Aircraft interior sandwich panels are most commonly built with an aramid (Nomex) honeycomb core or an aluminium honeycomb core, laminated with glass-fibre or carbon-fibre reinforced polymer skins. These combinations deliver the high strength-to-weight ratio, fire resistance and dimensional stability that aviation authorities and aircraft manufacturers require. The sections below answer the most frequently asked questions about how these panels are specified, manufactured and applied in a commercial aircraft cabin.

Note: This article covers the broader sandwich panel market as it applies to aircraft interiors. Our range at Compoform focuses on thermoplastic sandwich panels with PP honeycomb and PET foam cores, primarily for commercial vehicles and scaffolding.

Which core materials are most commonly used in aircraft sandwich panels?

The two most commonly used core materials in aircraft interior sandwich panels are aramid (Nomex) honeycomb and aluminium honeycomb. Nomex honeycomb dominates cabin interior applications because it is lightweight, inherently fire resistant and well suited to absorbing impact energy. Aluminium honeycomb is used in structural floor panels and cargo compartments where higher compressive loads are expected.

Nomex is a meta-aramid paper produced by DuPont that is formed into a hexagonal honeycomb structure before being impregnated with resin. The cell geometry distributes load efficiently across the panel surface while keeping the areal weight very low. This matters greatly in aviation, where every kilogram of structural dead weight reduces payload capacity or increases fuel consumption.

Aluminium honeycomb offers higher compressive strength than Nomex at a comparable density, which makes it the preferred choice for aircraft floor panels that must withstand point loads from passenger seats, trolleys and cargo equipment. The drawback is that aluminium is heavier and less resistant to long-term moisture ingress, which can cause corrosion in the core if the bond between skin and core is compromised.

Foam cores, including rigid polymethacrylimide (PMI) and polyetherimide (PEI) foam, are used in some secondary interior structures where complex curvatures or thermoforming are required. These materials are easier to machine and shape than honeycomb, but generally offer lower shear stiffness at a comparable weight.

Which skin materials are laminated onto aircraft interior sandwich panels?

Aircraft interior sandwich panels are most often skinned with glass-fibre reinforced epoxy or phenolic laminates, or with carbon-fibre reinforced polymer (CFRP) skins in weight-critical structural applications. The choice of resin system is driven primarily by fire, smoke and toxicity (FST) regulations rather than by mechanical performance alone.

Phenolic resin systems are the traditional choice for cabin interior panels because phenolics char rather than melt when exposed to flame, releasing relatively little smoke and toxic gas. This behaviour directly supports compliance with aviation fire safety standards. Woven glass-fibre fabrics or non-crimp fabrics are the most widely used reinforcement and offer a good balance of stiffness, impact resistance and cost.

Carbon-fibre skins are used in overhead bins, galley structures and primary cabin monuments where the stiffness-to-weight ratio is the priority. Carbon-fibre laminates are considerably stiffer than glass fibre at a comparable thickness, allowing thinner skins and further weight savings. The higher material cost is justified in applications where weight reduction translates directly into fuel savings or payload revenue over the aircraft’s service life.

Surface finishes on aircraft interior panels typically include decorative films, paint-ready primer coatings or pre-finished decorative laminates bonded to the outer skin surface. These finishes must also meet FST requirements and are tested independently of the structural laminate.

Why do aircraft interiors require fire-resistant sandwich panels?

Aircraft interiors require fire-resistant sandwich panels because cabin fires spread quickly in an enclosed, pressurised environment, and regulatory standards impose strict limits on flame spread, smoke density and toxic gas emissions for every interior component. The primary regulation governing this is FAR 25.853 in the United States and its European equivalent under EASA CS-25.

The fire safety requirements for aircraft interior materials are among the strictest of any industry. Panels must pass vertical and horizontal burn tests, and in many applications they must also meet the Ohio State University (OSU) heat release rate test, which limits the total heat released in the first two minutes of a fire event. This test is specifically designed to give passengers sufficient time to evacuate before the fire becomes unsurvivable.

Smoke density and toxicity requirements add a further layer of complexity. Even materials that resist ignition can produce dense, toxic smoke that incapacitates passengers before they can reach the exits. Phenolic resin systems have become the dominant matrix materials for aircraft interior laminates, largely because they produce significantly less smoke than epoxy or polyester systems when they burn.

The consequence for sandwich panel design is that core and skin materials cannot be selected on structural or weight criteria alone. Every material in the panel stack, including any adhesive film used to bond the skins to the core, must be tested and certified as part of the complete panel assembly. A skin material that passes FST tests on its own may fail when tested as part of a bonded sandwich panel. This is why aircraft interior panels are always qualified as complete systems.

What is the difference between aircraft interior panels and standard composite sandwich panels?

The fundamental difference is regulatory certification. Aircraft interior sandwich panels must be individually qualified against aviation fire, smoke and toxicity standards and approved by airworthiness authorities before installation. Standard composite sandwich panels used in ground transport, construction or industrial composite panel applications across different sectors are not subject to these requirements and are instead specified on the basis of structural and durability standards relevant to their application.

