W DOC AIRBUS | AMM A320F

CABIN EMERGENCY LIGHTING - DESCRIPTION AND OPERATION

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1. General
A. The cabin emergency-lighting system supplies power for:

  • The illumination of the cabin and the exit areas in the event of a failure of the main lighting system

  • The illumination of an exit location and an exit marking sign at each of the passenger/crew doors and at each of the emergency exit hatches

  • The illumination of the marking system of the emergency escape path

  • The illumination of the lavatories that does not include the main lighting system of the lavatories

  • The illumination of the escape route over the wings

  • The illumination of the door escape slides and the emergency-exit escape slides

  • The illumination of the emergency escape hatch-handles.

  • The illumination of the cabin and the exit areas in the event of a failure of the main lighting system

  • The illumination of an exit location and an exit marking sign at each of the passenger/crew doors and at each of the emergency exit doors

  • The illumination of the marking system of the emergency escape path

  • The illumination of the lavatories independent of the main lighting system of the lavatories

  • The illumination of the door escape slides.
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2. Component Location
F Cabin Emergency Lighting - Component Location ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Component Location ** ON A/C NOT FOR ALL
F Cabin Emergency Lights - Component Location ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Component Location ** ON A/C NOT FOR ALL
F Emergency-Power Supply Unit-Component Location ** ON A/C NOT FOR ALL
F Emergency-Power Supply Unit - Component Location ** ON A/C NOT FOR ALL
F Exit Marking and Exit Location Signs - Component Location ** ON A/C NOT FOR ALL
F Exit Marking and Exit Location Signs - Component Location ** ON A/C NOT FOR ALL
F Overwing Emergency Light and Escape-Hatch Handle Light - Component Location ** ON A/C NOT FOR ALL
F Overwing Emergency Light and Escape Hatch Handle Light - Component Location ** ON A/C NOT FOR ALL
F Wall Mounted Exit Marking Signs - Component Location ** ON A/C NOT FOR ALL
F Wall-Mounted Exit-Marking Signs - Component Location ** ON A/C NOT FOR ALL
F Seat- and Wall-Mounted Emergency-Lights - Component Location ** ON A/C NOT FOR ALL
F Photoluminescent Light Strips - Component Location ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Lights - Component Location ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Lights - Component Location ** ON A/C NOT FOR ALL
F Cabin Emergency Lights - Component Location ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Component Location ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Component Location ** ON A/C NOT FOR ALL
FIN FUNCTIONAL
DESIGNATION		 PANEL ZONE ACCESS
DOOR		 ATA REF
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10WL POWER-EMERGENCY SUPPLY 223 33-51-38
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10WL POWER-EMERGENCY SUPPLY 221 33-51-38
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11WL EPSU 241KW 241 33-51-38
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11WL EPSU 251 33-51-38
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12WL EPSU 242KW 242 33-51-38
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12WL EPSU 252 33-51-38
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13WL EPSU 261KW 263 33-51-38
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14WL EPSU 231JC 232 33-51-38
15WL EPSU 231JC 231 33-51-38
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16WL EPSU 242 33-51-38
17WL EPSU 243 33-51-38
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20WL LIGHT-EMERGENCY, CABIN 222 33-51-11
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20WL LIGHT-EMERGENCY, CABIN 221 33-51-11
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21WL LIGHT-EMERGENCY, CABIN 221 33-51-11
32WL LIGHT-EMERGENCY, CABIN 262 33-51-11
33WL LIGHT-EMERGENCY, CABIN 261 33-51-11
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34WL CABIN EMERGENCY LIGHTS 232 33-51-11
35WL CABIN EMERGENCY LIGHTS 231 33-51-11
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36WL CABIN EMERGENCY LIGHTS 252 33-51-11
37WL CABIN EMERGENCY LIGHTS 251 33-51-11
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40WL SIGN-EXIT MARKING 222 33-51-16
41WL SIGN-EXIT MARKING 221 33-51-16
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42WL SIGN-EXIT MARKING 242 33-51-16
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42WL SIGN-EXIT MARKING 252 33-51-16
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43WL SIGN-EXIT MARKING 241 33-51-16
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43WL SIGN-EXIT MARKING 251 33-51-16
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44WL SIGN-EXIT MARKING 262 33-51-16
45WL SIGN-EXIT MARKING 261 33-51-16
