View Latest Blog Entries
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 Maintenance Electromagnetic Interference (EMI) 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 accessibility 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 installation 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 distance 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 impact of series arcing


While electrical arcing on aircraft is often associated with a dramatic failure event, a much more common occurrence on aircraft is series arcing. Series arcing can contribute to overheating and component damage, reduction in signal quality, and poor/sporadic performance of electrical equipment. In this article, we discuss the basics of series arcing, the failure effects, and mitigation techniques.

Basic Process

The basic process of a series arc is that the electrical energy still passes through the load as opposed to parallel arcing where the load is bypassed. As seen in the circuit diagram below, series arcing may occur at several locations within a circuit as long as there is a current limiting load. This may occur at any of the connection points including connectors (poor mating), terminal boards (not sufficiently tightened), and or ground studs (lock nut not in good contact).

series arcing

Although there are many methods for the arcing to start, a simple example of series arcing is a wire terminated with a ring terminal on a terminal board with a loose terminal. The figure below is an example of series arcing. On the left side, a wire terminated with a ring terminal is connected to a circuit with a resistive load and left with a loose connection. Without mechanical stress, it is possible that this would go undetected with functional checks. To simulate an aircraft environment, this was placed on a vibration table and the power was applied. The figure on the right shows the series electrical arcing captured during this test.

series arcing

Failure Effects

As mentioned earlier, series arcing is not as dramatic as parallel arcing, but can impact airworthiness. The arcing at the loose connection creates a hot point in the circuit. Although the wire conductor acts as a heat sink, the heat can increase quickly depending on the circuit load (e.g. a circuit with a 10A load will cause more heating due to series arcing than a circuit with a 5A load).

This localized heating can damage the terminal, wire insulation, and the protective sleeving. If the wire is in a harness, this may also damage other wires and lead to a more dramatic failure event if different voltages are present. This is also a concern as it may create a scenario in which uncommanded activation of a circuit occurs. Lastly, this heating may cause the ignition of any flammable materials of fluids.

Mitigation Techniques

Diagnosing series arcing can be difficult as the issue will likely only occur when there is a vibration or other mechanical stress on the system.  As such, a component may appear to be malfunctioning while in-flight, but operate normally when on the ground. Simple point-to-point checks will not be able to detect this as the ring-terminal connection will be made (albeit not with an ideal connection, but still good enough for an ohm check). As such, maintenance and troubleshooting will require shaking at or near the connection points while the system is under electrical stress. The breaks in the circuit are likely to be brief, so using the right equipment for the task is important.

Arc fault circuit protection devices that comply with SAE standard AS5692 are designed to identify series arcing and open the circuit once detected. The obvious difficulty is that some devices can generate current and voltage signatures that are very similar to those of series arcing. As such, care must be taken to check the circuit protection compatibility.

New Research

During the week of September 8th, at the Federal Aviation Administration (FAA) Tech Center in Atlantic City, Lectromec, Ametek, the Navy, and the Air Force came together to work on common research goals. In addition to examining the effects of electrical arcing damage on composite materials (to be discussed in a future article), the group evaluated the characteristics of 270VDC series arcing. Although the results are preliminary and we are still examining the data, there were some interesting discoveries that the preliminary results showed. As the data is examined and the implications better understood, we will post the results in future blogs.

If you are interested in contrasting parallel and serial arcing, you may want to read Understanding Series and Parallel Arcing for Aircraft Engineers.

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.