Aerospace sandwich panels must meet certification requirements set by aviation authorities and international standards bodies before they can be used in any aircraft structure or interior. The specific certifications depend on the panel’s application, the materials used, and whether the aircraft operates under FAA (US) or EASA (European) jurisdiction. The questions below unpack the key certification bodies, applicable standards, and what the process looks like in practice.

Note: This article covers the broader aerospace sandwich panel market. Our range at Compoform is focused on thermoplastic sandwich panels for commercial vehicles and scaffolding applications, not aerospace. If you are sourcing panels for truck bodies, trailers, or scaffolding, the standards and processes described here do not apply to your procurement decision.

Which certification bodies govern aerospace sandwich panels?

Aerospace sandwich panels are governed primarily by the Federal Aviation Administration (FAA) in the United States and the European Union Aviation Safety Agency (EASA) in Europe. Both bodies set airworthiness requirements that any structural or interior panel must satisfy before it can be installed in a certified aircraft. Additional oversight comes from the panel manufacturer’s own quality management system, which must typically hold AS9100 certification.

Beyond the two main aviation authorities, several other bodies play a role depending on the application:

• ASTM International and ISO publish the material and mechanical test standards that certification submissions reference.
• SAE International produces aerospace material specifications (AMS) that define allowable material properties.
• EASA’s Design Organisation Approval (DOA) system governs which European manufacturers can self-certify design changes.
• National aviation authorities (NAAs) of individual EU member states may also be involved in validating imported designs.

For interior panels specifically, the FAA’s Aircraft Certification Service and EASA’s Certification Directorate both issue type certificates and supplemental type certificates (STCs) that cover the panel as part of a broader aircraft interior system, not as a standalone product.

What specific standards apply to sandwich panel materials?

Aerospace sandwich panel materials are tested against a combination of mechanical, thermal, and flammability standards. The most commonly referenced include ASTM C393 for core shear properties, ASTM C297 for flatwise tensile strength, and ASTM D7250 for determining sandwich beam flexural and shear stiffness. Fire performance is tested under FAR 25.853 (for FAA) and the equivalent EASA CS-25 provisions.

The full set of relevant standards covers several performance categories:

• Mechanical performance: ASTM C393 (core shear), ASTM C365 (flatwise compression), ASTM D7766 (damage tolerance after impact)
• Skin material properties: ASTM D3039 for tensile strength of composite laminates, though European programmes increasingly use EN ISO 527 as the equivalent
• Thermal performance: ASTM C518 or ISO 8301 for thermal conductivity, relevant for insulated fuselage panels
• Environmental durability: Resistance to humidity, fuel, hydraulic fluid, and cleaning agents, tested per ASTM or OEM-specific protocols
• Fire, smoke, and toxicity (FST): FAR 25.853 vertical and horizontal burn tests, OSU heat release rate testing, and NBS smoke density chamber tests

Aircraft OEMs such as Airbus and Boeing also publish their own material specifications, which suppliers must satisfy in addition to regulatory standards. These OEM specs often set tighter limits than the regulatory minimums.

How does the certification process for aerospace sandwich panels work?

The certification process for aerospace sandwich panels follows a structured qualification path that begins with material characterisation and ends with approval as part of a certified aircraft design. The process is not a single test but a series of documented stages, each requiring evidence that the panel performs within defined limits across its intended service conditions.

Material qualification

Before a panel enters any certification submission, the constituent materials must be qualified. This means generating a statistically valid dataset of mechanical properties across multiple batches and environmental conditions. The FAA’s Composite Materials Handbook (CMH-17) provides the statistical methodology for establishing design allowables. EASA accepts equivalent approaches under its certification memoranda.

Structural substantiation

Once materials are qualified, the panel must be substantiated for its specific structural role. This involves analysis supported by test evidence, following the “building block” approach: coupon tests, element tests, subcomponent tests, and finally full-scale component tests. Each level of testing reduces uncertainty before committing to the most expensive full-scale validation.

The certification dossier submitted to the FAA or EASA must document the entire chain of evidence, including material traceability, test procedures, test results, and the analysis methods used to extrapolate from test conditions to the full operational envelope. Any deviation from approved materials or processes requires a new certification submission or an approved engineering change.

What’s the difference between FAA and EASA certification requirements?

The FAA and EASA share broadly similar technical requirements for aerospace sandwich panels, but they differ in regulatory structure, documentation format, and the degree to which they accept each other’s approvals. The FAA operates under Federal Aviation Regulations (FARs), while EASA uses Certification Specifications (CS). Both reference the same underlying physics, but the administrative pathways diverge.

Key practical differences include:

• Bilateral agreements: The FAA and EASA operate under a Bilateral Aviation Safety Agreement (BASA), which allows some mutual recognition of approvals, but this does not mean automatic acceptance. Shadow approvals are still common for structural items.
• Design organisation approval: EASA requires a formal Design Organisation Approval (DOA) for companies that want to self-certify design changes. The FAA uses a Designated Engineering Representative (DER) system, which is more individual-based.
• Fire testing specifics: Both reference similar burn test methodologies, but EASA CS-25 and FAR 25.853 have minor differences in test configurations and acceptance criteria that can require separate test campaigns.
• Material specification references: FAA submissions frequently reference ASTM standards; EASA submissions increasingly accept EN ISO equivalents, which matters for European panel manufacturers.

