14 CFR § 27.807

Number and location. (1) There must be at least one emergency exit on each side of the cabin readily accessible to each passenger. One of these exits must be usable in any probable attitude that may result from a crash;

Doors intended for normal use may also serve as emergency exits, provided that they meet the requirements of this section; and

If emergency flotation devices are installed, there must be an emergency exit accessible to each passenger on each side of the cabin that is shown by test, demonstration, or analysis to;

Be above the waterline; and

Open without interference from flotation devices, whether stowed or deployed.

Type and operation. Each emergency exit prescribed by paragraph (a) of this section must—

Consist of a movable window or panel, or additional external door, providing an unobstructed opening that will admit a 19-by 26-inch ellipse;

Have simple and obvious methods of opening, from the inside and from the outside, which do not require exceptional effort;

Be arranged and marked so as to be readily located and opened even in darkness; and

Be reasonably protected from jamming by fuselage deformation.

Tests. The proper functioning of each emergency exit must be shown by test.

Ditching emergency exits for passengers. If certification with ditching provisions is requested, the markings required by paragraph (b)(3) of this section must be designed to remain visible if the rotorcraft is capsized and the cabin is submerged.