Text in force at CS25-28: from CS25-28, effective 20 Dec 2023.
(See AMC 25.563) If certification with ditching provisions is requested, those parts of the airframe structure that are necessary to maintain flotation of the aeroplane must withstand ditching loads, considered as ultimate, associated with a planned emergency landing on water. Damages may occur provided that these are accounted for in the assessments required by CS 25.801(b), and that the airframe structural integrity is maintained. The airframe loads must account for reasonable variations in the flight parameters when the aeroplane enters the water.
ED Decision 2023/021/R · Source