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14 CFR Ch. I (1–1–14 Edition)
§ 25.812
the control device from the ‘‘armed’’ or
‘‘on’’ positions.
(g) Exterior emergency lighting must
be provided as follows:
(1) At each overwing emergency exit
the illumination must be—
(i) Not less than 0.03 foot-candle
(measured normal to the direction of
the incident light) on a 2-square-foot
area where an evacuee is likely to
make his first step outside the cabin;
(ii) Not less than 0.05 foot-candle
(measured normal to the direction of
the incident light) for a minimum
width of 42 inches for a Type A
overwing emergency exit and two feet
for all other overwing emergency exits
along the 30 percent of the slip-resist-
ant portion of the escape route re-
quired in § 25.810(c) that is farthest
from the exit; and
(iii) Not less than 0.03 foot-candle on
the ground surface with the landing
gear extended (measured normal to the
direction of the incident light) where
an evacuee using the established escape
route would normally make first con-
tact with the ground.
(2) At each non-overwing emergency
exit not required by § 25.810(a) to have
descent assist means the illumination
must be not less than 0.03 foot-candle
(measured normal to the direction of
the incident light) on the ground sur-
face with the landing gear extended
where an evacuee is likely to make
first contact with the ground outside
the cabin.
(h) The means required in
§§ 25.810(a)(1) and (d) to assist the occu-
pants in descending to the ground must
be illuminated so that the erected as-
sist means is visible from the airplane.
(1) If the assist means is illuminated
by exterior emergency lighting, it
must provide illumination of not less
than 0.03 foot-candle (measured normal
to the direction of the incident light)
at the ground end of the erected assist
means where an evacuee using the es-
tablished escape route would normally
make first contact with the ground,
with the airplane in each of the atti-
tudes corresponding to the collapse of
one or more legs of the landing gear.
(2) If the emergency lighting sub-
system illuminating the assist means
serves no other assist means, is inde-
pendent of the airplane’s main emer-
gency lighting system, and is auto-
matically activated when the assist
means is erected, the lighting provi-
sions—
(i) May not be adversely affected by
stowage; and
(ii) Must provide illumination of not
less than 0.03 foot-candle (measured
normal to the direction of incident
light) at the ground and of the erected
assist means where an evacuee would
normally make first contact with the
ground, with the airplane in each of
the attitudes corresponding to the col-
lapse of one or more legs of the landing
gear.
(i) The energy supply to each emer-
gency lighting unit must provide the
required level of illumination for at
least 10 minutes at the critical ambient
conditions after emergency landing.
(j) If storage batteries are used as the
energy supply for the emergency light-
ing system, they may be recharged
from the airplane’s main electric power
system:
Provided, That, the charging
circuit is designed to preclude inad-
vertent battery discharge into charg-
ing circuit faults.
(k) Components of the emergency
lighting system, including batteries,
wiring relays, lamps, and switches
must be capable of normal operation
after having been subjected to the iner-
tia forces listed in § 25.561(b).
(l) The emergency lighting system
must be designed so that after any sin-
gle transverse vertical separation of
the fuselage during crash landing—
(1) Not more than 25 percent of all
electrically illuminated emergency
lights required by this section are ren-
dered inoperative, in addition to the
lights that are directly damaged by the
separation;
(2) Each electrically illuminated exit
sign required under § 25.811(d)(2) re-
mains operative exclusive of those that
are directly damaged by the separa-
tion; and
(3) At least one required exterior
emergency light for each side of the
airplane remains operative exclusive of
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