Repairs related to electrical systems including electrical wirings should possess a higher workmanship. While adhering to standards and recommended practices, you will also need to focus on the perfect tool for repair accomplishment as well. As an electrician or technician, it is a good practice to use the perfect tool for the specific repair task. So, it is better to check below mentioned tools below are already in your workshop tool checklist.

Image reference – https://www.instagram.com/p/B2Pf_binyi2/?utm_medium=copy_link

BRIEF ON ELECTRICAL /AVIONICS WIRING INTERCONNECTION SYSTEM & RELATED REPAIRS

Generally, an Electrical Interconnection System (ELS) is an integral part of the electrical system of an aircraft or a product with a wiring system with components. This term is frequently used as ‘EWIS’ – Electrical Wiring Interconnection System in the aviation industry focusing on wires and the wiring of systems in aircraft. The wiring system of a component or a system is a major concern as well as the repair or maintenance practices. It may sound simple, but this system has severe damage to the overall reliability or safety operation of the product under failure conditions. Many aviation-related incidents have been reported during the last decade due to the failure of electrical wiring causing fatal accidents. Thus, major regulation authorities like the FAA and EASA have set up EWIS-related safety practices to mitigate failures during aircraft operations. The wire degradation is the main reason for the failure of the Electrical Interconnection System. The degradation deals with the physical properties of the wire, insulation of the wire or wire bundle, maintenance, and the environment. Aging is also affecting the degradation, and it will depend on the type of wires installed.

Apart from inadvertent indirect damages due to failure of structure or product, the wiring systems tend to degrade with time and the causes for wire degradation due to the environment would be heat, moisture, chemical contamination, poor installation, and maintenance. Exposure to high-heat areas will cause insulation dryness and cracking in the wiring system. In aircraft, especially for engines, galleys, and lighting systems, this degradation is prone to cause. Most insulation material is a very complex long-chain polymer in which moisture affects the changes to this polymer decreasing the insulation qualities over time. This will not cause only the insulation, but also high moisture areas generally prone to corrosion of terminals, pins, sockets, and conductors. It should be noted that wiring installation provisions must be free from moisture with moderate temperature conditions. Poor maintenance and installation are another cause that can be categorized as a human error. Always need to comply with minimum standards applied to each field and OEM recommendations whenever conducting an installation or maintenance work. The vibration will also cause wire aging, especially in aircraft where vibration levels are not at a constant rate throughout the frames.

In order to follow repair and maintenance procedures in an aircraft wiring system or any product in the engineering industry the appropriate tool selection is necessary.

CONVENTIONAL TOOL TYPES

STRIPPING OF WIRES

The repair procedure of the wiring system includes stripping of wires. This is the initial stage of repair where wires are prepared to assemble into connectors, terminals, and splices. There are some safety practices that need to be followed to achieve a perfect repair.

• When using a wire stripper, hold the wire perpendicular to the cutting blades of the wire stripper.
• Proper use of automatic stripping tools. Always adhere to OEM (Original Equipment Manufacturer) instructions.
• Use stripping blades appropriate to the insulation thickness.
• Make sure that the insulation is cut cleanly with no frayed or ragged edges.
• Make sure all insulation is removed from the stripped area. Some wire types are supplied with a transparent layer of insulation between the conductor and the primary insulation which can be missed.
• If required, re-twist strands to restore natural lay and tightness.

Keep in mind that the stripping plier jaws are in good condition and appropriate for the wire. Manual insulation stripping with cutting tools is limited to the following.

• Cable cross-section above 5mm² or wire gauge 10.
• Fire-resistant cable insulation
• Screened cables (braided or helical screening)
• Coaxial cables

Wire strippers should be able used under the above instances and strippers should allow the stripping of wire smoothly with a minimum pressure applied on it. Most of the strippers used in the aviation industry are qualified with SAE standards and poor-quality wire strippers or mismatched blades can compromise the performance of wiring. A wire stripper must clearly mark the applicable wire size per blade and a cushioned plastic grip with spring action mechanical design would probably ideal stripper specification to implement in a repair. A lightweight stripper made from die-cast zinc; and carbon steel materials makes it easy to accomplish tasks with high productivity. Along with strippers, some accessories are used to make stripping much easier. They are gripper pads, wire stop, shortstop latches which are customized per stripper configuration.

Product review – The above product is an automatic multifunctional wire cable stripper which is designed with a mechanical spring design with cutting capability of max. 10AWG and stripping capability of (22-8) AWG. It has already marked specific features and gauge lengths on the stripper upper body clearly. Include a fine grip and the upper body made up of Carbon steel. Overall design is under recommended limitations and ideal for general electrical wire stripping and cutting tasks.