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46WL EXIT MARKING SIGN 242 33-51-00
47WL EXIT MARKING SIGN 241 33-51-13
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50WL SIGN-EXIT LOCATION, 1 SIDED 3700VU 220 33-51-17
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51WL SIGN-EXIT LOCATION, 2 SIDED 3704VU 240 33-51-17
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51WL SIGN-EXIT LOCATION, 2 SIDED 3704VU 250 33-51-17
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52WL SIGN-EXIT LOCATION, 1 SIDED 3701VU 260 33-51-17
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53WL SIGN-EXIT 3704VU 240 33-51-17
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53WL SIGN-EXIT 240 33-51-17
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53WL SIGN-EXIT 3704VU 250 33-51-17
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54WL EXIT SIGN 3702VU 240 33-51-17
55WL EXIT SIGN 3702VU 240 33-51-17
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60WL LIGHT-FWD EMER, OVERWING 242 33-51-15
61WL LIGHT-FWD EMER, OVERWING 241 33-51-15
62WL LIGHT-AFT EMER, OVERWING 242 33-51-15
63WL LIGHT-AFT EMER, OVERWING 241 33-51-15
70WL1 ESCAPE HATCH-HANDLE LIGHT 241 33-51-11
70WL2 ESCAPE HATCH-HANDLE LIGHT 242 33-51-11
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70WL3 ESCAPE HATCH-HANDLE LIGHT 241 33-51-11
70WL4 ESCAPE HATCH-HANDLE LIGHT 242 33-51-11
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90WL1 EXIT MARKER 221 33-51-13
90WL2 EXIT MARKER 222 33-51-13
90WL3 EXIT MARKER 241 33-51-00
90WL4 EXIT MARKER 242 33-51-00
90WL5 EXIT MARKER 241 33-51-13
90WL6 EXIT MARKER 242 33-51-13
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90WL7 EXIT MARKER 261 33-51-13
90WL8 EXIT MARKER 262 33-51-13
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95WL1 EMERGENCY LIGHT 221 33-51-13
95WL2 EMERGENCY LIGHT 222 33-51-13
95WL3 EMERGENCY LIGHT 241 33-51-13
95WL4 EMERGENCY LIGHT 242 33-51-13
95WL5 EMERGENCY LIGHT 241 33-51-13
95WL6 EMERGENCY LIGHT 242 33-51-13
95WL7 EMERGENCY LIGHT 2069VU 251 33-51-13
95WL8 EMERGENCY LIGHT 2068VU 252 33-51-13
95WL9 EMERGENCY LIGHT 261 33-51-13
95WL10 EMERGENCY LIGHT 262 33-51-13
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200WL LIGHT EMERGENCY 223 33-51-11
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202WL LIGHT EMERGENCY 230 33-51-11
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201WL LIGHT EMERGENCY 230 33-51-11
203WL LIGHT EMERGENCY 240 33-51-11
204WL LIGHT EMERGENCY 240 33-51-11
205WL LIGHT EMERGENCY 240 33-51-11
206WL LIGHT EMERGENCY 240 33-51-11
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200WL LIGHT EMERGENCY 230 33-51-11
202WL LIGHT EMERGENCY 240 33-51-11
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200WL LIGHT EMERGENCY 220 33-51-11
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207WL LIGHT EMERGENCY 250 33-51-11
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208WL LIGHT EMERGENCY 250 33-51-11
209WL LIGHT EMERGENCY 250 33-51-11
210WL LIGHT EMERGENCY 250 33-51-11
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350WL1 WIRE HARNESS 200 33-51-12
350WL2 WIRE HARNESS 200 33-51-00
350WL3 WIRE HARNESS 200 33-51-00
350WL4 WIRE HARNESS 200 33-51-00
350WL5 WIRE HARNESS 200 33-51-00
350WL6 WIRE HARNESS 200 33-51-00
350WL7 WIRE HARNESS 200 33-51-00
350WL8 WIRE HARNESS 200 33-51-00
350WL9 WIRE HARNESS 200 33-51-00
350WL10 WIRE HARNESS ASSY 200 33-51-00
361WL1 LAMP MODULE (CLEAR) 200 33-51-19
361WL2 LAMP MODULE (CLEAR) 261 33-51-19
361WL3 LAMP MODULE (CLEAR) 260 33-51-19
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365WL111 LAV LIGHT 261 33-51-14
400WL EXIT MARKING SIGN 222 33-51-16
410WL EXIT MARKING SIGN 221 33-51-16
420WL EXIT MARKING SIGN 242 33-51-16
430WL EXIT MARKING SIGN 241 33-51-16
440WL EXIT MARKING SIGN 252 33-51-16
450WL EXIT MARKING SIGN 251 33-51-16
460WL EXIT MARKING SIGN 262 33-51-16
470WL EXIT MARKING SIGN 261 33-51-16
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500WL EXIT SIGN 220 33-51-00
510WL EXIT SIGN 240 33-51-00
520WL EXIT SIGN 240 33-51-00
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530WL EXIT SIGN 250 33-51-00
540WL EXIT SIGN 250 33-51-00
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550WL EXIT SIGN 260 33-51-00
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800WL EMERG. LIGHT SEAT MOUNTED (FPEEPMS) 200 33-51-19
801WL EMERG. LIGHT SEAT MOUNTED (FPEEPMS) 200 33-51-19
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365WL6 LAV LIGHT 261 33-51-14
365WL13 LAV LIGHT 261 33-51-14
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3. System Description
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL

F Lavatory Auxiliary Lights - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Lights - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Lights - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Lights - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Light - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Light - Schematic ** ON A/C NOT FOR ALL
A. Emergency Lighting System

