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A350 cabin architecture
The objective of the new cabin architecture Airbus has developed for its next wide-body aircraft is to facilitate airlines’ needs for cabin customisation in a way that is manageable industrially both for the airframer and its major vendors.
The starting point, says head of aircraft interiors Bob Lange, was the fact that airlines know the cabin configuration they start out with in a new long-range aircraft is going to change during its service life: “In some cases it may change between the initial thoughts they have at the time they order the aircraft and what they actually select when they come to freeze their definition of the aircraft,” he says. “Then it will continue to change once the aircraft enters service, with cabin elements typically changed every five to seven years in an aircraft with a service life of 20+ years.”
Airlines, Lange says, have been looking for years for the flexibility to vary the number of classes of seating in their aircraft, the proportions of seats in each class, the location of boundaries between different classes of service, and the appropriate number of galleys and lavatories to support them: “That’s the starting point in our business.” The passing years have added complicating factors such as new and improved safety standards, the ability to withstand 16g deceleration forces, head impact criteria for seat certification and improved flammability characteristics.
At the same time, Lange says, “we’re seeing more and more longer range services, which means the importance of the cabin as a crew workplace has increased.” Seats have become more complicated, with electrical actuation, full flat beds and units mounted on pallets because they are at unusual angles relative to flight direction. “And in IFE we’ve seen a move towards video on demand in every seat and a far richer offer for the consumer.”
Airbus started to address this growing challenge by studying the A330/A340 programme, whose products are now in service with more than 100 operators. “That means we’ve done a whole lot of different cabin definitions,” says Lange. And one conclusion was that flexibility has more value in some areas than in others.
In the forward passenger door area, for example, “we don’t see the inherent flexibility used very highly. People don’t want to put passenger accommodation there, so you tend to get a lot of similarity in the way we arrange galleys and lavatories in that area.” The same can be said for the rear door area at the back of economy class. “But when it comes to the mid-cabin areas, particularly the area around Door 2 in a wide-body, this is quite often close to the boundary between premium and economy accommodation, we see a lot of variation in what is required in that area. Which tells us that providing flexibility in that area is valuable to our customers.”
For the A350, Lange says, “we realised it was important to be able to cater for flexibility and that we have a very stable baseline platform for any subsequent adaptation.” Airbus calls it the enabling platform.
Martin Latrille, enabling platform architect in the A350 chief engineering team, explains that airlines ask for geometrical as well as functional flexibility. Giving them the ability to move monuments such as lavatories and galleys an inch at a time in the Door 2 area can help them optimise the seat count, he says. “But how do you connect the water provided by the aircraft to the lavatory if the lavatory can move?”
Answering that question involved a complete analysis, he says, starting with the primary structure of the aircraft fuselage structure, the floor and the brackets that support the big monuments and act as adjustment points: “We clearly say today these are the non-customised parts of our platform. We have a standard green aircraft which is not customised, which is ready to host whatever the customer selects from the catalogue.”
Also protected in the digital mock-up of the A350 are spaces for all the interfaces that might be necessary for the water, air, cooling, waste and electrical interfaces to support the customer’s specification. “Whatever the combination or configuration of monuments in a customer-defined aircraft, we know exactly what will be the maximum demand from the aircraft and we are ready to provision it,” says Latrille. “So we know that whatever catalogue solutions we put together with the customer to optimise his layout, we will not have the burden of a newly developed integration on the head of version [Airbus nomenclature for the first of a series of aircraft in a new customer configuration] for the customer. We just plug and play.”
Left: Airlines seek the greatest flexibility where premium seating meets economy
Moving a galley even a couple of inches involves more than just moving the mechanical attachments to the floor and ceiling, points out Lange: “You need to move the fresh water connection, the electrical connection, the waste water and the refrigeration. You want it to look nice, so you have various transition panels in the ceiling that have to mate with it, and they all have to be moved or changed as well. So if you don’t have a stable starting point you very quickly get a snowball of consequential design and certification work. And whether it’s for the supplier or us as the OEM, that work builds cost, lead time and risk into the finished product.”
The enabling platform is that starting point. To capitalise on it, he says, mechanical and system interfaces are all designed to be standard but adjustable, enabling their positions to be adjusted using known design solutions rather than having to start the work from scratch. And this modular approach extends to the galleys and lavs themselves.
