CS 25.812 Emergency lighting

• ED Decision 2017/015/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

CS 25.812 Emergency lighting ED Decision 2017/015/R (See [AMC 25.812](#_DxCrossRefBm1709821285)) (a) An emergency lighting system, independent of the main lighting system, must be installed. However, the 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 include - (1) Illuminated emergency exit marking and locating signs, sources of general cabin illumination, interior lighting in emergency exit areas, and floor proximity escape path marking. (2) Exterior emergency lighting. (b) Emergency exit signs – (1) For aeroplanes that have a passenger-seating configuration, excluding pilot seats, of 10 seats or more must meet the following requirements: (i) Each passenger emergency exit locator sign required by [CS 25.811(d)(1)](#_DxCrossRefBm1709821274) and each passenger emergency exit marking sign required by CS 25.811(d)(2) must have red letters on an illuminated white background or a universal symbol, of adequate size (See [AMC 25.812(b)(1)](#_DxCrossRefBm1709821277)). These signs must be internally electrically illuminated with the brighter area having a brightness of at least 86 candela/m2 (25 foot lamberts) and a high-to-low contrast within the white background of a letter-based sign or green area of a universal symbol no greater than 3:1. These signs must also have a contrast between the brightest and darkest elements of at least 10:1. (ii) Each passenger emergency exit sign required by CS 25.811(d)(3) must have red letters on a white background or a universal symbol, of adequate size (See [AMC 25.812(b)(1)](#_DxCrossRefBm1709821277)). These signs must be internally electrically illuminated or selfilluminated by other than electrical means and must have an initial brightness of at least 1.27 candela/m2 (400 microlamberts). The colours may be reversed in the case of a sign that is self-illuminated by other than electrical means. (2) For aeroplanes that have a passenger seating configuration, excluding pilot seats, of 9 seats or less, each sign required by CS 25.811(d)(1), (2), and (3) must have red letters on a white background or a universal symbol, of adequate size (See [AMC 25.812(b)(2)](#_DxCrossRefBm1709821276)). These signs may be internally electrically illuminated, or self-illuminated by other than electrical means, with an initial brightness of at least 0.51 candela/m2 (160 microlamberts). The colours may be reversed in the case of a sign that is self-illuminated by other than electrical means. (c) General illumination in the passenger cabin must be provided so that when measured along the centreline of main passenger aisle(s), and cross aisle(s) between main aisles, at seat armrest height and at 1.02 m (40-inch) intervals, the average illumination is not less than 0.5 lux (0.05 foot candle) and the illumination at each 1.02 m (40-inch) interval is not less than 0.1 lux (0.01 foot candle). A main passenger aisle(s) is considered to extend along the fuselage from the most forward passenger emergency exit or cabin occupant seat, whichever is farther forward, to the most rearward passenger emergency exit or cabin occupant seat, whichever is farther aft. (d) The floor of the passageway leading to each floor-level passenger emergency exit, between the main aisles and the exit openings, must be provided with illumination that is not less than 0.2 lux (0.02 foot candle) measured along a line that is within 15 cm (6 inches) of and parallel to the floor and is centred on the passenger evacuation path. (e) Floor proximity emergency escape path marking must provide emergency evacuation guidance for passengers when all sources of illumination more than 1.2 m (4 ft) above the cabin aisle floor are totally obscured. In the dark of the night, the floor proximity emergency escape path marking must enable each passenger to: (1) After leaving the passenger seat, visually identify the emergency escape path along the cabin aisle floor to the first exits or pair of exits forward and aft of the seat; (2) Readily identify each exit from the emergency escape path by reference only to markings and visual features not more than 1.2 m (4 ft) above the cabin floor. (See [AMC 25.812(e)(2)](#_DxCrossRefBm1709821275)); and (3) In the case of passengers seated in seats authorised for occupancy during taxiing, take-off, and landing, in a compartment that does not incorporate any part of the main cabin aisle, in lieu of CS 25.812(e)(1), egress this compartment and enter the main cabin aisle using only markings and visual features not more than 1.2 m (4 ft) above the cabin floor, and proceed to the exits using the marking system necessary to complete the actions as described in CS 25.812(e)(1) and (e)(2) above. (f) Except for sub-systems provided in accordance with sub-paragraph (h) of this paragraph that serve no more than one assisting means, are independent of the aeroplane’s main emergency lighting system, and are automatically activated when the assisting means is erected, the emergency lighting system must be designed as follows: (1) The lights must be operable manually from the