Within aircraft cabins, electrical and electronic systems are contributing to improving the passenger experience, thanks to technological advancements.

Electrical systems generate electricity, which is an increasingly important commodity needed during flights. “We are seeing increasing demand for commercial technologies to be adapted and installed on our seating programmes.

“Everything from accent lighting, personal electronic device (PED) seating controls, connectivity to the internet during flight, wireless charging, seat heating and cooling, heated and cooled cup holders, occupant comfort detection and notification, locking boxes for personal valuables,” says Ashraf Sherif, senior technical fellow at Collins Aerospace. “The list goes on and on. Simply put, if you have it in your daily life it is wanted on the aircraft. If it is in our cars, it is being requested on our seats.”

Portable electronic devices

In the lasts 10 years, an important development that has influenced electrical systems has been PEDs. More and more people have the necessity to use electricity to charge electronic devices during flights.

Sherif explains: “The increase of portable electronics has created increased demand for additional recharging power on the seat. PC power, USB ports, and now wireless charging are all in high demand. From a seating perspective, this has resulted in additional wire routing, mounting of power conversion units and considerations for placement and location of the recharging unit itself. Each new device adds additional power wiring and more total power draw.”

The electrical power supply of aircraft is indeed in a constant state of change, and the focus is progressively on cabin applications. “In the past, a reading lamp was sufficient for the passenger, but it has become a fully digital entertainment application on own servers (audio/video on demand). Digital change is becoming the norm, and with it so is connectivity.

“In this context, a possibility for recharging PEDs was standard in long haul aircraft, now a USB port on each seat is getting increasingly popular on single aisle aircraft. A twin engine aircraft with a full PED power installation may even reach the limits for power generation,” sayViktor Daubner, principal design engineer (Cabin Electronics) and Joachim Kienzler-Cleuvers, principal design engineer (Avionics) at Lufthansa Technik.

“Nowadays, more and more seats are equipped with USB or wireless charging modules. However, standard USB ports require up to 10 Watts each, at 5 V/DC,” explains Lothar Trunk, chief engineer & programme manager of Innovation at Diehl Aviation.

“So, assuming an aircraft has capacity for 300 seats, we need to ensure the supply of additional power up to 3000 Watts. Realistically, however, not all devices will need to be charged simultaneously. So, although we can expect the actual burden to be significantly lower, we must nevertheless cater to the maximum potential requirement.”

According to Trunk, an important debate is open about “whether and how the classic seat-back in-flight entertainment will be replaced with handhelds such as smartphones or tablets. Quite apart from the potential cost reduction, this would lead to a significant reduction in the aircraft’s weight, and its power requirements,” he says.

“It is necessary nowadays to offer passengers USB connections to charge batteries. It means to install new dedicated wires to provide power to new ‘in-seat power’ systems.These wires are installed under the floor, respecting both safety and design requirements.

“Indeed, it is not always easy to make something smart and perform well.We try every day to solve this trade off by offering high tech systems in an attractive cabin,” says Cyril Brand, design manager at Air France Industries KLM Engineering & Maintenance.

“If we add the fact that wifi systems are also expected with this new way of travelling, it is clear that requirements have evolved and a lot more power is expected. Nowadays, electronic load analyses are much more difficult, as aircraft are charged a lot.

“It is also necessary to do more tests after a modification, to check electromagnetic interference (EMI) requirements.Wire segregation is also harder, and specific attention must be paid to this certification item. So, more constraint must be taken into account.”

Wiring and lightweight fibre optics

According to Daubner and Kienzler-Cleuvers, PEDs are important for the demand of power management in aircraft: “Since the use of a user’s own PEDs is much more normal today than it was 5-10 years ago, the demand is the greater challenge.

In the meantime, data is transmitted wirelessly, but energy still has to run over electrical cables. So wiring and LRUs required for PED power systems have a weight impact. LHT is generally supporting the operator’s vendor selection in order to source the best suitable and cost-effective solution for their fleet.”

Lightweight fibre optics in networks and electronics systems and other new technologies are seen to provide solutions to the increasing demand for power in aircraft. For now, lightweight fibre optics is mostly used by aircraft manufacturers to provide a complete network in the latest cabins.

Daubner and Kienzler- Cleuvers affirm that peripheral equipment outside of enclosed systems like in-flight entertainment with fibre optics is still very rare on the market.

“Fibre optics is a fixture in inflight entertainment systems that gets supplied to Collins by either partners or OEMS and are integrated into our systems,” says Sherif. “The use of fibre is increasing; however, there may be an inflection point where it gets refocused on high speed data busses and concentrators/multiplexors only as there will be a trend towards wireless communication for low speed/ critical busses where large number of LRUs are required (seats, lighting, sensors, data collection).”

“Design organisation like ours will use this wire type in the next few years. Our design organisation is actively working on it, trying to find partners to introduce optical fibre in the next cabin retrofit,” explains Brand.

