(a) An emergency lighting system, independent of the main cabin lighting system, must be installed. However, the source of general cabin illumination may be common to both the emergency and main lighting systems if the power supply to the emergency lighting system is independent of the power supply to the main lighting system.
(b) There must be a crew warning light that illuminates in the cockpit when power is on in the airplane and the emergency lighting control device is not armed.
(c) The emergency lights must be operable manually from the flightcrew station and be provided with automatic activation. The cockpit control device must have “on,” “off,” and “armed” positions so that, when armed in the cockpit, the lights will operate by automatic activation.
(d) There must be a means to safeguard against inadvertent operation of the cockpit control device from the “armed” or “on” positions.
(e) The cockpit control device must have provisions to allow the emergency lighting system to be armed or activated at any time that it may be needed.
(f) When armed, the emergency lighting system must activate and remain lighted when—
(1) The normal electrical power of the airplane is lost; or
(2) The airplane is subjected to an impact that results in a deceleration in excess of 2g and a velocity change in excess of 3.5 feet-per-second, acting along the longitudinal axis of the airplane; or
(3) Any other emergency condition exists where automatic activation of the emergency lighting is necessary to aid with occupant evacuation.
(g) The emergency lighting system must be capable of being turned off and reset by the flightcrew after automatic activation.
(h) The emergency lighting system must provide internal lighting, including—
(1) Illuminated emergency exit marking and locating signs, including those required in §23.811(b);
(2) Sources of general illumination in the cabin that provide an average illumination of not less than 0.05 foot-candle and an illumination at any point of not less than 0.01 foot-candle when measured along the center line of the main passenger aisle(s) and at the seat armrest height; and
(3) Floor proximity emergency escape path marking that provides emergency evacuation guidance for the airplane occupants when all sources of illumination more than 4 feet above the cabin aisle floor are totally obscured.
(i) The energy supply to each emergency lighting unit must provide the required level of illumination for at least 10 minutes at the critical ambient conditions after activation of the emergency lighting system.
(j) If rechargeable batteries are used as the energy supply for the emergency lighting system, they may be recharged from the main electrical power system of the airplane provided the charging circuit is designed to preclude inadvertent battery discharge into the charging circuit faults. If the emergency lighting system does not include a charging circuit, battery condition monitors are required.
(k) Components of the emergency lighting system, including batteries, wiring, relays, lamps, and switches, must be capable of normal operation after being subjected to the inertia forces resulting from the ultimate load factors prescribed in §23.561(b)(2).
(l) The emergency lighting system must be designed so that after any single transverse vertical separation of the fuselage during a crash landing:
(1) At least 75 percent of all electrically illuminated emergency lights required by this section remain operative; and
(2) Each electrically illuminated exit sign required by §23.811 (b) and (c) remains operative, except those that are directly damaged by the fuselage separation.
[Doc. No. 26324, 59 FR 25774, May 17, 1994]