The emergency lighting system of the cabin has:
  • Six emergency power-supply units
  • A number of 6VDC escape slide lights as parts of the escape slides
  • Nineteen 6VDC cabin emergency lights
  • Eight 6VDC exit marking signs
  • Six 6VDC exit location signs
  • Eight 6VDC wall-mounted exit-marking signs
  • Four 28VDC auxiliary lights, one installed in each lavatory
  • Photoluminescent strips in the aisle for the marking system of the floor-proximity emergency escape-path.
The emergency lighting system of the cabin consists of:
  • four emergency power-supply units,
  • four 6VDC overwing emergency lights, installed in the wing fairings,
  • eleven 6VDC cabin emergency lights,
  • two 6VDC escape hatch-handle lights,
  • four 6VDC exit location signs,
  • six 6VDC exit marking signs,
  • six 6VDC wall-mounted exit-marking signs,
  • twenty-five 6VDC seat/wall-mounted emergency lights,
  • six 6VDC seat/wall-mounted emergency-exit location-lights,
  • three 28VDC auxiliary lights, one installed in each lavatory.

The emergency lighting system of the cabin consists of:
  • Four emergency power-supply units
  • Four 6VDC overwing emergency lights, installed in the wing fairings
  • A number of 6VDC escape slide lights as parts of the escape slides
  • Twelve 6VDC cabin emergency lights
  • Four 6VDC escape hatch-handle lights
  • Four 6VDC exit location signs
  • Six 6VDC exit marking signs
  • Eight 6VDC wall-mounted exit-marking signs
  • Photoluminescent strips in the aisle for the marking system of the floor-proximity emergency escape-path
  • Three 28VDC auxiliary lights, one installed in each lavatory.

The emergency lighting system of the cabin consists of:
  • six emergency power-supply units
  • nineteen 6VDC cabin emergency lights
  • eight 6VDC exit marking signs
  • six 6VDC exit location signs
  • eight 6VDC wall-mounted exit-marking signs
  • four 28VDC auxiliary lights, one installed in each lavatory.
  • a number of 6VDC escape slide lights as parts of the escape slides
  • photoluminescent strips in the aisle for the marking system of the floor-proximity emergency escape-path.

The emergency lighting system of the cabin has:
  • Six emergency power-supply units
  • Four 6VDC overwing emergency lights, installed in the wing fairings
  • A number of 6VDC escape slide lights as the parts of the escape slides
  • Seventeen 6VDC cabin emergency lights
  • Four 6VDC escape hatch-handle lights
  • Six 6VDC exit location signs
  • Eight 6VDC exit marking signs
  • Ten 6VDC wall-mounted exit-marking signs
  • Photoluminescent strips in the aisle for the marking system of the floor-proximity emergency escape-path
  • Four 28VDC auxiliary lights, one installed in each lavatory.
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4. Power Supply
28VDC essential busbar 801PP and the 115VAC normal busbar 103XP supply the Emergency Power Supply Units (EPSUs). The EPSUs convert 28VDC into 6VDC to operate the lights in the system. A battery in each EPSU is charged continuously when the essential busbar is energized and the circuit breakers are closed. Each of the EPSUs supplies electrical power to different emergency lights and signs. The emergency lights and signs are always supplied with power, even if the aircraft has crashed and the fuselage has broken. This is because the EPSUs are installed in different places in the cabin.
EMER EXIT LT switch 4WL on overhead panel 25VU controls the emergency lighting system. Self-monitoring circuit breakers 1WL, 2WL and 3WL protect the system from too much current flow. EMER EXIT LT switch 4WL has three positions, OFF, ARM and ON. Each of these positions gives a discrete ground signal to all EPSUs. The EPSUs also monitor the correct voltage of the AC and DC busbars. When the voltage on these busbars falls below a specified level, the emergency lighting automatically comes on. This is when EMER EXIT LT switch 4WL is in the ARM position.
When only the AC normal busbar fails:
  • The 28VDC essential busbar supplies the emergency lighting system through the 28VDC/6VDC converter in each EPSU.
When the 28VDC essential busbar fails:
  • The internal batteries in the EPSUs supply the emergency lighting system.

When EMER EXIT LT switch 4WL is in the ON position:
  • The converters or the internal batteries in the EPSUs supply the emergency lighting system.

When the LIGHT EMER pushbutton switch and its integral light on forward attendant panel 120RH are on:
  • The converters or the internal batteries in the EPSUs supply the emergency lighting system.

An open or short circuit in the control lines causes the emergency lighting to come on. The internal test program in the EPSUs finds defects in the load circuits.
EMER EXIT LT switch 4WL on overhead panel 25VU controls the emergency lighting system. Self-monitoring circuit breakers 1WL, 2WL and 3WL protect the system from too much current flow. EMER EXIT LT switch 4WL has three positions, OFF, ARM and ON. Each of these positions gives a discrete ground signal to all EPSUs. The EPSUs also monitor the correct voltage of the AC and DC busbars. When the voltage on these busbars falls below a specified level, the emergency lighting automatically comes on. This is when EMER EXIT LT switch 4WL is in the ARM position.
When only the AC normal busbar fails:
  • The 28VDC essential busbar supplies the emergency lighting system through the 28VDC/6VDC converter in each EPSU.
When the 28VDC essential busbar fails:
  • The internal batteries in the EPSUs supply the emergency lighting system.

