View Latest Blog Entries
Close
Categories
Testing & Assessment Certification Standard & Regulation Aging Wires & Systems Maintenance & Sustainment Protection & Prevention Management Conference & Report Research Miscellaneous Arcing
Popular Tags
Visual Inspection High Voltage AS50881 MIL-HDBK MIL-HDBK-525 FAR Electromagnetic Interference (EMI) AS4373 Maintenance FAR 25.1707 Wire System Circuit Protection
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 Aluminum arc damage Arc Damage Modeling Tool Arc Fault (AF) Arc Fault Circuit Breaker (AFCB) Arc Resistance 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 B230 ASTM B355 ASTM B470 ASTM D150 ASTM D2671 ASTM D495 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 EMI 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 Filter Line Cable 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-F-5372 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 Scrape Abrasion 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

Heat shrink tubing application and aircraft EWIS components

Protection & Prevention

Heat shrink tubing can be found in nearly every location on aircraft and can interact with aircraft EWIS components. These materials protect wire repairs, provide additional abrasion protection, and prevent the ingress of fluids (and in a pinch, may be used as a secondary harness support when other options are not viable). Although this product can be found everywhere, there are still challenges that are common to manufactures and maintainers.

Product Identification

Currently there are no requirements for marking or identifying mark on heat shrink tubing; the product is identified at the spool level, but not on the product itself. As the product moves through the acquisition and distribution process, a length of tubing may be cut from the spool and sold without identifying marks on the delivered package. As such, the end user of the product may not know the original material source.

There are a couple of reasons why an end user would want the identification at the item level:

  • Counterfeiting protection
  • Determine the material source
EWIS components
Typical EWIS components

What is seen in the fleet is that, if there is any problems with the product, it is hard to trace back to the source. For example: a heat shrink sleeve is placed onto an aircraft wiring system, and sometime during the service life (far earlier than anticipated), the tubing degrades and becomes unusable. Because there is a lack of identify marks, going back through the supply chain to identify the root cause may be impossible.

Given that the typical application of heat shrink tubing is only a couple of inches, it would be difficult to have all necessary identifying information placed on each segment. The lack of tubing identification may be a problem without a practical solution.

Flammability

For those that are not familiar with the flammability classifications for heat shrink, there are three currently defined:

An obvious caution here is that a user may look at class #1 as non-flammable, and class #3 as being highly nonflammable and may think that the class #2 product is a mid-range product in terms of flammability (also, class #2 products are cheaper as they do not have the flame retardant chemicals).

For those in the aerospace industry, an immediate question should be considered: Why is a flammable material included in an aerospace standard? Great lengths are taken to ensure that nearly everything on an aircraft is non-flammable (with the small exception of fuel). Unfortunately, because this material is used widely outside aerospace, the class #2 heat shrink tubing cannot be removed from the standard. As such, there should be an aerospace restriction for Class 2 heat shrink sleeving.

Storage and Shelf Life

It is fairly obvious why there is a maximum storage temperature of heat shrink tubing, but should there be a minimum? The recommended storage temperature for many of the heat shrink tubes is 18-35oC. The fact is, the impact that cold has on heat shrink tubing can be much lower. The idea with heat shrink tubing is that the application of heat will cause the contraction; lower temperatures do not impact the heat shrink tubing.

As a final point of creating a shelf life on heat shrink tubing is to consider what should be a practical shelf life for heat shrink tubing? From a practical perspective, one must consider the following – if you churn through your stock once every 10 years, the annual usage is likely a low quantity? Except for distributors, a 10 year shelf life is not a large concern.

For everyone else, keep the tubing in a cool, dry, limited light exposed area to maximize the shelf life.

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.