Appendix C C-16
ELECTRICAL WIRING INTERCONNECTION SYSTEMS (EWIS) LESSON PLAN MODULE F: CONNECTIVE DEVICES Overview With Module F, the instructor lays the groundwork for safe, effective maintenance, alteration, and repair of airplane electrical wiring interconnection systems (EWIS) by teaching identification, inspection, and repair of connective devices found on the airplane. The instructor may vary the depth and scope of the topics to be covered depending on the type of airplane to be maintained and the skills of the students.
Objectives At the completion of this module the student is able to demonstrate the following:
1. Knowledge of the general types of connective devices and how to identify them (airplane specific).
2. Knowledge of the various safety procedures, cautions, and warnings prior to inspection.
3. Knowledge of the relevant visual inspection procedures for each type of connector so that any internal or external damage can be found.
4. How to recognize typical external and internal damage to the connector.
5. Where to find the relevant repair schemes from the standard wiring practices manual for connector repair.
Hands-On Equipment and Teaching Aids Normal classroom lecture can be used for the majority of this training. The standard wiring practices manual should be made available to the class for hands-on use. Connector identification, inspection, and repair procedures should be fully explored. Color photographs of typical external damage and internal damage could be used to show problems on the airplane.
The Aging Transport Systems Rulemaking Advisory Committee (ATSRAC) Task Group 1 Non-Intrusive Inspection Report and chapter 7 of ATSRAC’s Intrusive Inspection Final Report could be used to identify typical connector issues. AC 25-27, Development of Transport Category Airplane Electrical Wiring Interconnection Systems Instructions for Continued Airworthiness Using and Enhanced Zonal Analysis Procedure, is recommended as a source for typical aircraft wiring installations and areas of concern.
Appendix C C-17
MODULE F
CONNECTIVE DEVICES
1. General types and identification
a. Part number identification
b. Reference tables
c. Specific connective devices chapters
2. Cautions and protections
a. Safety precautions
b. Maintenance precautions
3. Visual inspection procedures
a. Inspection criteria for installed connectors
b. Inspection criteria for removed connectors
4. Typical damage found
a. Exterior damage
b. Internal damage
5. Repair procedures
a. Finding the correct section
b. Finding the correct part
c. Finding the correct tooling
d. Confirming the correct repair
Appendix C C-18
ELECTRICAL WIRING INTERCONNECTION SYSTEMS (EWIS) LESSON PLAN MODULE G: CONNECTIVE DEVICES REPAIR Overview With Module G, the instructor lays the groundwork for safe, effective maintenance, alteration, and repair of airplane electrical wiring interconnection systems (EWIS). This module is primarily a hands-on class, emphasizing the repair and replacement of connective devices found on the airplane. The list of replacement procedures can be used to cover typical connectors for airplanes, and can be adjusted to suit training requirements. The instructor may vary the depth and scope of the topics to be covered, depending on the type of airplane to be maintained and the skills of the students.
Objective At the completion of this module the student is able to demonstrate the following:
1. Replacement of components for circular connectors.
2. Replacement of components for rectangular connectors.
3. Replacement of components for terminal blocks-modular.
4. Replacement of components for terminal blocks-non-modular.
5. Replacement of components for grounding modules.
6. Replacement of pressure seals.
Hands-On Equipment and Teaching Aids This is primarily a hands-on class to give students motor skills in the repair of connective devices from their airplane. The standard wiring practices manual and the appropriate connective devices should be available to the class so repair procedures can be fully explored. Photographs of typical internal conditions and external damage could be made available. It is recommended that Module F: Connective Devices precede this module. AC 25-27, Development of Transport Category Airplane Electrical Wiring Interconnection Systems Instructions for Continued Airworthiness Using and Enhanced Zonal Analysis Procedure, is recommended as a source for typical aircraft wiring installations and areas of concern.
Appendix C C-19
MODULE G
CONNECTIVE DEVICES REPAIR
1. Circular connectors
a. Disassembly
b. Back-shell maintenance
c. Contact extraction and insertion
d. Contact crimping
e. Assembly and strain relief
2. Rectangular connectors
a. Disassembly
b. Back-shell maintenance
c. Contact extraction and insertion
d. Contact crimping
e. Assembly and strain relief
3. Terminal blocks – modular
a. Disassembly
b. Contact extraction and insertion
c. Contact crimping
d. Assembly and strain relief
4. Terminal block – non-modular
a. Disassembly
b. Terminal lug crimping
c. Terminal lug stacking
d. Assembly, torque, and strain relief
5. Grounding modules
a. Disassembly
b. Contact extraction and insertion
c. Contact crimping
d. Assembly and strain relief
6. Pressure seals
a. Disassembly
b. Maintenance
c. Assembly and strain relief
Appendix D D-1
APPENDIX D
DEFINITIONS Arc Tracking—A phenomenon in which a conductive carbon path is formed across an insulating surface. This carbon path provides a short circuit path through which electrical current can flow. Arc tracking is normally the result of electrical arcing. Also referred to as “carbon arc tracking,” “wet arc tracking,” or “dry arc tracking.”
