(2)
As a general rule, in a harness made up of several groups of wires, each group of wires must be tied with lacing tape NSA8420 (Enclosed cable tie NSA935401 is prohibited). Cable ties NSA935401 are used on the outside of harnesses to attach the groups of wires together. (Ref. Fig. 002)
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Manufacture and Installation of Wiring - Harness Tying Recommendations
Distribution and Tying Pitch
Figure 001
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Manufacture and Installation of Wiring - Harness Tying Recommendations
Lacing Tape and Cable Ties
Figure 002
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(3) The harness must include at least:
-3 wires of gauge 22 or 24,
- or two wires of gauge 20,
- or one wire of gauge 20, plus two wires of gauge 22 or 24.
(For installation on aircraft of a smaller number of cables and if these cables are attached to a cable support NSA935504 or equivalent, apply protection tape ASNA5107 or equivalent around the harness).
(4) At branches
(Ref. Fig. 003)
-To prevent harnesses twisting when installed on aircraft, the position and direction of the branches on aircraft must be anticipated before the harnesses and branches are tied.
-Crossed tying is only permitted with lacing tape NSA8420. (The use of cable tie NSA935401 is prohibited).
D. Specific recommendations
(1)
At hinge points: Where a harness follows the movement of a component, it can be twisted (4 turns/meter) to provide suitable travel when the moveable component is operated.
(2)
EFCS (Electrical Flight Control System) wiring On EFCS harnesses, any defects detected during the harness manufacturing stage in the workshop, and before assembly of the main associated harness, must be corrected by replacing the damaged wires. The installation of any additional non-EFCS wires in EFCS harnesses is prohibited. EFCS harnesses are made up and tied separately and then, where necessary, attached to the relevant harness. (Ref. Fig. 004)
____
NOTE : All defects detected on an EFCS harness or cable installed on the aircraft must be corrected (cable(s) replaced or temporarily repaired according to chapter: EFCS Wire Repair -20-53-27).
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Manufacture and Installation of Wiring - Harness Tying Recommendations
At Branches
Figure 003
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Manufacture and Installation of Wiring - Specific Tying Recommendations
EFCS Harness with another harness
Figure 004
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(3)
For optical fiber cables or harnesses (Ref. Fig. 005, 006)
(a) General
Optical fiber cables or harnesses are protected:
-
At a cable tie, by a bushing NSA5539,
-
At a cable support or on a tubular support, by a bushing NSA5539 or a self-amalgamating silicon tape ASNA5107 (3 turns minimum). The standard tightening pitch on the harness is between 150 mm (5.9055 in.) and 200 mm (7.8740 in.). In particular cases (curve, junction, branch), two cable ties must not be installed too close together, 20 mm (0.7874 in.) minimum in order not to stress the optical fiber cable.
(b)
Optical fiber cables or harnesses wired alone.
(Ref. Fig. 005)
(c)
Optical fiber cables or harnesses wired with an electrical harness. (Ref. Fig. 005) A maximumn of four optical fiber cables or optical fiber harness (less than four cables) can be attached on the side of an electrical harness (secured by cable ties placed between those of the electrical harness and outside the harness attachments (clamps NSA5516 or equivalent)). If there are more than four optical fiber cables, they must be installed inside the electrical harness attachments (clamps NSA5516 or equivalent). If necessary a larger size clamp must be used.
(d)
Optical fiber cables wired on a cable tubular support, protected by a bushing NSA5539 and attached with a cable tie. Optical fiber harnesses (two or more cables) wired on a cable tubular support, protected by self-amalgamating silicon tape ASNA5107 (3 turns minimum) and with a cable tie. (Ref. Fig. 006)
(4)
For coaxial cables wired in an electrical harness: (Ref. Fig. 007) Set the cable tie installation tools to minimum tension. Cross the cable tie to spread out the pressure. The head of the cable tie must be located in the half of the harness circumference opposite the coaxial cable.
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Manufacture and Installation of Wiring - Specific Tying Recommendations 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(45)
