The Oil Burner for Seat Cushion test (also known as the Fireblock test) is used to evaluate the burn resistance and weight loss characteristics of aircraft seat cushions when exposed to a high-intensity open flame. This test is typically used to show compliance to the requirements of 14 CFR 25.853(c), which states:
"...seat cushions, except those on flight crewmember seats, must meet the test requirements of part II of appendix F of this part, or other equivalent methods, regardless of the passenger capacity of the airplane."
[Amdt. 25-83, 60 FR 6623, Feb. 2, 1995, as amended by Amdt. 25-116, 69 FR 62788, Oct. 27, 2004]
An overview of the requirements is described below. Please note that this is a very simplified summary of the requirements, and is only intended as a brief overview. For further details, refer to the FAA documents listed below or contact your local FAA office.
Test Articles: A vertical assembly and horizontal assembly are built as a set, and are representative of the production seat back, seat bottom, arm rest, or headrest. The test articles have identical construction and materials proportioned to correspond to the production part. Three seat test samples of the same construction and configuration are tested.
Apparatus & Equipment: The test sample apparatus includes a seat test sample mounting frame on which the test articles are placed and a drip pan. This apparatus sits on a bench scale that weighs the test samples before and after testing. The test requires a modified gun type oil burner described in Appendix F of 14 CFR 25 as the flame source.
Calibration: Prior to testing, the flame must be calibrated to the proper temperature and heat flux requirements using thermocouples and a foil type Gardon Gage.
Testing: The test sample is weighed prior to testing, then the flame is applied to the samples for two minutes. The test ends when the sample self-extinguishes (or is extinguished by the technician after 5 minutes). Immediately after test termination, the sample is weighed again and the four burn lengths are measured.
Passing Criteria: For each of the burn lengths measured, the burn length may not exceed 17 inches on at least two-thirds of the total number of samples tested. In addition, the combined average percentage weight loss of all samples tested will not exceed 10 percent, and the individual percentage weight loss of at least two-thirds of the total number of samples tested will not exceed 10 percent.
For further rules, regulations, and guidance on the subject, please consult the following FAA documents:
- 14 CFR 25.853 (previously referred to as FAR 25.853)
- 14 CFR 25, Appendix F, Part II
- FAA Aircraft Materials Fire Test Handbook, Chapter 7
- AC 25.853-1, Flammability Requirements for Aircraft Seat Cushions
- PS-ANM-25.853-01-R2, Flammability Testing of Interior Materials