The Magic in the Cabin

Once, it was considered supernatural to contemplate shedding the confines of the earth’s gravity. Sorcerers, wizards, and mythical beasts had the power to achieve feats of controlled flight. In days of old, enchanted airborne journeys were full of peril...


Once, it was considered supernatural to contemplate shedding the confines of the earth’s gravity. Sorcerers, wizards, and mythical beasts had the power to achieve feats of controlled flight. In days of old, enchanted airborne journeys were full of peril with humans, willing or not, experiencing new sensations with no time during the journey for boredom.

When we reduced the peril associated with flight, the probability of passenger boredom increased. With mega-airliners carrying 500+ passengers 18-20 nonstop hours, artificial stimulants are required. The primary mission for those engaged in business aviation is to provide an airborne environment conducive to getting the job done while en route to remote corporate locations. Modern corporate aircraft can truly be considered a state-of-the-art boardroom in the sky.

 

The need to stay connected

Recent advancements in consumer electronics coupled with the need for many to always be “connected” has provoked the aviation industry into creating an environment where something other than a cold beverage and a bag of peanuts is required to keep passengers happy.

The concept of being connected while flying close to the speed of sound at 40,000 feet again conjures up visions of wizards and sorcerers. Keeping many of these technological wonders functioning does involve incantations (at least that is one way to describe the string of four letter words uttered when the equipment is reported to be out of order).

Expectations are driving the future of cabin management systems (CMS). Today, passengers can enter an aircraft cabin, log in to the aircraft network and start sending or receiving email while interacting with the cabin using an app on a personal electronic device (PED) to start a movie or switch on/off a reading light.

Many CMS being installed accomplish their magic through the use of software and communication systems connecting all the devices. Transferring digital data efficiently makes software and data storage possible in many of the remote devices. This philosophy lessens the number and size of control components but can make system maintenance challenging. As an example: if the cabin speaker audio control software is stored in a video monitor and the monitor has to be removed, then the speakers will not function.

 

Technician knowledge

Technician knowledge of system architecture is essential to sustain proper system functionality. System startup will require a time frame that can typically not be rushed. In many cases boot up sequences require a disturbance-free duration. Interaction during the system startup phase most frequently either delays initialization or causes the system to lock requiring yet another restart.

Digital data has been used in aviation for about 40 years and Federal Aviation Regulations (FAR) have been recently created to take into account installation and inspection techniques critical to digital data transmission. Electrical wiring interface system or EWIS has been included in FAR Part 25 governing transport category aircraft. This should be required reading for anyone planning for an EWIS compliant aircraft or even an upgrade to an existing cabin entertainment system. The FAA has published numerous training guides to assist in understanding the critical importance of aircraft wiring and treating it more like other systems when it comes to ensuring longevity. Several means are employed to transfer data between system components and Ethernet is one of the most common. Bend radius for a CAT 5 Ethernet cable is not referenced in Advisory Circular 43.13 but is mentioned in EWIS discussions. Unfortunately folding over digital buses and tying the excess back in the bundle is still a frequent practice. Another common mistake is overtightening wire clamps or cable ties surrounding coax cables and digital buses. Compressing multi-conductor cables can impact impedance resulting in data transfer issues. Specific cable tie pullers are recommended and even have calibration requirements to ensure compression does not occur with the cables being captured. In addition EWIS targets routing like cables together and discourages situations where power cables are collocated with data buses.

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