Aircraft Cabin Management

Power trip: The major drains of modern aircraft cabin electrical power

Aircraft cabin, electrical power, IFE & Connectivity

Inflight entertainment systems, LED lights and complicated, electrically actuated seats are standout features of the modern aircraft cabin, and it seems entirely logical that they ought to be its major consumers of electrical power.

However, according to Embraer, the major drain is, as it has been for decades, rather more prosaic.

Inflight entertainment and connectivity are among the dominating factors in airliner cabin design, in some cases adding hundreds of screens, passenger interaction points and power outlets to seatbacks.

Aircraft cabin, electrically actuated seats, IFE and connectivity

That they complicate cabin electrical system configurations is inevitable, yet they are not the primary energy consumer.

Step forward to business class and beyond, and the IFE works in concert with the electrically actuated comfort of convertible seats and other gadgetry, poseable reading lights and individual suites.

All of which places further demands on electrical system design, but does not add up to create the major consumer. In fact, the galley has been the primary drain on cabin electrical power since full galley installations became standard equipment from the DC-3 onwards.

With an eye firmly on the recently certificated E2, an Embraer spokesperson explained: “Internet connectivity, the cabin management system, seat power, and water and waste systems are all part of the cabin electrical system. The provisions for each have evolved as the technology of individual systems has advanced, bringing changes to wiring and signals requirements.

“Systems including IFE&C can benefit from standardised provisions, including wiring and buses, providing benefits in flexibility, lower development cycles and lower installation lead times. Delivering common smart and modular provisions from multiple suppliers is among the E2 IFE&C product strategies.”

While few would argue for a return to the retractable overhead IFE screens of the past, the latest systems raise new challenges.

Aircraft cabin, IFE & connectivity, electric seats

“Overhead screens were used because there was no way of installing displays on seats. With the advent of LCD technology, smaller displays could be manufactured, allowing seat integration and providing every passenger their own display and content control, the AVOD [advertising video on demand] model.

“Having a display and additional controls on every seat does demand more power and adds weight, not to mention increasing cost, compared to the option of employing fewer overhead displays. More recently, however, we have seen a trend towards bring your own device, or BYOD. Content is distributed wirelessly in the cabin, allowing passengers to access entertainment through their personal electronic devices.”

Potentially simplifying wiring and electrical requirements while at the same time delivering quality IFE, the BYOD solution is among the E2 IFE&C portfolio options.

Even when content is streamed to personal devices, a requirement for servers and wifi, of course, remains, which means wireless access points (WAPs) and, if off-board connectivity is desired, connections to a broadband ‘pipe’, via an antenna or antennas, to a satellite and or ground-based network.

From a passenger experience perspective, the only requirements for wifi are that it works every time and works well.

In part, at least, reliable connection is down to even signal distribution throughout the cabin, requiring that WAPs be installed and supported at various points in the cabin and potential interference between systems suppressed.

Aircraft cabin, IFE and connectivity: personal electronic devices

“The optimal location of WAPs through the cabin is defined using RF software simulation, which shows signal strength in the cabin and identifies when a WAP position needs to be changed.

“This informs precise positioning, since the cabin, its panels and dividers are included in the simulation, leading to actual installation in the best available positions, which are then validated by real measurements on the aircraft post-installation.

“To ensure interference-free operation, an initial assessment is done on equipment qualification levels. Embraer only moves on with system development after confirming that all LRUs are tested to defined RF emission and susceptibility standards. For final certification, aircraft RF testing is performed, verifying there is no interference to aircraft critical systems.”

Lighter light

Factor in that seatback screen and power installations are still the most likely solution to IFE and that wifi inevitably adds electrical complexity, and the solution to keeping passengers entertained and connected through the modern technology they demand has driven the development of systems that are still relatively new to the industry and will continue to evolve.

Compared to the traditional seatback system, BYOD delivers a clear benefit in reduced weight and installation complexity, reducing power demand, as well as simplifying maintenance.

Supplying power to every seat poses another set of tricky demands, as the Embraer spokesperson explained: “Equipment to seat integration and the required wiring installation are the main challenges. Equipment and wiring integration to the seat must comply with specific authority standards (Technical Standard Orders) and requires integrated effort from the seat supplier, system supplier and OEM.

