-
The harness, when positioned on the various supports, is held by untightened ties to allow it to be positioned.
-It is prohibited to leave the harness suspended even temporarily (for attachment to a support or an operation on the structure), the harness must be protected and held to stop it coming into contact with any item that may damage it by fretting.
-Unconnected connectors must be protected (caps), (Refer to chapter: Protection by Caps - 20-54-10).
D. (Re)Connection
(1) Overlength at ends
(a) General
(Ref. Fig. 017, 018)
-Around 50 mm (1.9685 in.) of overlength is added to the length of the harness for the reasons that follow:
-
To facilitate installation and removal of connectors and the
locking and unlocking of contacts.
-
To allow possible end fitting replacements (contacts, lugs)
(except for optical cables):
. 2 for 26 to 12 gauge wires.
20-33-11 Page 28
Manufacture/Installation of Wiring - Wiring Installation Recommendations Harness Identification and Positioning R Figure 016
20-33-11 Page 29
Manufacture/Installation of Wiring - Wiring Installation Recommendations Overlength at Ends R Figure 017
20-33-11 Page 30
Manufacture/Installation of Wiring - Wiring Installation Recommendations Overlength at Ends and Drip Loops R Figure 018
20-33-11 Page 3120-33-11 Page 32
. 1 for 10 to 0000 gauge wires. In this case, the overlength will be reduced to 20 mm (0.7874 in.). . For coaxial cables (for number of repairs allowed, refer to chapter: Coaxial Cable Repair - 20-53-23). - Cables which could become wet through contact with liquids must end in a drip loop (a loop with a low point) where they reach a connection. - Cables must be installed so that there is no stress at the connection points. They must never be under tension after connection.
(b) Specific cases
R _1 Twisted wires (Ref. Fig. 009) To facilitate the insertion of the contacts in the modules and to check that each contact is locked, twisted cables must be untwisted over a length of 60 mm (2.3622 in.) (+ or - 10 mm (0.3937 in.)) before connecting to connectors or modules.
____NOTE : The locking check must be performed on each wire individually by pulling on the wire.
_2 Quadrax cables A minimum length of 250 mm (9.8425 in.) must be provided at the ends to prevent the cable twisting during connection. It is very important to avoid twisting at the ends.
R R R R R R R R (2) Spare wire Obey the general wiring recommendations when you connect the spare wire. Before you use a spare wire, make sure that there is full compatibility between: - The spare wire type and gauge and the system it is connected to, - The spare wire route and the related system (obey the segregation rules).
R (3) Attachment items For more information, refer to chapter: Harness Attachment -20-33-40.
E. Inspection procedure After installation of the wiring, it must be checked periodically. Refer to chapter: Inspection Check - 20-52-10.
________________________________________________
SEPARATION / ROUTING - DESCRIPTION AND OPERATION
_______
1. General
General wiring designs used on transport aircraft vary significantly between manufacturers and models. The continuing safe operation of aircraft during their expected service life depends on the safe transfer of electrical energy by the electrical wiring interconnection system (EWIS). The EWIS is designed and installed in aircraft: - To prevent the propagation of the effects of electrical faults to other independent power sources, - To prevent the possibility that the failure of a component in a redundant system could cause the failure of another related redundant system, - To avoid electromagnetic interference (EMI) between electromagnetic compatibility (EMC) circuits that are not compatible. The chapters that follow give the definition and requirements related to the EWIS separation/routing applied on aircraft.
______________________________________2. Structure of the chapters that follow:
A. Routes definition (Ref.20-33-21)
B. Separation/routing rules (Ref.20-33-22)
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