A New Revision of MIL-HDBK-522
A new version (Revision C) of MIL-HDBK-522 was released on May 11, 2021. This article examines many of the changes made between Revision B and Revision C. Read more
Standard & Regulation
Aerospace High Voltage Systems: Addressing the Gaps in Current Standards
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.
Read moreDetailed Discussion of MIL-STD-1353 (Part 2): Nickel and Gold Plating
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.
Read moreAn Introduction to AS50881
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?
Read moreDetailed Discussion of MIL-STD-1353 (Part 1): Tin Plating
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
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
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
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
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
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