FAR 25.853 Aircraft Flammability Guide

FAR 25.853 (14 CFR § 25.853, "Compartment interiors") is the U.S. Federal Aviation Regulation governing the flammability of materials used in transport-category aircraft cabin interiors. It defines the fire-test criteria — chiefly the vertical Bunsen-burner test in Part I of Appendix F — that interior materials and the tapes used with them must meet.

Paragraph (a) requires materials in crew and passenger compartments to meet the test criteria in Part I of Appendix F, or an approved equivalent method, regardless of the airplane's passenger capacity. For most materials that means a vertical-burn test, and a material passes only if its averaged results stay within the burn-length, flame-time and drip-time limits for the applicable 12-second or 60-second version.

For the 60-second test under Appendix F Part I (a)(1)(i): a maximum 6-inch burn length, 15-second flame time and 3-second drip flame time. For the 12-second test under (a)(1)(ii): a maximum 8-inch burn length, 15-second flame time and 5-second drip flame time. All results are averaged across three specimens.

Paragraph (b) of the current 14 CFR § 25.853 is marked [Reserved], so a citation to 25.853(b), (b-2) or (b-3) is quoting an earlier edition of the regulation. Manufacturers reprint the callout their original qualification testing was written against. The horizontal burn-rate criteria those references pointed to still exist in Appendix F Part I, at (a)(1)(iv) for 2.5 inches per minute and (a)(1)(v) for 4.0 inches per minute.

Not on its own. The FAA's procedure qualifies each type of tape on the specific surface it is applied to, so compliance is established for the tape-plus-substrate combination as installed. A tape data sheet shows the typical burn values from testing to the 25.853(a) criteria. Always confirm qualification for your substrate and application.

It follows from the material category in Appendix F Part I (a)(1). The 60-second test at (a)(1)(i) covers ceiling and wall panels, partitions, galley structure and structural flooring. The 12-second test at (a)(1)(ii) covers floor coverings, textiles, coated fabrics, air ducting, trim strips and molded parts — which is where most interior tapes sit, and why aerospace tape data sheets usually quote the 12-second criteria.

25.853 covers cabin compartment interior flammability, 25.855 covers cargo and baggage compartment liners, and 25.856 covers thermal and acoustic insulation including burnthrough resistance. Many aerospace tapes are tested to more than one depending on where they are installed — our cargo tapes reference 25.853(a) and 25.855(d), and the insulation splicing tapes add 25.856(a).

Only if it has a passenger capacity of 20 or more. Paragraph (d) adds the heat release and smoke tests in Parts IV and V of Appendix F for ceiling and wall panels, partitions, galley structure and large cabinets, on top of the paragraph (a) requirement. Paragraph (e) then exempts isolated compartments that are closed off from the main cabin by a normally-closed door, such as the flight deck, galleys, lavatories and crew rest areas.

A Certificate of Conformance is included with every order where available. It is what ties the roll you received to the specification your drawing calls out, so tell us the callout when you order and we will make sure the paperwork names it.