is likely that the circuit can be affected by another circuit in the cable assembly. When wires come close to each other, they can couple enough interference to cause a negative effect to the attached circuitry. Shielded the wires prevents this from happening.

Lacing and tying cable assemblies

It is very important to secure wire groups and bundles for ease of maintenance, installation, and inspection. This procedure could involve the use of ties, laces, and straps. However, straps cannot be used in areas like wheel wells, near wing flaps, near wing folds, in the presence of UV light, and in high vibration areas, where damage could be caused to the insulation and other mechanical components. This tying of cable assemblies can be done by the use of single cord lacing, tape tying, knotting, and double cord lacing. Also, wire groups or bundle ties can be used where the supports for the wire are more than 12 inches apart.