When EMER EXIT LT switch 4WL is in the ON position:
  • The converters or the internal batteries in the EPSUs supply the emergency lighting system.

When the EMER pushbutton switch and its integral light on Flight Attendant Panel (FAP) 120RH are on:
  • The converters or the internal batteries in the EPSUs supply the emergency lighting system.

An open or short circuit in the control lines causes the emergency lighting to come on. The internal test program in the EPSUs finds defects in the load circuits.
When the emergency exit hatches are open and the slides are released, the respective overwing emergency lights and the integral lights in the respective escape slide come on.
When the passenger/crew doors are open and the slides are armed, the integral lights in the respective escape slide come on.
When the passenger/crew doors or the emergency exit doors are open and the slides are armed, the integral lights in the respective escape slide come on.
In an emergency condition it is possible that the normal cabin emergency-lighting system is not sufficient. This is when smoke enters the cabin. In order to give sufficient illumination of the aisle, exits and emergency exits, a low-level emergency lighting system is installed. These emergency lights are installed in the aisle seats (LH) and at the passenger exits. They come on when the emergency lighting system is activated.
In an emergency condition it is possible that the normal cabin emergency-lighting system is not sufficient. This is when smoke enters the cabin. In order to give sufficient illumination of the aisle, exits and emergency exits, a floor-level marking-system for the emergency escape-path is installed.
The electrical marking system has a wall-mounted exit-marking sign at each passenger/crew door and emergency exit. These signs come on when the emergency lighting system is energized.
The photoluminescent marking system has a number of flexible photoluminescent strips. They are installed on the floor on the two sides of the aisle.
In an emergency condition it is possible that the normal cabin emergency-lighting system is not sufficient. This is when smoke goes into the cabin. To give sufficient illumination of the aisle, exits and emergency exits, a low-level emergency-lighting system is installed.
These electrical marking system has a wall-mounted exit-marking sign at each passenger/crew door and emergency exit. They come on when the emergency lighting system is energized.
When EMER EXIT LT control switch 4WL is in the OFF position and DC essential busbar 801PP is energized:
  • EMER EXIT LT OFF annunciator light 5WL in the cockpit comes on.
You can test the emergency lighting system through Programming and Test Panel (PTP) 110RH of the Cabin Intercommunication Data System (CIDS).
There are two tests :
  • The BAT test indicates the battery capacity condition of emergency power-supply units 10WL thru 13WL.
  • The SYS test indicates the condition of the internal loads, the external loads and the battery charge limiter of emergency power-supply units 10WL thru 13WL.
    Internal loads are all electrical loads located inside the cabin and served by these emergency power-supply units.
    External loads are all electrical loads located outside the cabin and served by these emergency power-supply units.
You can test the emergency lighting system through the Programming and Test Panel (PTP) 110RH of the Cabin Intercommunication Data System (CIDS).
There are two tests:
  • The BAT test indicates the battery capacity condition of emergency power-supply units 10WL thru 15WL.
  • The SYS test indicates the condition of the internal loads, the external loads and the battery charge limiter of emergency power-supply units 10WL thru 15WL.
    Internal loads are all electrical loads located inside the cabin and served by these emergency power-supply units.
    External loads are all electrical loads located outside the cabin and served by these emergency power-supply units.
You can test the emergency lighting system through the Centralized Fault Display System/Multipurpose Control and Display Unit (CFDS/MCDU).
There are two tests :
  • The BAT test indicates the battery capacity condition of emergency power-supply units 10WL thru 13WL.
  • The SYS test indicates the condition of the internal loads, the external loads and the battery charge limiter of emergency power-supply units 10WL thru 13WL.
    Internal loads are all electrical loads located inside the cabin and served by these emergency power-supply units.
    External loads are all electrical loads located outside the cabin and served by these emergency power-supply units.
You can examine the emergency lighting system through the Centralized Fault Display System/Multipurpose Control and Display Unit (CFDS/MCDU).
There are two tests :
  • The BAT test shows the battery capacity condition of emergency power-supply units 10WL thru 15WL.
  • The SYS test shows the condition of the internal loads, the external loads and the battery charge limiter of emergency power-supply units 10WL thru 15WL.
Internal loads are all the electrical loads in the cabin supplied by these emergency power-supply units.
External loads are all the electrical loads out of the cabin supplied by these emergency power-supply units.
Before you start the BAT test, you must select the applicable code on PTP 110RH. A note 'BATTERY TEST ACTIVATE' comes on the PTP display. Two hours could be necessary to complete the test. When the TEST EMER LIGHT BAT membrane switch on PTP 110RH in the cabin is pushed:
  • A Light Emitting Diode (LED) in the TEST EMER LIGHT BAT membrane switch comes on to show the start of the battery test.
  • The BAT OK annunciator light adjacent to the membrane switch comes on when the battery test in all the power supply units is completed.
When the test is completed, an acknowledge code is selected on the PTP. The LED in the TEST EMER LIGHT BAT membrane switch and the BAT OK annunciator light go off.
When the TEST EMER LIGHT SYS membrane switch on programming and test panel 110RH is pushed:
  • The SYS OK annunciator light adjacent to the membrane switch comes on when the system test of all power supply units is completed.
The emergency lights come on automatically when NO SMOKING switch 190RH is in the ON position. They also come on, when NO SMOKING switch 190RH is in the AUTO position and when the landing gear extends.
The emergency lights come on automatically when EXIT switch 190RH is in the ON position. They also come on, when EXIT switch 190RH is in the AUTO position and when the landing gear extends.
The emergency lights come on automatically when NO PED switch 190RH is in the ON position. They also come on, when NO PED switch 190RH is in the AUTO position and when the landing gear extends.
One 28VDC auxiliary light is installed in each lavatory. The light is permanently on when essential busbar 401PP is energized and circuit breaker 79WL is closed.
The circuit breakers used in the emergency lighting system are a special type. When a circuit breaker is open a pair of contacts closes to complete the monitoring circuit (Ref. 31-59-00).
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5. Component Description
F Emergency Power-Supply Unit
A. Emergency Power-Supply Units

