Come Fly with Me: Aircraft Upholstery Textiles—Requirements and Testing

Squawk 7700!

“Fire! Smoke!” the passengers on an American Airlines Boeing 737-823 flight shouted when their plane, which had been redirected from Colorado Springs to Denver, Colorado, arrived. As reported by the National Transportation and Safety Board (NTSB) in its Aviation Investigation Preliminary Report regarding the March 13, 2025, incident, after the flight crew landed, taxied to the gate, and turned off the engines, a fire broke out in one of the latter. Fortunately, just twelve of the 172 passengers experienced minor injuries while deplaning, and ramp agents extinguished the fire; unfortunately, the Boeing 737 was considerably damaged. According to the Federal Aviation Administration (FAA), airplane cabin fires can occur after a crash or forced landing when burning fuel breaches the crew and passenger area, while an aircraft is in flight, or while a plane is being serviced. Depending on the emergency, aircraft upholstery fabrics can help to foil ignition or prevent a fire from spreading. They also provide travelers with a relatively comfortable ride, which, in the early days of aviation history, wasn’t always the case.

Note: Squawk 7700 is a transponder code that pilots use to inform Air Traffic Control (ATC)  they’re experiencing an emergency.

 

 

Early Commercial Aircraft Cabin Linings and Seats

During the Golden Age of Aviation (approximately 1919-1939), choice of commercial aircraft passenger seats was driven first by function and size and later by customer appeal and comfort. For example, the armchairs in the Lawson C-2 prototype had lignocellulosic rattan frames and seats woven from tropical vines, a breathable, lightweight, and sturdy solution in 1919. Upgrades to the rattan chairs on the historic Ford Tri-Motor or “Tin Goose,” a “luxury” aircraft that debuted in 1926, included headrests and seat cushions; subsequent versions were made from fireproof aluminum frames upholstered with leather, as shown in the image below.

As described in a Maintenance and Service Manual for the Boeing 247 Transport Airplane issued in 1933, the cabin interior of the first contemporary commercial airplane was lined with wool broadcloth. Fast forward to the “Golden Age of Air Travel” of the 1950s and 1960s and the first flight of the Boeing 707 jetliner in 1957. The establishment of the Federal Aviation Administration (FAA) in 1958 and the introduction of safety protocols aligned with new technologies helped to reassure flyers that commercial airlines were not only a fast and luxurious but also a secure way to travel.   

Aircraft Upholstery Safety Requirements: FAR 25.853 for Beginners

In the US, aircraft upholstery fabrics, such as leather, synthetic leather, wool, and wool blends, must comply with Title 14 (Aeronautics and Space) Code of Regulation (CFR) Section 25.853 — Compartment Interiors, as outlined in Appendix F to Part 25 of the document. Please note that aircraft regulations associated with Federal Aviation Regulation (FAR) 25.853 are a subset of Title 14 and not a separate group of rules governing fire prevention and flammability. As found in Part I of Appendix F, fabrics subject to safety requirements include floor coverings, seat cushions, and upholstery. (Overseas, FAA administrative and code equivalents include the European Union Aviation Safety Agency (EASA) and CS25.853.) To ensure that aircraft manufacturers meet the administration’s certification and safety requirements, throughout its regulatory history, “The FAA has never allowed companies to police themselves or self-certify their aircraft,” as noted on its website. Outside of the center, approved representatives can include aircraft material manufacturers, designated engineering representatives (DERs), and independent labs, with the integrity of the results confirmed by operators of design organizations (ODAs).

 

Aircraft Upholstery Tests at a Glance

To meet aircraft upholstery safety requirements, fabrics must pass small-scale tests developed by the Materials Fire Test Facility in the FAA’s William J. Hughes Technical Center. Detailed descriptions of the equipment and procedures used for in-flight, post-crash, and other fire threat assessments can be found in the Aircraft Materials Fire Test Handbook: Revision 3, last revised in July 2019. As of September 2025, the FAA’s Fire and Cabin Safety Research Group (FCSRG) has revised the handbook’s website to reflect pending assessments for flammability based on existing methods that comply with 14-CFR 25.853, as summarized below:

• Heat Release Rate Test for Cabin Materials (can help to predict the spread of a fire)—assesses the average maximum amount of heat energy produced by three burning samples over five minutes, expressed as kW/m²
• Horizontal Bunsen Burner Test for Cabin, Cargo Compartment, and Miscellaneous Materials—evaluates the average flame resistance of three samples over fifteen seconds of ignition time
• Oil Burner Flammability Test for Seat Cushions—measures the burn resistance and weight loss for four burn lengths on three sample cushions subjected to an open flame, for a maximum burn length of seventeen inches and a weight loss of ten percent, respectively
• Smoke Test for Cabin Materials—assesses the smoke-producing behaviors of materials subjected to a flame-based or flameless radiant heat source over a period of four minutes, for a maximum optical density (Dm) of smoke of 200 or less
• Twelve-Second Vertical Bunsen Burner Test for Cabin and Cargo Compartment Materials—evaluates the average flame resistance of three samples following twelve seconds of exposure, for a maximum burn length of eight inches
• Sixty-Second Vertical Bunsen Burner Test for Cabin and Cargo Compartment Materials—measures the average flame resistance of three samples following sixty seconds of exposure, for a maximum burn length of six inches

According to Keith Krueger of Krueger Testing & Consulting in Stanwood, Washington, USA, which provides DER services for interior aircraft materials, “The early days of fire safety required materials to burn very slowly. As technology progressed, we added the requirement to be self-extinguishing.” [For example], “The vertical burn test is an in-flight safety test. We want materials in the cabin to self-extinguish during an in-flight fire.” By comparison, “The oil burn test is for survivable post-crash fire safety. [Here], we are trying to limit the involvement of the seats during a survivable accident.” When asked if a sample set might pass a test in the lab and then fail to perform in real life, Krueger stated that it was not only conceivable but had also occurred in aviation history. In general, he noted, fire properties tests are screening tests that are intended to prevent the installation of materials that could function as “bad actors” and “don’t always relate to a real installation.” For instance, in the twelve-second vertical Bunsen burner test, “a seat pan with a dress cover is not installed vertically, it’s just how we test the material.” “The insulation flame propagation rule,” Krueger pointed out, “is a good example. It was found (through catastrophic loss) that insulation did not age in service as was [previously] thought and failed to meet the minimum requirements shortly after being put into service. The result was a new rule and test.”  

Effects of Perspiration on Aircraft Upholstery Fabrics

Cabin pressure and temperature, air sickness, and fear of flying are just a few of the reasons why some of us may sweat on airplanes. Sebahat Osanmaz, Technical Manager (US and Canada Softlines) for SGS North America Inc., addresses this when she talks about the effects of perspiration and the indirect impact of poor colorfastness on aircraft upholstery fabrics. Osanmaz explains that, “The pH of human sweat varies but is generally slightly acidic, contributing to the long-term weakening of fibers, depending on their type. Acids weaken cotton by breaking down cellulose chains, while alkalis damage wool by degrading its protein structure; nylon is generally resistant to both under normal conditions. By comparison, salts cause physical abrasion and retain moisture, [accelerating] chemical degradation. [In combination], acids and salts compromise fiber structure and reduce a fabric’s ability to withstand tension over time. ‘’Perspiration can compromise the performance of fire-blocking layers (FBLs) in airline seat cushions by introducing acids and salts that gradually degrade the material. Although FBLs are engineered for fire resistance using materials, prolonged exposure to sweat can weaken protective coatings, reduce fiber integrity, and diminish fire retardant effectiveness, particularly under repeated thermal and chemical stress. [Additionally], absorbed sweat creates a moist, nutrient-rich environment that promotes bacterial growth, [which], over time, can cause odors, material degradation, and potential health risks, especially if cushions are not properly cleaned or maintained.” The colorfastness of a fabric to perspiration depends on the dyeing chemistry and method, fiber type, fabric construction, and finishing treatment and can be confirmed using AATCC TM15. Osanmaz describes that, during the test, “a 6 x 6 cm colored fabric specimen is wetted with a simulated acid perspiration solution and placed on an acrylic plate in contact with multifiber strips. The specimen is then subjected to a fixed mechanical pressure of 4.54 kg and allowed to dry for six hours at a temperature of 38°C, [after which] the colored textile is assessed for any color change, and the multifiber strips are evaluated for color transfer using the AATCC Gray Scale for Color Change.” When exposed to simulated acidic perspiration, a specimen may fail AATCC TM15 due to:

• Deficiencies in the dyeing process, for example, curing or washing
• Inadequate dye chemistry that lacks resistance to acidic or moist environments
• Insufficient fixation of a dye to the fiber substrate, resulting in bleeding, dye migration or movement, or fading
• Unsuitable fabric finishes or treatments that destabilize dyes and promote color degradation or transfer
• Weak chemical or physical bonding between dye molecules and fiber polymers

AATCC TM15 is an important assessment because, says Osanmaz, “Colorfastness can indirectly impact the safety of airline upholstery fabrics. Poor colorfastness may cause fading or bleeding that obscures safety labels or markings. Additionally, dye degradation may affect the fabric’s surface treatments, potentially reducing flame resistance or other protective properties. Thus, good colorfastness helps preserve both the appearance and safety features of a fabric.”  

