Aerospace Plastics: Materials, Specs & Approvals

Selecting plastics for aerospace applications requires more than choosing a material with good mechanical properties — it means meeting regulatory burn, smoke, and toxicity (BST) requirements, surviving wide thermal cycles, and carrying documented traceability. This guide covers the six materials most commonly specified on aircraft interior, structural, and fluid-system drawings, along with the certifications and sourcing practices engineers need to close out procurement correctly.

TL;DR — Aerospace plastic requirements at a glance:

FAR 25.853 governs flammability for cabin interior components; tested per OSU heat release (≤65/65 kW·min/m² peak/2-min) and vertical/horizontal Bunsen burn.
NBS smoke density (Ds ≤ 200 at 4 min, flaming and non-flaming) is required for most interior trim.
AMS 3650 series and ASTM D6778 govern specific thermoplastic forms and properties.
Traceability to material lot is mandatory; mill certifications must accompany every shipment.
Most high-performance aerospace plastics are machined from stock shapes — injection molding is the exception, not the rule, for low-volume structural parts.
ESD-safe grades (surface resistivity 10⁶–10⁹ Ω/sq) are specified for electronics bays and fuel-system adjacent hardware.
Chemical compatibility with hydraulic fluid (Skydrol), jet fuel (Jet-A), and cleaning agents must be verified for any wetted part.

Specifications & Approvals

Aerospace plastic procurement sits at the intersection of federal airworthiness rules and material standards. Engineers should understand which standard governs which property.

FAR 25.853 — Flammability

Title 14 CFR Part 25.853 sets flammability requirements for materials used in transport-category aircraft cabins. The appendices to Part 25 specify test methods:

Appendix F, Part I — vertical and horizontal Bunsen burn (60-second exposure).
Appendix F, Part IV — OSU heat release rate calorimeter; 65/65 rule (peak heat release ≤ 65 kW/m², 2-minute integrated heat release ≤ 65 kW·min/m²).
Appendix F, Part V — smoke density; NBS chamber, Ds(4 min) ≤ 200.

Materials used in overhead bins, seat components, sidewall panels, and ducting typically require FAR 25.853 compliance documentation from the material manufacturer.

AMS Specifications

The Aerospace Material Specifications (AMS) published by SAE International define composition, mechanical properties, and form tolerances for aerospace plastics:

AMS 3651 — PTFE sheet and rod
AMS 3672 — glass-filled PTFE
AMS 3678 — unfilled PTFE
AMS 5760 — polyimide film
Supplier data sheets often reference ASTM D638, D695, and D790 as the underlying test methods.

OSU Heat Release and NBS Smoke

OSU (Ohio State University) heat release testing is performed per ASTM E906/E1354. The test fires a 15 cm × 15 cm specimen at 35 kW/m² radiant flux and records peak and two-minute integrated values. NBS smoke is measured per ASTM E662. Reputable plastic distributors stock certified material with these test reports available on request.

Toxicity (AIRBUS ABD0031, Boeing BSS 7239)

OEM-specific toxicity standards govern cabin air quality during and after fire events. Airbus ABD0031 and Boeing BSS 7239 require low emissions of hydrogen cyanide, carbon monoxide, sulfur dioxide, and other toxic gases. PAI (Torlon) and polyimide materials are scrutinized particularly closely due to nitrogen content.

Materials for Aerospace Applications

PEEK (Polyetheretherketone)

PEEK is the dominant high-performance thermoplastic in aerospace structural applications. Its continuous service temperature of 480°F (250°C), tensile strength of 14,500 psi, and excellent chemical resistance to Skydrol and jet fuel make it a natural fit for brackets, bushings, and fluid-system components. Virgin PEEK passes FAR 25.853 vertical burn and OSU heat release in most tested configurations. Carbon-fiber-reinforced PEEK (30% CF) reaches tensile strengths above 30,000 psi at roughly one-fifth the density of aluminum, enabling direct metal replacement where fatigue life and corrosion resistance matter.

