DO-160 Section 26 is one of the environmental qualification tests in RTCA DO-160, and of all 23 DO-160 environmental sections, this is the one where a galley insert sits at the center of the hazard rather than the edge of it. Active heating elements, combustible service materials nearby, a high-occupancy cabin, the galley is where fire safety regulation’s concerns concentrate, which makes Section 26 less a test to pass than a design philosophy to commit to early.

What DO-160 Section 26 Covers, and Why It Exists

Section 26 covers fire resistance and flammability across three categories: Category A, Fireproof; Category B, Fire Resistant; and Category C, Flammability. The fireproof and fire-resistant tests involve calibrated burner exposure, controlling flame temperature and intensity under steady-state conditions with defined flame direction and location. Flammability testing covers several distinct methods depending on material type: a vertical Bunsen burner test for cabin and cargo-compartment materials, a horizontal Bunsen burner test for miscellaneous materials, and a 60-degree Bunsen burner test specifically for electric wire.

A Real Example: The Britax Sell Galley Appliance AD

This is one of the clearest, most directly galley-specific cases in all of DO-160. Starting in 2000, Germany’s Luftfahrt-Bundesamt identified an unsafe condition on Britax Sell water boilers, coffee makers, and beverage makers installed across a wide range of Airbus and Boeing aircraft, after ten reports of discolored wires and two reports of partially melted wires. Investigation traced the cause to insufficient crimping of the electrical terminal contact pins: the under-crimped terminals had increased contact resistance, which raised terminal temperature, discolored the insulation, and began melting it. The FAA’s superseding AD 2002-21-01 required replacing the wiring on affected appliances whether or not visible damage had yet appeared, specifically to prevent a galley-compartment fire that could put smoke in the cockpit and cabin and lead to loss of control of the airplane.

The Engineering Judgment Behind It

The most important judgment in this section happens before any flammability test is run: material and connection choices made in early design are what actually determine the outcome. Enclosure materials, insulation, wiring insulation, gasket compounds, and terminal and crimp specifications all flow into which test method applies and what category result is achievable. By the time a unit reaches the flammability bench, most of the decisions that decide its fate are already locked in. Treating Section 26 as a late-stage verification step rather than an early design input is the most common and most expensive mistake here.

The Britax Sell case sharpens a second, less obvious judgment: in galley equipment, the flammability risk often doesn’t start with a material igniting on its own. It starts with an electrical connection generating enough resistive heat to ignite what’s next to it. An under-crimped terminal looks fine on inspection and tests fine electrically at low current, then degrades into a heat source under sustained full load. That means crimp quality and terminal selection on current-carrying connections deserve explicit specification and verification, not an assumption that a connection which “looks right” is right. The mechanism that grounded a fleet’s worth of galley appliances was a crimp, not a material flammability rating.

The third judgment is matching the test method to the material, because the vertical, horizontal, and 60-degree wire tests are not interchangeable. Wiring insulation in particular has to be evaluated against the 60-degree test requirements, an easy detail to overlook until late, when changing a wire spec is expensive.

How to Mitigate This

• Treat flammability requirements as a material and connection design input from the earliest stage, not a late verification step, most of the outcome is decided before the test
• Specify and verify crimp quality on current-carrying terminals explicitly, the Britax Sell case shows how much fire risk hides in a connection that looks fine until it’s measured under load
• Match the test method to the actual material type, and check wiring insulation against the 60-degree wire test specifically

Further reading: FAA Airworthiness Directive 2002-21-01 (Federal Register).

How Eminent Helps: In galley equipment, fire risk usually traces back to early material and connection decisions, and sometimes to a single under-crimped terminal, not to a late test result. Building flammability and connection integrity into the design from the start, the way the Britax Sell case shows you have to, is exactly the work we do. See how we support galley insert programs, or talk it through with us.