Airworthiness Chapter 525 Subchapter H - Electrical Wiring Interconnection Systems (EWIS) - Canadian Aviation Regulations (CARs)

Preamble

Subchapters 

• A (525.1-525.3), 
• B (525.21-525.255), 
• C (525.301-525.581),
• D (525.601-525.899),
• E (525.901-525.1207),
• F (525.1301-525.1461),
• G (525.1501-525.1587)
• H (525.1701-525.1733)

Appendices 

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O

Subchapter H Electrical Wiring Interconnection Systems (EWIS)

525.1701 Definition

(amended 2009/05/11; no previous version)

• (a) As used in this chapter, electrical wiring interconnection system (EWIS) means any wire, wiring device, or combination of these, including termination devices, installed in any area of the aeroplane for the purpose of transmitting electrical energy, including data and signals, between two or more intended termination points. This includes:
  (amended 2009/05/11; no previous version)
  • (1) Wires and cables.
    (amended 2009/05/11; no previous version)
  • (2) Bus bars.
    (amended 2009/05/11; no previous version)
  • (3) The termination point on electrical devices, including those on relays, interrupters, switches, contactors, terminal blocks and circuit breakers, and other circuit protection devices.
    (amended 2009/05/11; no previous version)
  • (4) Connectors, including feed-through connectors.
    (amended 2009/05/11; no previous version)
  • (5) Connector accessories.
    (amended 2009/05/11; no previous version)
  • (6) Electrical grounding and bonding devices and their associated connections.
    (amended 2009/05/11; no previous version)
  • (7) Electrical splices.
    (amended 2009/05/11; no previous version)
  • (8) Materials used to provide additional protection for wires, including wire insulation, wire sleeving, and conduits that have electrical termination for the purpose of bonding.
    (amended 2009/05/11; no previous version)
  • (9) Shields or braids.
    (amended 2009/05/11; no previous version)
  • (10) Clamps and other devices used to route and support the wire bundle.
    (amended 2009/05/11; no previous version)
  • (11) Cable tie devices.
    (amended 2009/05/11; no previous version)
  • (12) Labels or other means of identification.
    (amended 2009/05/11; no previous version)
  • (13) Pressure seals.
    (amended 2009/05/11; no previous version)
  • (14) EWIS components inside shelves, panels, racks, junction boxes, distribution panels, and back-planes of equipment racks, including, but not limited to, circuit board back-planes, wire integration units, and external wiring of equipment.
    (amended 2009/05/11; no previous version)
• (b) Except for the equipment indicated in (a)(14) of this section, EWIS components inside the following equipment, and the external connectors that are part of that equipment, are excluded from the definition in (a) of this section:
  (amended 2009/05/11; no previous version)
  • (1) Electrical equipment or avionics that are qualified to environmental conditions and testing procedures when those conditions and procedures are:
    (amended 2009/05/11; no previous version)
    • (i) Appropriate for the intended function and operating environment, and
      (amended 2009/05/11; no previous version)
    • (ii) Acceptable to the Minister.
      (amended 2009/05/11; no previous version)
  • (2) Portable electrical devices that are not part of the type design of the aeroplane. This includes personal entertainment devices and laptop computers.
    (amended 2009/05/11; no previous version)
  • (3) Fiber optics.
    (amended 2009/05/11; no previous version)

525.1703 Function and Installation: EWIS

(amended 2009/05/11; no previous version)

• (a) Each EWIS component installed in any area of the aircraft must:
  (amended 2009/05/11; no previous version)
  • (1) Be of a kind and design appropriate to its intended function.
    (amended 2009/05/11; no previous version)
  • (2) Be installed according to limitations specified for the EWIS components.
    (amended 2009/05/11; no previous version)
  • (3) Perform the function for which it was intended without degrading the airworthiness of the aeroplane.
    (amended 2009/05/11; no previous version)
  • (4) Be designed and installed in a way that will minimize mechanical strain.
    (amended 2009/05/11; no previous version)
• (b) Selection of wires must take into account known characteristics of the wire in relation to each installation and application to minimize the risk of wire damage, including any arc tracking phenomena.
  (amended 2009/05/11; no previous version)
• (c) The design and installation of the main power cables (including generator cables) in the fuselage must allow for a reasonable degree of deformation and stretching without failure.
  (amended 2009/05/11; no previous version)
• (d) EWIS components located in areas of known moisture accumulation must be protected to minimize any hazardous effects due to moisture.
  (amended 2009/05/11; no previous version)