PEEK stock shapes are routinely supplied with material certifications traceable to resin lot. ESD-dissipative PEEK (loaded with carbon fiber or carbon black) is stocked for electronics enclosures and connector housings where surface resistivity must fall in the 10⁶–10⁹ Ω/sq range.

Explore PEEK stock shapes and grades

Ultem / PEI (Polyetherimide)

Ultem 1010 and Ultem 2300 (30% glass-filled) are the standard materials for aircraft interior components that require both FAR 25.853 compliance and structural performance at temperatures up to 340°F (170°C). PEI inherently passes flammability and smoke tests without halogenated flame retardants — a critical advantage for interior certification.

Ultem 9085 is the additive-manufacturing variant widely used in ULTEM FDM printing for tooling, jigs, and low-volume interior brackets, and carries its own FAR 25.853 test data. For machined parts, Ultem 1010 (unfilled) and 2300 (glass-filled) are stocked as sheet, rod, and tube for machining seat hardware, oxygen-system brackets, and avionics housings.

See Ultem/PEI material hub

PPS / Ryton (Polyphenylene Sulfide)

PPS offers a unique combination: a continuous service temperature of 425°F (220°C), near-zero water absorption (< 0.02%), and excellent resistance to aircraft fluids including fuel, hydraulic fluid, and lubricating oil. Glass-filled PPS (40% GF) reaches flexural modulus values above 1,700,000 psi, making it useful for housings and brackets that must hold tight tolerances over wide humidity swings.

PPS passes FAR 25.853 vertical burn and has low NBS smoke density values. It is frequently machined into fuel-system valve bodies, sensor housings, and fluid connectors where chemical resistance and dimensional stability are equally critical. Carbon-filled PPS provides ESD protection in fuel-system applications.

PPS/Ryton properties and machining

PAI / Torlon (Polyamide-Imide)

Torlon 4203 (unfilled) and 4301 (graphite/PTFE-filled) are the highest-performing thermoplastics used in aerospace bearing and wear applications. Torlon maintains a flexural strength above 25,000 psi at 500°F (260°C), and its coefficient of friction can be reduced to 0.1–0.15 with solid-lubricant fillers. These properties make it the first choice for self-lubricating bearings in flight control linkages, actuator bushings, and thermal management valve seats.

Torlon requires a post-cure cycle at 450–500°F after machining to develop full mechanical properties — a step that must be confirmed in supplier qualification. Mill certs traceable to resin lot and ASTM test reports are required on aerospace purchase orders.

PAI/Torlon technical data and grades

G7 (Glass-Fabric Silicone Laminate / Phenolic-Glass-Silicone)

G7 is a glass-woven-fabric reinforced silicone laminate with a continuous service temperature of 450°F (232°C) and excellent cryogenic performance down to −452°F (−269°C). It is non-tracking, arc-resistant per ASTM D495, and retains structural integrity under wet and high-humidity conditions. These properties make G7 the standard material for high-voltage electrical insulation, avionics standoffs, bus bar insulators, and terminal boards in aircraft.

G7 is supplied per MIL-I-24768/10 (Class GSI) and ASTM D709. Sheet stock is typically cut to size and machined to close tolerances. Unlike PEEK and Ultem, G7 is a thermoset — it cannot be remelted — which means machining scrap cannot be recycled.

G7 (Phenolic-Glass-Silicone) properties and forms

Polyimide (Vespel / Kapton-type)

Polyimide (PI) stock shapes — primarily marketed as Vespel (DuPont) — offer the highest continuous-use temperature of any unfilled polymer at 550°F (288°C) in air, with short-term capability to 900°F (482°C). This puts polyimide in a class of its own for applications adjacent to turbine components, engine bays, and propulsion systems where other thermoplastics fail.

