(b) Any fuel tank meeting all of the criteria stated in paragraphs (b)(1), (b)(2) and (b)(3) of this section must have flammability reduction means (FRM) or ignition mitigation means (IMM) that meet the requirements of 14 CFR 25.981 in effect on December 26, 2008.
(1) The fuel tank is Normally Emptied.
(2) Any portion of the fuel tank is located within the fuselage contour.
(3) The fuel tank exceeds a Fleet Average Flammability Exposure of 7 percent.
(c) All other fuel tanks that exceed an Fleet Average Flammability Exposure of 7 percent must have an IMM that meets 14 CFR 25.981(d) in effect on December 26, 2008, or an FRM that meets all of the requirements of Appendix M to this part, except instead of complying with paragraph M25.1 of that appendix, the Fleet Average Flammability Exposure may not exceed 7 percent.
[Doc. No. FAA–2005–22997, 73 FR 42499, July 21, 2008, as amended by Amdt. 26–3, 74 FR 31619, July 2, 2009]