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Results for: as4373

The Impact of a Short Circuit on Conductor Performance

March 17, 2020 Laura Wishart

Over-current and shorting are an ever-present risk to power wires and cables. The hope is that circuit protection can quickly respond to over-current conditions fast enough to prevent any damage to the circuit components. Wire conductors have a temperature rating, limited by the plating, because that is the established temperature for long-term reliability. But what happens when a single wire is exposed to repeat over-current conditions? Does the latest generation of circuit protection sufficiently protect the wiring? Read more

Notch Testing and the Impact of 1000 Cuts

March 4, 2020 Michael Traskos

How much damage can a single wire take? Does the failure of a wire’s insulation require one large trauma (think of dropping a hammer on it), or is it possible for the insulation to fail due to 1,000 small cuts? That has been a question plaguing wire system sustainment for decades. Identifying one large trauma can be easy, but to catalog all the minor traumas is impossible. Read more

Non-Standard Standard Part Performance

November 11, 2019 Michael Traskos

Standardized products made by different manufacturers through different processes will undoubtedly yield variable product performance. The expectation is that each ‘qualified’ product should perform comparatively well, but anecdotal evidence suggests that this is not the case. This paper reviews recent work performed by Lectromec investigating the qualified wire/cable performance variability in both qualification tests as […] Read more

Wires and Fuel Compatibility

August 7, 2019 Michael Traskos

Whether by design or by accident, some wires in an aircraft will be exposed to jet fuel. Because of this, it is necessary to be prepared and select wires/cable types that will not suffer adverse effects of the exposure. Considering the impact of fuel on wiring is not idle musing about wiring systems; to quote the FAA AC120-97A, “Since 1959, there have been 18 fuel tank explosions on transport category airplanes”. Read more

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

International Test Standards for Aircraft Wire Tests

January 15, 2019 Michael Traskos

Frequently, Lectromec’s articles have focused on wire and cable testing from US-focused standards such as the SAE and US military (MIL) documents. While these are standards frequently cited, there are other standards organizations that support the aerospace wiring community. Thankfully, many of the standards share a common base and, as is the case with many of the SAE standards, these have been harmonized with European standards. In this article, we will review some of the European wire/cable test standards, variation from similar test methods, and their availability in Lectromec’s lab. Read more

Have we Reached the End of Aging Aircraft Wiring Systems?

October 17, 2018 Michael Traskos

The way some in the aerospace industry maintain their aircraft wiring system can only lead an external observer to reason that aircraft wiring is impervious to damage with a life-span greater than the sun. When considering this thought, the question arose, “It is possible that aircraft wiring reached a point where aging/degradation is a thing of the past?” Read more

Mechanical Performance of Cables at Low Temperatures

October 5, 2018 Michael Traskos

The environmental extremes under which wiring exists in aircraft can rapidly degrade materials that are not prepared or designed for those conditions. Without a doubt, high-temperature ranges that are typically considered for aircraft wiring eliminate most wire insulation types that are suitable for ground-based home applications. Lectromec has covered several types of high-temperature tests in past articles. But at low temperatures, what tests exist to help identify which wires are ideally or adequately suited for aerospace applications? One of the tests that investigates the performance of wires in cold conditions is known as the cold bend test. Read more

Should Polyimide Insulated Wire be Trusted?

September 25, 2018 Michael Traskos

The history of polyimide insulated wire is one that has numerous opinions and a lot of misconceptions. After several incidents involving polyimide wire on aircraft in both military and commercial, many within the aerospace industry refused to put any polyimide insulated wire/cable onto the aircraft they design/maintain. As is often the case with components involved in incidents, a lot of facts and myths get jumbled together. Read more

High Current Testing

August 14, 2018 Tristan Epp Schmidt

Several things can go wrong when a wire or cable is subjected to an electrical current exceeding its design limitation and none of them are good. These include, but are not limited to, melting of the insulation, smoking, insulation degradation, promotion of intermetallic growth between the plating and conductor, melting of the conductor, melting of the conductor plating, and conductor embrittlement. Thankfully, if the wire/cable is being used within its temperature and current ratings, the wire should experience very little of the above phenomena. Read more