Look Beyond Fire Ratings to Specify Sheet
for Thermoformed Aircraft Parts
By Adam Mellen
Unlimited availability of colors, textures and patterns including integral metallics, brushed aluminum, Carbon Weave (foreground) and Honeycomb (background), expand design possibilities while meeting aircraft fire, smoke and toxicity requirements.
At a minimum, sheet for thermoforming and fabricating of aircraft interior components must carry FAA fire, smoke and heat release ratings, and in some cases also comply with recent toxicity standards established by Boeing and Airbus. Since allowable sheet products must be certified to these standards, the specifier's search for an ideal sheet product should begin, not end, with fire-related certifications, and instead focus on significant differences in functional attributes, aesthetic qualities, and supplier policies to pinpoint the high performance sheet product that best satisfies your individual requirement.
1. The baseline: Consider only sheet products that meet aircraft fire, smoke and toxicity standards
High performance thermoplastic alloy sheet products that qualify for aircraft interior applications must be certified as meeting stringent FAA (Federal Aviation Administration) standards for flammability, heat release and smoke generation including:
FAR 25.853 A1 F, Part IV-6565; FAR 25.853 (d); FAR 25.853 A1(i); FAR 25.853 A1.
In addition, many aircraft interior applications also require compliance with Airbus ABD-0031 and Boeing D6-51377 toxicity standards, which were enacted to limit toxic gas emissions when burned.
It is therefore fundamental that the sheet you purchase carry the above certifications. It is important to note, however, that thermoplastic formulations developed to meet these standards typically incur significant reductions in physical property values, particularly impact resistance. Since the properties of competing fire-rated sheet can vary widely, it is incumbent on you, the specifier, to identify those sheet products that offer the most desirable properties for any given fire rating and/or category of product.
2. Maximize property-to-cost ratios
Be certain to specify a sheet product that offers the greatest physical property values especially impact resistance at the same cost as lower performing sheets, or better, sheet products offering the superior physical properties as well as the lowest cost.
You can easily evaluate aircraft rated sheet products of major manufacturers in terms of Izod impact resistance, specific gravity, tensile strength, flexural modulus, Rockwell hardness, heat deflection, heat release, NBS Smoke and thermal expansion, by comparing specifications of individual grades online.
Less obvious but as important in many cases, are other product characteristics that affect performance in the field. For example, some sheet products simulate a metallic appearance by reverse printing of metallic ink on clear cap film that is laminated onto a thermoplastic substrate, whereas other metallic sheet is comprised of a cap film with integral metallic coloration, offering greater scratch resistance. You should acquaint yourself with such differences before purchasing any sheet product.
Also critically important is sheet quality, which should not be assumed. If you are not yet experienced in aircraft interior sheet sales, you should confirm that the brand of sheet you are considering is known to be free of pits and inclusions-problems you can research through other specifiers or through sheet suppliers themselves.
3. Offer designers what they most desire: selection
Designers yearn for the widest possible selection of colors, metallics, wood grains, patterns and textures the tools they need to create interior environments that owners and passengers will prefer over the interiors of competing aircraft.
You should therefore attempt to maximize the aesthetic options offered by the sheet manufacturer you are considering, in terms of:
- Solid colors in a standard or unlimited range
- Translucent colors
- Clear sheet
- Wood grain prints
- Custom patterns
- Thicknesses from .003 to 3.0 in. (.076 to 76.2 mm)
- Standard or unlimited surface textures
- Scratch resistant surfaces
- Scratch resistant, integral metallic colors
- Low, medium and high gloss surface textures
Because aircraft interior projects generally start small and then grow, the sheet supplier you select should also offer very low minimums on all variants of its sheet products, enabling you to initiate a project without cost penalties or long deliveries.
Flame and smoke requirements, once the determining factors in sheet specification for thermoformed aircraft interior components, are now satisfied by a wide range of certified sheet products. As a result, specifiers can shift their attention to differences in the physical properties, cost and appearance of sheet products, and in the manufacturers that offer them.