_________________________________________________________
6.
Separation of Fuel System Wiring (A340-500 and -600 only) For intrinsic safety reasons, wiring associated with the fuel quantity system must be included in the specific Q route with associated connectors.
________________________________
7.
Separation of Commercial Systems (Ref. Fig. 002) In all cases, technical and commercial circuits must be segregated. (Except for A300, where there is no specific route for commercial systems). In fuselage area, optional commercial P or M routes must be wired along basic commercial routes. In crossbeam area, optional commercial P or M routes must be wired separately.
20-33-22 Page 4
Separation/Routing Rules - Addition of Optional Wire(s) - Example
Figure 002
20-33-22 Page 5
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PROTECTION - DESCRIPTION AND OPERATION
_______
1. General The wire bundles are routed in such a way that under no circumstances, even temporary, can they come into contact with the structure or adjacent equipment. In locations where the wire bundles could come into contact with the structure or to ensure segregation rules, bundle protections are provided.
____
NOTE : The lack of distance or the contact between a protected harness and the structure is allowed if this protected harness does not have a relative movement against this part of the structure.
____NOTE : For routes consisting of:
-1 wire of 20 or 22 or 24 gauge (not acceptable for 26 gauge)
- or 2 wires of 22, 24 or 26 gauge,
- or 1 wire of 20 gauge and 1 wire of 22, 24 or 26 gauge.
The wire or small bundle must be protected at the structural fastener
points.
Bundle protections can be of the following types:
-Convoluted conduit type, insulating material (Ref. 20-33-31)
-Metallic conduit type, rigid metal tube with an internal insulation
coating over-braided metal with insulating interior (Ref. 20-33-32) R - Miscellaneous conduit type, textile or elastomer, removable or not (Ref. R 20-33-33) R - Heat Shrink conduit (Ref. 20-33-34)
The chapters that follow give the description and requirements related to each type of electrical bundle protection installed on aircraft.
___________________________2. Main Rules and Instructions
A. General (Ref. Fig. 001) When installing electrical cables inside a conduit, the following rules must be observed:
-Use of tie wraps NSA935401 inside conduits is prohibited.
-The convoluted conduit must be of one piece. Connection of two conduits to make up required length is unacceptable.
-
Make sure there is a draw wire in all conduits whose length is greater than 50 mm (1.9685 in.) (except for conduits shorter than 50 mm (1.9685 in.) and those where all the cables have a disconnectable termination such as connectors, terminal blocks,etc...)
-
Make sure there is a drain hole in conduits with a diameter greater than 10 mm (0.3937 in.) with low points. No drain hole must be provided:
-for textile conduits.
20-33-30 Page 1
R Wire Protection - Main Rules Figure 001
20-33-30 Page 2
-
for conduits with an exterior diameter of less than 10 mm (0.3937 in.).
-
for conduits located on sealed harness. In addition, drain loops (drop of water) are provided to prevent fluid contamination of the connectors (in lavatories, galleys, by leaks from water or hydraulic systems,etc...) Same rule for protected or unprotected bundles.
-When adding cables on aircraft, conduits located on routes can be used but segregation must be observed.
-Make sure the radius of curvature (R) of the cable outlet at the conduit ends is respected (this rule does not apply to draw wires installed inside the conduits).
____
NOTE : The harness identification label must be installed over the bundle protection.
B. Selection Normally, conduit P/Ns are given in the IPC. Any modification of the original requirements must be approved by the AIRBUS design office. However, select the conduit type on the basis of the following points:
(1) Type of conduit As a general rule, selection of the conduit type is as follows:
____
NOTE : Split (open) conduits (EN6049-006 or ABS0596 type) must be installed on the aircraft in areas with a good accessibility to the harness fastener attachments (support, clamps, cable ties,etc...).
*EN6049-006 must not be used:
-
In fire areas > 200 deg.C (392.00 deg.F)
-
In inaccessible areas
-
In fluid immersion
20-33-30 Page 3
Apr 01/04
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