View Latest Blog Entries
Close
Categories
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 Electromagnetic Interference (EMI) Maintenance 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 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

The year of 2018 was yet again another substantial year in commercial air travel. The first quarter of 2018 saw commercial flights carry over 202 million passengers in the US, approximately 8 million more than in the first quarter of 2017. Air travel remains increasingly popular, accessible to the public, and statistically the safest way to travel. This level of safety has been earned through decades of groundbreaking innovation, sometimes undeniably spurred by the desire to avoid repeating past tragedy.

An impactful and memorable incident that caused the industry to reevaluate its processes and procedures was the crash of Swissair Flight 111. Occurring almost two years after the Trans World Airlines Flight 800 (TWA800), the Swissair Flight 111 and TWA800 shared a common issue: wiring system failure.

The Background

On September 2nd, 1998, Swissair Flight 111 departed from New York’s J.F.K. airport at 8:18 p.m. The seven-year-old MD-11 aircraft was bound for Geneva carrying 215 passengers and 14 crew members. About 53 minutes after departure, the flight crew detected an abnormal odor in the cockpit. Initially dismissing it as a minor air conditioning problem, they quickly assessed that in fact it was smoke, and radioed air traffic control at 9:14pm declaring an issue. Originally turning back towards Boston, upon recommendation by air traffic control they diverted towards the closer Halifax International Airport in Nova Scotia and began landing procedures.

SwissAir111 Crash Investigation
The crash investigation found evidence of arcing wires. Source NASA.

About 13 minutes after the initial detection of smoke, the aircraft’s flight data recorder began to record a cascade of system failures. The flight crew then officially declared an emergency with the need to land immediately. One minute later, radio communications and secondary radar contact with the aircraft were lost, and the flight recorders ceased functioning. At 9:31pm, the aircraft crashed into the ocean about five nautical miles southwest of Peggy’s Cove, Nova Scotia, Canada. There were no survivors. The official report here.

The Recover Operation

The recovery of the remains of the aircraft and passengers began almost immediately and proved to be a harrowing task; the plane had hit the water at a high speed and the wreck was 180 feet below the waters of the Atlantic. Eventually, more than 4,000 people recovered about two million pieces of wreckage. Although the flight recorders proved to be a dead end since they stopped working six minutes after the pilots radioed emergency, the investigators quickly turned to the wreckage itself, as it was clear an onboard fire was the culprit.

The intense burn marks on pieces of debris reflected the heat intensity of the flames at various points in the aircraft, and the hottest temperatures of over 1,000oF were exclusively in the front of the plane. An extensive investigation concluded that the fire started when a damaged wire produced an arcing event — a phenomenon in which a wire’s damaged insulation leads to sparking — in the plane’s improperly installed new entertainment system that ignited a flammable insulation in the overhead of the cockpit.

SwissAir111 Crash Investigation
The investigation of SwissAir111 found the new entertainment system was connected to the emergency power bus. When load shedding began, power could not be removed from this system. Source TSB.

Investigation and Impact

The investigation of the Swissair Flight 111 crash has had a resounding impact on aviation safety for the hundreds of millions of travelers around the world. Twenty of the 23 Transportation Safety Board recommendations have resulted in major safety actions (many of these captured in the 25.1700 series of regulations that elevated wiring to a system). The flammable materials that were ignited in the attic fire, such as metallized polyethylene terephthalate (MPET), are no longer used in aircraft in order reduce the risk of fires. In addition, much more rigorous flammability testing and standards have been introduced in order to certify thermal insulation materials before usage.

The loss of the Swissair 111 flight was one more incident adding to the case against the use of polyimide insulation for aircraft wiring such as MIL-W-81381 constructions (other constructions such as AS22759/80 – /92 were deemed acceptable); new standards to separate and protect insulation materials from abrasion have emerged in order to increase resistance to arcing damage.

The FAA also began conducting a rigorous test program to evaluate arc fault mitigation in products like circuit breakers, new wire/cable insulation, and thermal acoustical blanket material. Despite the disastrous loss of life from a single event, the immense, invaluable knowledge and change that occurred from such an incident has improved commercial air safety for decades to come.

Devon Gonteski

Devon Gonteski

Engineer, Lectromec

Devon has been with Lectromec since 2017 and has been a key contributor on projects involving wire degradation assessment and wire/cable certification testing. Her skills in Lectromec’s lab ensure regular delivery of accurate test results across multiple disciplines.