The EPSUs supply different lights and signs:
  • cabin emergency lights,
  • exit location signs,
  • exit marking signs,
  • wall-mounted exit-marking signs,
  • escape slide lights.

The EPSUs supply different lights and signs:
  • Cabin emergency lights
  • Escape hatch-handle lights
  • Exit location signs
  • Exit marking signs
  • Wall-mounted exit-marking signs
  • Overwing emergency lights
  • Escape slide lights.
The EPSUs supply different lights and signs:
  • Cabin emergency lights
  • Escape hatch-handle lights
  • Exit location signs
  • Wall-mounted exit-marking signs
  • Seat/wall-mounted emergency-lights
  • Seat/wall-mounted emergency-exit location-lights
  • Exit marking signs
  • Overwing emergency lights
  • Escape slide lights.

The emergency power-supply units supply different lights. These lights are exit signs, cabin emergency lights, overwing emergency lights, escape hatch handle lights, escape slide lights and floor proximity lights.
The emergency power-supply units supply different lights. These lights are exit signs, cabin emergency lights and escape slide lights.
The Emergency Power-Supply Units (EPSU) supply different lights. These lights are:
  • Cabin emergency lights
  • Exit-marking signs
  • Exit-location signs
  • Escape slide lights
  • Wall-mounted exit-marking signs.
(1) Each EPSU has these components:
  • Electronic logic and switching circuits.
  • A 28VDC/6VDC converter which supplies electrical power when the essential busbar is energized and the emergency lighting system is activated.
  • A 6VDC battery supplies the loads when the system is not set to off and the power supply from the essential busbar is not available. The essential busbar charges the battery through the 28VDC/6VDC converter. When the ambient temperature is less than +20 deg.C (68.00 deg.F), the 28VDC essential busbar provides electrical heating for the battery. You can change the battery without removal of the EPSU.
  • A test circuit tests the condition of the battery, the logic unit and the related loads.
    The battery test procedure starts when you push the TEST EMER LIGHT BAT membrane switch and when you select a code on the programming and test panel 110RH (CIDS). If all batteries are serviceable, the BAT OK annunciator light adjacent to the membrane switch comes on.
    The system test procedure starts when you push the TEST EMER LIGHT SYS membrane switch on the programming and test panel 110RH. The test circuit carries out an interrogation of the EPSUs and monitors the output current. If all EPSUs are serviceable, the SYS OK annunciator light adjacent to the membrane switch comes on. This test loop completes only when all EPSU output currents are within the expected value.
    You must do isolated tests of each EPSU when either the BAT OK or SYS OK annunciator light does not come on. The isolated test starts when you push the TEST membrane switch on the EPSU. A defective emergency lighting system will cause a red LED on the EPSU to come on. The green LED SYSTEM OK on the EPSU shows a serviceable emergency lighting system.
    The four red LEDs show the indication of defects:
  • in the exterior lights (external loads),
  • in the interior lights (internal loads),
  • in the battery,
  • in the unit.
Each output has its own fuse. The fuses are installed in the EPSU.
(2) Each EPSU has these components:
  • Electronic logic and switching circuits
  • A 28VDC/6VDC converter which supplies the loads whenever the essential busbar is energized and the emergency lighting system is activated.
  • A 6VDC battery supplies the loads whenever the system is not selected OFF and the power supply from the essential busbar is not available. The essential busbar charges the battery through the 28VDC/6VDC unit converter. Whenever the ambient temperature falls below +20 DEG. C (68 DEG. F) the 28VDC essential busbar provides electrical heating for the battery. The battery could be replaced without removal of the emergency power-supply unit.
  • A test circuit tests the condition of the battery unit, the unit logic and the related loads. The battery test procedure starts after coding selection when the EPSU BAT CAP TEST on the Cabin Intercommunication Data System (CIDS) page of the MCDU/CFDS is selected. If all batteries are serviceable, the TEST OK legend is shown on the MCDU.
    The system test procedure starts when EPSU SYS TEST on the CIDS page of the MCDU/CFDS is selected. The test circuit carries out an interrogation of the units and monitors the output current.
    If all units are serviceable the TEST OK legend is shown on the MCDU. This test loop completes only when all unit output currents are within the expected value. An individual test on each emergency power-supply unit must be carried out when the EPSU BAT CAP TEST or the EPSU SYS TEST thru the CFDS/MCDU fails.
    The isolated test starts when you push the TEST membrane switch on the EPSU. A defective emergency lighting system will cause a red Light Emitting Diode (LED) on the EPSU to come on. The green LED SYSTEM OK on the EPSU shows a serviceable emergency lighting system.
    The four red LEDs show the indication of defects:
  • In the exterior lights (external loads)
  • In the interior lights (internal loads)
