This standard specifies the basic dimensional requirements and the necessary access for the fittings for the pressurization test of pressurized aircraft to guarantee coupling with the hoses or with the adapters of the ground pressurization equipment. Three fitting sizes are specified below: Fitting size Recommended cabin volume 22.22 mm* (0.875 in) Not exceeding 10 m3 (300 ft3) 46.04 mm (1.8125 in) 10 m3 to 45 m3 ( 300 ft3 to 1,500 ft3) 72.39 mm (2.88 in) 45 m3 to 170 m3 (1,500 ft3 to 6,000 ft3)