Indeed, lightweight fibre optics provide for advantages and disadvantages. An important advantage is the high data transmission rate. “Optical fibre technology will allow to use one wire to transmit several data. Today, we have like a wire type for each specific data. That is why we are able to see huge bundles in aircraft. For airlines, bundles are the enemies, because of their weight which has an impact on fuel efficiency,” explains Brand.

Another important fact is that, despite the high rate of data, there is no EMI risks, according to Daubner and Kienzler-Cleuvers. A further advantage of fibre optics is that they facilitate data movement more rapidly over standard communication infrastructures, allowing for better performance of the entertainment systems on current aircraft.

“They also have advantage in cyber security protection that enables a more reliable data transmission. Another distinct advantage is the complete elimination of electrical connections/ ground loops.This allows systems that are powered by different busses (AC/DC/three phase) to communicate without isolators, reducing cost and surprises,” says Sherif.

However, there are also some limitations associated to fibre optics. According to Daubner and Kienzler- Cleuvers, fibre optics can be difficult to repair, and require special tools and trained personnel. In relation to point-to-point connections, there may be difficulties in connecting other LRUs to fibre architecture for sharing data with other devices if needed for system modification. Moreover, fibre optics are sensible to install.

Another disadvantage is that fibre optics routings can be more complicated, as the ben radius is much more important than in a classical wire. “It can be also more complicated to make interconnection. Classical connectors cannot be used anymore, as fibre optics concern light; moreover, interconnections must be really clean in order to avoid information losses,” Brand explains.

New technologies

In addition to fibre optics, according to Brand, the future of aircraft electric and electronic system technology revolves around software architecture. “It will strongly impact aircraft design modifications. It will reduce the costs significantly and provide much more safety. MROs and design organisations will have to change their way of working. It is a huge challenge, but today, being flexible and adaptable is the key,” he says.

Another important issue to consider in technology is data. Daubner and Kienzler-Cleuvers point out that digital change does not stop at the aircraft door. “Today, an airline must strive to offer the same standard of digital communication as at home or in the office. Data is increasingly transmitted wirelessly in digital form in aircraft. In the meantime, this is not only data for passenger comfort, but also data that is transferred from systems important for flight operations to other systems or to ground for operational benefits,” they say.

“LHT is a member in the definition of a new Wireless Avionics Intra-Communication (WAIC) standard that
shall subsequently reduce aircraft wiring in future. The future in aircraft will be more and more wireless. In return, energy management will become increasingly complex and special in the future.”

According to Trunk, the trend towards wireless connections could consist of a combination of several wireless standards such as wifi, lifi and WAIC.” In addition to this, the potential for the integration of powerline communication – such as communication via the power supply – is particularly good. This follows the main trend we are currently observing in this field: facilitating or simplifying the integration of new functions and systems – and above all with the minimum amount of rewiring. The iCabin initiative of leading aircraft manufacturers, suppliers and airlines is also heading towards wirelessness,” he says.

In relation to the future of wireless connections, Sherif believes that ‘wireless mesh networks will be coming, and will change the architecture of all devices installed in the aircraft’. This will allow the addition of new devices where all is needed is power and a software update.

“There will be an increase of hybrid systems that take advantage of the speed/ agility of consumer electronics, but still protect the aircraft with a DO160/178/254 front end. Quantum dot LED technology will enable unique glowing surfaces that are driven indirectly by the complex light spectrum of cabin lighting (eliminating cables/ communications/weight),” he says.

Training and skills

The new technologies and processes that are being introduced into aircraft cabins require that the high safety standards and quality demands are met without delay. For this reason, training becomes key – as well as mandatory – for the achievement of good performance, and to guarantee that requirements are well complied with.

Technical skills are not ‘hard to source’, say Daubner and Kienzler-Cleuvers.There is a need for ‘high level of training and skills in order to repair or install fibre optics, special tooling repairs and crimping, as well as for installation test and troubleshooting’, they say.

Seats are covered under TSO. As such, the maintenance and repair are covered in the component maintenance manuals. “The electronic details of the LRU are controlled and certified by the seat manufacturer. Maintenance and repair of the seat electronics are limited to LRU (Line Repairable Unit) replacement, and can be accomplished without any additional training by a qualified aircraft maintenance engineer,” says Sherif.

“If we have to sum up the skills needed for an MRO, we should focus on curiosity, strictness and pragmatism. Of course, technical skills are expected, but everything can be learned. Soft skills are much more difficult to improve, and that is why it is sometimes hard to source them,” says Brand.

With regards to training, an important role has been played by electrical wiring and interconnection systems (EWIS) training requirements.The current EWIS standard has become an important point in the certification of aircraft and their modifications.

“With the EWIS training, the awareness for EWIS related problems has significantly increased throughout all parties involved in aircraft operation, especially in EASA and FAA regulated areas: starting with the design and certification process, keeping the high standards maintained in every aircraft check. This focus on EWIS helps to keep the issues even with modern aircraft and its complex EWIS architecture to a minimum,” conclude Daubner and Kienzler-Cleuvers.