In the aviation industry, we sure LOVE using acronyms. It doesn’t matter if the aircraft is for military or commercial application, we LOVE our acronyms. Lately, I have noticed more and more references to the acronym EWIS. So, what does EWIS mean? EWIS is an acronym for Electrical Wiring InterConnect System or Electrical Wiring InterConnection System (EWIS). EWIS means any wire, wiring device, or combination of these, including termination devices, installed in any area of the aircraft for transmitting electrical energy, including data and signals between two or more intended termination points. EWIS is basically the wiring system of an aircraft, including all the wiring harnesses that InterConnect currently makes for various aerospace and defense companies and countries. Essentially, EWIS includes the wires, connectors, backshells, splices, etc.; the entire bundles that make up the aircraft wiring system. So, I wondered why EWIS seemed so much more prevalent today than in the early 1990s when John and I started InterConnect Wiring. Here is what Wikipedia says:
Prior to the aviation accidents of TWA Flight 800 and SwissAir 111, the wiring on aircraft was a minor concern. In response to these accidents, the Aging Transport Systems Rulemaking Advisory Committee (ATSRAC) was chartered to gather industry leaders to examine the current state of aging aircraft systems. The committee included several key organizations and businesses such as ATA, NASA, Northwest Airlines, Boeing, Airbus, and the FAA. The following is an excerpt from the FAA’s regulations released November 8, 2007 governing aspects of EWIS on aircraft as to the reason for the increased concerns regarding EWIS:
“Safety concerns about wiring systems in airplanes were brought to the forefront of public attention by a mid-air explosion in 1996 involving a 747 airplane. Ignition of flammable vapors in the fuel tank was the probable cause of that fatal accident, and the most likely source was a wiring failure that allowed a spark to enter the fuel tank. All 230 people aboard the airplane were killed. Two years later, an MD–11 (Swissair Flight 111) airplane crashed into the Atlantic Ocean, killing all 229 people aboard. Although an exact cause could not be determined, the presence of re-solidified copper on a portion of a wire of the in-flight entertainment system cable indicated that wire arcing had occurred in the area where the fire most likely originated.
Investigations of those accidents and later examinations of other airplanes showed a collection of common problems. Deteriorated wiring, corrosion, improper wire installation and repairs, and contamination of wire bundles with metal shavings, dust, and fluids (which would provide fuel for fire) were common conditions in representative examples of the ‘‘aging fleet of transport airplanes.’’
Unfortunately, like commercial aerospace, defense aircraft, including fighter jets and utility helicopters, have experienced significant EWIS issues as well. Kapton wire has been a problem for many aircraft including the F-16, F-15, and the UH-60.
There you have it. EWIS in a nutshell. A terrific source for more information about EWIS is InterConnect’s eBook which you can find at https://www.interconnect-wiring.com/introduction-to-aircraft-wiring-harness-diagrams-engineering-design-and-disconnects/.
