§25.832 Cabin ozone concentration

(a) The aeroplane cabin ozone concentration during flight must be shown not to exceed – (1) 0·25 parts per million by volume, sea level equivalent, at any time above flight level 320; and (2) 0·1 parts per million by volume, sea level equivalent, time-weighted average during any 3-hour interval above flight level 270. (b) For the purpose of this paragraph, “sea level equivalent” refers to conditions of 25° C (77° F) and 1 013·2 hPa (760 millimetres of mercury) pressure. (c) Compliance with this paragraph must be shown by analysis or tests based on aeroplane operational procedures and performance limitations, that demonstrated that either – (1) The aeroplane cannot be operated at an altitude which would result in cabin ozone concentrations exceeding the limits prescribed by sub-paragraph (a) of this paragraph; or (2) The aeroplane ventilation system, including any ozone control equipment, will maintain cabin ozone concentrations at or below the limits prescribed by sub-paragraph (a) of this paragraph.