7. MINIMUM SWPM CONTENT.
a. A definition and description of SWPM minimum content is necessary and should ensure that operators and repair stations have at their disposal the information necessary to maintain their airplanes (see Appendix A). The airframe manufacturer’s electrical installation design philosophy concerning components, installation procedures, segregation rules, etc., need not be included in the SWPM, although sufficient minimum information should be provided to enable the end user to maintain the aircraft in a condition that conforms to that design philosophy.
b. To ensure that the SWPM contains the information operators and repair stations need, it should be consistent with the following minimum guidelines on areas of content and types of information to be included.
(1) Front Matter. Provide information about content and use of the SWPM. Describe changes to the document in a record of revisions. Ensure the document contains a table of contents or index to allow users to retrieve necessary information quickly.
(2) Safety Practices. Provide general instruction, cautions, and warnings describing safety precautions to be taken before starting any or all of the specific standard electrical practices contained in the core of the SWPM. Safety cautions, warnings, or notes specific to a procedure would be placed in the text describing that procedure.
(3) Cleaning Requirements and Methods.
(a) Encourage “Protect and clean as you go” philosophy.
(b) Identify non-destructive methods for cleaning dust, dirt, foreign object debris (FOD), lavatory fluid, and other contaminants produced by an aircraft environment from wiring systems.
(c) Specify wire replacement guidelines when an accumulation of contaminants, either on the surface and/or imbedded in the wire bundle, cannot be safely removed.
(4) Wire and Cable Identification.
(a) Specify requirements for identification and marking of wire and cable to provide safe operation, ease of maintenance, and safety for maintenance personnel.
(b) Specify methods of direct wire marking. Identify specific requirements and cautions associated with certain types of wire marking.
(5) Wire and Cable Damage Limits.
(a) Specify limits to positively identify thresholds where repairs can be safely accomplished and where damaged wire/cable replacement may be necessary.
Establish limits for each applicable wire/cable type, if necessary.
(b) Include damage limits for terminals, studs, connectors, and other wiring system components, as necessary.
(6) Installation, Clamping, and Routing Requirements.
(a) Specify requirements for wiring system installation relating to physical attachment to aircraft structure. Requirements must be compatible with the different environments applicable to the aircraft and aircraft systems.
(b) Specify applicable methods of clamping, support, termination, and routing to facilitate installation, repair, and maintenance of wires, wire bundles, and cabling.
(c) Establish minimum bend radii for different types of wire and cable.
(d) Specify minimum clearance between wiring and other aircraft systems and aircraft structure.
(e) Include requirements for wiring conduit installation relating to physical attachment, routing, bend radii, drain holes, and conduit end coverings.
(f) Emphasize special wiring protection features, such as spatial separation, segregation, heat shielding, and moisture protection, that are required to be maintained throughout the life of the aircraft.
(g) Include necessary information for the maintenance of bonding, grounding, and protections against lightning and high-intensity radio frequency (L/HIRF).
(7) Repair and Replacement Procedures. Describe methods to safely repair and/or replace wiring and wiring system components.
(a) Include types and maximum number of splice repairs for wiring. (When splicing wire, environmentally sealed splices are highly recommended over splices that are not environmentally sealed.) Guidance should be provided on how long a temporary splice may be left in the wire.
(b) Specify procedures for the repair, replacement, and maintenance of connectors, terminals, modular terminal blocks, and other wiring components and the type of tools to be used.
(8) Inspection Methods.
(a) Specify a general visual inspection (GVI) or a detailed inspection (DET), as determined by an enhanced zonal analysis procedure. Typical damage to inspect for includes heat damage, chafing, cracked insulation, arcing, delaminated insulation, corrosion, broken wire or terminals, incorrect bend radii, contamination, loose terminals, and deteriorated repairs.
(b) Identify, where applicable, established and emerging new technologies for non-destructive test methods to complement the visual inspection process.
Whenever possible, ensure that inspection methods can detect wiring problems without compromising the integrity of the installation.
(9) Customized Data. Provide a location and procedure to allow users to include customized or unique data such as that for supplemental type certificates, operator-unique maintenance procedures, etc.
8. ALTERNATE PROCEDURE FOR LEGACY DOCUMENTS.
a. The adoption of a new layout and chapter organization may require each organization with an existing SWPM to reorganize and republish that document using the new standardized format. Whether the organization produces a stand-alone manual or provides the SWPM as chapter 20 of a wiring diagram manual, this reorganization would result in a significant economic impact on both the authoring organization and end-users.
b. To address this concern, a conversion tool, identified in paragraph e. below, was devised which takes the following variables into account:
• Effects on manufacturers’ current technical document editorial policy as it exists in current legacy documents.
• Costs resulting from an immediate major manual overhaul.
• Inconvenience to end-users who are accustomed to the format they are currently using.
c. When using a traditional paper format SWPM, the most efficient method of retrieving standard procedures and maintenance information has traditionally been to search by using−
• the table of contents (TOC) and/or
• the indexes (alpha-numerical index and/or numerical index as available).
