View Latest Blog Entries
Testing & Assessment Certification Aging Wires & Systems Standard & Regulation Management Conference & Report Maintenance & Sustainment Protection & Prevention Research Arcing Miscellaneous
Popular Tags
Visual Inspection MIL-HDBK MIL-HDBK-525 AS50881 FAR High Voltage FAR 25.1707 Electromagnetic Interference (EMI) Maintenance Wire System Arcing Damage Degradation
All Tags in Alphabetical Order
25.1701 25.1703 Accelerated Aging ADMT Aging Systems Aircraft Power System Aircraft Service Life Extension Program (SLEP) arc damage Arc Fault (AF) Arc Fault Circuit Breaker (AFCB) Arc Track Resistance Arcing Arcing Damage AS22759 AS22759/87 AS4373 AS4373 Method 704 AS50881 AS5692 AS6019 AS83519 AS85485 AS85485 Wire Standard ASTM D150 ASTM F2799 ATSRAC Attenuation Automated Wire Testing System (AWTS) batteries Bent Pin Analysis Best of Lectromec Best Practice bonding Cable cable testing Carbon Nanotube (CNT) Certification Chafing Chemical Testing Circuit Breaker circuit design Circuit Protection Coaxial cable cold bend comparative analysis Compliance Component Selection Condition Based Maintenance Conductor conduit Connector connectors contacts Corona Corrosion Corrosion Preventing Compound (CPC) Cracking D-sub data analysis data cables degradat Degradation Delamination Derating diagnostic dielectric constant Distributed Power System DO-160 Electrical Aircraft Electrical Component Electrical Testing Electromagnetic Interference (EMI) Electromagnetic Vulnerability (EMV) EMC EMF EN3197 EN3475 EN6059 End of Service Life End of Year Energy Storage engines Environmental Environmental Cycling ethernet EWIS Component EWIS Design EWIS Failure EWIS Thermal Management EZAP FAA AC 25.27 FAA AC 25.981-1C 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 testing Fundamental Articles Future Tech Green Taxiing Grounding Harness Design Hazard Analysis health monitoring heat shrink tubing high current high Frequency high speed data cable High Voltage History Hot Stamping Humidity Variation ICAs IEC60172 Instructions for Continued Airworthiness Insulation insulation resistance IPC-D-620 ISO 17025 Certified Lab Kapton Laser Marking life limited parts life projection Lightning Maintenance Maintenance costs Mandrel Mechanical Testing MECSIP MIL-C-38999 MIL-C-85485 MIL-DTL-17 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-1560 MIL-STD-1798 MIL-STD-464 MIL-T-7928 MIL-T-81490 MIL-W-22759/87 MIL-W-5088 Military 5088 modeling MS3320 NASA NEMA27500 No Fault Found off gassing Outgassing Overheating of Wire Harness Parallel Arcing part selection Performance physical hazard assessment Physical Testing polyimdie Polyimide-PTFE Power over Ethernet Power systems predictive maintenance Presentation Probability of Failure Product Quality Radiation Red Plague Corrosion Reduction of Hazardous Substances (RoHS) regulations relays Reliability Research Rewiring Project Risk Assessment SAE Secondary Harness Protection Separation Requirements Series Arcing Service Life Extension Severe Wind and Moisture-Prone (SWAMP) Severity of Failure Shield Shielding signal cable silver plated wire smoke Solid State Circuit Breaker Space Certified Wires Splice standards stored energy supportability Sustainment Temperature Rating Temperature Variation Test methods Test Pricing Testing Thermal Circuit Breaker Thermal Endurance Thermal Index Thermal Shock Thermal Testing Tin plated conductors Troubleshooting TWA800 UAVs verification Visual Inspection voltage white paper whitelisting Wire Ampacity Wire Certification Wire Comparison wire damage wire failure wire properties Wire System wire testing Wire Verification work unit code

AS4373 – Testing Aerospace Cables – Part 1

Testing & Assessment

When testing aerospace wire, there are several test standards that might be considered; however, the one that is most commonly referenced is the SAE AS4373 “Test Methods for Insulated Electric Wire” which covers a wide range of mechanical, electrical, environmental, and workmanship tests. In this first article of a two part series, we describe the tests that are included in the method and how they can be used to determine wire performance.

