_____________________________________________3. (Re)Installation and (Re)Connection of Wiring
A. Recommendations
(1) When harnesses are moved, they must be carried and not dragged.
(2) Protect edges and through-holes with foam or non-abrasive fittings when harnesses are routed near or through holes on installation.
(3) Avoid contact between harnesses and sharp edges.
(4) Before installation of a harness, check that: - The installation and routing areas are clean. - The harness and the insulation are in correct condition. - The through holes in the structure are protected. - The raceways are clipped and tied (if applicable).
(5) The head of a cable tie must never be in contact with an adjacent harness.
B. Tools and tooling Tools are necessary to install the wiring on the aircraft. Make sure these tools are applicable for use and checked periodically according to the applicable maintenance regulations.
R C. (Re)Installation of wiring
R R R (1) Overlength of wiring The length of the harness is calculated in compliance with the installation rules (minimum distance from the structure, normal harness shape, etc.)
R (a) General - An overlength of around 50 mm (1.9685 in.) max. is provided on the length of harnesses to limit the effects of vibrations on devices and loads on wires, attachments and junctions. This overlength must be distributed at each end of the harness so this must be taken into account during the (re)installation of the harness. - When necessary, harness length control is provided in each interface area. (Ref. Fig. 011)
(b) Coaxial cables Some coaxial cables have a strictly defined length. This length is specified in the AWL.
Manufacture/Installation of Wiring - Wiring Installation Recommendations Overlength of wiring R Figure 011
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NOTE : If a repair shortens the cable length to below the minimum tolerance, the cable must be replaced in full (Refer to chapter: Coaxial Cable Repair - 20-53-23).
(c) Quadrax cables Quadrax cables have a strictly defined length. This length is specified in the AWL. This length between 2 items allows 1 repair only, after that the cable must be replaced. The overlength for contact repairs is distributed over the quad cable run.
(2) Bend radii R (Ref. Fig. 012)
(a) Harness The minimum bend radius for a harness that has no optical or coaxial cables attached, must be equal to 6 times the outside diameter of the the largest group of wires included in the harness. With coaxial or optical cables attached, the minimum bend radius must be equal to 10 times the outside diameter of the largest coaxial or optical cable. The bend radius must never be less than the minimum allowable radius of the largest wires included in the harness.
(b) 26 to 12 gauge copper and aluminum wires -------------------------------------------------------------------| CABLE GAUGE | MINIMUM BEND RADIUS (R) | |--------------------------------|--------------------------------| | 26 to 22 | 6 mm (0.2362 in.) | |--------------------------------|--------------------------------| | 20 | 7.5 mm (0.2952 in.) | |--------------------------------|--------------------------------| | 18 to 12 | 10 mm (0.3937 in.) | -------------------------------------------------------------------
(c)
Coaxial and 10 to 0000 gauge copper and aluminum wires The minimum bend radius is 10 times the outside diameter. In exceptional cases, this value may be reduced to 6 times the diameter.
(d)
BE or BF flexible cables The minimum bend radius is 3 times the outside diameter of the cable.
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Manufacture/Installation of Wiring - Wiring Installation Recommendations Bend Radius and Minimum Distances R Figure 012
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(e) Quad/quadrax and optical cables The minimum radius must be equal to 10 times the outside diameter of the wire. For optical cables and in exceptional cases, this value can be reduced to not less than 20 mm (0.7874 in.). 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：A320 ESPM Electrical Standard Practices Manual 2(47)
