Section 135.178

14 CFR Ch. I (1-1-19 Edition)

wing) that is more than 6 feet from the
ground, with the airplane on the
ground and the landing gear extended,
must have an approved means to assist
the occupants in descending to the
ground. The assisting means for a
floor-level emergency exit must meet
the requirements of Section 25.809(f)(1) of this
chapter in effect on April 30, 1972, except that, for any airplane for which
the application for the type certificate
was filed after that date, it must meet
the requirements under which the airplane was type certificated. An assisting means that deploys automatically
must be armed during taxiing, takeoffs, and landings; however, the Administrator may grant a deviation from
the requirement of automatic deployment if he finds that the design of the
exit makes compliance impractical, if
the assisting means automatically
erects upon deployment and, with respect to required emergency exits, if an
emergency evacuation demonstration
is conducted in accordance with
Section 121.291(a) of this chapter. This paragraph does not apply to the rear window emergency exit of Douglas DC-3
airplanes operated with fewer than 36
occupants, including crewmembers,
and fewer than five exits authorized for
passenger use.
(b) Interior emergency exit marking.
The following must be complied with
for each passenger-carrying airplane:
(1) Each passenger emergency exit,
its means of access, and its means of
opening
must
be
conspicuously
marked. The identity and locating of
each passenger emergency exit must be
recognizable from a distance equal to
the width of the cabin. The location of
each passenger emergency exit must be
indicated by a sign visible to occupants
approaching along the main passenger
aisle. There must be a locating sign - 
(i) Above the aisle near each overthe-wing passenger emergency exit, or
at another ceiling location if it is more
practical because of low headroom;
(ii) Next to each floor level passenger
emergency exit, except that one sign
may serve two such exits if they both
can be seen readily from that sign; and
(iii) On each bulkhead or divider that
prevents fore and aft vision along the
passenger cabin, to indicate emergency
exits beyond and obscured by it, except

that if this is not possible, the sign
may be placed at another appropriate
location.
(2) Each passenger emergency exit
marking and each locating sign must
meet the following:
(i) For an airplane for which the application for the type certificate was
filed prior to May 1, 1972, each passenger emergency exit marking and
each locating sign must be manufactured to meet the requirements of
Section 25.812(b) of this chapter in effect on
April 30, 1972. On these airplanes, no
sign may continue to be used if its luminescence (brightness) decreases to
below 100 microlamberts. The colors
may be reversed if it increases the
emergency illumination of the passenger compartment. However, the Administrator may authorize deviation
from the 2-inch background requirements if he finds that special circumstances exist that make compliance impractical and that the proposed
deviation provides an equivalent level
of safety.
(ii) For an airplane for which the application for the type certificate was
filed on or after May 1, 1972, each passenger emergency exit marking and
each locating sign must be manufactured to meet the interior emergency
exit marking requirements under
which the airplane was type certificated. On these airplanes, no sign may
continue to be used if its luminescence
(brightness) decreases to below 250
microlamberts.
(c) Lighting for interior emergency exit
markings. Each passenger-carrying airplane must have an emergency lighting
system, independent of the main lighting system; however, sources of general
cabin illumination may be common to
both the emergency and the main
lighting systems if the power supply to
the emergency lighting system is independent of the power supply to the
main lighting system. The emergency
lighting system must - 
(1) Illuminate each passenger exit
marking and locating sign;
(2) Provide enough general lighting
in the passenger cabin so that the average illumination when measured at 40inch intervals at seat armrest height,
on the centerline of the main passenger
aisle, is at least 0.05 foot-candles; and

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