Electrical Wiring Interconnection System (EWIS)—is defined by 14 CFR part 25, § 25.1701 as follows:
§ 25.1701 Definition.
(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 airplane for the purpose of transmitting electrical energy, including data and signals, between two or more intended termination points. This includes:
(1) Wires and cables.
(2) Bus bars.
(3) The termination point on electrical devices, including those on relays, interrupters, switches, contactors, terminal blocks and circuit breakers, and other circuit protection devices.
(4) Connectors, including feed-through connectors.
(5) Connector accessories.
(6) Electrical grounding and bonding devices and their associated connections.
(7) Electrical splices.
(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.
(9) Shields or braids.
(10) Clamps and other devices used to route and support the wire bundle.
(11) Cable tie devices.
(12) Labels or other means of identification.
(13) Pressure seals.
(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.
(b) Except for the equipment indicated in paragraph (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 paragraph (a) of this section:
(1) Electrical equipment or avionics that are qualified to environmental conditions and testing procedures when those conditions and procedures are—
(i) appropriate for the intended function and operating environment, and
(ii) acceptable to the FAA.
(2) Portable electrical devices that are not part of the type design of the airplane.
This includes personal entertainment devices and laptop computers.
(3) Fiber optics.
Appendix D D-2 Combustible—The ability of any solid, liquid, or gaseous material to cause a fire to be sustained after removal of the ignition source. The term is used in place of inflammable/flammable. It should not be interpreted as identifying material that will burn when subjected to a continuous source of heat as occurs when a fire develops.
Contamination—With regard to wiring, this term refers to either of the following situations:
• The presence of a foreign material that is likely to cause degradation of wiring.
• The presence of a foreign material that is combustible.
Detailed Inspection (DET)—An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors, magnifying lenses, or other means may be necessary. Surface cleaning and elaborate access procedures may be required.
Foreign Object Damage (FOD)—FOD is standardly known throughout industry. Such particles may accumulate on and between wires within a wire bundle.
Functional Failure—Failure of an item to perform its intended function within specified limits.
General Visual Inspection (GVI)—A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.
Lightning/High Intensity Radiated Field (L/HIRF) Protection—The protection of airplane electrical systems and structure from induced voltages or currents by means of shielded wires, raceways, bonding jumpers, connectors, composite fairings with conductive mesh, static dischargers, and the inherent conductivity of the structure. May include aircraft specific devices,
e.g., RF (radio frequency) gaskets.
Maintenance—As defined in 14 CFR part 1, § 1.1, “maintenance means inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance.” For the purposes of this advisory circular, it also includes preventive maintenance as described in both § 1.1 and 14 CFR part 43 appendix A(c). Section 1.1 provides the following definition:
“Preventive maintenance means simple or minor preservation operations and the replacement of small standard parts not involving complex assembly operations.” Part 43 appendix A(c) lists the tasks that are considered preventive maintenance.
Maintenance Significant Item (MSI)—Items identified by the manufacturer whose failure—
• Could affect safety (on the ground or in flight).
• Is undetectable during operations.
• Could have significant operational impact.
• Could have significant economic impact.
Appendix D D-3 Needling—The puncturing of a wire’s insulation to make contact with the core to test the continuity and presence of voltage in the wire segment.
Special Detailed Inspection (SDI)—An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. The examination is likely to make extensive use of specialized inspection techniques and/or equipment. Intricate cleaning and substantial access or disassembly procedures may be required.
Stand-Alone GVI—A general visual inspection which is not performed as part of a zonal inspection. Even in cases where the interval coincides with the zonal inspection, the stand-alone GVI shall remain an independent step within the work card.
Structural Significant Item (SSI)—Any detail, element, or assembly that contributes significantly to carrying flight, ground, pressure, or control loads and whose failure could affect the structural integrity necessary for the safety of the aircraft.
Zonal Inspection—A collective term comprising selected general visual inspections and visual checks that are applied to each zone, defined by access and area, to check system and power plant installations and structure for security and general condition.
Appendix E E-1
APPENDIX E
RELATED REGULATIONS AND DOCUMENTS
a. Regulations. You can download an electronic copy of 14 CFR from the Internet at https://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&tpl=/ecfrbrowse/Title14/14tab_02.tpl. A paper copy can be ordered from 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 facsimile (202) 512-2250.
• Part 21, Certification Procedures for Products and Articles.
• Part 25, Airworthiness Standards: Transport Category Airplanes.
