EN4165: A New Generation of Production Break Connectors

By Connector Supplier | November 03, 2017

The use of production breaks in aircraft minimizes weight, size, and power consumption.

The primary purpose of production-break connectors is to facilitate the ease of installation for long, heavy, complex, multi-leg cable harness assemblies. Without the use of production breaks in the aircraft, it would be virtually impossible to build, repair, or upgrade today’s complex aircraft, which contain as many as 20 miles or more of wiring, 200 or more harnesses, and 15,000 or more connection points.

To accomplish this task, the US defense industry has long preferred Mil-DTL circular-type connectors, such as 38999, 5015, 26482, and 83723. The primary reasoning for this is increased structural strength; a circular hole cut-out generally has improved structural strength over an oval or rectangular hole cut-out. The additional benefit to these connectors is commonality throughout the aircraft. Typically, MIL-DTL circular connectors are the baseline connectors used in aircraft. Selecting these connectors means fewer components and fewer tools, making repairs on the aircraft somewhat less complicated and expensive.

Modern aircraft utilize an increasing number of optical and electrical interconnect cables and connectors. The complexity of systems such as C4ISR has dramatically increased size, weight, and power consumption, and those factors are critical problems for aircraft, either manned or unmanned. Therefore, electrical system design engineers are looking at ways to reduce these three key factors.

Another factor to consider is globalization within the defense industry. Aircraft sales are global, and each country has its own set of requirements for aircraft systems. This often requires the defense contractor to either make changes, which can be very costly, or to carry additional wiring and/or connectors, which impacts both the size and the weight of the electrical interconnect harnesses.

A Brief History on EN4165

In the early 1980s, Eurocopter’s (Airbus Helicopters) division in France was looking for a rugged modular rectangular connector to use on its Tiger attack helicopter. Not long after that, Dassault Aviation in France had a need for a modular rectangular application on its Falcon 7X program. In an effort to reduce costs and provide commonality, a request was made to the European Standards Committee to develop an EN specification that would meet rigid military requirements, which came to be known as EN4165.

The Problem-Solver: EN4165

The aerospace and defense industry needed to address major concerns regarding size, weight, and power — while also incorporating the added benefit of modularity and lower costs — through multiple sourcing. The solution: standard modules that could be interchanged within either a rectangular connector shell or, for larger and more complex applications (like production breaks), a machined aluminum plate that allowed a varying number of modules to be snapped into place and easily removed with the use of a simple tool. It should be noted that MIL-DTL circular connectors are not modular and have no interchangeability. If changes need to be made, there must be an allowance made within the insert currently in place. That can be very unpredictable, based on what system might be added or modified. So, in many cases, connectors may need to be swapped out with a different insert arrangement. In most cases, the same shell size must be used to avoid cutting additional holes into the structure. The other alternative is simply to add another connector, which cuts more holes into the structure and adds cost and weight.

The Benefits of a Modular Connector for Production Breaks

Due to the complexity of aircraft wiring systems, achieving circular connector optimization in production break areas is nearly impossible, so the end result is inefficiency in connector selection. This increased the number of connectors needed for a given production break area. In some recent studies that compared modular EN4165 rectangular solutions to the conventional MIL-DTL circular connectors, the EN4165 solutions led to a 50-70% reduction in the number of connectors needed and the size of the panel area, meaning that fewer cut-outs were needed in the structure. There is also the added benefit of modularity, utilizing inserts that can be quickly and easily inserted and removed without the need to add or subtract connectors.


TE EN 4165 connectors

Photo courtesy of TE Connectivity


Amphenol’s PCD version of the EN4165 connector.

EN4165 A Family of Products

EN4165 standard modules include signal, power, high-data-rate, RF, fiber optics, high-density signal modules, junction modules, EMI backshells, and custom designs.

TE EN 4165 connectors

Photo courtesy of TE Connectivity

The use of EN4165 rectangular connectors is gaining momentum around the globe. With a proven track record of reliability and maintainability, the EN4165 is solution that improves efficiency, reduces footprint, reduces part count, saves weight, and lowers costs.

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