  • In the battery
  • In the unit.
Each output has its own fuse. The fuses are installed in the EPSU.
(3) Each EPSU has these components:
  • Electronic logic and switching circuits.
  • A 28VDC/6VDC converter which supplies electrical power when the essential busbar is energized and the emergency lighting system is activated.
  • A 6VDC battery supplies the loads when the system is not set to off and the power supply from the essential busbar is not available. The essential busbar charges the battery through the 28VDC/6VDC converter. When the ambient temperature is less than +20 deg.C (68.00 deg.F), the 28VDC essential busbar provides electrical heating for the battery. You can change the battery without removal of the EPSU.
  • A test circuit tests the condition of the battery, the logic unit and the related loads.
    The battery test procedure starts when you push the TEST EMER LIGHT BAT membrane switch and when you select a code on programming and test panel 110RH (CIDS). If all batteries are serviceable, the BAT OK annunciator light adjacent to the membrane switch comes on.
    The system test procedure starts when you push the TEST EMER LIGHT SYS membrane switch on programming and test panel 110RH. The test circuit carries out an interrogation of the EPSUs and monitors the output current. If all EPSUs are serviceable, the SYS OK annunciator light adjacent to the membrane switch comes on. This test loop completes only when all EPSU output currents are within the expected value.
    You must do isolated tests of each EPSU when either the BAT OK or SYS OK annunciator light does not come on. The isolated test starts when you push the TEST membrane switch on the EPSU. A defective emergency lighting system will cause a red LED on the EPSU to come on. The green LED SYSTEM OK on the EPSU shows a serviceable emergency lighting system.
    The four red LEDs show the indication of defects:
  • In the exterior lights (external loads)
  • In the interior lights (internal loads)
  • In the battery
  • In the unit.
Each output has its own fuse. The fuses are installed in the EPSU.
(4) Each EPSU has these components:
  • Electronic logic and switching circuits.
  • A 28VDC/6VDC converter which supplies the loads whenever the essential busbar is energized and the emergency lighting system is activated.
  • A 6VDC battery supplies the loads whenever the system is not selected OFF and the power supply from the essential busbar is not available. The essential busbar charges the battery through the 28VDC/6VDC unit converter. Whenever the ambient temperature falls below +20 DEG. C (68 DEG. F) the 28VDC essential busbar provides electrical heating for the battery. The battery could be replaced without removal of the emergency power-supply unit.
  • A test circuit tests the condition of the battery unit, the unit logic and the related loads. The battery test procedure starts after coding selection when the EPSU BAT CAP TEST on the CIDS page of the MCDU/CFDS is selected. If all batteries are serviceable, the TEST OK legend is shown on the MCDU.
    The system test procedure starts when EPSU SYS TEST on the CIDS page of the MCDU/CFDS is selected. The test circuit carries out an interrogation of the units and monitors the output current.
    If all units are serviceable the TEST OK legend is shown on the MCDU. This test loop completes only when all unit output currents are within the expected value. An individual test on each emergency power-supply unit must be carried out when the EPSU BAT CAP TEST or the EPSU SYS TEST thru the CFDS/MCDU fails.
    The isolated test starts when you push the TEST membrane switch on the EPSU. A defective emergency lighting system will cause a red LED on the EPSU to come on. The green LED SYSTEM OK on the EPSU shows a serviceable emergency lighting system.
    The four red LEDs show the indication of defects:
  • In the exterior lights (external loads)
  • In the interior lights (internal loads)
  • In the battery
  • In the unit.
Each output has its own fuse. The fuses are installed in the EPSU.
(5) Each EPSU has these components:
  • Electronic logic and switching circuits.
  • A 28VDC/6VDC converter which supplies the loads when the essential busbar is energized and the emergency lighting system is activated.
  • A 6VDC battery which supplies the loads when the system is not selected OFF and the power supply from the essential busbar is not available. The essential busbar charges the battery through the 28VDC/6VDC unit converter. When the ambient temperature falls below +20 DEG. C (68 DEG. F) the 28VDC essential busbar gives electrical heating for the battery. The battery can be replaced without removal of the emergency power-supply unit.
  • A test circuit which tests the condition of the battery unit, the unit logic and the related loads.
    The battery test procedure starts after selection of the EPSU BAT CAP TEST on the CIDS page of the MCDU/CFDS. If all the batteries are serviceable, the TEST OK legend shows on the MCDU.
    The system test procedure starts after selection of the EPSU SYS TEST on the CIDS page of the MCDU/CFDS. The test monitors the circuits of the EPSUs and the output currents.