Aircraft wiring distribution also needs to be done in a way that allows cabin reconfiguration with minimum impact, avoiding the need for major wiring rework owing to seat pitch changes.”

Aircraft cabin, ife and connectivity, overhead screens

How passengers subsequently use power outlets is carefully controlled through specific policies. Combined with system certification requirements, these should ensure safe operation, but other precautions are built in.

An initial protection test at system power on, power and current limitations on every outlet, ground fault protection and plug connection checks are among the embedded protections for outlet systems, according to Embraer.

Elsewhere in the cabin, however, new technologies have arrived to reduce energy requirements and complexity, save weight across the board and bring other longer-term benefits. LED has truly brought about a cabin lighting revolution.

“It delivers known benefits in power and weight savings compared to standard lights, with better reliability as well. The improvement in weight could be a reduction of 20 per cent compared to the same level of lighting delivered by fluorescent units.”

Back to the galley

Among the cabin systems, the galley’s total power consumption still makes it the most demanding.

“Although the technology has improved over the years, power consumption has remained at similar levels since galley functionality has remained essentially the same, with electricity powering coffee makers, ovens and water boilers that are basically electrical heaters. Safety has improved though through the evolution of certification requirements and other industry standards, including RTCA DO-160 and DO-313.”

Elsewhere in the cabin, evolved systems have replaced older equipment, changing electrical requirements and consumption. Individual LCD/LED seat displays and AVOD have replaced overhead/VHS broadcast IFE, while 115 VAC outlets have ousted older DC ports.

More recently, USB ports have added to cabin equipment, while the LED light revolution has largely coincided with the replacement of mechanical switches, used to control individual cabin systems by integrated cabin management systems (CMS) with touchscreen interfaces.

Considering the modern cabin, Embraer says a major improvement in electrical system usage has been achieved through the crew interface, the CMS representing a “major evolution in how cabin systems are managed and controlled.

The highly integrated CMS provides control and status reports for several systems in a single display, with an optimised user interface.”

Meanwhile, the passenger interface has also changed dramatically with touchscreen IFE controls, which Embraer describes as “a serious improvement over the older controls, with switches and buttons located on the seat. It not only reduces the seat integration effort and maintainability issues of replacing failed controls, but creates a friendlier interface, aligned with what we experience on our PEDs.”

E2 Electrics

With the E2 promising better than expected range and real benefits in fuel economy, it is interesting to consider what impact the additional electrical demands of its modern cabin have on fuel consumption and the requirements for electricity generation.

“The cabin systems’ effects on fuel efficiency are mainly related to weight. On initial development, as with any other system, the cabin’s power demands are considered in defining the total electrical power required and the generator.”

Aircraft cabin, Ife and connectivity, seat power outlets

As the next of the new-generation airliners into service, the E2 inevitably embodies several important improvements in cabin electrical systems. The cabin lighting is naturally fully LED, with optional mood scenarios.

The galley inserts can be selected with the new ARINC-810 interface standard and the possibility of upgrading to ARINC-812 data standard when compatible insert options become available. Standard AC or high-power USB seat power will be available for every passenger.

Embraer considers the E2’s CMS as the most important innovation of all. “It integrates the status and control of several cabin systems in a single cabin crew interface, enabling control of systems including cabin lighting, water and waste, and IFE&C, as well indicating individual seat attendant calls. Other functions, among them PRA [passenger revenue accounting] and the ability to play music are also integrated into the CMS.”

Aircraft cabin, electrical power, IFE & Connectivity

The E2 also offers a portfolio of inflight entertainment and connectivity products, Embraer choosing to select from multiple suppliers while installing customer options through common smart, modular provisions that will also accommodate future equipment designs.

Wireless streaming to personal devices or seat backs, internet via Ku and Ka bands and air-to-ground connectivity, including real-time TV via iPTV are also part of the standard option list.

In support, an external tri-band radome that houses either a Ku or Ka antenna system – the latter proof of passenger demands for connectivity and airline recognition that it represents an important revenue stream – is extending the cabin electrical system beyond the confines of the cabin itself.

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