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A Comprehensive Guide on the Aircraft Wire Harness Assembly

In order to carry current as well as electronic signals out of the nose to the tail, the aircraft wire harness assembly plays a crucial role as the aircraft’s nervous system. From the fuselage harness to the power distribution assembly, wire harness makers create extremely intricate electrical harnesses as well as harness assemblies enabling the operating as well as controlling of practically every component of the aircraft. Such assemblies are frequently used in applications which require intricate electronics and dense wiring.

High-performance cables and wiring that are flame-resistant or resistant to the majority of fuels, solvents, or lubricants are used in the construction of the aircraft wire harness assembly. Cobra helicopters, trainers, fighter jets, and other aircrafts, use aircraft wire harness assemblies because they are built to deliver dependable, high performance even under the most challenging environmental conditions.

What is Aircraft Wiring Harness?


The most typical part of aircraft engines is the wire harness. It is a collection of electrical cables enclosed in an insulating substance. This insulated substance is primarily thermoplastic, that is noted because of its versatility. This thermoplastic offers electrical insulation towards the application while being able to handle hard conditions and high temperatures.

It is crucial that such materials utilized to house these wires be robust and capable of withstanding the movement as well as vibrations of aerospace applications in conditions where tear and wear are particularly likely. Such harnesses are sometimes mistaken with the cable harnesses, however they are two different parts.

Why Is the Wire Harness Crucial for the Aerospace Industry?

Wire harnesses can be customized for a particular application. It is essential to utilize components which can survive harsh environments in aircraft applications. Because of their extraordinary flexibility, wires are perfect for confined, compact places. For some purposes, they are preferred over wires.

Also, because they are significantly lighter than cable, the wire harnesses seem to be preferable. Weight plays a significant role in the process of manufacturing for aerospace applications since the aircraft must be able to securely transport big loads of passengers or cargo for, in certain cases, extended periods.

Manufacturing of Electrical Cables and Wiring Harnesses for Aircraft

Conductor wires enclosed in insulated covers make up the wiring harness. Such jacketed cables could be singles, triplets, twisted pairs, etc.

Copper and Aluminum are the two conductors that are most frequently utilized, with each having unique properties. There is a lot of use for aluminum because of its light weight, which allows for long spans as well as its comparatively large diameter meant for a specific conductivity, which lessens the release of electricity out from wires. Copper is easier to solder, has a better conductivity, and a comparatively high tensile strength.

Inside the aerospace sector, an aircraft’s wiring harnesses might extend for miles. Uses include those for the wing, engine, fuselage, and landing gear.

Advancement of the Aircraft Wire Harness Assembly

Advances in Aircraft Technology

In the high-tech world of today, flying could appear like a routine activity that the majority of us have already done. Nonetheless, because of its lengthy history, aviation technology has advanced significantly. Aerodynamics has been the secret to traveling from one location to another when airplanes initially flew. The earliest aircraft to transport people were thermal airships, sometimes known as hot air balloons.

But, developments in aerodynamics as well as motor technology throughout the beginning of the twentieth century increased the prevalence of powered-controlled flights. These early versions, which resemble modern aircraft, were created by 1909. Since aircraft engines have become more powerful and aircraft wiring harnesses have undergone new developments, aerospace engineering has progressed over time.

Without technological advancements, aircraft as well as the aviation industry would not operate as it does today without the breakthroughs experienced technologically.

Nonetheless, despite the advancements it has introduced to the aerospace sector, an aviation wire harness performs the same basic purpose like other wiring systems.

Why Do Wiring Harnesses Exist in Aircraft?


Early on in the creation of airplanes, there wasn’t anything like wiring harness because there were no electrical systems. They were limited to utilize structural components, ropes, including pulleys for moving its flying control surfaces.

Soon, these metal cables took the place of such ropes; today, numerous planes still use pulleys and cables rather to “fly by wire.” A battery, switch, as well as light bulb were eventually added by an aviation designer after he finally chose to wire inside a light. By using cables to connect these components, he built the first-ever electrical lighting systems for the airplane.

As this system simply needed a few wires, its harness manufacturers placed each one in a secure area.

Other architects then followed suit and added additional electrical infrastructures. Although groups of wiring flowed from one section to another, the aircraft mechanics ultimately recognized they have been installing the cables one after the other. Moreover, they required additional wires for every such device.

The setup procedure took a long time. To boost productivity, mechanics started bundling cables together as well as routing them. The aviation sector took notice & thought this was an important development. They connected the wire bundles there after conceiving them as one unit. They did this to produce the first-ever wire harness. These wire harnesses for aircrafts serve this function.

The Functions of the Aircraft Wiring Harness Assembly

The wire harness of an airplane controls electrical impulses for the entire aircraft, just like the harness of a car does. Among the things it controls are the landing gear, engine, wings, as well as fuselage. There is frequently a lot going on within the wire harnesses. An aviation wiring harness is made up of miles of wires, cables, as well as tens of thousands of components. Also, they must all work together to maintain the plane’s smooth flight.

