Wire and Cable: Aircraft EWIS and SWAP in Focus

By By Woodrow Bellamy III | April 1, 2016
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Aircraft wire and cable needs continue to be a major trend for readers of Avionics Magazine, as 100 percent of respondents to our industry survey this year said they need to acquire new wire and cable solutions to support such capabilities as Automatic Dependent Surveillance Broadcast Out (ADS-B Out) mandate compliance, new radar or navigation technologies or — the biggest commercial trend sweeping the industry — new cabin-based In-Flight Entertainment (IFE). The leading need driving purchasing decisions for new wire and cable solutions is to support installation of new avionics systems because of upgrades or retrofits on in-service commercial, business, general aviation and military aircraft. And with operators, installers and airframe manufacturers always looking to improve the efficiency of in-service aircraft with aftermarket upgrades, wire and cable continues to be strong market.

New Solutions and Trends

Aircraft network data rates have reached 10 gigabits per second, and the industry is continually introducing speedy optical fiber cables into aircraft today. This is nothing new, as one of the first benefits of optical fiber in military aircraft was recognized as far back as 1976, when a re-wiring project for an A-7 Corsair fighter jet replaced 300 copper wired circuits with 13 optical fiber cables, according to aerospace wire and cable manufacturer KSaria.

Carlisle is a company that could be looked at as one of the most important suppliers in the wire and cable industry. “Our philosophy is to stay ahead of the curve on protocols so we really offer, in our eyes, the broadest breadth of product support for whatever the latest required protocols are, whether it’s Ethernet or fiber channels or Serial AT Attachment (Serial ATA), Peripheral Component Interconnect Express (PCI Express), Digital Video Interface (DVI), High Definition Multimedia Interface (HDMI), all of those different architectures that people are using to transfer data over, we have a cable to support it,” said Al Kelly director of product management of wire and cable at Carlisle Interconnect Technologies (Carlisle IT),. CarlisleIT recently introduced the latest Gigabit-STP CAT 7 Ethernet cable, featuring 10 Gb Category 7 performance to 50 meters. This NF26GBSTP-100 is designed for Ethernet backbone and other high-speed data applications within the aerospace, defense and military markets. CarlisleIT’s USB 3.0 cable will provide faster transfer speeds for IFE and other avionics applications.

Rush Holladay, manager of business development at WireMasters, says demand for new IFE equipment is driving demand for new wire and cable solutions to support the reliability of that equipment. “The growth area the demand area in our world has been IFE. There’s different methodologies to try to get content to the seat back — different people do it different ways — but at the end of the day it takes some type of cable to have enough bandwidth to handle all of that and to do it reliably,” said Holladay.

Results from the Avionics wire and cable survey showed readers ranked solutions from Pic Wire & Cable, B/E Aerospace’s Emteq and TE Connectivity as the wire and cable products that they have used most frequently.

Holladay says research and interaction with customers by WireMasters has shown that on a helicopter, removing just one pound of weight can equate to a fuel savings of up to $3,000 over the course of an average operation per year.

Size, Weight and Power (SWAP) needs drive manufacturers of components that wiring and cabling cannot function without: connectors.

“There are some trends specifically in the market we’ve been working to address. Three major ones, continued work on reduction of weight, the other one is building higher reliability products to reduce risk, and the third one is to build products that address the market need for higher bandwidth and data within the aircraft, whether it’s in the passenger cabin or at the glass cockpit avionics side for pilots themselves,” said Wes Morgan, senior manager for aerospace products at ITT Corp. Morgan lists imaging and sensor related functionality as some of the more data intensive applications that ITT’s connectors support. ITT notes that its OctoGig connector is one of its latest that can serve as a single termini solution for 10 GB data transfer rates over copper. Regarding copper, Morgan said ITT also sees commercial aviation needs for fiber optics to reduce weight.

