How Aircraft Seating Differs From Design to Finished Product

Introduction

Events such as the Aircraft Interiors Expo, which took place in Hamburg in May, showcase new and exciting passenger seats from various manufacturers.

Each company hopes that their display garners the interest of airlines and eventually results in their seats being installed in the fleet, used daily by passengers who expect a premium experience while travelling on business or first-class.

The industry relies heavily on new features and innovation, so the seat exhibited at a show like AIX sets expectations but is unlikely to be complete in terms of its engineering development or fully certified for flying. The pressure is on the engineering community to ensure that the show experience is reflected in the final product.

Lifecycle

At the start of a product lifecycle, the concept is created by an industrial design team that works to decide upon the ‘styling’, which defines features of the seat such as surface materials and intended functionality for components such as armrests, meal tables, privacy screens and storage types. Each aspect of the seat will be designed to cater to a particular market segment, with styling that is relevant and appealing.

Physical mock-ups can be produced by model makers using the styling data as a guide, which may be displayed at trade shows or sent to airlines to get the experience first-hand. These mock-ups may have functional prototype versions of the seats and other moving components.

In parallel, engineering teams will plan how to bring the concept to market, facing strict regulatory and budget constraints along the way, without compromising details that make the conceptual styling and mock-up attractive. The mechanisms show that mock-ups are to be replicated using production materials and processes. Here are some of the many challenges they might face along the way:

Stress

In service, parts of the seat must survive tens of thousands of uses and potential abuse by passengers. There are requirements for in-flight loads, turbulence, and crash landing whilst keeping weight to a minimum. The design will go through thorough analysis/simulation and cyclic testing where required.

Often, critical dimensions have already been locked in as requirements, such as bed length/width, monitor sizes, etc. Any component or location where material is added to increase strength can compromise these selling points.

Making the product physically robust, while packaging the many features into a small space requires skill and expertise. Stress engineers must be familiar with all requirements regarding the load cases mentioned, fully understand how the product will be used and be able to produce accurate simulations.

If done well, analysis will correlate with the physical static and dynamic testing that the seat and furniture must undergo to be considered airworthy.

Assembly

The overall suite must be designed in such a way that it can be assembled in the aircraft with limited space to manoeuvre by technicians on a strict time limit.

There are limits to the types of tools that can be used for maintenance that restrict the choice of the designer. Even the size and shape of the aircraft door must be considered so that it can be carried on to the aircraft. As a result, it must be possible to break suites down into smaller parts without creating unsightly split-lines or visible fixings.

Flammability

Meeting customers’ expectations with regards to trim and finish can be complicated. Plush materials are an obvious way to make a statement feature and to improve comfort but the composition of the material and its substrate on the seat will influence flammability properties.

With most trim requiring some form of burn testing, knowledge of materials is important and making compromises such as synthetic alternatives to natural materials are key to delivering a certifiable product on time. Different material substrates and types of adhesives are also critical variables for the engineer to consider.

Requirements

The production product must adhere to all the relevant safety requirements outlined by the airframer and regulating bodies such as EASA. Often the safety related requirements will be contradictory when compared with requirements outlined by the airline to please passengers or maintenance crew. This can result in a complex matrix of requirements that can affect the final seat design.

Robust verification and validation activities must be conducted along the way, and requirements management tools, including Model-Based Systems Engineering, must be used. Communication with all stakeholders is vital.

Interfaces

The mock-up will likely be standing on its own plinth or pallet with minimal restriction on how/where it is attached. When designing for a specific aircraft, the designer needs to be aware of the locations of structural rails that run along the aircraft floor and be able to create ‘foot fittings’ that serve as the interface connection and elevate the suite off the floor panels to avoid load sharing.

These foot fittings must cater for aircraft build tolerances and stresses caused by pitch and roll, whilst being accessible for maintenance teams.

The designer must also be aware of other systems that are part of the aircraft structure such as electrical junctions so that the complex In Flight Entertainment (IFE) systems can be integrated.

Conclusion

The subsequent articles will look at some challenges faced during the design of aircraft interiors in more detail.