“When you look inside a galley today,” says Lange, “you see a structural box providing cooling, water, waste and electricity systems. Within that you have functional parts – ovens, refrigerators, coffee makers, rice cookers, toasted sandwich makers, there’s a long list.” Airlines’ requirements for inserts vary according to their service concept and process. “So inside these monuments the locations of these inserts are also flexible.”
Not infinitely flexible, Lange cautions: people usually want to put the sink in one of two places in a particular galley, for example. But the 1,000-plus A330s and A340s Airbus has delivered have involved many heads of version: “We have a lot of experience in listening to our customers’ needs and knowing what their expectations are. And our modular concept is built from that customer expectation. So we’re able to avoid that snowball, because the combinations are already being designed and will be certified, and then you can choose from the catalogue and mix and match.”
The extra width of the A350’s XWB fuselage meant the galleys could be widened to incorporate a central port bay 5in wide. Flexible couplings are used to connect the galley port to the fixed handover points in the water, waste, cooling and vacuum pipes under the floor. In the areas where flexibility is allowed, the system ports are 25in apart, says Latrille: “If I move more than 25in with my monument I have to connect to the next port, but this port is connected with the same type of pipe as the port before, because even the supply pipes are standardised.” A similar arrangement of dedicated handover points and flexible couplings is used for the lavatory water and waste connections, and for the overhead air-related systems in the crown of the aircraft.
For the mechanical interfaces, he says, flexible solutions mean there is no need to do a new design for a new monument position. The seat tracks provide a connection every inch, and in the A350 the monuments are attached to the seat tracks, either directly or using a large floor panel in the case of heavier monuments, using standardised upper and lateral attachments.
Right: Window reveals are available in a range of options
Desire for differentiation
“We’re in an industry which has been crying out for differentiation between different aircraft for different airlines,” Lange observes. “Airlines absolutely need that when you walk onto their aircraft you immediately identify with their brand and their cabin and their choices and the products in that cabin.” Legacy platforms were not designed to accommodate that, he says. “So we’ve ended up with a kind of can-do approach which at the end of the day gets a quality product into the cabin, but in a way which is extremely onerous for all the actors involved – not least the airline customers. What we have tried to do is create a structure and a platform that allow for flexibility and innovation in the cabin but based on what is fundamentally an inviolable platform. So when people do need to develop new cabin products they know exactly what they’re designing to match with.”
The result is a catalogue of highly modular design solutions. “The catalogue for the lavatory, for example, has a huge variety of mix and match options,” he says. And in a first for a large commercial aircraft, customers can not only delay their final decision until as little as eight to 12 months before delivery, but can change those options once the aircraft is in service without removing the lavatory.
There is also a process to accommodate future innovation, whether from the airlines or their suppliers. “We are always looking for new ideas,” Lange explains. “When we see a new idea we look at how it can be developed in a way which enhances the catalogue.” And if an airline wants a degree of exclusivity over an idea, “our process allows that to happen, but not at the same lead time and cost as taking a solution from the catalogue.”
The advantages of the modular approach extend beyond simply allowing the airlines a less risky flexibility to get what they want, Lange says. “It also provides us savings when we’re building the aircraft and it creates opportunities to reconfigure the aircraft that airlines haven’t had on previous generations of aircraft.”
In fact, the catalogue will include optional reconfiguration provisions, with additional interfaces to support “a light reconfiguration in a short lead time,” he explains. “That again is an industry first. It will be the first time that the selection catalogue of a commercial aircraft lets you choose a reconfiguration pack as an option. And what that allows you to do is if you take that pack, once your aircraft is delivered there is a particular scope of change you will be able to accommodate typically in an overnight stop.”
The scope of change in an overnight stop may not run to moving the monuments around to a significant extent, but it allows for seats to be re-pitched and class boundaries moved. “Where we saw market demand for that from the airlines was for seasonal schedule changes,” he says. “For lessors of aircraft, and let’s not forget that a good third of aircraft are on operating leases, it gives much more freedom to reconfigure the aircraft between customers, which ultimately makes that business support from the lessors to the airlines more dynamic.”
The reconfiguration provisions liberate some cabin configuration changes from the heavy maintenance cycle to which they have traditionally been tied, but they do need to be specified and installed before the aircraft is built and delivered. “It doesn’t mean you can’t do it later,” Lange says, “but that would involve a much greater scope of work.”
Left: Business-class cabin rendering
Author: Bernard Fitzsimons
29 November 2011