“Historically, the head in of the aircraft network starts with the avionics in the cockpit where the control is happening and the various motors, actuators, pumps around the aircraft that are being controlled from that point. You have a lot of copper wiring that’s going through that area through the e bay usually and then out to these various locations throughout the aircraft and there’s a lot of weight associated with that. It’s in the interest of the airframers and the industry as a whole to try to eliminate that,” said Morgan.

Aircraft Electrical Wiring Interconnect System (EWIS). Photo: Lectromec.


Assessing Electrical Wiring Interconnect Systems (EWIS) safety was tied for the second most compelling reason respondents to our Avionics survey are purchasing new wire and cable solutions.

Michael Traskos is president and CEO of Lectromec, a company that specializes in assessing wire and cable system degradation, services that it has performed for the U.S. Air Force and Boeing, among others. Lectromec performed an analysis of the commercial operating service difficulty reporting system that the FAA requires commercial airspace users to report to while operating in the National Airspace System (NAS).

Their analysis discovered that about once every five days, an aircraft is diverted due to a wire or cable failure. While that it a small percentage of annual flights, any diversion for any reason can be extremely expensive, especially for airlines.

Traskos, who is also an FAA Designated Engineering Representative (DER), says there are four main areas for consideration when selecting the proper wire and cable solutions for special aircraft applications. These four main aspects include the severe wind and moisture prone Severe Wind and Moisture-Prone (SWAMP) areas of the aircraft, where the EWIS system has the most exposure to external elements. He recommends the FAA’s EWIS job aid as guidance for addressing these areas. Secondly, a simple flex testing is not enough to identify issues with wires, instead, EWIS components in flex-prone applications require tests such as the AS4373 Method 704. Finally, Electromagnetic Interference (EMI) can be resolved using varieties of NEMA27500 cables or AS85485 wire standards, and the bend radius of thermocouple wiring used as part of temperature monitoring circuits should also be assessed based on the installation recommendations in the FAA’s EWIS job aid.

The Hard Part of IFEC

U.S. airlines offer In-Flight Entertainment and Connectivity (IFEC) on 78 percent of their available seat miles, compared to about 24 percent of internationally available seat miles, according to aviation research firm Routehappy. A report on aircraft Wi-Fi adoption by Euroconsult expects the number of in-service connected aircraft to grow from 5,300 in 2015 to 23,100 globally by 2025. That’s going to require hundreds of thousands of new wire and cable installations, and to learn about the importance of wire and cable diagramming, harness durability and reliability and the other factors of installing new IFEC equipment on aircraft that is rarely discussed at industry conferences and on mainstream news reports, Avionics caught up with one of the experts that has acquired some experience in this area. Dusty Walker, a former aircraft electrical engineer for Gogo, who has also worked with Booz Allen Hamilton, has founded his own company, Conscious Systems Engineering (CSE). CSE provides electrical engineering support for commercial and business aviation aircraft. Walker said there can be wiring challenges to look out for when upgrading IFEC technology on any aircraft.

“Some of the challenges involve routing IFE wire bundles with existing aircraft bundles while maintaining bundle separation in accordance with SFAR88 requirements and EMI spacing requirements from OEM specifications, for starters. There have been instances where aircraft data packages were not accurate and routing had to be moved based upon seeing the actual condition of the aircraft during a site survey, this involved drawing and instruction changes during the installation. In the case of system prototype installations for [Standard Type Certificate] STC approvals, there have been situations where initial power-up faltered because of missing contacts or ground wires not properly terminated, etc., and troubleshooting had to be performed with the avionics technicians. Another challenge is data wiring in specialized Quadrax connectors, 26- or sometimes even 28-gauge wiring is very difficult to terminate at the aircraft much less a workbench,” said Walker.

Providing detailed wire and cable harness designs for an aircraft EWIS must be done in accordance with the Original Equipment Manufacturer’s (OEM) guidelines and the regulations enforced by the civil aviation authority of the country that the work is being done in. A key focus for companies like CSE is also ensuring that every IFEC upgrade is completed on time, to the customer’s satisfaction.

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