525.1705 Systems and Functions: EWIS

(amended 2009/05/11; no previous version)

• (a) EWIS associated with any system required for type certification or by operating rules must be considered an integral part of that system and must be considered in showing compliance with the applicable requirements for that system.
  (amended 2009/05/11; no previous version)
• (b) For systems to which the following rules apply, the components of EWIS associated with those systems must be considered an integral part of that system or systems and must be considered in showing compliance with the applicable requirements for that system.
  (amended 2009/05/11; no previous version)
  • (1) 525.773(b)(2) Pilot compartment view.
    (amended 2009/05/11; no previous version)
  • (2) 525.981 Fuel tank ignition prevention.
    (amended 2009/05/11; no previous version)
  • (3) 525.1165 Engine ignition systems.
    (amended 2009/05/11; no previous version)
  • (4) 525.1310 Power source capacity and distribution.
    (amended 2009/05/11; no previous version)
  • (5) 525.1316 System lightning protection.
    (amended 2009/05/11; no previous version)
  • (6) 525.1331(a)(2) Instruments using a power supply.
    (amended 2009/05/11; no previous version)
  • (7) 525.1351 General.
    (amended 2009/05/11; no previous version)
  • (8) 525.1355 Distribution system.
    (amended 2009/05/11; no previous version)
  • (9) 525.1360 Precautions against injury.
    (amended 2009/05/11; no previous version)
  • (10) 525.1362 Electrical supplies for emergency conditions.
    (amended 2009/05/11; no previous version)
  • (11) 525.1365 Electrical appliances, motors and transformers.
    (amended 2009/05/11; no previous version)
  • (12) 525.1431(c) and (d) Electronic equipment.
    (amended 2009/05/11; no previous version)

525.1707 System Separation: EWIS

(amended 2009/05/11; no previous version)

• (a) Each EWIS must be designed and installed with adequate physical separation from other EWIS and aeroplane systems so that an EWIS component failure will not create a hazardous condition. Unless otherwise stated, for the purposes of this section, adequate physical separation must be achieved by separation distance or by a barrier that provides protection equivalent to that separation distance.
  (amended 2009/05/11; no previous version)
• (b) Each EWIS must be designed and installed so that any electrical interference likely to be present in the aeroplane will not result in hazardous effects upon the aeroplane or its systems.
  (amended 2009/05/11; no previous version)
• (c) Wires and cables carrying heavy current, and their associated EWIS components, must be designed and installed to ensure adequate physical separation and electrical isolation so that damage to circuits associated with essential functions will be minimized under fault conditions.
  (amended 2009/05/11; no previous version)
• (d) Each EWIS associated with independent aeroplane power sources or power sources connected in combination must be designed and installed to ensure adequate physical separation and electrical isolation so that a fault in any one aeroplane power source EWIS will not adversely affect any other independent power sources. In addition:
  (amended 2009/05/11; no previous version)
  • (1) Aeroplane independent electrical power sources must not share a common ground terminating location.
    (amended 2009/05/11; no previous version)
  • (2) Aeroplane system static grounds must not share a common ground terminating location with any of the aeroplane's independent electrical power sources.
    (amended 2009/05/11; no previous version)
• (e) Except to the extent necessary to provide electrical connection to the fuel systems components, the EWIS must be designed and installed with adequate physical separation from fuel lines and other fuel system components, so that:
  (amended 2009/05/11; no previous version)
  • (1) An EWIS component failure will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
  • (2) Any fuel leakage onto EWIS components will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
• (f) Except to the extent necessary to provide electrical connection to the hydraulic systems components, EWIS must be designed and installed with adequate physical separation from hydraulic lines and other hydraulic system components, so that:
  (amended 2009/05/11; no previous version)
  • (1) An EWIS component failure will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
  • (2) Any hydraulic fluid leakage onto EWIS components will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
• (g) Except to the extent necessary to provide electrical connection to the oxygen systems components, EWIS must be designed and installed with adequate physical separation from oxygen lines and other oxygen system components, so that an EWIS component failure will not create a hazardous condition.
  (amended 2009/05/11; no previous version)
• (h) Except to the extent necessary to provide electrical connection to the water/waste systems components, EWIS must be designed and installed with adequate physical separation from water/waste lines and other water/waste system components, so that:
  (amended 2009/05/11; no previous version)
  • (1) An EWIS component failure will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
  • (2) Any water/waste leakage onto EWIS components will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
• (i) EWIS must be designed and installed with adequate physical separation between the EWIS and flight or other mechanical control systems cables and associated system components, so that:
  (amended 2009/05/11; no previous version)
  • (1) Chafing, jamming or other interference are prevented.
    (amended 2009/05/11; no previous version)
  • (2) An EWIS component failure will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
  • (3) Failure of any flight or other mechanical control systems cables or systems components will not damage the EWIS and create a hazardous condition.
    (amended 2009/05/11; no previous version)
• (j) EWIS must be designed and installed with adequate physical separation between the EWIS components and heated equipment, hot air ducts, and lines, so that:
  (amended 2009/05/11; no previous version)
  • (1) An EWIS component failure will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
  • (2) Any hot air leakage or heat generated onto EWIS components will not create a hazardous condition.
    (amended 2009/05/11; no previous version)
• (k) For systems for which redundancy is required, by certification rules, by operating rules, or as a result of the assessment required by 525.1709, EWIS components associated with those systems must be designed and installed with adequate physical separation.
  (amended 2009/05/11; no previous version)
• (l) Each EWIS must be designed and installed so there is adequate physical separation between it and other aeroplane components and aeroplane structure, and so that the EWIS is protected from sharp edges and corners, to minimize potential for abrasion/chafing, vibration damage, and other types of mechanical damage.
  (amended 2009/05/11; no previous version)

