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 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

Corrosion prevention compounds (CPCs) and aircraft EWIS


Corrosion prevention compounds (CPCs) are compounds that are placed on many aircraft components. Applied to a variety of mechanisms, these compounds have been found to increase structural life by reducing corrosion. While there are benefits to reducing corrosion, the impact of the CPCs on wire insulation and the aircraft Electrical Wire Interconnection System (EWIS) in general is not well understood.

Current CPC Requirements

Section 4.6.3 from MIL-PRF-81309G, the military performance specification on “Corrosion Preventive Compounds, Water Displacing, Ultra-Thin Film”, states the following with regard to testing of wires:

Compatibility with polyimide, wiring insulation. Approximately 24 inches (61 cm) of wire conforming to MIL-W-81381/11, shall be formed into a coil. Place the coil in a 4-ounce (118 ml) wide mouth jar and add enough corrosion preventive compound to the jar to completely cover the coil of wire. Cap the jar and store it at room temperature for 14 days. Repeat this procedure using distilled water as the test medium. At the end of the storage period, remove the coil and rinse thoroughly with tap water at room temperature. Suspend the coil and allow it to drain until completely dry. Each wire shall be wrapped tightly around a 0.125-inch mandrel and unwrapped slowly, noting the appearance and number of any cracks in the insulation. The wire shall meet the requirements specified in Table I. The wire shall be immersed in a 5 percent by weight sodium chloride solution and subjected to a one-minute dielectric test of 2,500 volts (rms).

Note that this is the only wire specification that is required to be tested in this specification that is not permitted on new military aircraft. There is nothing about ETFE, FEP, or other common wire insulation types. There is nothing about impact evaluation to heat shrink tubing, clamp cushions, or splices. Clearly, the existing standard needs to catch up with the modern EWIS.

Use of CPCs and Connectors

When using CPCs, it is important to ensure that the internal parts of the connectors (the parts conducting energy) are not exposed. Open connectors should be capped with the proper size cap to limit the ingress or exposure of CPCs. If caps cannot be located, the connector should be placed in a plastic bag and closed. The reason for doing this is that the CPCs can leave a thin residue on connector terminals, which can impede signal conduction or create high resistance locations, thereby limiting electrical current flow.

At no point should CPCs be sprayed into connectors with fiber optics as this can degrade the transmission through the connector. Although there is documented evidence that this is being applied in at least one platform, this application appears to be used as a bandage for a design error.

Examination of EWIS CPCs Effects

corrosion prevention compounds (cpcs) and aircraft EWIS
Flammability testing of a wire or cable is done with direct flame application.

A project to be taken up by the USAF will try to determine the impact of CPCs on wire insulation and other EWIS components. Because of the different characteristics of wire insulations, it will become necessary to test all modern wire insulations. In case CPCs negatively impact one or more wire insulations, it will become necessary to quantify this and recommend that EWIS be protected during the spraying of CPCs or when compartments are fogged.

As a proactive measure, the Navy 505 wire installation and repair manual recommends against applying CPCs into the mating areas of connectors. Furthermore, the manual states that CPCs should not be placed on wire/cables as the contamination may degrade the wire insulation and performance.

Impact to the User

Although more data is necessary (and research results are pending), it is recommended at this time that EWIS be protected in any area in which CPCs are being applied.

Michael Traskos

Michael Traskos

President, Lectromec

Michael has been involved in wire degradation and failure assessments for more than a decade and has written over 100 EWIS-related articles, technical papers, and research reports.