    If all the units are serviceable the TEST OK legend shows on the MCDU. This test loop is completed only when all the unit output currents are in the correct tolerance.
    You must do a test of each emergency power-supply unit when the EPSU BAT CAP TEST or the EPSU SYS TEST thru the CFDS/MCDU do not give the correct results.
    The isolated test starts when you push the TEST membrane switch on the EPSU. A defective emergency lighting system will cause a red LED on the EPSU to come on. The green LED SYSTEM OK on the EPSU shows a serviceable emergency lighting system.
    The four red LEDs show the indication of defects:
  • In the exterior lights (external loads)
  • In the interior lights (internal loads)
  • In the battery
  • In the unit.
Each output has its own fuse. The fuses are installed in the EPSU.
(6) Each EPSU has these components:
  • Electronic logic and switching circuits.
  • A 28VDC/6VDC converter and a 6VDC/115VAC inverter which supplies the loads whenever the essential busbar is energized and the emergency lighting system is activated.
  • A 6VDC battery supplies the loads whenever the system is not set OFF and the power supply from the essential busbar is not available. The essential busbar charges the battery through the 28VDC/6VDC unit converter. Whenever the ambient temperature falls below +20 DEG. C (68 DEG. F) the 28VDC essential busbar provides electrical heating for the battery. The battery could be replaced without removal of the EPSU.
  • A test circuit tests the condition of the battery unit, the unit logic and the related loads. The battery test procedure starts after coding selection when the EPSU BAT CAP TEST on the CIDS page of the MCDU/CFDS is set. If all batteries are serviceable, the TEST OK legend is shown on the MCDU.
    The system test procedure starts when EPSU SYS TEST on the CIDS page of the MCDU/CFDS is set. The test circuit carries out an interrogation of the units and monitors the output current.
    If all units are serviceable the TEST OK legend is shown on the MCDU. This test loop completes only when all unit output currents are within the expected value. An individual test on each EPSU must be carried out when the EPSU BAT CAP TEST or the EPSU SYS TEST thru the CFDS/MCDU fails.
    The isolated test starts when you push the TEST membrane switch on the EPSU. A defective emergency lighting system will cause a red LED on the EPSU to come on. The green LED SYSTEM OK on the EPSU shows a serviceable emergency lighting system.
    The four red LEDs show the indication of defects:
  • In the exterior lights (external loads)
  • In the interior lights (internal loads)
  • In the battery
  • In the unit.
Each output has its own fuse. The fuses are installed in the EPSU.
B. Exit Signs
(1) The exit signs consist of a plastic case housing, a lens and a number of 6VDC lamps connected in parallel. There are different types:
(a) The ceiling-mounted exit-location signs 50WL and 52WL, single-sided, one for the forward and one for the aft passenger/crew doors.
(b) The ceiling-mounted exit-location signs 51WL and 53WL, single-sided, for the emergency exits.
(c) The exit marking signs 40WL thru 45WL, single-sided, one for each passenger/crew door and one for each emergency exit.
(2) The escape hatch-handle lights 70WL1 and 70WL2 consist of a plastic case housing, a lens and two 6VDC lamps connected in parallel.
One escape hatch-handle light is installed in each emergency exit.
(3) The exit signs consist of a plastic case housing, a lens and a number of LED connected in parallel. There are different types:
(a) The ceiling-mounted exit-location signs 50WL and 52WL, single-sided, one for the forward and one for the aft passenger/crew doors.
(b) The ceiling-mounted exit-location signs 51WL and 53WL, single-sided, for the emergency exits.
(c) The exit marking signs 40WL thru 45WL, single-sided, one for each passenger/crew door and one for each emergency exit.
(4) The escape hatch-handle lights 70WL1 and 70WL2 consist of a plastic case housing, a lens and LED lamps connected in parallel.
One escape hatch-handle light is installed in each emergency exit.
(5) The exit signs consist of a plastic case housing, a lens and a number of LED connected in parallel. There are different types:
(a) Ceiling-mounted exit-location signs 50WL and 52WL, single-sided, one for the forward and one for the aft passenger/crew doors.
(b) Ceiling-mounted exit-location signs 51WL, 53WL, 54WL and 55WL, single-sided, two for each pair of emergency exit doors.
(c) Exit marking signs 40WL thru 47WL, single-sided, one for each passenger/crew door and one for each emergency exit door.
(6) The exit signs have:
  • A plastic case housing
  • A lens
  • A number of LEDs connected in parallel.
There are different types:
(a) Ceiling-mounted exit-location signs 50WL and 52WL are single-sided. There is one for the forward and one for the aft passenger/crew doors.
(b) Ceiling-mounted exit-location signs 51WL and 53WL are single-sided for the emergency exits.
(c) Exit marking signs 40WL thru 45WL are single-sided. There is one for each passenger/crew door and one for each pair of emergency exits.
(7) Escape hatch-handle lights 70WL1 thru 70WL4 have:
  • A plastic case housing
  • A lens