525.1709 System Safety: EWIS

(amended 2009/05/11; no previous version)

Each EWIS must be designed and installed so that:
(amended 2009/05/11; no previous version)

• (a) Each catastrophic failure condition:
  (amended 2009/05/11; no previous version)
  • (1) Is extremely improbable; and
    (amended 2009/05/11; no previous version)
  • (2) Does not result from a single failure.
    (amended 2009/05/11; no previous version)
• (b) Each hazardous failure condition is extremely remote.
  (amended 2009/05/11; no previous version)

525.1711 Component Identification: EWIS

(amended 2009/05/11; no previous version)

• (a) EWIS components must be labeled or otherwise identified using a consistent method that facilitates identification of the EWIS component, its function, and its design limitations, if any.
  (amended 2009/05/11; no previous version)
• (b) For systems for which redundancy is required, by certification rules, by operating rules, or as a result of the assessment required by 525.1709, EWIS components associated with those systems must be specifically identified with component part number, function, and separation requirement for bundles.
  (amended 2009/05/11; no previous version)
  • (1) The identification must be placed along the wire, cable, or wire bundle at appropriate intervals and in areas of the aeroplane where it is readily visible to maintenance, repair or alteration personnel.
    (amended 2009/05/11; no previous version)
  • (2) If an EWIS component cannot be marked physically, then other means of identification must be provided.
    (amended 2009/05/11; no previous version)
• (c) The identifying markings required by (a) and (b) of this section must remain legible throughout the expected service life of the EWIS component.
  (amended 2009/05/11; no previous version)
• (d) The means used for identifying each EWIS component as required by this section must not have an adverse effect on the performance of that component throughout its expected service life.
  (amended 2009/05/11; no previous version)
• (e) Identification for EWIS modifications to the type design must be consistent with the identification scheme of the original type design.
  (amended 2009/05/11; no previous version)

525.1713 Fire Protection: EWIS

(amended 2009/05/11; no previous version)

• (a) All EWIS components must meet the applicable fire and smoke protection requirements of 525.831(c) of this chapter.
  (amended 2009/05/11; no previous version)
• (b) EWIS components that are located in designated fire zones and used during emergency procedures must be fire-resistant.
  (amended 2009/05/11; no previous version)
• (c) Insulation on electrical wire and electrical cable, and materials used to provide additional protection for the wire and cable, installed in any area of the aeroplane, must be self-extinguishing when tested in accordance with the applicable portions of Appendix F, part I, of this chapter.
  (amended 2009/05/11; no previous version)

525.1715 Electrical Bonding and Protection Against Static Electricity: EWIS

(amended 2009/05/11; no previous version)