Apart from manual stripping process by using automatic strippers, for wire stripping of below 5mm² or wire gauge 10, electrical automatic wire stripping machine can be implemented. These are in form of pneumatic, thermal processes which perform stripping of general wire gauges from 10-30 AWG. The main advantage is accuracy and reduce the human error when performing the stripping using manual tool. This may have some accessories like gripper assemblies, standard blade and bushings, air regulator, transformer (220v, 50 Hz), 12V adaptor, hex key set etc.

PRODUCT REFERENCE – https://digitalzakka.com/product/110v-220v-portable-powered-electric-automatic-wire-stripping-machine-scrap-cable-stripper-machine/

Product review – The above electrical stripping machines works with a powerful motor with phase 220V- 50Hz and generates 370 W power. It has 10 blades with capability of stripping wires range between 1.5-3.8 mm diameter with up to 89 ft/min. The design is a solid metal material and include an adjustable hand crank and gear box that can provide power manually also. This machine is suitable for removing plastic and rubber insulation from undamaged scrap wires.

CRIMPING OF WIRES

Crimping is another process in wire interconnections which is to join wire to wire or wire to terminal. At the wire junction bonding of wires accomplished by metal compressed and deformed tightly over one another. The crimping tool is used to perform above process and crimping tool type is varied per the function such as:

• End cap crimp tool used to crimp the spare wire end caps.
• Close end splice crimp tool used to crimp close end splices.
• T – Head crimping tool & Hand crimping tool used to crimp pre-insulated diamond grip (PIDG) terminals and moisture proof splices.
• Modular crimping tool used to crimp contacts for modular terminal blocks.
• Connector contact crimping tools used to crimp standard contacts. A locator in crimp tool used to position the contact in the correct position for crimp.

As of above different practices, the crimping tool type may vary, but need to keep in mind that type of crimp tool you are using is capable of performing the intended function as no damages will be present post-crimping process. So proper knowledge on tool selection is necessary and pre crimping checks need to be performed to make sure that the crimp tool parts are free from damages, corrosion, and wear. As per aviation regulations and manuals these variety of crimp tool types are inspected periodically after 1000 or 2000 crimps. A GO/NO-GO gauge is used to check the condition of crimping tools. It is always best practice to check the labeling of each crimp tool type mentioning the wire type, gauge, part number and manufacturer, die number if applicable.

Here are few types of crimping tools that widely used in Industrial applications of crimping processes.

Product review – This crimp tool is a modular type crimping tool that used crimp modular terminals such as standard RJ11 / RJ12 connectors and RJ45 CAT5 CAT5e, CAT6 connectors. The design is a compact , ergonomic design made up of metal with plastic grip and blades are made up of high quality steel blades. Includes wire stripping and cutting options and markings are well depicted in the tool surface. Ideal for standard industrial engineering appliances.

Product review – IWISS IWS-0540HX Hand Crimper Plier Tool is capable of performing crimping for 26-12 AWG gauges and include a multi-functional locator set for heavy duty power connectors such as Han D, Han E & C. The design is ergonomic with a plastic grip and includes an automatic release mechanism when fully crimped. Ideal for heavy duty connector crimping applications in industry.

Product review – The above multifunctional kit is ideal for general engineering use as it includes rachet crimping tool, wire stripper and die kit for general used gauges. It also includes a screwdriver to set up the appropriate die for the crimping process. The kit comes with a handy canvas bag and designed for convenient usage. The upper body of wire stripper is made up of alloy steel and include a fine grip on the handle. The crimping tool body made up of high-quality steel heat treated and coated with black oxide to make it more durable. Both tools have a better ergonomic design with providing extra safety for wire crimping and stripping.

FINAL TALK

The wire interconnection system is separate system of any electrical driven product that need to pay more attention unless upon a failure the whole systems will be led to catastrophic failure mode. Each working personnel or technicians should have a proper training on electrical wiring tool usage as well as knowledge of selecting perfect tool for the required repair procedure. The recommended tool types discussed here are in compliance with general industrial standards and perfect for general industrial applications. But make sure to purchase the tool type that is clearly recommended per manual references and standards based in applicable industry. Keep in mind that, each standardized tool contains a product sheet which include all the specifications and material properties. It is best practice to choose perfect tool wisely, because ultimately it would affect the overall workmanship of the repair or modification.

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REFERENCES

1. https://www.sae.org/standards/content/as5768/
2. https://camsaviation.net/our-services/workshop/
3. https://www.faa.gov/training_testing/training/air_training_program/job_aids/media/ewis_job-aid_2.0_printable.pdf
4. https://digitalzakka.com/