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Table 2: Requirements for emergency exit provision excluding ditching requirements
Emergency exits for each side of the fuselage Passenger seating capacity
Type I Type II
Type III Type IV
1 to 10 1
11 to 19 1 or
2 20 to 39
1 1
40 to 59 1
1 60 to 79
1 1 or
2 Table taken from JARFAR 29.807b
Helicopters operating over water and certified for ditching are further regulated. Those helicopters with a seating capacity of nine passengers or less are required to be provided
with one emergency exit above the waterline in each side of the helicopter, meeting at least the dimensions of a Type IV exit. Helicopters certified for ditching, with a seating
capacity of ten passengers or more are required to be provided with one exit above the waterline in a side of the rotorcraft meeting at least the dimensions of a Type III exit, for
each unit or part of a unit of 35 passenger seats, but no less than two such exits in the passenger cabin, with one on each side of the rotorcraft.
The types of passenger emergency exits have been defined as follows
JARFAR
29.807: Type I - a rectangular opening of at least 610 mm wide by 1219 mm high 24 by
48, with corner radii not greater than one third the width of the exit, in the passenger area in the side of the fuselage at floor level and as far away as
practicable from areas that might become potential fire hazards in a crash.
Type II – the same as Type I, except that the opening must be at least 508 mm wide by 1118 mm high 20 by 44.
Type III – the same as Type I, except that the opening must be at least 508 mm wide by 914 mm high 20 by 36; and the exits need not be at floor level.
Type IV - a rectangular opening of at least 483 mm wide by 660 mm high 19 by 26, with corner radii not greater than one third the width of the exit, in the side of
the fuselage with a step-up inside the helicopter of not more than 737 mm 29.
4.3 GUIDANCE ON ESCAPE WINDOWS
Escape windows are not considered emergency exits due to being smaller than the minimum size requirements for an emergency exit. According to Leaflet 11-18 CAA,
2006 an escape window is a window fitting a rectangular aperture with a minimum acceptable size of is 432 mm x 355 mm 17 x 14. Underwater escape through a
window of this size has been shown to be achievable by the 95
th
percentile male person wearing survival clothing and an uninflated lifejacket CAA, 2006. The CAA guidance
thus suggests all suitable openings in the passenger compartment which are of this approximate size or larger need to be considered for designation as an additional escape
route in the event of capsize, and made openable. The means of opening should be rapid and obvious. It also suggests that placarding and passenger briefing be used to ensure
that larger passengers do not occupy seats next to escape windows that are smaller than 483 mm x 432 mm 19 x 17.
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Two groups have recommended changes to the current JARFAR Regulations Parts 27 and 29, as described in CAA Paper 200506 CAA, 2005. The JAA Helicopter Offshore
Safety and Survivability HOSS working group were concerned that current helicopter ditching requirements preclude the helicopter being capsized by a wave. They cite an
accident when a helicopter ditched and then inverted in severe wave conditions and where all 11 passengers and one crew member escaped through push-out windows in
the cabin. Push-out windows were acknowledged as having made a fundamental contribution to occupant survivability. However, they considered that hand holds close to
the windows would be needed to help occupants to apply sufficient force to ensure removal of the windows. They also considered that emergency lighting systems should
be extended to apply to push-out windows, automatically activated following flooding of the cabin. Their third concern related to the high risk of disorientation following a capsize,
making location and use of push-out windows difficult and looked at optimising seating configuration to reduce possible escape times. HOSS thus recommended Appendix F;
CAA 2005:
FARJAR 27.807 and 29.809 be amended to require that all apertures in passenger compartments suitable for the purpose of underwater escape shall be made
openable in such an emergency, and hand holds should be provided adjacent to such apertures to assist their location and operation. Associated advisory material
should be developed to indicate what constitutes a suitable aperture.
Emergency exit marking systems should also be required on push-out windows and be automatically activated following flooding of the cabin.
Seat rows should be aligned with windows. The FAAJAAIndustry Joint Harmonisation Working Group on Water Impact Appendix G;
CAA, 2005 recommended:
All apertures in the passenger compartment suitable for the purposes of underwater escape shall be equipped so as to be usable in an emergency.
This recommendation was based upon the fact that there were specific regulatory requirements for emergency exits relating to ditching certification, but none for escape
routes underwater in the event of a submersion or capsize. They argued that research and accident experience has shown that occupant survivability is improved when the
opportunity for emergency egress is increased in a water impact. A rule change for helicopters operating over water would allow push-out windows to be marked with
appropriate emergency exit markings and thus improve occupant safety.
4.4 EXIT MECHANISMS AND DESIGN
