NextGen: Avionics and the A&P
March 20, 2015
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  • With the onset of the new millennium came forth an abundance of even newer technology.  So just when does change stop? Contrary to the acceptance of some, that are still of the belief computers are a passing fancy and eventually the world will escape from the digital quagmire, I personally suspect the digital age is here to stay and evolution of technology will be routine. Just where does that leave the Airframe and Powerplant technician?

    Having recently viewed a film made in 1945 and produced by the US department of Education, it appeared the Federal Aviation Administration (FAA) never did intend to create a dedicated Avionics endorsement but instead empowered qualified airframe technicians with responsibility to validate airworthiness and authorize most maintenance operations for return to service.

    Federal Aviation Regulation (FAR) 65.81 dictates the requirements for a technician to legitimately approve an item for return to service and paragraph “b” of the regulation further states: “A certificated mechanic may not exercise the privileges of his certificate and rating unless he understands the current instructions of the manufacturer, and the maintenance manuals, for the specific operation concerned.” There are very few practicing technicians that actually profess to understand digital circuits.

    The talk today is all about NEXTGEN which focuses on three broad areas including: communications, navigation and surveillance. The FAA has a Next Generation Implementation Plan (NGIP) as announced by Michael Huerta the FAA administrator and has suggested six programs be initially profiled.

    •Automatic Dependent Surveillance–Broadcast (ADS-B)
    •Data Communications (Data Comm)
    •En Route Automation Modernization (ERAM)
    •Terminal Automation Modernization and Replacement (TAMR)
    •NAS Voice System (NVS)
    •System Wide Information Management (SWIM)

    Huerta was quoted: “Improvements in technology and procedures represent a widespread, transformative change in the management and operation of the way we fly. As the FAA continues to apply lessons learned and establish best practices in the pursuit of deploying capabilities, NextGen is delivering tangible benefits to users.”

    NextGen aircraft

    The next generation aircraft technician has a significantly different need to know than our predecessors. NextGen aircraft do tend to utilize digital data networks and engage satellites to provide navigation and communications. From a maintenance perspective, technicians caring for the next generation aircraft from the small single engine variety up through the largest transport will need a strong knowledge of connectivity which includes awareness of the various means of digital communications along with the care and maintenance of equipment and wiring. The good news is: the airworthiness authorities have aligned with industry partners to ensure our profession is prepared for the challenges associated with the future.

    Connectivity can take on many forms and in simple terms is defined as: the ability to connect or communicate with another computer or a multiple computer network.

    Means of communicating can utilize various protocol including standardized forms such as the frequently used Arinc 429 specification, which defines the wiring type along with the order of the digital words being transmitted. This standard was developed in the late 1970s and evolved from a basic computer communications system created in 1966.

    There are of course more recent developments in digital networks with Ethernet systems being widely implemented. Unfortunately, Advisory Circular 43.13 does not provide guidance for installing or inspecting many of the more recent digital highways installed in aircraft. Wiring makes up only part of connectivity, as it is routine for digital devices to communicate utilizing wireless technology. Wi-Fi and Bluetooth are very common mediums for connecting electronic devices and both have found homes in aircraft.

    Business aviation has encompassed the principle of flying the modern office in the sky complete with internal wireless networks enabling travelling executives to access on-board printers or even connect to the outside world through satellites or air to ground systems. Unfortunately many business travelers have not as yet realized that an aircraft cruising at Mach .9 at FL 450 will probably not yield the same connectivity experience as while seated in corporate headquarters.

    Cabin management along with passenger entertainment are areas where connectivity thrives. It is now common to be able to stream a video from a personal electronic device (PED) to the aircraft audio-video system for the enjoyment of all passengers. It is also possible to access the aircraft media library or airshow to obtain pertinent flight information and play any stored program on most any Smart Device. In addition APPs are available to download on a wide range of PEDs to interact with the aircraft cabin allowing control of lighting, temperature and even some interior doors and electric window shades.

    Connectivity is not limited to passenger convenience as systems such as Automatic Dependence Surveillance Broadcast (ADS-B) which is now mandated by many worldwide airworthiness authorities and will be required in the United States by 2020. This facilitates digital data relative to aircraft movement and position be transmitted continuously and then monitored by Air Traffic Control as well as other aircraft with similar equipment. The plan is to eventually replace current version transponders. Controller-Pilot Data Link Communications (CPDLC) is yet another connectivity based advancement providing a data link between an air traffic control center and flight crews. Digital messages take the place of voice calls and flight crews can even communicate through an email format with authorized subscribers.

    Worldwide space-based connectivity services have been in existence since the very first communications satellites were activated. INMARSAT in fact is an acronym describing the INternational MARitime SATellite network and was launched in 1979. Celestial communications using INMARSAT do provide unique challenges to a fast moving aircraft. First, the exact location of the satellite must be known then current aircraft position is used to steer a high gain antenna to establish the best possible data path. Just being connected to the INMARSAT constellation requires aircraft navigation computers to converse with satellite communications processors. Once connected, the system still needs to know when the aircraft attitude changes to make antenna corrections maintaining a seamless data throughput.

    Electrical Wiring Interconnect Systems (EWIS) is another recent initiative that is crucial to not only connectivity but also aircraft safety. EWIS is now required per FAR Part 25-1701 as well as 25-1309 and treats wiring as a stand-alone system. This means wire or cable placement has to be engineered into the airframe or engine without conflict from other devices such as power feeder cables being segregated from wiring carrying digital data.

    This is a four-element initiative including design, installation, operation and inspection. It is not uncommon while accomplishing non-routine maintenance to find wire looms encased in dust and possibly contaminated with aluminum shavings from previous work. Such findings bring to light the necessity to have dedicated wiring inspections. EWIS also identifies specific installations and addressed concerns where over tightening cable clamps on wire bundles may alter buss or coax impedance resulting in decayed data flow or weakened radio transmissions.

    The NextGen concept will no doubt provide increases in the safety of air transportation along with streamlining flight routes allowing for reduced flight times and significant cost savings. The introduction of this technology does provide significant challenges to the global aviation maintenance profession. With aircraft of today it becomes increasingly more difficult to determine where airframe stops and avionics begin. A change in technician “need to know” is imperative and rejuvenation from legacy airframe and powerplant training necessitates a coalition between regulators and industry requiring worldwide engagement. It all starts with the adaptability of today’s technicians. Are you planning to become the NEXTTECH for NextGen?

    Jim Sparks has been in aviation for more than 30 years and is a licensed A&P. His career began in general aviation as a mechanic, electrician, and avionics technician. Currently when not writing for AMT, he is the manager of aviation maintenance for a private company with a fleet including light single engine aircraft, helicopters, and several types of business jets. You can reach him at sparks-jim@sbcglobal.net.