For a European manufacturer supplying panels for an aircraft certified under both authorities, running parallel certification tracks from the outset is more efficient than seeking validation after the fact.

Do thermoplastic sandwich panels face different certification hurdles than thermoset panels?

Thermoplastic sandwich panels face a higher initial certification burden than thermoset panels primarily because the aerospace industry’s existing design allowables database is built almost entirely on thermoset composites. Most CMH-17 data, OEM material specifications, and historical precedent reference epoxy-based systems. Thermoplastic panels must generate their own qualification datasets from scratch, which increases upfront cost and timeline.

Beyond the data gap, thermoplastic panels present specific technical considerations that certification authorities scrutinise carefully:

• Creep behaviour: Thermoplastics are more susceptible to long-term creep under sustained load than thermosets. Certification submissions must demonstrate that creep deformation remains within structural limits over the aircraft’s design life.
• Temperature sensitivity: Thermoplastic matrices soften at elevated temperatures. Panels used near heat sources or in hot climate operations require testing at the upper end of the service temperature range.
• Joining and repair: Thermoset panels are typically bonded or mechanically fastened using well-established methods. Thermoplastic panels can be welded, but approved repair procedures must be developed and documented as part of the certification package.
• Impact resistance: Thermoplastic composites generally offer better impact resistance than thermoset equivalents, which can be an advantage in certification for damage tolerance requirements.

Regulatory acceptance of thermoplastic composites in aerospace is growing, particularly for secondary structures and interiors, but primary structural applications still require extensive substantiation that thermoset programmes can partially offset with legacy data.

What fire, smoke, and toxicity standards must aerospace panels meet?

Aerospace sandwich panels used in aircraft interiors must meet fire, smoke, and toxicity (FST) requirements defined under FAR 25.853 (FAA) and CS-25 Amendment 25 (EASA). These regulations set mandatory limits on how quickly a panel ignites, how much heat it releases, how much smoke it produces, and what toxic gases it emits during combustion. FST compliance is non-negotiable for any interior panel on a commercial aircraft.

The specific tests required depend on the panel’s location within the aircraft:

• Vertical burn test (60-second and 12-second): Measures flame propagation and burn length after a controlled ignition source is applied. Panels must self-extinguish within defined time limits.
• OSU heat release rate test (ASTM E906): Measures peak heat release rate and total heat released in the first two minutes. FAR 25.853(d) sets limits of 65 kW/m² peak and 65 kW·min/m² total for most interior panels.
• NBS smoke density test (ASTM E662): Measures optical density of smoke in both flaming and non-flaming modes. Maximum specific optical density is typically limited to 200 in flaming mode.
• Toxicity testing: No single FAA-mandated toxicity test exists at the federal level, but many airlines and OEMs require compliance with the Airbus ABD0031 or Boeing BSS7239 toxic gas emission specifications.

FST requirements are among the most demanding aspects of aerospace panel certification. Materials that perform well mechanically often fail FST testing, which is why aerospace-grade core and skin materials are developed specifically to balance structural performance with fire safety compliance.

How Compoform Supports Sandwich Panel Projects Outside Aerospace

Our focus at Compoform is thermoplastic sandwich panels for commercial vehicles and scaffolding, where the certification landscape looks very different from aerospace. For truck body builders, trailer manufacturers, and scaffolding companies, the relevant benchmarks are load performance standards such as EN 12811 for scaffolding and structural requirements for vehicle floors and walls, not aviation airworthiness codes. You can explore our thermoplastic panel applications for transport and scaffolding to see where our panels are used in practice.

Here is what working with us on a panel project looks like in practice:

• Panel configuration review: We review your structural requirements and specify the right core material (PP honeycomb or PET foam), core density, skin architecture, and number of plies for your application, rather than offering a catalogue selection.
• Custom dimensions: Panels are produced to your exact dimensions, up to 13,500 mm x 2,950 mm, on our 72-metre double belt press production line. No secondary cutting from oversized stock.
• Test-backed performance data: Our floor panels, for example, are tested to ISO 14125 for bending performance, with results documented in technical data sheets. You receive actual test data, not estimated values.
• Integration support: We work with you through the integration phase, flagging potential issues with edge sealing, fastening, or surface finish before they become production problems.
• Lifespan argument for procurement: Thermoplastic panels last significantly longer than plywood in heavy transport applications. Over a 15-year vehicle life, eliminating two or three plywood replacement cycles, including panel cost, installation labour, and vehicle downtime, makes the composite option cheaper per year of service even at a higher unit price.

If you are specifying panels for a truck body, trailer floor, or scaffolding board and want to understand which configuration fits your load requirements and assembly process, contact our engineering team to review your design before committing to a specification.

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