View Latest Blog Entries
Close
Categories
Testing & Assessment Certification Aging Wires & Systems Standard & Regulation Management Maintenance & Sustainment Conference & Report Research Protection & Prevention Arcing Miscellaneous
Popular Tags
Visual Inspection AS50881 MIL-HDBK MIL-HDBK-525 High Voltage FAR Electromagnetic Interference (EMI) FAR 25.1707 AS4373 Maintenance Wire System Arcing Damage
All Tags in Alphabetical Order
2021 25.1701 25.1703 abrasion AC 33.4-3 Accelerated Aging ADMT Aging Systems AIR6808 AIR7502 Aircraft Power System aircraft safety Aircraft Service Life Extension Program (SLEP) altitude arc damage Arc Damage Modeling Tool Arc Fault (AF) Arc Fault Circuit Breaker (AFCB) Arc Track Resistance Arcing Arcing Damage AS22759 AS22759/87 AS23053 AS4373 AS4373 Method 704 AS50881 AS5692 AS6019 AS83519 AS85049 AS85485 AS85485 Wire Standard ASTM D150 ASTM D2671 ASTM D8355 ASTM F2696 ASTM F2799 ASTM F3230 ASTM F3309 ATSRAC Attenuation Automated Wire Testing System (AWTS) Automotive backshell batteries Bent Pin Analysis Best of Lectromec Best Practice bonding Cable Cable Bend cable testing Carbon Nanotube (CNT) Certification Chafing Chemical Testing Circuit Breaker circuit design Circuit Protection Coaxial cable cold bend collision comparative analysis Compliance Component Selection Condition Based Maintenance Conductor conductors conduit Connector connector selection connectors contacts Corona Corrosion Corrosion Preventing Compound (CPC) Cracking D-sub data analysis data cables degradat Degradation Delamination Derating design safety development diagnostic Dielectric breakdown dielectric constant Dimensional Life disinfectant Distributed Power System DO-160 dry arc dynamic cut through E-CFR Electrical Aircraft Electrical Component Electrical Power Electrical Testing Electromagnetic Interference (EMI) Electromagnetic Vulnerability (EMV) EMC EMF EN2235 EN3197 EN3475 EN6059 End of Service Life End of Year Energy Storage engines Environmental Environmental Cycling environmental stress ethernet eVTOL EWIS certification EWIS Component EWIS Design EWIS Failure EWIS sustainment EWIS Thermal Management EZAP FAA FAA AC 25.27 FAA AC 25.981-1C FAA Meeting failure conditions Failure Database Failure Modes and Effects Analysis (FMEA) FAQs FAR FAR 25.1703 FAR 25.1707 FAR 25.1709 fault tree Fixturing Flammability fleet reliability Flex Testing fluid exposure Forced Hydrolysis fuel system fuel tank ignition Functional Hazard Assessment functional testing Fundamental Articles Future Tech galvanic corrosion Glycol Gold Gold plating Green Taxiing Grounding hand sanitizer handbook Harness Design Hazard Analysis health monitoring heat shrink heat shrink tubing high current high Frequency high speed data cable High Voltage HIRF History Hot Stamping Humidity Variation HV system ICAs IEC60172 IEEE Inspection installation installation safety Instructions for Continued Airworthiness insulating material insulating tape Insulation insulation breakdown insulation resistance insulation testing interchangeability IPC-D-620 ISO 17025 Certified Lab ISO 9000 J1673 Kapton Laser Marking life limit life limited parts Life prediction life projection Lightning liquid nitrogen lunar maintainability Maintenance Maintenance costs Mandrel mean free path measurement mechanical stress Mechanical Testing MECSIP MIL-C-38999 MIL-C-85485 MIL-DTL-17 MIL-DTL-23053E MIL-DTL-3885G MIL-DTL-38999 MIL-E-25499 MIL-HDBK MIL-HDBK-1646 MIL-HDBK-217 MIL-HDBK-454 MIL-HDBK-516 MIL-HDBK-522 MIL-HDBK-525 MIL-HDBK-683 MIL-STD-1353 MIL-STD-1560 MIL-STD-1798 MIL-STD-464 MIL-T-7928 MIL-T-81490 MIL-W-22759/87 MIL-W-5088 MIL–STD–5088 Military 5088 modeling moon MS3320 NASA NEMA27500 Nickel nickel plating No Fault Found OEM off gassing Outgassing Over current Overheating of Wire Harness Parallel Arcing part selection Partial Discharge partial discharge at altitude Performance physical hazard assessment Physical Testing polyimdie Polyimide-PTFE Power over Ethernet power system Power systems predictive maintenance Presentation Probability of Failure Product Quality PTFE pull through Radiation Red Plague Corrosion Reduction of Hazardous Substances (RoHS) regulations relays Reliability Research Resistance Revision C Rewiring Project Risk Assessment S&T Meeting SAE SAE Committee Sanitizing Fluids Secondary Harness Protection Separation Requirements Series Arcing Service Life Extension Severe Wind and Moisture-Prone (SWAMP) Severity of Failure shelf life Shield Shielding Shrinkage signal cable Silver silver plated wire silver-plating skin depth skin effect Small aircraft smoke Solid State Circuit Breaker Space Certified Wires Splice standards Storage stored energy supportability Sustainment System Voltage Temperature Rating Temperature Variation Test methods Test Pricing Testing testing standard Thermal Circuit Breaker Thermal Endurance Thermal Index Thermal Runaway Thermal Shock Thermal Testing tin Tin plated conductors tin plating tin solder tin whiskering tin whiskers top 5 Transient Troubleshooting TWA800 UAVs UL94 USAF validation verification video Visual Inspection voltage voltage differential Voltage Tolerance vw-1 wet arc white paper whitelisting Wire Ampacity Wire Bend Wire Certification Wire Comparison wire damage wire failure wire performance wire properties Wire System wire testing Wire Verification wiring components work unit code

