FAR 91.613 — Compartment Interior Materials
FAR 91.613 explains compartment interior and thermal/acoustic insulation flammability requirements for certain large and transport category airplanes.
In Plain English
FAR 91.613 sets fire-safety standards for the materials used inside the cabins of certain larger airplanes. It has two parts:
- SFAR No. 41 airplanes (over 12,500 lbs MTOW): If an airplane was modified under an amended or supplemental type certificate issued under SFAR No. 41 to operate above 12,500 pounds maximum certificated takeoff weight, the compartment interior must meet the flammability requirements of § 25.853(a), (b), (b-1), (b-2), and (b-3) (as in effect September 26, 1978) within one year of the initial airworthiness certificate.
- Thermal/acoustic insulation in transport category airplanes (type certificated after January 1, 1958):
- Airplanes built before September 2, 2005: any blanket-style insulation, or insulation installed around air ducting, that is replaced after that date must meet the flame propagation requirements of § 25.856 (effective September 2, 2003).
- Airplanes built after September 2, 2005: all fuselage thermal/acoustic insulation must meet § 25.856.
Why it matters: cabin fires spread fast. These rules ensure interior materials and insulation resist ignition and flame propagation, buying time for evacuation.
Regulation Text
14 CFR § 91.613§ 91.613 Materials for compartment interiors.
(a) No person may operate an airplane that conforms to an amended or supplemental type certificate issued in accordance with SFAR No. 41 for a maximum certificated takeoff weight in excess of 12,500 pounds unless within 1 year after issuance of the initial airworthiness certificate under that SFAR the airplane meets the compartment interior requirements set forth in § 25.853 (a), (b), (b-1), (b-2), and (b-3) of this chapter in effect on September 26, 1978.
(b) Thermal/acoustic insulation materials. For transport category airplanes type certificated after January 1, 1958:
(1) For airplanes manufactured before September 2, 2005, when thermal/acoustic insulation is installed in the fuselage as replacements after September 2, 2005, the insulation must meet the flame propagation requirements of § 25.856 of this chapter, effective September 2, 2003, if it is:
(i) Of a blanket construction or
(ii) Installed around air ducting.
(2) For airplanes manufactured after September 2, 2005, thermal/acoustic insulation materials installed in the fuselage must meet the flame propagation requirements of § 25.856 of this chapter, effective September 2, 2003.
[Docket 18334, 54 FR 34318, Aug. 18, 1989, as amended by Amdt. 91-279, 68 FR 45083, July 31, 2003; Amdt. 91-290, 70 FR 77752, Dec. 30, 2005]
Oral Exam Questions a DPE Might Ask
Q1Under what condition does FAR 91.613(a) require an airplane to meet the § 25.853 compartment interior requirements?
Per FAR 91.613(a), an airplane modified under an amended or supplemental type certificate issued under SFAR No. 41 for a maximum certificated takeoff weight over 12,500 pounds must meet § 25.853(a), (b), (b-1), (b-2), and (b-3) within one year of its initial airworthiness certificate.
Q2When does replacement thermal/acoustic insulation in a pre-2005 transport category airplane have to meet § 25.856 flame propagation standards?
Under FAR 91.613(b)(1), if the airplane was manufactured before September 2, 2005, replacement insulation installed in the fuselage after September 2, 2005 must meet § 25.856 if it is of blanket construction or installed around air ducting.
Q3What insulation rule applies to a transport category airplane manufactured after September 2, 2005?
FAR 91.613(b)(2) requires that all thermal/acoustic insulation materials installed in the fuselage of such airplanes meet the flame propagation requirements of § 25.856, effective September 2, 2003.
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Related Sections in Part 91