As floor panels are a component of an aircraft’s primary structure, they have more of a role than simply providing a flat surface to walk on. They are important for the overall safety of an aircraft during its normal operations, bearing high loads and resisting impact.
But what are the options in the market for floor panels and what are the advantages and disadvantages of those options?
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Aircraft floor panels: What are they exactly?
Firstly, what are we talking about here? What are floorboards, what are they made of and what are they required to do? Floor panels are those panels or boards that are mounted to the aircraft’s floor beams to provide a surface for passengers and crew to walk on and provide attachment points for certain furnishings and other components.
The structural makeup of an aircraft floor panel
Most floor panels have common components, each adding functionality to the overall panel performance. They are usually made from honeycomb sandwich panels with faces consisting of different pre-impregnated glass and cole fibres. The amount of this pre-impregnated material, the direction of each layer and the honeycomb core (the type of paper used and thickness) all have a small influence on the panel’s technical properties.
A thermic pressing compounds all the materials with resin, followed by a final deep-frying of the panel. This is followed by a hardening process to ensure enduring product quality.
Inserts are installed in the panel to provide a means of attaching the panel to the airframe. Most panels include edge fillers, which help prevent liquids from getting into the panel structure and reducing its durability.
The requirements of floor panels
Floor panels must be adequately strong and stiff to act as a supporting structure and durable to withstand use over time. At the same time, they need to be light enough to help keep aircraft weight low. For some aircraft, floor panels must also be versatile to enable a variety of cabin configurations.
Floor panels transfer high shear loads and cabin weights to the fuselage, so must be designed to bear high loads and shear force. They must also meet all fire safety and toxicity requirements.
Airlines therefore regularly check and replace their floor panels during heavy maintenance checks or cabin retrofit work. The replacement of a floor panel is assessed based on whether its damages exceed the repair limits listed in the Allowable Damage List of the aircraft’s Structure Repair Manual (SRM). These damages include delamination, scratches, holes and dent caused by dropped objects.
So, what are the different aircraft floor panel options available?
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The finished aircraft floor panel – and its pros and cons
The finished panel is a highly customised product that is purchased, cut and finished in production and ready for installation upon delivery. They tend to be a more lightweight option which can be important for fuel savings purposes.
Finished panels are used for line-fit in the production of aircraft, designed for specific aircraft types and installation positions and are proprietary parts solutions. But they are also used in aftersales for replacing floor panels.
Finished floor panels are usually the only option for lessees of aircraft, as their contractual terms often stipulate that upon their return, the leased aircraft must constitute the same materials and configuration as when delivered.
Similarly, aircraft that continue to be under guarantee or subject to insurance policies must also constitute the same configuration and materials as when originally purchased, making a finished product the only option also.
However, although lightweight and installation-ready, finished panels do have some disadvantages.
Disadvantages of the finished floor products
Firstly, different panels need to be made for different aircraft types and this can lead to huge complexity for airlines. Most airlines will define a ‘head of version' aircraft which then determines the floor panel configuration for 10 aircraft in a fleet, for example. When subsequent ‘heads of versions’ set different configurations, suddenly the airline is faced with needing a large number of varying customised panels. Some versions may have common features but some will not, making it particularly difficult for the airline to prepare for future needs.
This leads to the second issue: finished products involve long lead times. This is compounded by the fact that airlines don’t commence ordering replacement panels until damage is found, which is only revealed when cabins are removed from the aircraft. This often results in unavailability of stock or stock not being able to be delivered fast enough. And when stock is anticipated and replenished, inventories are increased, requiring more storage space.
As they are highly customised products, ready for installation in their fit, form and functionality, finished floor panels are also very expensive.
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The semi-finished floor panel – and its pros and cons
An increasingly popular option for floor panels is the semi-finished product. These floor panels are boards of a standard measurement (such as Airbus’ 1.9m x 2.95m boards) which are supplied to the airline in a pre-cut condition. Two or three floor panels can be cut from just one board, depending on the supplier and application area. A single Airbus semi-finished board will yield up to three panels.
Inserts and hardpoints for fitting the panel to the floor structure are also provided or purchased separately. Airbus offers improved Torlon inserts, completely reducing the risk of micro corrosion on the floor structure. It has also implemented new and improved potting processes.
As an alternative to finished panels, semi-finished panels can boast the following features.
5 important factors about semi-finished floor panels
- Increased robustness: Some semi-finished panels on the market are more robust – and longer-lasting – because a smaller honeycomb composition is used, providing greater compression and higher impact resistance.
- Cross-solution: An important advantage of Airbus’ semi-finished panels is that they are a cross-solution for a number of aircraft in the Airbus family. A semi-finished floor panel bought for an A320 can also be used for an A350, A380 and an A330, for example. Instead of requiring a dedicated finished panel for one ‘head of version’ aircraft, the semi-finished panel is a single repair solution for multiple aircraft, positively impacting the administration and handling of panels. They can even support aircraft now out of production, such as the A380.
- 100 percent availability: Another significant benefit of this option is that it provides 100 percent availability, enabling operational flexibility. By having one board in stock, up to three panels are immediately available for repair or retrofit as soon as they are cut. This means there are no lead time issues for the airline and maintenance duration can be considerably reduced.
- Complete aircraft coverage: Airbus’ semi-finished solutions cover the complete aircraft layout and are 100 percent installable. They will be repairable to the same standards as finished floor panels and follow existing repair procedures.
- Affordability: Semi-finished floor panels are often a more affordable option, being competitively priced and less expensive than their finished-panel counterparts. They can be a cost-savings option given their higher usability, particularly those from which three panels can be cut.
Disadvantages of the semi-finished floor products
One disadvantage of the semi-floor panel is that it needs to be cut to size. It is not ready for installation, so will involve time and resources. And today, it is not a replacement solution but a pure repair solution, in that a semi-finished panel will only be used when a normal panel is damaged. However, this may change in the future.
In addition, the strength and robustness of the semi-finished floor panel mean that they are heavier than finished panels. Within the semi-finished panel market, however, some products are lighter than others and the increased weight of Airbus’ semi-finished panel is not significant and can be balanced by carrying less fuel. Moreover, there are cargo panels for both the container area and the bulk area currently under development for the A320 Family, A330, A340, A350, A380. Additionally, a passenger light variant (seat, aisle and galley) will be developed for the A320 family.
The grey market in floor panels
While these options are available from qualified suppliers, such as the panels that receive the Airbus stamp, a grey market for the production of both finished and semi-finished floor panels also operates.
Highly customised floor panel derivatives, similar to Airbus floor panels, for example, are available on the market.
Floor panels made by holders of Parts Manufacturer Approvals (PMA) can be sourced. But while PMA holders have received, for example, FAA approval for both design and production of the floor panels, they do not bear the Airbus stamp of quality and performance.
Similarly, Supplementary Type Certificates (STC) may be granted by local authorities for floor panels that are based on the Airbus qualified product, but also do not carry the Airbus stamp of quality and performance. As such, the use of these uncertified panels by an airline carries a risk.
The Satair Takeaway
Floor panels are important supporting structures that must be strong enough to withstand use over time. The finished floor panel is a good option, particularly for those with contractual, guarantee or insurance obligations.
The semi-finished option is a very robust, less expensive option that has the added benefit of being usable for multiple aircraft types and covering the complete aircraft layout. Importantly, it is immediately available, reducing maintenance downtime. Those semi-floor panels that are produced with the Airbus stamp guarantee that they meet or exceed all current standards, quality and performance.