ICA Guidance for HIRF and Lightning Protection
The advisory circular 33.4-3, issued by the FAA offers guidance for developing adequate ICA for an aircraft’s HIRF and lighting protection functions. Read more
By: Laura Wishart
S&T 2021 Meeting Report
A discussion covering the topics of interest presented at the FAA’s annual S&T meeting in 2021. Read more
Top 5 Articles of 2021
It was a busy year for Lectromec’s publishing team; in 2021 we published 22 articles, one brand new whitepaper, and several of our articles were picked up for redistribution. We took some time at the start of this new year to review these articles and we present here our annual round-up of Lectromec’s most popular articles from 2021.
Read moreAS23053 Dimensional Life of Heat Shrink Tubing
We are told that low humidity and cool temperatures are the best way to extend component life, but even in such conditions not all components can sit on a warehouse shelf indefinitely awaiting the day of installation. One of the more susceptible EWIS components to aging on the warehouse shelf are heat shrink tubing. Here, we examine concept of dimensional life of heat shrink tubing.
Read moreLow Temperature Bend Testing for Lunar Applications
NASA sought to evaluate wire and cable flexibility for lunar applications; specifically looking to evaluate the ease of reeling/unreeling wire and cable in lunar environments. Bend testing was performed on 35 different insulated wire and cable constructions at liquid nitrogen temperature to evaluate flexibility in extreme cold conditions. It was the intent of this effort that, “testing at the extreme cold temperature of liquid nitrogen will begin to build a database of what off-the-shelf types of wires and eventually cabling may be applicable to the lunar environment.” Read more
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
Partial Discharge at Altitude
PD is not a simple phenomenon to model as there are many environmental factors that have influence. Factors such as heat, humidity, pressure, are some that can change the voltages required to initiate and extinguish PD within a wire/cable’s insulation. This article specifically discusses the influence of altitude on partial discharge events. The consideration of the operational altitude effect on partial discharge is particularly necessary for aerospace applications as aircraft tend to spend a lot of operating time at high altitudes.
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 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