When to Pull the Component – End of EWIS Component Service Life

Maintenance & Sustainment

What is the end of life for a wire, cable, connector, or any Electrical Wiring Interconnect System (EWIS) component? This is a straightforward question that should have a straightforward answer, but often, this is an unanswered question. Regulatory guidance such as Fuel Tank Ignition Source Prevention Guidelines from the FAA think of wiring as something that should remain reliable throughout the airplane’s operational life.

When other components are considered, there are life-limits and assessments utilizing tools and techniques to identify when replacement is necessary. Looking at a vehicle’s tires, there are signs when they are no longer viable for use, and based on typical usage and tire wear, it is possible to predict when the tires will need to be replaced. Why is this not done more often with EWIS components? Too often the technologies that are available for EWIS to predict the future reliably are ignored.

As a framework to establish the end of EWIS component service life, Lectromec has prepared this article covering the factors that often create the end of life condition and how they can be assessed. This follows the considerations outlined in AS50881 on the prioritization of EWIS design and installation principles.

Cost

This life-limiting factor considers the economic impact of wire system failures and seeks to determine if the EWIS can no longer be maintained in an economic fashion. In this case, EWIS issues appear so frequently that the cost of patchwork maintenance actions becomes a burden for the maintainer. The maintenance cost is then combined with the loss of aircraft availability and rescheduled flights. This maintenance element of this cost determination would be straightforward if the maintenance data correctly identified all the wire system issues (see NFF), but all too often it is not.

A review conducted by the Air Force on the maintenance codes used found that a high percentage were assigned to the incorrect system. These data entry errors create a heavy burden on those looking to identify the EWIS costs and are likely to need either advanced analysis or additional time and effort to correctly identify the frequency of maintenance issues.

EWIS and End of Service Life
This is how all systems should be designed and maintained, but all to often, the pyramid is flipped without consideration for safety of flight. Is your organization doing enough to care for EWIS throughout its life cycle?

