Text in force at CS25-28: from CS25-28, effective 20 Dec 2023.
(See AMC 25.801)
(a) Whether or not ditching certification is requested, it must be shown that, following an unplanned ditching, the flotation time and trim of the aeroplane will allow the occupants to leave the aeroplane.
(b) If certification with ditching provisions is requested, the aeroplane must comply with CS 25.563, CS 25.807(i), CS 25.1411, CS 25.1415 and the following:
(1) Each practicable design measure, compatible with the general characteristics of the aeroplane, must be taken to minimise the probability that in a planned emergency landing on water, the behaviour of the aeroplane would cause immediate injury to the occupants or would make it impossible for them to escape.
(2) The probable behaviour of the aeroplane in a planned emergency landing on water must be investigated by model tests or by analytical methods supported by tests. Features likely to affect the hydrodynamic characteristics of the aeroplane must be considered.
(3) It must be shown that, following a planned emergency landing on water, the flotation time and trim of the aeroplane will allow the occupants to leave the aeroplane and enter the rafts. The flotation and evacuation assessment must account for all sources of water leakage that may be present after the planned emergency landing.
ED Decision 2023/021/R · Source