14 C.F.R. § 121.247 Fire-wall construction.
Title 14 - Aeronautics and Space
Each fire wall and shroud must— (a) Be so made that no hazardous quantity of air, fluids, or flame can pass from the engine compartment to other parts of the airplane; (b) Have all openings in the fire wall or shroud sealed with close-fitting fire-proof grommets, bushings, or firewall fittings; (c) Be made of fireproof material; and (d) Be protected against corrosion.
Title 14: Aeronautics and Space
PART 121—OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS
Subpart J—Special Airworthiness Requirements
§ 121.247 Fire-wall construction.