View Latest Blog Entries
Close
Categories
Testing & Assessment Certification Standard & Regulation Aging Wires & Systems Maintenance & Sustainment Management Conference & Report Protection & Prevention Research Miscellaneous Arcing
Popular Tags
Visual Inspection High Voltage AS50881 MIL-HDBK MIL-HDBK-525 FAR AS4373 Electromagnetic Interference (EMI) Maintenance FAR 25.1707 Wire System Arcing Damage
All Tags in Alphabetical Order
2021 25.1701 25.1703 abrasion AC 33.4-3 AC 43 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 AS29606 AS4373 AS4373 Method 704 AS50881 AS5692 AS6019 AS6324 AS81824 AS83519 AS85049 AS85485 AS85485 Wire Standard ASTM B355 ASTM B470 ASTM D150 ASTM D2671 ASTM D8355 ASTM D876 ASTM F2639 ASTM F2696 ASTM F2799 ASTM F3230 ASTM F3309 ATSRAC Attenuation Automated Wire Testing System (AWTS) Automotive Avionics backshell batteries bend radius Bent Pin Analysis Best of Lectromec Best Practice bonding Cable Cable Bend cable testing Carbon Nanotube (CNT) Certification cfr 25.1717 Chafing Chemical Testing Circuit Breaker circuit design Circuit Protection cleaning clearance Coaxial cable cold bend collision comparative analysis Compliance Component Selection Condition Based Maintenance Conductor Conductor Testing conductors conduit Connector Connector rating connector selection connector testing connectors contacts Corona Corrosion Corrosion Preventing Compound (CPC) corrosion prevention Cracking creepage 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 electric aircraft Electrical Aircraft Electrical Component Electrical Power Electrical Testing Electrified Vehicles Electromagnetic Interference (EMI) Electromagnetic Vulnerability (EMV) Electrostatic Discharge 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 fault tree Fixturing Flammability fleet reliability Flex Testing fluid exposure Fluid Immersion Forced Hydrolysis fuel system fuel tank ignition Functional Hazard Assessment functional testing Fundamental Articles Fuse Future Tech galvanic corrosion Glycol Gold Gold plating Green Taxiing Grounding hand sanitizer handbook Harness Design harness protection hazard Hazard Analysis health monitoring heat shrink heat shrink tubing high current high Frequency high speed data cable High Voltage High Voltage Degradation HIRF History Hot Stamping Humidity Variation HV connector HV system ICAs IEC 60851 IEC60172 IEEE immersion insertion loss 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 lightning protection liquid nitrogen lithium battery lunar Magnet wire 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-7928/5 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 polyamide polyimdie Polyimide-PTFE Power over Ethernet power system Power systems predictive maintenance Presentation Preventative Maintenance Program 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 Separation Requirements Series Arcing Service Life Extension Severe Wind and Moisture-Prone (SWAMP) Severity of Failure shelf life Shield Shielding Shrinkage signal 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 superconductor 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 volume resistivity vw-1 wet arc white paper whitelisting Winding wire 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

The field of aircraft Electrical Wiring Interconnection Systems (EWIS) has changed significantly in the last two decades. These changes have impacted the design, installation, maintenance, and sustainment of electrical wiring systems on aircraft. For example, increased electrical load requirements, materials restrictions, system safety assessment, and new regulations are just some of the areas that have required an augmented approach to signal and power delivery. In this article, we consider the area which will likely see a significant evolution in the coming year.

Distributed Power/Data Systems

The purpose of distributed power systems is that multiple power nodes existing in the aircraft electrical system and equipment connect to these nodes rather than connect to circuit breakers in the flight deck. The benefit of the distributed power system network is an improvement in system reliability. The loss of a single node/component in this network, unless at the origin or destination, is not a system crippling event.

Looking more closely at what an idealized network would look like, a networked system would not only handle power but signal and data. As with any system design, there are drawbacks. The additional interconnection points will create an increase in data latencies and noise. Any connected system to this distributed data network must be designed to handle the additional latency with each connection point.

Furthermore, the adaptability of these systems is high. In an idealized implementation, if a new device is added to aircraft, a configuration update is made to the distributed power system and the device is connected to the closest node. This can provide a huge reduction in time to implement any new device or technology. There are some concerns that come with this means of deployment, in particular, how isolated are the systems in term of EMI, regenerative power, and if a power quality. Each of these must be considered during implementation.

Compliance with Regulations

Further, there are significant challenges when it comes to understanding the complexity of these systems as they become more networked. The certification requirements for EWIS, such as those that cover the risk assessment of the wiring system, set expectations both on assessing the physical and functional impact of failure.

Consider the power cables. Before the use of distributed power systems, the wiring was spread across multiple areas within the aircraft. One of the benefits of this design approach was that the amount of electrical power available at any single harness was much less. By going to networked power, each section of the network distribution must have larger gauge interconnections. This creates an issue by requiring a greater physical separation distance from nearby systems.

Considering the complexity of the network, depending on how the system is designed, it may be possible to effectively engineer out the need to consider a failure of EWIS in fault tree assessment. However, until that is achieved, showing the reliability of EWIS will become more difficult. The network figure shows an example of a network with the loss of a single node. Historically this has been simplified in risk assessments, to a single value to the EWIS of a given system; however, the increased complexity requires a more in-depth review. Tools like Lectromec’s EWIS RAT can reduce the complexity of assessment.

Distributed Power Risk Calculation
Simplified representation of node failure in a distributed power/data network.

EWIS Component Design

To determine what will need to be addressed for the next generation of EWIS components, the requirements and trends of other parts of the aircraft design must be considered. Often, EWIS is not a design driver, other systems are designed and the EWIS must match the requirements of these systems.

Without a doubt, data generated by components and health monitoring will require more data generation. How this data is transmitted will create the need for deployment of high-quality data cables will be a larger portion of the next generation EWIS design. This may be pushed toward fiber or shielded copper cables, but the data rate and reliability will drive the market.

The big stressors on aircraft wire will still be the installation and maintenance. How will the next generation handle this? Tougher insulating materials will be the starting point. Currently, there are significant improvements in insulation technologies that are working their way to market and they show promise for long-term longevity.

Higher Voltage Systems

At sea level, it takes 1000V to cross a 1mm gap, and that scales linearly as the voltage increases. If we look at a typical connector with a pin spacing of 2.5mm (minimum separation distance between contacts), that would suggest that a need to use less than a 2500V differential (peak voltage, not RMS) between two pins and still be safe (safe is defined here as not having energy jump from one pin to another).

With this in mind, how the EWIS will support the higher voltages requires consideration at the device level and system implementation level. Each of these high voltage switching devices will need to be able to break the circuit, and thus, will require larger gaps between contact pads and larger packaging to contain the switching. At the system level, this may require that system wiring is further separated from critical aircraft components (e.g. fuel tanks) and from signal wiring to avoid EMI. These are only some of the challenges of implementation of the higher voltage system.

Conclusion

The changes to aircraft EWIS over the next generation will be driven by distributed networks and higher voltage power. The only way to achieve this in a safe and reliable fashion will be with a focus on the risk assessment of the aircraft’s EWIS design. Let Lectromec quantify these risks through testing and/or EWIS risk assessment.

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. In September 2014, Michael was appointed as an FAA DER with a delegated authority covering EWIS certification.