View Latest Blog Entries
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

Latest Developments in Wire and Cable (Spring 2019)

Conference & Report

Key Takeaways
  • Progress has been made on defining wire/cable voltage ratings for airborne systems.
  • The next revision of AS50881 is near release.
  • There is new guidance on wire harneess derating.

Wire and cable standards are never proactive, but reactive to industry needs, and as the aviation world moves to high power systems, wire and cable must catch up to ensure the products are available for long reliable service life. Twice a year the SAE wire/cable community comes together to slowly push the standards and industry guidance forward; this year, New Orleans was the setting.

During this three-day meeting, several topics were discussed impacting the next generation of aircraft designs. Here, we cover a couple of these developments.

Crank Up the Voltage

As with past meetings, a fair bit of time and discussions were devoted to voltage ratings of wire. For those that have not been following the saga of voltage ratings, Lectromec has covered this in several previous articles. In short, the voltage power systems being employed and/or developed for aircraft applications are greater than previously deployed. The concern among the power distribution and Electrical Wiring Interconnection System (EWIS) component communities is the high voltages may stress the wire insulation and result in more rapid ageing/deterioration.

To address these issues, the SAE AE-8D/A and AE-7 committees held a joint session. One presentation from the AE-7 community proposed several voltage levels for aircraft power applications. These voltage levels specifically identify the maximum allowable voltage for a particular configuration (e.g. Voltage Category 4: AC 300 – 450VAC, DC 210 – 320). With this as a basis, a strong backing exists for the wire/cable committee to develop standards that fit the voltage category needs.

It is uncertain how the application of wire/cable voltage categories will evolve wire/cable standards, but it does help to set a greater level of certainty in the voltage rating arena. The AE-8D community has performed a significant amount of research investigating methods and techniques for evaluating long-term high-voltage endurance; prior to this meeting, the application was at a bit of an impasse. One hopes that the community will use this as an opportunity.

To do this, the community will need to:

  1. Define voltage ratings for wires,
  2. Define the expected performance criteria on the power system to ensure safe continued operation at those voltage levels (i.e. a Voltage Category 4 wire can last 100,000 hours at voltage assuming use below maximum rated temperature and a power system frequency at or below 400Hz), and
  3. Publish an Aerospace Information Report (AIR) cataloging the work already done and guidance on potential wire/cable derating when used outside set performance levels (e.g. what can be expected when a 400Hz rated wire is used at 1200Hz).

Lectromec is looking forward to assisting in the development of these standards.

Coming Soon – AS50881 Rev G

The latest round of balloting on the AS50881 standard was completed just a couple weeks ago. At the AE-8A committee, the final changes to the standard were agreed-upon and Revision G may soon be out as a final edition (assuming no hiccups occur between now and final publication).

Among the changes to the standard include:

  • A prohibition on wire harness termination with the D-sub connectors. These connectors that have been popular for decades, are not suited for airborne applications. Frequently, these connectors do not have any EMI protection, environmental protection, or any of the other typical performance requirements of aircraft EWIS components.
  • To be more in line with separation requirements of redundant systems in FAA EWIS regulations (25.1709), the AS50881 specifically now calls out for redundant systems (identified as equipment with the duplicate functions) shall be run in separate bundles. In summary, this requirement goes hand-in-hand with the best practices for achieving maximum reliability for flight critical systems (i.e. those systems that require redundancy).
Twisted Thermally aged wire
Determining what a wire/cable’s temperature will be in-service is not straight forward. Even the best thermal modeling still runs into issues with temperature estimation. Thankfully, the generalized principles for wire harness derating are pretty good.

Tools for Harness Derating

A presentation during the AE7 meeting was on the work performed on AIR6540. This AIR on “Fundamentals in Wire Selection and Sizing for Aerospace Applications”, runs through many of the fundamental principles for the selection of wire sizes for aircraft applications. Thankfully, much of the process outlined in this document follows the methods prescribed in AS50881.

The document also goes beyond what is described in the AS50881 to ensure that the wire selection is performed in such a way that the physical and environmental conditions within the operational environment are considered. The AIR6540 goes through a thorough step-by-step process and examples to show how to properly derate a wire/wire harness.

Those that have been reading Lectromec articles for a while have probably seen several articles discussing wire derating both for voltage and thermal reasons. The AIR6540 is just one more piece of information engineers can rely upon to guide their engineering process.

Next Meeting

The next SAE AE-8A and 8D meetings will be in San Diego and will coincide with the Aerospace Electrical Interconnect Systems Symposium (AEISS). The AEISS occurs once every two to three years and brings together several groups for a day of presentations. Those interested in submitting an abstract should review the information here.

Latest Developments

To keep on top of the latest developments, make sure that you are subscribed to the Lectromec newsletter .

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.