Aircraft interior sandwich panels are most commonly built with aramid (Nomex) honeycomb cores or aluminium honeycomb cores, 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 regulators and aircraft manufacturers require. The sections below answer the most common questions about how these panels are specified, manufactured, and used inside a commercial aircraft cabin.
Note: This article covers the broader sandwich panel market as it applies to aircraft interiors. Our range at Compoform is focused on thermoplastic sandwich panels with PP honeycomb and PET foam cores, primarily for commercial vehicles and scaffolding.
Which core materials are most common in aircraft sandwich panels?
The two most widely 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 absorbs impact energy well. Aluminium honeycomb appears in structural floor panels and cargo areas where higher compressive loads are expected.
Nomex is a meta-aramid paper manufactured by DuPont and formed into a hexagonal honeycomb structure before being resin-impregnated. Its cell geometry distributes load efficiently across the panel surface while keeping areal weight very low. This matters enormously in aviation, where every kilogram of structural dead weight reduces payload capacity or increases fuel burn.
Aluminium honeycomb offers higher compressive strength than Nomex at equivalent density, making it the preferred choice for aircraft floor panels that must withstand concentrated point loads from passenger seats, trolleys, and cargo equipment. The trade-off is that aluminium is heavier and less resistant to moisture ingress over time, which can cause corrosion in the core if the skin-to-core bond is compromised.
Foam cores, including rigid polymethacrylimide (PMI) and polyetherimide (PEI) foams, appear in some secondary interior structures where complex curvature or thermoforming is required. These materials are easier to machine and shape than honeycomb but generally offer lower shear stiffness at equivalent weight.
What skin materials are laminated onto aircraft interior sandwich panels?
Aircraft interior sandwich panels are most commonly 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 mechanical performance alone.
Phenolic resin systems are the traditional choice for cabin interior panels because phenolics char rather than melt when exposed to flame, producing relatively low smoke and toxic gas emissions. This behaviour directly supports compliance with aviation fire safety standards. Glass-fibre woven fabrics or non-crimp fabrics are the most common reinforcement, offering a good balance of stiffness, impact resistance, and cost.
Carbon-fibre skins appear in overhead bins, galley structures, and primary cabin monuments where stiffness-to-weight performance is prioritised. Carbon-fibre laminates are significantly stiffer than glass-fibre at equivalent thickness, which allows 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 rapidly in an enclosed, pressurised environment, and regulatory standards mandate 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 most demanding of any industry. Panels must pass vertical and horizontal burn tests, and in many applications 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 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 exits. Phenolic resin systems became the dominant matrix material for aircraft interior laminates largely because they produce significantly less smoke than epoxy or polyester systems when they do 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 skins to the core, must be tested and certified as part of the complete panel assembly. A skin material that passes FST tests in isolation may fail when tested as part of a bonded sandwich panel, which is why aircraft interior panels are always qualified as complete systems.
What’s 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 to 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 industries are not subject to these requirements and are instead specified to structural and durability standards relevant to their application.
Beyond certification, several technical differences distinguish aviation panels from industrial sandwich panels:
- Resin systems: Aviation panels use phenolic or specialised epoxy resins that meet FST requirements. Industrial panels more commonly 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 commonly use polypropylene honeycomb, PET foam, or polyurethane foam cores.
- Tolerances and traceability: Aviation panels require full material traceability, documented cure records, and non-destructive inspection. 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, requiring CNC trimming, insert installation, and integration of fittings. Industrial panels are more commonly produced in large flat sheets and cut to size by the end user or fabricator.
The cost difference reflects these requirements. Aviation-qualified sandwich panels carry significant certification overhead 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 and with the added benefit of full recyclability.
Where are sandwich panels used inside an aircraft cabin?
Sandwich panels are used throughout the aircraft cabin interior, covering floor panels, overhead stowage bins, sidewall liners, ceiling panels, galley structures, lavatories, and cabin monuments such as crew rest compartments and divider walls. The sandwich construction is chosen in every case because it delivers the required stiffness and strength at the lowest possible weight.
Structural floor panels
Aircraft floor panels carry the highest loads of any interior panel, 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 concentrated point loads from seat tracks and trolley wheels without permanent deformation. Floor panels are also required to maintain structural integrity during emergency landing load cases.
Cabin liners, 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 manufactured primarily through autoclave or press curing of pre-impregnated (prepreg) composite skins bonded to a honeycomb core using a film adhesive. 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 manufacturing sequence runs as follows:
- 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.
- Skin layup: Prepreg fabric plies are laid up on a tool surface in the specified fibre orientation sequence. For aviation panels, the layup schedule is defined by the structural analysis and must be reproduced exactly on every panel.
- Assembly: Film adhesive is applied between the skins and the core. The assembled panel is placed in a vacuum bag to remove air and consolidate the layers before curing.
- 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 press curing is used for some secondary interior components.
- Trimming and finishing: After cure, panels are CNC trimmed to final dimensions, inspected by ultrasonic or tap-test methods for disbonds or voids, and fitted with edge closeouts, inserts, and surface finishes as required.
Out-of-autoclave manufacturing methods, including resin transfer moulding (RTM) and vacuum infusion, are increasingly used for aircraft interior panels where the 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-grade 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 materials. The difference is that outside aviation, thermoplastic sandwich panels offer a more practical and cost-effective solution.
We design and produce fully custom thermoplastic sandwich panels using PP honeycomb and PET foam cores, laminated with glass-fibre reinforced thermoplastic skins. Our panels are engineered for applications where weight reduction, durability, and total cost of ownership matter:
- Truck body and trailer floors: A 30 mm PP honeycomb floor panel is self-supporting, eliminating the aluminium subframe that plywood floors require. That removes a production step and reduces vehicle weight in a single change.
- Scaffolding boards: Our 10.5 mm panel achieves EN 12811 load class 4 with no support underneath, 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 fabrication required on your end.
- Long service life: Thermoplastic composite panels last three to four times longer than plywood in heavy transport applications. Over a 15-year vehicle life, 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 service even at a higher unit price.
- EV fleet relevance: Every kilogram saved in body structure extends battery range in 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 starts, optimise the panel configuration for your assembly process, and flag potential issues before they become production problems. If you are specifying panels for a truck body, trailer, or scaffolding application and want to understand which configuration fits your load requirements, speak with our engineering team directly.