26.415 Underwater emergency exits

The objective is for no passenger to be in a worse position than the second person to egress through an exit in the event of a capsize. The time available for evacuation is very short in such situations, and the provision of sufficient underwater emergency exits and ensuring that no occupant should need to wait for more than one other person to escape before being able to make their own escape will minimise the passengers’ time to escape. The provision of an underwater emergency exit in each side of the fuselage for each unit (or part of a unit) of four passenger seats will make this possible, provided that the seats are positioned relative to the exits to maximise the probability of safe egress. With regard to the location of the seats relative to the exits, the most obvious layout that maximises the achievement of the objective that no passenger is in a worse position than the second person to egress through an exit is a four-abreast arrangement with all the seats in each row located appropriately and directly next to the emergency exits. However, this might not be possible in all rotorcraft designs due to issues such as limited cabin width, the need to locate seats such as to accommodate normal boarding and egress, and the installation of items other than seats in the cabin. Notwithstanding this, an egress route necessitating movement such as along an aisle, around a cabin item, or in any way other than directly towards the nearest emergency exit, to escape the rotorcraft is not considered to be compliant with this provision.

[Issue: 26/4]

A possible design solution for the provision of sufficient underwater emergency exits may be to use the passenger cabin windows as additional emergency egress means by including a jettison feature. The jettison feature may be provided by modifying the elastomeric window seal such that its retention strength is either reduced, or can be reduced by providing a removable part of its cross section, i.e. the so-called push out window. Exit designs with the following characteristics, when operated in an upright or any foreseeable floating attitude, would be considered to be compliant with point 26.415(b)(1) of Part-26 and CS 26.415(c):

(a)the use of only one hand is needed to operate the exit itself;

(b)no part of the opening means (e.g. an operating handle or control) is located remotely from the exit (that requires the person to move away from the immediate vicinity of the exit in order to reach it);

(c)any operating handle or control can be gripped using either a bare or a gloved hand;

(d)the exit meets the opening effort limitations set by FAA AC 29-2C AC 29.809. The required test, demonstration or analysis may be conducted in a non-capsized attitude (i.e. dry) but considering obstructions that may be present when capsized.

[Issue: 26/4]

Disorientation of occupants may result in the normal emergency exit markings in the cockpit and passenger cabins being ineffective following the rotorcraft capsizing and the cabin flooding. The additional markings of underwater emergency exits may be in the form of illuminated strips that give clear indications in all environments (e.g. at night, underwater) of the location of the underwater emergency exits.

[Issue: 26/4]