Vespel SP-1 (unfilled) provides the baseline thermal and dielectric performance. SP-21 (15% graphite) and SP-3 (15% MoS₂) reduce friction and wear for dry-running bearing applications. SP-22 combines graphite and PTFE for the lowest friction coefficient (≈ 0.1 in dry sliding). Lead times for polyimide are typically 4–12 weeks from resin manufacturers; finished machined parts from stock shapes are faster at 2–6 weeks.

Polyimide/Vespel material hub and grades

Common Aerospace Applications

Interior Components

Seat brackets, armrest structures, tray table hardware, overhead bin latches, and lavatory fittings are routinely machined from Ultem 1010 or Ultem 2300 for their FAR 25.853 compliance and strength-to-weight advantages over aluminum at low-volume production quantities. PEEK replaces aluminum in seat-back attachment brackets and floor-track fittings where fatigue and corrosion are primary concerns.

Ducting and Air Management

Bleed-air ducts, environmental control system (ECS) fittings, and gaskets are machined from PPS or PEEK where temperatures exceed the capability of general-purpose engineering plastics. G7 is used for thermal isolation pads and standoff bushings between metallic duct flanges.

Bearings and Bushings

Self-lubricating Torlon 4301 and PEEK-CF bearings replace grease-lubricated metal bearings in flight control systems, cargo door hinges, and seat-track rollers. These dry-running assemblies eliminate contamination risk from grease migrating onto interior surfaces or wiring.

Electrical Insulation and Connectors

G7 sheet and rod are the standard insulators for terminal boards, circuit breaker panels, and bus bar supports. PEEK and Ultem are machined into connector bodies and backshells where the combination of dielectric strength (≥ 400 V/mil), FAR compliance, and tight-tolerance machinability is required.

Fluid System Components

PEEK and PPS valve bodies, manifold blocks, and fitting bodies handle jet fuel, hydraulic fluid, and liquid oxygen (LOX) service. PEEK's chemical inertness to LOX and oxidizers makes it one of the few thermoplastics approved for oxygen-system components under oxygen compatibility assessments per NASA/ASTM G94.

*G7 tensile strength reflects laminate warp direction; weaker in cross-grain.

Sourcing Notes

Lead Times

Standard unfilled PEEK, Ultem 1010, Ultem 2300, and G7 sheet and rod are typically in stock at qualified distributors with same-week or next-week shipment. Filled grades (CF-PEEK, ESD-PEEK, 40% GF-PPS) carry 2–4 week lead times. Polyimide (Vespel) stock shapes are specialty items with 4–12 week manufacturer lead times; plan accordingly for prototype programs.

Certifications and Traceability

Aerospace purchase orders typically require:

Material certification (cert of conformance) to material specification number, resin lot, and UTS/elongation test data.
FAR 25.853 test reports — referenced by ASTM method and OSU/NBS results. Confirm which configuration (thickness, color) was tested.
RoHS and REACH compliance declarations — required for European-registered aircraft and OEM Tier 1 suppliers operating in the EU.
Country of origin documentation — US, EU, or certified Allied Country sourcing required for some defense-adjacent programs.

REACH / RoHS

All six materials listed here are RoHS-compliant (free of cadmium, lead, mercury, hexavalent chromium, and restricted brominated flame retardants). REACH SVHC declarations are available from qualified distributors for each resin system. PTFE, PPS, and PVDF materials may contain fluorine-based process aids; confirm with supplier REACH declarations when low-molecular-weight PFAS are restricted by customer specification.

Minimum Order Quantities

Most stock shapes are available in cut-to-length or sawn-to-size quantities with no minimum beyond one piece. Full-length rod (typ. 4 ft) and full sheets (24 × 48 in or 48 × 96 in) are economical for multi-part programs. Certified-to-specification material may carry a per-lot test fee; confirm with your distributor.

Request a quote on FAR 25.853-compliant sheet, rod, and tube

Request a Quote →

More related guides

Where Aerospace Plastics cross with other content on the site:

Featured materials

Applications

Forms typically stocked