Blog

An Introduction to AS50881

June 30, 2021 Michael Traskos

For the last 17 years, Lectromec publications have discussed items related to the aerospace wiring installation standard AS50881. The standard is often referenced in many of our articles, but Lectromec has never really talked about what this standard is, why it should be used, who should use the standard, and what should be considered when the standard is employed.

To remedy this oversight, this article seeks to address the question many come to ask when approaching EWIS: why should I care about AS50881?

Addressing the Big Questions of Partial Discharge

June 11, 2021 Michael Traskos

In this high-voltage present, wires and cables must address new challenges, perhaps the most notable is partial discharge (also referred to as corona). This article discusses the fundamentals of partial discharge, its impacts on wiring design, and test methods used to assess a component’s partial discharge performance. The PD may occur between (1) the conductor and insulation, (2) within void in the insulation, (3) between insulation layers, or (4) between the insulation surface and shield. Read more

Integrating EWIS into Fleet Sustainment and MECSIP

May 6, 2021 Michael Traskos

While the Electrical Wiring Interconnection System (EWIS) evaluations and sustainment requirements have been part of the Mechanical Equipment and Subsystems Integrity Program (MECSIP) since 2013, it is only just recently that EWIS elements are part of performance measurements. This webinar, presented by Lectromec, provides an excellent opportunity to improve your understanding of EWIS, EWIS requirements, and highlights a path for better and more cost-effective EWIS evaluation. Read more

Detailed Discussion of MIL-STD-1353 (Part 1): Tin Plating

April 21, 2021 Laura Wishart

The mating of the electrical wiring interconnect system (EWIS) is a non-trivial task. Between the functional requirements (the correct number of pins, sizing of contacts, etc.), there are also the performance requirements (operational environment, corrosion resistance, impedance matching, etc.). This is then further complicated by installation requirements (sizing), maintenance requirements (mating/demating cycles), and regulatory requirements (limitations of materials that can be used). Obviously, adding a connector to a wire harness is not a five-second activity. This article looks at the MIL-STD-1353 specific requirements for tin usage in aircraft connectors. Read more

A Summary of MIL-STD-1353, A Guide to Connector Selection

March 26, 2021 Laura Wishart

Due to the diversity of connector applications, each connector is liable to be subject to entirely different electrical stress, mechanical stress, environmental conditions, etc. Knowing the severity of conditions a connector will be exposed to during its service life is imperative during the selection process. The MIL-STD-1353 (Electrical Connectors, Plug-in Sockets and Associated Hardware, Selection and Use of) document aims to provide guidance in the selection of connectors used in equipment intended for military use. The document references several standards/ requirements that must be met for military equipment qualification and combines them into one easy-to-reference guide. Read more

Electric Aircraft Design Considerations

March 18, 2021 Michael Traskos

Electrical energy storage has reached a point where it is possible for the manned vehicle propulsion to use non-petroleum based energy. To achieve this goal, it has required a lot of research, design, and innovation that has pushed these vehicles to depend on high voltage electrical power systems and forego the use of hydraulics and pneumatics. If electrical aircraft are the aircraft of the future, what are the design factors that the EWIS community will have to address? Read more

ASTM F3309- A Simplified Safety Analysis for Small Aircraft

March 10, 2021 Laura Wishart

Aircraft safety requirements vary depending on the size of the aircraft. Typically, larger aircraft have stricter requirements as a catastrophic failure in large aircraft has the potential for a much larger loss of life than that of small aircraft which hold far fewer passengers. The ASTM F3309 provides a simplified qualitative approach to evaluate the safety of small aircraft. Read more

EN2235 Review and Comparison to NEMA 27500

February 4, 2021 Laura Wishart

Cables are complicated engineered products. They range from the simple twisted pair (simple but requiring precise twists per foot) to the complicated signal and data cables used in many applications. Just as the NEMA 27500 cable standard is the go-to cable for many aerospace applications in the US, the EN2235 shares the same status in the EU. The requirements for these cables are outlined in this article. Further, we examine the differences between the EN2235 cables and the NEMA 27500 cables. Read more

EWIS and Aircraft Maintainability

January 19, 2021 Laura Wishart

The maintainability of the electrical wiring interconnection system (EWIS) is integral to the longevity of an aircraft. EWIS maintainability affects not only the EWIS itself, but any nearby system whose maintenance access is restricted by the location or function of the EWIS. Thus, high maintainability of the EWIS allows for faster, more efficient, and more precise maintenance of surrounding equipment and systems.

Original aircraft design must comply with EWIS regulations in the development stage to ensure long-term maintainability. It is important to know which regulations apply and which standards to follow when designing an aircraft to determine the appropriate maintenance requirements.

Here we will explore the requirements of some of the more common standards for EWIS maintainability in aircraft design.