EWIS reassessment will be necessary to ensure reliable system performance.
Tight controls on every test are important, but there are some, like the scrape abrasion, where slight changes can have a large impact. Many of the AS4373 tests share this commonality.

This is the first article in this series, the next article will be published the last week of January 2017.


Wires undergo a variety of mechanical stresses, which are dependent upon their installed application. To determine their performance, one or more of the following test methods should be considered for performance evaluations. The following is a listing of the AS4373 mechanical tests that stress the insulation, conductor, or both.

Test Method

Test Name

Short Description


Needle Abrasion Test

The specimen is placed under an oscillating jig simulating abrasion across a surface.


Cold Bend

The specimen is slowly wrapped around a mandrel at extremely cold temperatures. If no insulation cracks are found, then the specimen has passed.


Dynamic Cut Through

A blunt edge is pressed into the specimen until the insulation is breached. May be performed at ambient or elevated temperatures.


Flex Life

The specimen is flexed until the conductor is broken. Important for high flex applications.


Insulation Tensile Strength and Elongation

The insulation is removed from the specimen and pulled until broken.


Notch Propagation

A small cut is made in the insulation and the specimen is flexed. If the notch propagates to the conductor, the specimen has failed.


Stiffness and Springback

The specimen is flexed and the flex memory is measured. Important metric to determine workability.


Mandrel and Wrapback Test

The specimen is wrapped on itself and heated. Any insulation crack constitutes a failure.


Wrinkle Test

Wrap the specimen and look for wrinkles in insulation. Particular application to tape wrapped constructions.


Durability of Wire Manufacturer’s Color/Identification

Similar to Method 301, but examining the durability of wire marking.


Durability of Wire Installer’s Identification

The specimen is exposed to mechanical, thermal, chemical, and environmental stresses to determine mark durability.


Bend Test

This test is typically used in coordination with other tests to mechanically stress a sample after environmental/thermal exposure tests.


Circumferential Insulation Elongation

The insulation is extracted from the specimen and expanded outward. Used to quantify insulation performance under radial stresses.


Wrap, (Mandrel Wrap)

Similar to Method 712.


Wires are designed to transfer electrical energy from end to end. Electrical tests are conducted to evaluate the wire’s capability to perform this basic function. The following tests are electrical tests that, for the most part, assess the electrical performance of the wire insulation.

One item to note here is that the following test methods do not cover anything that is related to signal integrity. Other standards, such as the AS6070 (*double check) is designed for signal application evaluation.

Test Method

Test Name

Short Description


Dielectric Constant

The capacitance per unit length of the wire is measured. (Article)


Corona Inception and Extinction Voltages

The specimen is wrapped around a grounded mandrel and the applied voltage is slowly increased until corona is detected (corona inception). The voltage is then lowered to find the extinction voltage. Useful to determine voltage rating.


Impulse Dielectric

The specimen is subjected to a high voltage pulse. No insulation breaches shall be detected.


Insulation Resistance

Also known as ‘volume resistance’, this measures the insulation resistance. Important for high impedance circuits.


Spark Test of Finished Wire Insulation

Assembly line style test where a high voltage is applied to the specimen as it is pulled through a grounded chainmail. Good for finding insulation breaches in spools of wire.


Surface Resistance

For most applications, the surface resistance of wire should be as non-conductive as possible.


Time/Current to Smoke

An electrical current is stepwise increased on a sample until smoke is visually detected.


Dry Arc Propagation Resistance

Mechanical abrasion of the specimen initiates an electrical fault to determine arc track resistance/propagation.


Wet Arc Propagation Resistance

A fluid is dropped on a pre-damaged specimen to initiate an electrical fault to determine arc track resistance/propagation.


Voltage Withstand (Wet Dielectric)

Most often used in combination with other tests. This test applies a high voltage to find insulation breaches.


Wire Fusing Time

A high current is placed on the wire to determine time to fusing (separation of conductor).


Voltage Rating

Still not defined. See here for a discussion on voltage ratings.


Smoke Resistance

Apply a current on the sample to reached target temperature. Visual detection of smoke shall be considered a failure.


The methods above provide the process for electrical and mechanical testing needed on aircraft wires to determine wire performance. The next article will cover the environmental tests, conductor, and final product quality checks that are included in the AS4373 test standard.

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.