Finishing Touches: Antimicrobial Coatings and Tests

While not as immediately threatening as an in-flight or post-crash fire, airborne fungal, bacterial, and viral stowaways can cause passengers to fall ill after they’ve reached their destinations. In commercial aircraft cabins, pathogenic hotspots include armrests and headrests, plus seats, seatbelts, and seat belt buckles. Antimicrobial fabric finishes are one solution, but as stated in CFR 25.853, “Materials (including finishes or decorative surfaces applied to the materials) must meet the applicable test criteria prescribed in Part I of Appendix F.” Robert A. Monticello, Ph.D. (Microbiology and Biochemistry), Chair of AATCC’s RA31 Antimicrobial and Odor Control Committee and Senior Technical Advisor for the International Antimicrobial Council (IAC), addresses the use of TM100: Test Method for Antibacterial Finishes on Textile Materials, on airline fabrics. Monticello clarifies that, ‘“Antimicrobial’ is a generic term that can apply to antibacterial agents, whereby ‘antibacterial’ is a more specific term; for example, while antimicrobial agents can be antibacterial agents, not all antibacterial agents are antimicrobial agents.” When exposed to pathogens, “fabrics can become a harbor” for E.coli, influenza, and Staphylococcus aureus (MRSA), among other frequent flyers. Antimicrobial agents are designed to prevent bacteria from growing on fabric and, most significantly, prevent odors from developing.

Their application is two-fold:

1) Prevent bacteria from building up on the surface of a fabric, where it could be transferred from person to person when it sloughs off the skin (almost any bacteria can be transferred).

2) Prevent bacteria from “chewing up” the fabric (breaking it down, discoloring and/or degrading it).

Antimicrobial agents include metal-based technologies (copper, silver, or zinc), which are often particle-based systems bound to the surface or incorporated directly into the synthetic fiber. Particle-based systems must “lock onto the surface of a fabric” or risk being laundered and washed away. In contrast, polymer-based binding systems containing either metal or non-metal antimicrobial agents “can become one with the surface.” The antimicrobial property occurs on contact with the bacteria, preventing growth. If properly cured to the surface, these active ingredients cannot be removed through abrasion or laundering. The TM100 assessment must be conducted in a microbiology lab, whereby initial development tests should ideally involve testing one-inch by one-inch samples treated and untreated in triplicate. Each sample is placed in a specimen cup with one milliliter of an inoculum containing bacteria and nutrients, incubated overnight, diluted as necessary, and plated. The percentage of bacteria remaining, if any, is compared with the original population or with standard reference control fabrics. Samples may appear to fail the test for several reasons, for instance, because the bacterial solution was improperly prepared/applied, the antimicrobial finish was deactivated, or the antimicrobial finish was concealed by an additional substance.

Finishes and Flammability: Potential Conflicts

In response to the topic of how antimicrobial and flammability agents may conflict with each other, Monticello notes that, ”Order of delivery of a product is very important. Many binding systems are carbon-based and conceivably flammable, and the bonding system may affect flammability. It’s critical to ensure that the added antimicrobial agent does not alter the flammability of the final good and that the flammability agent does not hinder the antimicrobial agent. Both functionalities must co-exist.” Additionally, antimicrobial tests “can go wrong on so many levels, and many traditional textile labs are not qualified to conduct both antimicrobial and flammability tests,” according to the International Antimicrobial Council. Monticello recommends that any laboratory wishing to run the AATCC TM100 (or other antimicrobial methods) become fully trained and certified in these microbiological techniques by the IAC. That said, it’s possible that samples may appear to “fail the test but still fully function in real life.” That’s why the RA31 Committee and the textile industry “continually study these methods to understand their potential limitations and to accommodate new technologies.”

  In the twenty-first century, it’s hard to imagine that our commercial aircraft predecessors once flew on rattan chairs with only a cushion to soften the ride, one that most likely wasn’t antibacterial, colorfast, or flame retardant. And while we may take cabin carpets and upholstered passenger seats for granted, since the “Golden Age of Air Travel,” along with flight and ground crews, they’ve been designed and tested to ensure that we arrive at our destinations as safely as possible.  

About the Author Juliana Barnes, a freelance writer and graduate of the Fashion Institute of Technology’s textile design program (concentration in woven design), has more than ten years of experience in e-learning and information services. Her LinkedIn address is https://www.linkedin.com/in/julianabarnes23/.