Heat Release Rate (OSU)

Test Sample Requirements

Test samples must meet the following requirements:

• The sample size is 5.9-inch x 5.9-inch.
• A minimum of 3 samples must be tested.
• The sample thickness must the same as the thickness of the part/construction. (Maximum Thickness = 1.75 inch)
• If the material could react differently depending which direction it is cut, it must be tested in the orientation thought to give the highest result. If the average maximum heat release rate exceeds 58 kW/m² during testing, a second set of samples oriented perpendicular to the first set must be tested.
• Samples may be tested either as a section cut from a fabricated part as installed in the aircraft, or constructed to simulate that part.
• Fabricated units, such as sandwich panels, may not be separated for testing.

History of the Heat Release Test

In 1978, the Federal Aviation Administration (FAA) established a committee to examine the factors affecting the survivability of aircraft occupants in a post-crash environment. This committee was known as the Special Aviation Fire and Explosion Reduction (AFER) Advisory Committee and was composed of fire safety experts from the National Aeronautics and Space Administration (NASA), the aerospace industry, and the general public. One of the recommendations of this committee was to further research and develop a test method for cabin materials using radiant heat. The FAA technical Center conducted full-scale fire tests using the fuselage of a military C-133 configured to represent a wide-body jet transport airplane. As a result of the full-scale tests, the Ohio State University (OSU) rate of heat release apparatus, as standardized by the American Society of Testing and Materials (ASTM), ASTM-E906, was determined to be the most suitable for material qualifications.

The OSU Rate of Heat Release apparatus employs radiant heat, which the SAFER Advisory Committee recommended because it is most representative of the post-crash fire environment. The ability of the test method to adequately discriminate acceptable from unacceptable materials was verified using several generic materials, whose results and rankings were identical to those obtained in the full scale fire tests.

In 1986, the FAA issued a final rule amending 14 CFR 25.853 to add a new requirement for heat release rate testing. This new rule required all large interior surface materials installed above the floor in compartments occupied by the crew or passengers to meet the heat release requirements of the newly created 14 CFR 25, Appendix F, Part IV. This would include sidewalls, ceilings, bins and partitions, galley structures, and any coverings on these surfaces.

The Heat Release test underwent a few changes since its creation, with five corrections or amendments to the test procedure and test apparatus requirements of Appendix F, Part IV. Individual manufacturers and organizations also established their own internal versions of the Heat Release Rate Test, such as Airbus (ABD0031/AITM 2.0006), Boeing (BSS 7322), McDonnell Douglas (DMS 2277), and ASTM International (ASTM E906, modified).

In order to facilitate improvements to the test standard without constantly changing the CFR, the FAA published Report DOT/FAA/CT-99/15 "Aircraft Materials Fire Test Handbook" in 1990. The tests in this handbook are considered an acceptable equivalent to those in the CFR. The handbook was updated in 2000 to DOT/FAA/AR-00/12, with the Heat Release Rate test located in Chapter 5 of the handbook.

Sources: Federal Register Vol. 51, No. 139

Additional Resources