• (a) EWIS components used for electrical bonding and protection against static electricity must meet the requirements of 525.899.
  (amended 2009/05/11; no previous version)
• (b) On aeroplanes having grounded electrical systems, electrical bonding provided by EWIS components must provide an electrical return path capable of carrying both normal and fault currents without creating a shock hazard or damage to the EWIS components, other aeroplane system components, or aeroplane structure.
  (amended 2009/05/11; no previous version)

525.1717 Circuit Protective Devices: EWIS

(amended 2009/05/11; no previous version)

Electrical wires and cables must be designed and installed so they are compatible with the circuit protection devices required by 525.1357, so that a fire or smoke hazard cannot be created under temporary or continuous fault conditions.
(amended 2009/05/11; no previous version)

525.1719 Accessibility Provisions: EWIS

(amended 2009/05/11; no previous version)

Access must be provided to allow inspection and replacement of any EWIS component as necessary for continued airworthiness.
(amended 2009/05/11; no previous version)

525.1721 Protection of EWIS

(amended 2009/05/11; no previous version)

• (a) No cargo or baggage compartment must contain any EWIS whose damage or failure may affect safe operation, unless the EWIS is protected so that:
  (amended 2009/05/11; no previous version)
  • (1) It cannot be damaged by movement of cargo or baggage in the compartment.
    (amended 2009/05/11; no previous version)
  • (2) Its breakage or failure will not create a fire hazard.
    (amended 2009/05/11; no previous version)
• (b) EWIS must be designed and installed to minimize damage and risk of damage to EWIS by movement of people in the aeroplane during all phases of flight, maintenance, and servicing.
  (amended 2009/05/11; no previous version)
• (c) EWIS must be designed and installed to minimize damage and risk of damage to EWIS by items carried onto the aeroplane by passengers or cabin crew.
  (amended 2009/05/11; no previous version)

525.1723 Flammable Fluid Fire Protection: EWIS

(amended 2009/05/11; no previous version)

EWIS components located in each area where flammable fluid or vapors might escape by leakage of a fluid system must be considered a potential ignition source and must meet the requirements of 525.863.
(amended 2009/05/11; no previous version)

525.1725 Powerplants: EWIS

(amended 2009/05/11; no previous version)

• (a) EWIS associated with any powerplant must be designed and installed so that the failure of an EWIS component will not prevent the continued safe operation of the remaining powerplants or require immediate action by any crew member for continued safe operation, in accordance with the requirements of 525.903(b).
  (amended 2009/05/11; no previous version)
• (b) Design precautions must be taken to minimize hazards to the aeroplane due to EWIS damage in the event of a powerplant rotor failure or a fire originating within the powerplant that burns through the powerplant case, in accordance with the requirements of 525.903(d)(1).
  (amended 2009/05/11; no previous version)

525.1727 Flammable Fluid Shutoff Means: EWIS

(amended 2009/05/11; no previous version)

EWIS associated with each flammable fluid shutoff means and control must be fireproof or be located and protected so that any fire in a fire zone will not affect operation of the flammable fluid shutoff means, in accordance with the requirements of 525.1189.
(amended 2009/05/11; no previous version)

525.1729 Instructions for Continued Airworthiness: EWIS

(amended 2009/05/11; no previous version)

The applicant must prepare Instructions for Continued Airworthiness applicable to EWIS in accordance with Appendix H sections H525.4 and H525.5 of this chapter that are approved by the minister.
(amended 2009/05/11; no previous version)

525.1731 Powerplant and APU Fire Detector System: EWIS

(amended 2009/05/11; no previous version)

• (a) EWIS that are part of each fire or overheat detector system in a fire zone must be fire-resistant.
  (amended 2009/05/11; no previous version)
• (b) No EWIS component of any fire or overheat detector system for any fire zone must pass through another fire zone, unless:
  (amended 2009/05/11; no previous version)
  • (1) It is protected against the possibility of false warnings resulting from fires in zones through which it passes; or
    (amended 2009/05/11; no previous version)
  • (2) Each zone involved is simultaneously protected by the same detector and extinguishing system.
    (amended 2009/05/11; no previous version)
• (c) EWIS that are part of each fire or overheat detector system in a fire zone must meet the requirements of 525.1203.
  (amended 2009/05/11; no previous version)

525.1733 Fire Detector Systems, General: EWIS

(amended 2009/05/11; no previous version)

EWIS associated with any installed fire protection system, including those required by 525.854 and 525.858, must be considered an integral part of the system in showing compliance with the applicable requirements for that system.
(amended 2009/05/11; no previous version)