Pressurized cabins.

CFR · 2024-01-01 · US · Title 14

(a) Except as provided in paragraph (c) of this section, pressurized cabins and compartments to be occupied must be equipped to provide a cabin pressure altitude of not more than 8,000 feet under normal operating conditions. (1) If certification for operation above 25,000 feet is requested, the airplane must be designed so that occupants will not be exposed to cabin pressure altitudes in excess of 15,000 feet after any probable failure condition in the pressurization system except as provided in paragraph (c) of this section. (2) The airplane must be designed so that occupants will not be exposed to a cabin pressure altitude that exceeds the following after decompression from any failure condition not shown to be extremely improbable: (i) Twenty-five thousand (25,000) feet for more than 2 minutes; or (ii) Forty thousand (40,000) feet for any duration. (3) Fuselage structure, engine and system failures are to be considered in evaluating the cabin decompression. (b) Pressurized cabins must have at least the following valves, controls, and indicators for controlling cabin pressure: (1) Two pressure relief valves to automatically limit the positive pressure differential to a predetermined value at the maximum rate of flow delivered by the pressure source. The combined capacity of the relief valves must be large enough so that the failure of any one valve would not cause an appreciable rise in the pressure differential. The pressure differential is positive when the internal press

official document · source cfr-2024 · id 14:§ 25.841