By: Michael Traskos

Consequences of EWIS Implementation

July 24, 2019 Michael Traskos

In June 2019, Lectromec was asked to present at the USAF Mechanical Equipment and Subsystems Integrity Program (MESCIP) conference. With the electrical wiring interconnect system (EWIS) working its way into fleet sustainment activities, fleets now must take and apply the EWIS lessons learned.

Since the commercial segment has been subject to the 25.17XX EWIS regulations for more than a decade, the presentation examined the intended and unintended consequences of these regulations. For those seeking to integrate EWIS concepts into their fleet maintenance practices, this presentation gives an overview of the factors to be considered for your fleet.

The Potential 270VDC EWIS Component Failure Impact

June 27, 2019 Michael Traskos

The More Electric Aircraft (MEA) design concept has placed, and will continue to place, a greater importance on aircraft electrical power and the supporting Electrical Wiring Interconnection System (EWIS) to accomplish flight critical tasks. To take the greatest advantage of weight savings from using electrically powered components, higher voltages have been brought into the aircraft power architecture.

The goal of Lectromec’s research was to generate data of the potential impact of EWIS component failure. Even with high voltage systems having been fielded for a couple decades, much of the published research provides information on the failure of 115VAC and 28VDC power systems. This research performed by Lectromec sought to fill in that gap.

New Guidance for Wiring System Inspection

June 21, 2019 Michael Traskos

Back in November 2018, the US Navy released the second revision to the military handbook on “Guidelines for inspection of aircraft electrical wiring interconnect systems” (MIL-HDBK-522). This handbook is a guide for the aircraft EWIS inspection and provides a lot of detailed examples of wiring evaluation from beginning to end of the EWIS. Read more

Common Questions About Kapton® Wire

June 12, 2019 Michael Traskos

Love it or hate it, the fact is that Kapton® insulated wires will be on aircraft for at least another couple of decades, and because of this, we should learn to live with the insulation type. Part of living with it is understanding it. If you have questions that you would like to see answered, please send them to Lectromec or add them to the comments section below. We plan to add to this article as the questions arise. Read more

Principles of EWIS System Safety (25.1709)

June 4, 2019 Michael Traskos

Of the regulations encapsulating the 25.17XX EWIS group, none is more complicated than 25.1709. This regulation, consisting of only 31 words, can be the result of thousands of hours of labor, hundreds of pages of documentation, and requiring inputs from just about every system group working on the vehicle. If you step back from the regulation and ask, “What is necessary to show compliance?” it comes down to several factors. Here, we review some of the basic principles of 25.1709, where it impacts and interacts with other systems in the vehicle. Read more

Latest Developments in Wire and Cable (Spring 2019)

May 14, 2019 Michael Traskos

Wire and cable standards are never proactive, but reactive to industry needs, and as the aviation world moves to high power systems, wire and cable must catch up to ensure the products are available for long reliable service life. Twice a year the SAE wire/cable community comes together to slowly push the standards and industry guidance forward; this year, New Orleans was the setting.

During this three-day meeting, several topics were discussed impacting the next generation of aircraft designs. Here, we cover a couple of these developments.

Thermal Life of Wires and Cables

April 22, 2019 Michael Traskos

While there is a wide range of products from which to choose, across many of these specifications there is a common element: maximum temperature rating. Here, we walk through a couple of the methods for assessing a wire/cable’s maximum temperature rating. At the end of this article, we delve into weaknesses of this assessment method and elements that should be considered when selecting a wire for your high temperature application. Read more

Where EWIS Stops

April 8, 2019 Michael Traskos

Having well-defined and recognized system boundaries is the best means to ensure an analysis of that system is robust and does not leave any analysis gaps. Without an established limit and assigned responsibilities, arguments will ensue as to who is the responsible party and time/effort will be wasted with duplicated analysis.

Because an aircraft’s wiring touches nearly all of the systems, it can be confusing to understand where the system starts and stops, and this has led to confusion as to the responsible party for the wiring system design and/or maintenance. Some organizations have seen the responsibility fall on the electrical power systems teams, others, avionics. Regardless of who takes up the responsibility, a clear definition of the wiring system’s physical and logical boundaries must be agreed upon. Thankfully, there are several industry documents that can be relied upon.

High Voltage Impact the Aircraft Wiring System

March 18, 2019 Michael Traskos

For aerospace applications, high-voltage power is a rapidly growing interest and being addressed across several industry technical committees. The basic idea is that the power generation is increasing the supplied voltage and creating a need for the electrical wiring interconnects systems (EWIS) to have components designed to sustain these higher voltages for the entire length of the aircraft life. Just as it should not be expected for a connector to operate in a 300°C environment if it is only rated to 150°C, a connector should not be expected to perform perfectly with voltages exceeding its voltage rating. Read more

How Much Does the Aircraft Environment Impact Wire Life?

March 1, 2019 Michael Traskos

When looking to select any aircraft component, typically the first means of down selecting from the wide variety of components that exists is based on the component’s performance characteristics i.e. can it perform the function to support the system. Next, the question then evolves to selecting those components that are best suited for the environmental conditions. This last part is more than just selecting the parts that are rated for the environmental conditions but also those that will have a long service life in those conditions. Ideally, the part will be reliable the entire service life of the aircraft and not require any replacement or additional maintenance; however, that usually is not the case (see Lectromec’s article on the immortal wire/cable). Read more