If cost calculation is used as a means to determine the wiring system’s end of service life, then this also acknowledges that the wiring system has degraded to the point that wire failures are a common occurrence. This also admits the vehicle is not airworthy; that is not an acceptable condition for any aircraft.

What about Risk?

Should the wire system component end of life be based upon its risk to the vehicle? A wire failure is not just a wire failure when it is supporting flight controls. A degraded connector does more than just complete a circuit, it is a critical factor in sending signals to the communications equipment. Thinking of the EWIS degradation and the aircraft level impact helps to identify where the risks may rest.

There are established procedures for assessing the risk of an aircraft’s EWIS. Military handbook 525 outlines and thoroughly discusses seven tasks for the performance of the EWIS evaluation. The overall structure of the handbook is to provide a customizable framework for EWIS assessment and an assessment can be expanded or contracted to the particular needs of the platform being assessed. But the assessment should not be done haphazardly. While some assessment is better than none, blindly selecting a task for the assessment is analogous to reaching into a bag full of marbles and hoping to get the best one. A thoughtful consideration of what the available inputs are, and the expected outputs are important for any project. With careful selection and direction that Lectromec can offer, the greatest value of the wire system assessment is possible. And with a valuable assessment, it is possible to determine the risk of the aging wiring system to the vehicle and identify specific actions that can be taken to return it to an airworthy condition.

Does it Work?

What about performance? Should wire system components be replaced and be considered to have reached the end of life if their electrical or mechanical performance has degraded? The subsequent question to that is how much performance degradation should be permitted?

There is natural variability in the performance of wires/cables from different manufacturers. Some manufacturers produce wires that consistently exceed the minimum performance requirements while others barely pass. If the performance criteria for end of life is the original product performance, then the end of EWIS component life of Company A’s product could potentially be years longer than that of Company B.

While this approach of limiting the component use to its original performance specifications is useful, many have identified this as impractical. Often, this line of thinking into a more fundamental question about any component performance; if a component is in a condition that would not be placed into a new aircraft design, why leave it on an existing aircraft?

Thankfully, most components placed in the aircraft will never be stressed to their maximum performance capabilities. The performance capabilities of many of these EWIS components will be stressed about 30 to 50% of their capabilities, and as such, there is significant leeway for component degradation.

End of Life

The end of component life can be assigned by economic, risk, or performance considerations. Each of these have their merits and potential benefits. One area that was not considered during this assessment or the review of these methods, was the future performance of the system. Each of these looked at the current condition for actions in the terminations. But if the goal is for the aircraft to be flown for another 10 or 20 years then additional assessment to determine the degradation and performance is necessary.

Aging EWIS can be Measured
No one wants EWIS problems to define the health of their aircraft. Get the information you need to properly maintain your aircraft. Contact Lectromec.

Lectromec has developed the technical capabilities to predict the remaining service life of EWIS components. By doing these assessments, it becomes possible to not only see the cost and risk of wire system issues today but also predict how those will evolve as the aircraft ages. By doing this assessment, it becomes possible to predict the operational costs and maintenance costs in the years to come.

The challenge of maintaining a reliable aircraft electrical system is a great challenge for maintainers. The aging aircraft systems work against maintainers repeated efforts, and this is a difficult uphill battle. Lectromec has been solving EWIS degradation problems for more than 30 years and we have helped numerous fleets proactively address their problems. With the assessment of the wiring system providing a clear path and costs for handling EWIS degradation, actions can be taken, and data-based decisions can be made.

Lectromec has produced a white paper covering past efforts. This is the first step to understanding how an EWIS can be evaluated which will help reduce decision uncertainty and ensures the decision you make for maintenance is the right one. To take the next step, set up an appointment with Lectromec.

Michael Traskos

Michael Traskos

President, Lectromec

Michael has been involved in wire degradation and failure assessments for more than a decade. He has worked on dozens of projects assessing the reliability and qualification of EWIS components. Michael is an FAA DER with a delegated authority covering EWIS certification and the chairman of the SAE AE-8A EWIS installation committee.