The ease and speed with which information may be found with these methods relies heavily on the quality of the TOC and/or the indexes. For aircraft maintenance technicians needing 6
to locate and extract the pertinent and applicable data necessary to perform a satisfactory design modification or maintenance action, finding relevant data may be time consuming.
d. When using an electronic format, a search engine can often be used. This allows the user to bypass the TOC or indexes in finding the needed procedure or data. By searching with such alternative methods, a user can find information without needing to know the rules, such as ATA references, governing assignment of the subject matter to its place in the TOC.
e. Use of a conversion tool, identified as a master breakdown index (MBI) is one way of presenting a standard means for finding SWPM information until existing paper legacy documents can be physically altered or digitized to an electronic format. The intent of the MBI is to supplement the TOC and existing indexes. It gives users a way to search existing documents using topical information rather than part number, alphabetic subject, or chaptersection-subject reference. The arrangement of the MBI duplicates the standardized format described in Appendix A of this AC, but does not require complete rearrangement of legacy documents to achieve a common way of finding information. The MBI acts as a conversion key to effectively convert an existing document arrangement into the standardized arrangement. In essence the MBI duplicates in paper form for legacy documents the electronic search engine used in HTML-based documents.
This is an example of an MBI that could be used to mitigate the need for reformatting legacy documents to achieve the standardized format discussed in this AC.
MASTER BREAKDOWN INDEX
GROUP MAJOR TOPIC APPEARS IN THIS
DOCUMENT AS
SUBJECT
SAFETY PRACTICES 20-10-10 AIRPLANE ENVIRONMENTAL AREAS 20-20-12 CONSUMABLE MATERIALS 20-00-11 WIRING MATERIALS 20-10-13
GENERAL DATA
COMMON TOOLS 20-00-13 EWIS PROTECTION DURING MAINTENANCE 20-10-20 EWIS CLEANING 20-10-20 EWIS INSPECTION 20-10-20 EWIS TESTING 20-10-13 EWIS DISASSEMBLY 20-10-19
ELECTRICAL WIRING
INTERCONNECTION
SYSTEM (EWIS)
MAINTENANCE
EWIS REPAIR AND REPLACEMENT 20-20-00
WIRE SEPARATION / SEGREGATION 20-10-11 20-10-12 ELECTRICAL BONDS AND GROUNDS 20-30-60 WIRING
INSTALLATION
WIRE HARNESS INSTALLATION 20-10-17 20-10-18 Installation of Sleeves on Wiring WIRE AND CABLE TYPES 20-00-15 WIRING ASSEMBLY WIRE MARKING 20-60-01 8
MASTER BREAKDOWN INDEX
GROUP MAJOR TOPIC APPEARS IN THIS
DOCUMENT AS
SUBJECT
WIRE HARNESS ASSEMBLY 20-50-01
WIRE INSULATION AND CABLE JACKET REMOVAL 20-90-12
TERMINATION TYPE (SPECIFICS OF TERMINATIONS) 20-61-44 ELECTRICAL DEVICES DEVICE TYPE (SPECIFICS OF ELECTRICAL DEVICE) 20-80-09 Assembly of Leach Relay Sockets SPECIFIC SYSTEM WIRING UNIQUE WIRING ASSEMBLIES/INSTALLATIONS 20-73-00 Fuel Quantity Indicating System
AIRLINE CUSTOMIZED DATA AIRLINE SPECIFIED 20-91-00
/s/Ali Bahrami Ali Bahrami Manager, Transport Airplane Directorate Aircraft Certification Service
Appendix A
APPENDIX A
STANDARDIZED ORGANIZATION FOR STANDARD WIRING PRACTICES MANUALS (SWPM) (Groups, Major Topics, Sequence, and Description of Minimum Content)
GROUP MAJOR TOPIC DESCRIPTION SAFETY PRACTICES Safety regulations and general safety precautions to prevent injury to personnel and damage to the airplane.
AIRPLANE
ENVIRONMENTAL AREAS Definition of types of areas within which wiring configuration and wiring component selection is constrained.
CONSUMABLE MATERIALS Wiring maintenance processing materials (solvents, aqueous cleaners, lubricants, etc.).
WIRING MATERIALS Materials that become an integral part of the wiring configuration excluding wire and cable; e.g., sleeves, shield material, tie material, sealants, etc.
GENERAL DATA COMMON TOOLS Description and operation of common tools.
EWIS PROTECTION DURING MAINTENANCE Procedures to protect EWIS during airplane maintenance and modification.
EWIS CLEANING To support inspection as well as prevention of degradation and preparation for repair, recommended cleaning materials and procedures based on type of contamination.
EWIS INSPECTION Criteria for correct installation, correct wiring assembly configuration; damage conditions and limits for wiring components (wire and cable, termination types, electrical devices); factors that warrant disassembly for inspection;
determination of cause of damage.