flight crew station and from a point in the passenger compartment that is readily accessible to a normal cabin crewmember seat. (2) There must be a flight crew warning light, which illuminates when power is on in the aeroplane and the emergency lighting control device is not armed. (3) The cockpit control device must have an ‘on’, ‘off’ and ‘armed’ position so that when armed in the cockpit or turned on at either the cockpit or cabin crew member station the lights will either light or remain lighted upon interruption (except an interruption caused by a transverse vertical separation of the fuselage during crash landing) of the aeroplane’s normal electric power. There must be a means to safeguard against inadvertent operation of 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 0.3 lux (0.03 foot candle) (measured normal to the direction of the incident light) on a 0.186 m2 (two-square-foot) area where an evacuee is likely to make his first step outside the cabin; (ii) Not less than 0.5 lux (0.05 foot-candle) (measured normal to the direction of the incident light) for a minimum width of 1.07 m (42 inches) for a Type A over-wing exit and 61 cm (24 inches) for all other over-wing emergency exits along the 30 % of the slip-resistant portion of the escape route required in CS 25.810(c) that is farthest from the exit; and (iii) Not less than 0.3 lux (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 contact with the ground. (2) At each non-overwing emergency exit not required by [CS 25.810(a)](#_DxCrossRefBm1709821268) to have descent assisting means the illumination must be not less than 0.3 lux (0.03 foot candle) (measured normal to the direction of the incident light) on the ground surface with the landing gear extended where an evacuee is likely to make his first contact with the ground outside the cabin. (h) The means required in CS 25.810(a)(1) and (d) to assist the occupants in descending to the ground must be illuminated so that the erected assisting means is visible from the aeroplane. In addition – (1) If the assisting means is illuminated by exterior emergency lighting, it must provide illumination of not less than 0.3 lux (0.03 foot candle) (measured normal to the direction of the incident light) at the ground end of the erected assisting means where an evacuee using the established escape route would normally make first contact with the ground, with the aeroplane in each of the attitudes corresponding to the collapse of one or more legs of the landing gear. (2) If the emergency lighting sub-system illuminating the assisting means serves no other assist means, is independent of the aeroplane’s main emergency lighting system, and is automatically activated when the assisting means is erected, the lighting provisions – (i) May not be adversely affected by stowage; and (ii) Must provide illumination of not less than 0.3 lux (0.03 foot candle) (measured normal to the direction of the incident light) at the ground end of the erected assisting means where an evacuee would normally make first contact with the ground, with the aeroplane in each of the attitudes corresponding to the collapse of one or more legs of the landing gear. (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 emergency landing. (j) If storage batteries are used as the energy supply for the emergency lighting system, they may be recharged from the aeroplane’s main electric power system: *Provided*, that the charging circuit is designed to preclude inadvertent battery discharge into charging 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 inertia forces listed in [CS 25.561(b)](#_DxCrossRefBm1709820989). (l) The emergency lighting system must be designed so that after any single transverse vertical separation of the fuselage during crash landing: (1) the percentage of electrically illuminated emergency lights required by this paragraph which are rendered inoperative, in addition to the lights that are directly damaged by the separation, does not exceed the values set in the following table (See [AMC 25.812(l)(1)](#_DxCrossRefBm1709821284)): <table border="1" cellpadding="0" cellspacing="0" width="532"><tr><td valign="top" width="392"><p><b>Maximum approved seating capacity of the type-certified aeroplane as indicated in the aeroplane’s type certificate data sheet (TCDS)</b></p></td><td valign="top" width="140"><p><b>Percentage</b></p></td></tr><tr><td valign="top" width="392"><p>More than 19</p></td><td valign="top" width="140"><p>25 %</p></td></tr><tr><td valign="top" width="392"><p>10 to 19</p></td><td valign="top" width="140"><p>33.33 % (i.e. one third)</p></td></tr><tr><td valign="top" width="392"><p>Less than 10</p></td><td valign="top" width="140"><p>50 %</p></td></tr></table> (2) Each electrically illuminated exit sign required under [CS 25.811(d)(2)](#_DxCrossRefBm1709821274) remains operative exclusive of those that are directly damaged by the separation; and (3) At least one required exterior emergency light for each side of the aeroplane remains operative exclusive of those that are directly damaged by the separation. [Amdt 25/3] [Amdt 25/5] [Amdt 25/12] [Amdt 25/19]