Beyond certification, several technical differences set aviation panels apart from industrial sandwich panels:

• Resin systems: Aviation panels use phenolic or specialised epoxy resin systems that meet FST requirements. Industrial panels more often use standard epoxy, polyester or thermoplastic matrix systems optimised for cost, processability or recyclability.
• Core materials: Nomex honeycomb is specific to aviation and high-performance aerospace applications. Industrial sandwich panels more often use polypropylene honeycomb, PET foam or polyurethane foam cores.
• Tolerances and traceability: Aviation panels require full material traceability, documented cure records and non-destructive testing. Industrial panels are typically produced to dimensional tolerances and mechanical property requirements without the same documentation burden.
• Panel size and geometry: Aircraft interior panels are often highly complex in shape and require CNC machining, insert placement and fastener integration. Industrial panels are more often produced as large flat sheets that are cut to size by the end user or manufacturer.

The cost difference reflects these requirements. Aviation-qualified sandwich panels carry substantial certification costs that industrial panels do not. For ground transport applications, thermoplastic sandwich panels with PP honeycomb or foam cores deliver comparable structural performance at a fraction of the cost, with the added benefit of full recyclability.

Where are sandwich panels used in an aircraft cabin?

Sandwich panels are used throughout the aircraft cabin, including floor panels, overhead bins, sidewall linings, ceiling panels, galley structures, lavatories and cabin monuments such as crew rest areas and partitions. In each case the sandwich construction is chosen because it delivers the required stiffness and strength at the lowest possible weight.

Structural floor panels

Aircraft floor panels carry the highest loads of all interior panels, supporting passenger seats, galley equipment and cargo in the cabin. These panels typically use aluminium honeycomb cores with glass-fibre or carbon-fibre skins and must withstand point loads from seat rails and trolley wheels without permanent deformation. Floor panels must also maintain structural integrity under emergency landing load scenarios.

Cabin linings, overhead bins and monuments

Sidewall panels, ceiling panels and overhead bin shells use Nomex honeycomb cores with glass-fibre phenolic skins. These components prioritise fire resistance and low weight over compressive strength. Galley and lavatory structures are more complex assemblies that integrate plumbing, electrical systems and structural attachment points, but the panel skins and cores follow the same FST-qualified material systems used elsewhere in the cabin.

How are aircraft interior sandwich panels manufactured?

Aircraft interior sandwich panels are primarily manufactured by autoclave or press curing of pre-impregnated (prepreg) composite skins bonded to a honeycomb core with an adhesive film. The process applies controlled heat and pressure to consolidate the laminate and create a strong, void-free bond between the skins and the core.

The typical production sequence is as follows:

1. Core preparation: The honeycomb core is cut to the required thickness and, where necessary, machined to shape or stabilised with a potting compound at edges and insert locations.
2. Skin lay-up: Prepreg fabric plies are built up on a tool surface in the specified fibre orientation sequence. For aviation panels, the lay-up schedule is determined by structural analysis and must be reproduced exactly on every panel.
3. Assembly: Adhesive film is applied between the skins and the core. The assembled panel is placed in a vacuum bag to remove air and consolidate the plies before curing.
4. Curing: The bagged assembly enters an autoclave or heated press, where temperature and pressure are applied according to a qualified cure cycle. Autoclave processing is standard for structural aviation panels; out-of-autoclave curing in a press is used for some secondary interior components.
5. Machining and finishing: After curing, panels are CNC machined to final dimensions, inspected using ultrasonic or tap-test methods for delamination or voids, and fitted with edge closures, inserts and surface finishes as required.

Out-of-autoclave manufacturing, including resin transfer moulding (RTM) and vacuum infusion, is increasingly used for aircraft interior panels where geometry and volume justify the tooling investment. These processes reduce energy consumption and cycle time compared with autoclave curing.

How Compoform supports composite panel applications beyond aviation

Aviation-qualified sandwich panels represent one end of the composite panel spectrum. For manufacturers in ground transport, scaffolding and construction, the same structural logic applies: a lightweight core separated by stiff skins delivers far better performance per kilogram than solid sheet material. The difference is that outside aviation, thermoplastic sandwich panels offer a more practical and cost-effective solution.

We design and produce fully customised thermoplastic sandwich panels with PP honeycomb and PET foam cores, laminated with glass-fibre reinforced thermoplastic skins. Our panels are designed for applications where weight reduction, durability and total cost of ownership matter:

• Truck and trailer floors: A 30 mm PP honeycomb floor is self-supporting and eliminates the aluminium subframe that wooden floors require. That removes one production step and reduces vehicle weight in a single change.
• Scaffold deck components: Our 10.5 mm panel achieves EN 12811 load class 4 without support beneath it, tested to the European standard your procurement team will recognise.
• Custom dimensions: Panels are produced up to 13,500 mm x 2,950 mm x 150 mm on our 72 metre double belt press, cut to your exact specification. No secondary machining is required on your side.
• Long service life: Thermoplastic composite panels last three to four times longer than wood in heavy-duty transport applications. Over a vehicle lifetime of 15 years, that eliminates two to three replacement cycles. When you factor in panel cost, installation labour and vehicle downtime, the composite floor is cheaper per year of use, even at a higher unit price.
• Relevance for EV fleets: Every kilogram saved in the body structure extends the battery range of electric trucks and vans. Weight reduction is a range argument as much as a payload argument, and it is a standard procurement question from EV fleet buyers in 2026.

We review your design before production begins, optimise the panel configuration for your assembly process and flag potential problems before they become production problems. If you are specifying panels for a truck body, trailer or scaffolding application and want to understand which configuration suits your load requirements, speak directly with our engineering team.

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