The quickly evolving technology and updated aircraft electrical connections that may accommodate cutting-edge upgrades must also be kept up with by today’s aircraft makers. An aviation wire harness not only increases manufacturing and production efficiency but also makes it simpler for mechanics in repairing and identifying plans that are experiencing some technical difficulties.

The requirement to install a massive plane’s electronic equipment separately is removed by wire harnesses. The afflicted component must be identified by mechanics in order to be repaired when issues emerge and maintenance is necessary.

Aircraft Wiring Harness Assembly Components

When building a plane which complies with military requirements, there are several factors you’ll need to consider, including the aircraft that it will be utilized in. This will influence the precise features as well as the wiring harness components. These include the three different categories of airplane parts.

Standard Components

The military frequently has the ultimate say about MIL-SPEC components in the electrical system of a plane. Nevertheless, before you think of certain firms as approved suppliers, the government should certify them.

Non-Standard Components

Variants of commercially accessible components that adhere to a marginally different military standards commonly make up non-standard components. Original equipment producers may set their own standards for the non-standard components.

Original Equipment Manufacturers can also choose which of their suppliers they want to allow to manufacture the non-standard components. The non-standard component for an aviation harness, however, usually costs more because there aren’t many of them.

Commercially available and off the shell components

Manufacturers develop off-the-shell components in large quantities in accordance with customer demand and market research. Without the approval of the government and the military, the manufacturer can improve its component designs. Any manufacturer can make their own parts and give each one a special part number.

Similar to the remaining two components, these alternatives are available from manufacturers for a lower price. Yet, manufacturers have sole control about how the components are distributed, giving them the ability to set the prices as well as decide on the market share. Also, they are free to change or adjust any requirements.

However, it can become problematic if new wiring harness components are required because the supply is running low.

Aircraft Connection and Wiring

Aircraft PCB

Wiring in the aircraft wire harnesses can be miles long. As a result, careful planning and structuring are required to avoid issues after as well as during construction. Creating a schematic within the CAD software seems to be the initial stage in the design process. This acts as a blueprint for further construction.

There was once a single type of insulating material that could be utilized to fulfill all needs, however today there are many possibilities. Which cables are used depends on the signal that you send as well as the electricity of the system. With these factors, wire insulation will also shift.

It would also be beneficial to label the wires enough so assembly as well as repairs don’t confuse them. However, keep such three things in mind when choosing a connector. The connector’s maximum connections must come first. ach wire’s thickness comes in second, followed by the kind of wire that goes into the aircraft connectors.

Aircraft Wire Harness Assembly Wire Selection

A system level is the place to start when designing the electrical system of an aircraft. The system diagram displays the bigger parts and their connections. The specification as well as size of these wire are not specified; they are merely joined together using a line in the system schematic.

Moreover, the wire splits are absent from this system schematic, such as whenever it goes through the bulkhead using two connectors. Despite its simple construction, the schematic would specify the kinds of signals which the wire would carry. The graphic also indicates the locations where shielded cables, twisted pairs, quads, and triplets are required.

The kind of signal the wire will broadcast as well as the current carried should guide your choice of wire. Usually speaking, you should choose the wire with its smallest gauge which has the ability to carry the needed current.

Also, reliable CAD software would figure out each gauge size’s current-carrying capacity automatically.

Testing of aircraft wire harness

Wiring analyzers are automated pieces of equipment used to assess aircraft wire harnesses. Wiring analyzers are made by many companies. Special programs instruct the analyzer on the tests to be performed, the voltage and current to be used, and the duration of applying current. Utilizing adapter cables, the technician joins this wiring analyzer onto that wire harness.

Insulation resistance and continuity are the two most often used tests. However, wiring analyzers are also capable of doing other tests, such as checking the functionality of diodes and conducting tests on the AC dielectric and empty contact cavities. They can also turn on lights and relays and measure capacitance and resistance.

Testing for continuity makes ensuring that every wire gets connected in line with the specific design. Continuous testing are run at 0.5 amps with constant voltage as well as a 0.2 second minimal dwell time.

The megohm test, commonly known as an insulation resistance test, looks for any short circuit. For instance, this insulation resistance testing will reveal a short circuit if there are two wires adjacent each other and both have nicks present in the insulation. This test on insulation resistance will also reveal a short circuit when a connector is improperly made and there isn’t sufficient material to divide two contacts.

Tests on insulation resistance are conducted with a continuous current at a value of 1,500 VDC and a 0.15 second minimum dwell period.

The test on insulation resistance performs exactly what its name implies: it guarantees there was enough resistance in-between 2 as well as more conductors to prevent short circuits. If this resistance is larger than one hundred megohms, then the test is passed.

Most OEMs prescribe how wire harnesses should be tested. MIL-STD-202 is the most popular military test specification.


Aircraft wire harness comprises several cables and connectors. Furthermore, other standard, non-standard, as well as commercial-off-the-shelf (COTS) parts complete and function the harness. You must consider your requirements before selecting the elements. The schematic will then be designed utilizing CAD software.




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