Standard & Regulation

Aerospace High Voltage Systems: Addressing the Gaps in Current Standards

October 6, 2021 Michael Traskos

The aerospace segment has been dealing with questions of high voltage systems for the last decade. Many of these questions revolve around the generation, storage, and use of this power, but what has also been a hindrance for progress is defining how the standards for the wiring system need to be updated to address these high voltage requirements. As should be done when any new technology is being applied to a field, we should first look at other fields which have undergone the implementation of similar technologies. For example, the automotive market has been using high voltage systems for quite some time and the standards committees have produced documents supporting these technologies.

In this article, we review one of these documents on high voltage directed to the automotive market and see how it lines up with the existing aerospace standards.

Detailed Discussion of MIL-STD-1353 (Part 2): Nickel and Gold Plating

July 12, 2021 Laura Wishart

Plating materials used on electrical connectors are imperative to the connector maintainability and dependability throughout its service life. In the last article on MIL-STD-1353, we discussed Tin as a plating metal, its restrictions in practical use, and the potential of whisker formation which can lead to destructive arcing or short circuit events. Here, we discuss the use of gold and nickel as plating metals and their effectiveness when used together.

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?

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

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

IEEE 1584-Arc Standard

September 16, 2020 Michael Traskos

Key Takeaways IEEE 1584 provides a basis and a model for arc flash protection and necessary safe separation distance. The standard targeted the necessary calculations for power distribution. While there is some overlap with the aerospace industry wiring system requirements, the model’s range inhibits its use for aircraft. Research down an unfamiliar path often includes […] Read more

AS4372 – Building a Wire/Cable Specification

July 27, 2020 Michael Traskos

While it is possible to start from scratch and develop an independent set of tests and performance requirements, there are existing standards that can be used to expedite the process. 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.