Maintenance & Sustainment

Selection of Zones for Degradation Testing

June 26, 2020 Michael Traskos

Maintenance zones within an aircraft are not homogeneous. They vary from the extreme Aircraft areas within the aircraft (engines) to more benign areas (inside pressure and temperature-controlled areas). And because of this, the components within each of these zones will age at different rates. Naturally, different components are selected for each of these zones; those components better able to handle the severe environments are installed in those environments, and lower requirements are placed on those parts installed in benign environments. Read more

Review of EWIS for Sustainment

January 30, 2020 Michael Traskos

We measure everything that matters. In the last decade, the efforts of organizations to measure EWIS has been progressively increasing. Perhaps this is because wiring is now considered a system, or because regulations and requirements have emerged, or it may be due to a better understanding of the EWIS maintenance costs. Whatever the reason for better EWIS maintenance issue quantification, it has been a positive because there is data available to substantiate aircraft maintenance actions. The old saying is, “You can’t beat something with nothing”, and for too many years, EWIS maintainers were trying to take on EWIS maintenance without supporting data. Read more

Wire Diagnostic Equipment

September 17, 2019 Michael Traskos

Finding wire faults/damage is not an easy task; now consider that problem across an entire aircraft. In-situ testing of wires/cables has always been viewed as something of a challenge to the industry. Given the branching that most harnesses undergo, the various wire lengths, splices, and numerous termination conditions, it can be difficult. Attempts to automate some of the testing has come to the development of Automatic Wire Test Sets (AWTS [pronounced “Eh-Wits”]).

Because there are so many ways to test a wire harness, the US military sought to create a performance standard to cover the general ideas and best practices of this equipment. Here, we review the standard and some of the performance features that can be expected when using equipment in compliance with the standard

Checking a Coaxial Cable for Damage with a Multimeter – Part II

September 11, 2019 Michael Traskos

In the last article, Lectromec introduced a damaged coaxial cable and tried three techniques to distinguish it from an undamaged cable. The standard multimeter tests (capacitance, inductance, and resistance measurements) found no appreciable difference.

The idea of this evaluation was to demonstrate that the classic multimeter, while a great tool, is not suitable for detecting damage to coaxial cables.

But we cannot run an article and leave it without a solution. In this article, we continue the testing of a damaged coax cable to see what technology, if any, can identify and perhaps locate the damaged section of cable.

Checking a Coaxial Cable for Damage with a Multimeter

August 23, 2019 Michael Traskos

The electronic multimeter is a great tool; invented in the 1920s, the multimeter has been used by millions of technicians and engineers seeking to measure circuits and troubleshoot electrical issues. So common are these tools now that it is almost impossible to consider a toolbox complete without one.

While these are great tools and can be employed in a million situations, they are not the magic tool that can diagnose every circuit. If only one thing is remembered from this article: multimeters are not the tool to use for coaxial cables

How Much Does the Aircraft Environment Impact Wire Life?

March 1, 2019 Michael Traskos

When looking to select any aircraft component, typically the first means of down selecting from the wide variety of components that exists is based on the component’s performance characteristics i.e. can it perform the function to support the system. Next, the question then evolves to selecting those components that are best suited for the environmental conditions. This last part is more than just selecting the parts that are rated for the environmental conditions but also those that will have a long service life in those conditions. Ideally, the part will be reliable the entire service life of the aircraft and not require any replacement or additional maintenance; however, that usually is not the case (see Lectromec’s article on the immortal wire/cable). Read more

Is my aircraft wiring serviceable?

January 29, 2019 Michael Traskos

A concept employed in the civil engineering field is that of serviceability. At its core, a structure should only remain in-service as long as it is serviceable. A serviceability limit should be based on measurable performance criterion that, if exceeded, remove it from service. In limit state design, the structure fails its serviceability if the criteria of the serviceability limit state are not met during the service life with the required reliability. Read more

EWIS Instructions for Continued Airworthiness

November 27, 2018 Michael Traskos

Here we look at the last 95% of an aircraft life: operation and maintenance. In this, we review the regulatory requirements around EWIS instructions for continued airworthiness (ICA) and some of the resources that can be used to ensure a smooth certification process for your wiring system. Read more

Have we Reached the End of Aging Aircraft Wiring Systems? – Part II

November 5, 2018 Michael Traskos

At the start of the last article, the question was posed, “Is it possible that aircraft wiring reached a point where aging/degradation is a thing of the past?” In that article, four elements were identified that must be satisfied for wires/cables to be considered as age-free. The insulation and conductor aging factors were examined in the last article, and here we consider the remaining two: Design limits and random shocks. Read more

Selecting Aircraft for Inspection and Work Unit Codes

July 24, 2018 Michael Traskos

What documents and standards are there for justifying the evaluation of an aircraft’s EWIS? There are actually several. Read more