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14 CFR Ch. I (1–1–19 Edition) 

§ 135.178 

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 § 25.809(f)(1) of this 
chapter in effect on April 30, 1972, ex-
cept 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 air-
plane was type certificated. An assist-
ing means that deploys automatically 
must be armed during taxiing, take-
offs, and landings; however, the Admin-
istrator may grant a deviation from 
the requirement of automatic deploy-
ment if he finds that the design of the 
exit makes compliance impractical, if 
the assisting means automatically 
erects upon deployment and, with re-
spect to required emergency exits, if an 
emergency evacuation demonstration 
is conducted in accordance with 
§ 121.291(a) of this chapter. This para-
graph does not apply to the rear win-
dow 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 over- 

the-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 ap-

plication for the type certificate was 
filed prior to May 1, 1972, each pas-
senger emergency exit marking and 
each locating sign must be manufac-
tured to meet the requirements of 
§ 25.812(b) of this chapter in effect on 
April 30, 1972. On these airplanes, no 
sign may continue to be used if its lu-
minescence (brightness) decreases to 
below 100 microlamberts. The colors 
may be reversed if it increases the 
emergency illumination of the pas-
senger compartment. However, the Ad-
ministrator may authorize deviation 
from the 2-inch background require-
ments if he finds that special cir-
cumstances exist that make compli-
ance impractical and that the proposed 
deviation provides an equivalent level 
of safety. 

(ii) For an airplane for which the ap-

plication for the type certificate was 
filed on or after May 1, 1972, each pas-
senger emergency exit marking and 
each locating sign must be manufac-
tured to meet the interior emergency 
exit marking requirements under 
which the airplane was type certifi-
cated. 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 air-

plane must have an emergency lighting 
system, independent of the main light-
ing 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 inde-
pendent 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 aver-
age illumination when measured at 40- 
inch 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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