EWIS TESTING Wiring integrity testing.
EWIS DISASSEMBLY Data and procedures for inspection, cleaning when applicable. Also supports new wiring installation.
EWIS
MAINTENANCE
EWIS REPAIR AND
REPLACEMENT Repair of wiring installation, wiring assembly configuration, wiring components (wire and cable, wiring terminations, electrical devices); wire and cable replacement; wiring functional identification.
WIRING
INSTALLATION WIRE
SEPARATION/SEGREGATION Explanation of separation/segregation categories, separation/segregation identification, and necessary conditions for maintaining separation/segregation.
A-1
Appendix A
STANDARDIZED ORGANIZATION FOR STANDARD WIRING PRACTICES MANUALS (SWPM) (Groups, Major Topics, Sequence, and Description of Minimum Content)
GROUP MAJOR TOPIC DESCRIPTION
ELECTRICAL BONDS AND
GROUNDS Bond surface preparation, ground hardware configurations, bond integrity testing.
WIRE HARNESS
INSTALLATION Routing, supports; wiring protection, factors affecting wiring assembly configuration; connection to equipment, new wiring, removal from service.
WIRE AND CABLE TYPES Principal material components of airplane wiring, including type identification, basic description, and alternative wire types (replacements, substitutions).
WIRE MARKING Marking, applicable conditions.
WIRE HARNESS ASSEMBLY Wiring assembly configuration: assembly materials, layout, overall protection, factors affecting wiring installation.
WIRE INSULATION AND
CABLE JACKET REMOVAL Wire and cable: insulation removal, jacket removal; associated damage limits, tool description and operation. WIRING ASSEMBLY
TERMINATION TYPE
(e.g., SOURIAU 8950 SERIES
CONNECTORS) Wiring terminations and accessories (connectors, terminal lugs, splices, backshells, etc.) grouped by termination type from simple to complex:
a. Common data or procedures by group (if any), e.g., tool description and operation, definition of internal damage and limits, internal cleaning, accessories.
b. By individual type - part numbers and description, definition of internal damage and limits (if not specified by common data), disassembly, assembly, installation.
ELECTRICAL
DEVICES
DEVICE TYPE
(e.g., KLIXON 7274 SERIES
CIRCUIT BREAKER) Electrical devices (circuit breakers, relays, switches, filters, lamps, etc.) grouped by device type:
a. Common data or procedures by group (if any), e.g., tool description and operation, definition of internal damage and limits, internal cleaning, accessories.
b. Devices by individual type - part numbers and description, definition of internal damage and limits (if not specified by common data), disassembly, assembly, installation.
A-2
Appendix A
STANDARDIZED ORGANIZATION FOR STANDARD WIRING PRACTICES MANUALS (SWPM) (Groups, Major Topics, Sequence, and Description of Minimum Content)
GROUP MAJOR TOPIC DESCRIPTION
SPECIFIC SYSTEM WIRING
SPECIFIC WIRING
ASSEMBLY For wiring that has a necessarily specific configuration (e.g., primary flight control, fuel quantity indicator system, etc.):
a. Applicable conditions for repair and replacement.
b. Disassembly, assembly, installation, assembly integrity testing.
AIRLINE
CUSTOMIZED DATA AIRLINE SPECIFIED Reserved for airline use.
A-3
Appendix B
APPENDIX B
RELATED REGULATIONS AND DOCUMENTS
a. Regulations. You can download an electronic copy of 14 CFR from the Internet at http://www.gpoaccess.gov/cfr/. A paper copy can be ordered by sending a request to the U.S. Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402-0001, or by calling telephone number (202) 512-1800; or by sending a request by facsimile to (202) 512-2250.
Part 21 Certification Procedures for Products and Parts.
Part 25 Airworthiness Standards: Transport Category Airplanes.
Part 43 Maintenance, Preventive Maintenance, Rebuilding, and Alteration.
Part 91 General Operating and Flight Rules.
Part 121 Operating Requirements: Domestic, Flag, and Supplemental Operations.
Part 125 Certification and Operations: Airplanes Having a Seating Capacity of 20 or More Passengers or a Maximum Payload Capacity of 6,000 Pounds or More; and Rules Governing Persons on Board Such Aircraft.
Part 129 Operations: Foreign Air Carriers and Foreign Operators of U.S.- Registered Aircraft Engaged in Common Carriage.
Part 145 Repair Stations.
b. Advisory Circulars (AC). You can download an electronic copy of the latest version of the following ACs from the FAA Internet at http://rgl.faa.gov.
• 25-16 Electrical Fault and Fire Protection and Prevention
• 25.981-1 Fuel Tank Ignition Source Prevention Guidelines
• 25.1701-1 Certification of Electrical Wiring Interconnection Systems on Transport Category Airplanes
• 43-12 Preventive Maintenance B-1