• Part 43, Maintenance, Preventive Maintenance, Rebuilding, and Alteration.
• Part 91, General Operating and Flight Rules.
• Part 119, Certification: Air Carriers and Commercial Operators.
• 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 135, Operating Requirements: Commuter and On-Demand Operations and Rules Governing Persons On Board Such Aircraft.
• Part 145, Repair Stations.
b. Advisory Circulars (AC). You can download an electronic copy of the latest version of the following ACs from the Regulatory and Guidance Library (RGL) at http://rgl.faa.gov.
• AC 20-53, Protection of Airplane Fuel Systems Against Vapor Ignition Caused by Lightning.
• AC 25-16, Electrical Fault and Fire Prevention and Protection.
• AC 25-26, Development of Standard Wiring Practices Documentation.
• AC 25-27, Development of Transport Category Airplane Electrical Wiring Interconnection Systems Instructions for Continued Airworthiness Using and Enhanced Zonal Analysis Procedure.
• AC 25.981-1, Fuel Tank Ignition Source Prevention Guidelines.
• AC 25.1701-1, Certification of Electrical Wiring Interconnection Systems on Transport Category Airplanes.
• AC 43-4, Corrosion Control for Aircraft.
Appendix E E-2
• AC 43-12, Preventive Maintenance.
• AC 43.13-1, Acceptable Methods, Techniques, and Practices—Aircraft Inspection and Repair.
• AC 65-15, Airframe & Powerplant Mechanics Airframe Handbook, Chapter 11, Aircraft Electrical Systems.
• AC 129-4, Maintenance Programs for U.S.-Registered Aircraft Operated Under 14 CFR Part 129.
c. Reports.
• Task 1, Task 2, Task 3, Task 4, Task 5, Task 6, Task 7, Task 9, and Task 11 Working Group Final Reports, Aging Transport Systems Rulemaking Advisory Committee. (You can download an electronic copy of these reports from the “Final Reports” section of the Aging Transport Systems Rulemaking Advisory Committee (ATSRAC) website at www.mitrecaasd.org/atsrac.)
• Airlines for America (A4A) Specification 117, Wiring Maintenance Practices/Guidelines. (http://www.iasa.com.au/folders/Safety_Issues/Aircraft_Wire/ATA onwiring.html)
• National Transportation Safety Board (NTSB) Safety Recommendations A-00-105 through -108, September 19, 2000. (https://www.ntsb.gov/safety/safetyrecs/_layouts/ntsb.recsearch/RecTabs.aspx)
d. Other Documents.
• FAA Aging Transport Non-Structural Systems Plan, dated July 1998.
(http://www.faa.gov/apa/PUBLICAT/fatnspcov.htm)
• A4A Operator/Manufacturer Scheduled Maintenance Development as revised, A4A Maintenance Steering Group - 3rd Task Force (MSG-3). (May be obtained from Airlines for America (A4A), 1275 Pennsylvania Ave NW, Suite 1300, Washington, DC 20004.)
Appendix F F-1
APPENDIX F Following is the discussion of training published in the Federal Register on October 6, 2005 (70 FR 58508), in Notice of Proposed Rulemaking (NPRM) No. 05-08, Enhanced Airworthiness Program for Airplane Systems/Fuel Tank Safety (EAPAS/FTS), at the time this rule was proposed.
“As a result of the revised maintenance programs that would be required for airplanes operating under part 121, maintenance personnel will be performing inspections and maintenance procedures to address safety issues specific to wiring systems. Although this NPRM does not specifically require new training, existing § 121.375 requires that certificate holders or persons performing maintenance have a training program to ensure that persons determining the adequacy of such work (including inspectors) are fully informed about the procedures and techniques involved and are competent to perform them. To comply with this requirement in relation to proposals for revised maintenance programs for EWIS included in this NPRM, certificate holders would be required to develop any additional training program needed to ensure that the appropriate personnel are adequately prepared to carry out the revised maintenance programs.”
Advisory Circular Feedback Form If you find an error in this AC, have recommendations for improving it, or have suggestions for new items/subjects to be added, you may let us know by contacting the Flight Standards Directives Management Officer at 9-AWA-AFB-120-Directives@faa.gov.
Subject: AC 120-94, Aircraft Electrical Wiring Interconnection Systems Training Program Date: _____________________ Please check all appropriate line items:
An e rro r (pro cedural or typographical) has been noted in paragraph ____________ on page _______.
Recommend paragraph _____________ on page __________ be changed as follows:
______________________________________________________________________ ______________________________________________________________________ In a future change to this AC, please cover the following subject:
(Briefly describe what you want added.)
______________________________________________________________________ ______________________________________________________________________ Other comments:
______________________________________________________________________ ______________________________________________________________________ I would like to discuss the above. Please contact me.
Submitted by: Date: ______________________