  • Two LEDs connected in parallel.
One escape hatch-handle light is installed in each emergency exit.
(8) The exit signs have a plastic case housing, a lens and a number of LEDs connected in parallel. There are different types:
(a) Ceiling-mounted exit-location signs 50WL and 52WL are single-sided. There is one for the forward and one for the aft passenger/crew doors.
(b) Ceiling-mounted exit-location signs 51WL and 53WL are single-sided for the emergency exits.
(c) Exit marking signs 40WL thru 45WL are single-sided. There is one for each passenger/crew door and one for each pair of emergency exits.
(9) Escape hatch-handle lights 70WL1 thru 70WL4 have a plastic case housing, a lens and two LEDs connected in parallel. One escape hatch-handle light is installed in each emergency exit.
(10) The exit signs have a plastic case housing, a lens and a number of LEDs connected in parallel. There are different types:
(a) Ceiling-mounted exit-location signs 50WL and 52WL, single-sided, one for the forward and one for the aft passenger/crew doors
(b) Ceiling-mounted exit-location signs 51WL, 53WL, 54WL and 55WL, single-sided, two for each pair of emergency exit doors
(c) Exit marking signs 40WL thru 47WL, single-sided, one for each passenger/crew door and one for each emergency exit door.
(11) The exit signs have a plastic case housing, a lens and a number of LEDs connected in a parallel line:
(a) Ceiling-mounted exit-location signs 500WL, 550WL are single-sided. One for the forward and one for the aft passenger/crew doors.
(b) Ceiling-mounted exit-location signs 510WL and 520WL are single-sided for the emergency exits.
(c) Ceiling-mounted exit-location signs 530WL and 540WL are single-sided for the passenger/crew doors.
(d) Exit marking signs 400WL, 410WL, 420WL, 430WL, 440WL, 450WL, 460WL and 470WL are single-sided. There is one exit marking sign for each passenger/crew door and one for each pair of emergency exits.
(12) Escape hatch-handle lights 70WL1 thru 70WL4 have a plastic case housing, a lens and two LEDs connected in a parallel line. One escape hatch-handle light is installed in each emergency exit.
C. Cabin Emergency Lights
(1) The cabin emergency lights 20WL, 21WL, 32WL, 33WL and 200WL thru 206WL consist of a housing, a lens and two 6VDC lamps connected in parallel.
(2) Cabin emergency lights 20WL, 21WL, 32WL, 33WL and 200WL thru 206WL consist of a housing, a lens and a number of LEDs connected in parallel.
(3) Cabin-emergency light units 20WL, 21WL, 32WL thru 37WL and 200WL thru 210WL consist of a housing and a lens, containing a number of LEDs in parallel.
(4) Cabin emergency lights 20WL, 21WL, 32WL, 33WL and 200WL thru 207WL consist of a housing, a lens and a number of LEDs connected in parallel.
(5) Cabin emergency lights 20WL, 21WL, 32WL, 33WL, 36WL, 37WL and 200WL thru 210WL have a housing, a lens and a number of LED connected in parallel.
D. External Lights
(1) The overwing emergency lights 60WL thru 63WL consist of a housing, a lens and one 6VDC lamp.
(2) The escape slide lights are integrated in the escape slides and consist of a number of 6VDC lamps.
(3) The overwing emergency lights 60WL thru 63WL consist of a housing, a lens and two 6VDC lamps connected in parallel.
(4) The escape slide lights are integrated in the escape slides and consist of a number of 6VDC lamps connected in parallel.
(5) The overwing emergency lights 60WL thru 63WL consist of a housing, a lens and one 6VDC lamp.
(6) The escape slide lights are integrated in the escape slides and consist of a number of 6VDC lamps.
(7) The escape slide lights are integrated in the escape slides and consist of a number of 6VDC lamps connected in parallel.
(8) Overwing emergency lights 60WL thru 63WL have:
  • A housing
  • A lens
  • Two 6VDC lamps.
(9) The escape slide lights are a part of the escape slides. Their 6VDC lamps are connected in parallel.
(10) Overwing emergency lights 60WL thru 63WL have a housing, a lens and two 6VDC lamps.
(11) The escape slide lights are a part of the escape slides. Their 6VDC lamps are connected in parallel.
(12) The escape slide lights are installed in the escape slides and have a number of 6VDC lamps.
E. Floor Proximity Lights
(1) The seat/wall-mounted emergency-lights and the seat/wall-mounted emergency-exit location-lights consist of a plastic case housing and one or two 6VDC lamp(s).
(2) The wall-mounted exit-marking signs 90WL1 thru 90WL6, single sided, one for each passenger/crew door and one for each emergency exit, contain five 6VDC lamps.
(3) The seat/wall-mounted emergency-lights and the seat/wall-mounted emergency-exit location-lights consist of a plastic case housing and one or two 6VDC lamp(s).
(4) The wall-mounted exit-marking signs 90WL1 thru 90WL6, single sided, one for each passenger/crew door and one for each emergency exit, contain five 6VDC lamps.
(5) Wall-mounted exit-marking signs 90WL1 thru 90WL8, single sided, one for each passenger/crew door and one for each emergency exit door, contain two LED.
(6) The wall-mounted exit-marking signs 90WL1 thru 90WL8 have a housing, a lens and a number of LEDs. There is one for each passenger/crew door and one for each emergency exit.
(7) Wall-mounted exit-marking signs 90WL are single-sided. There is one for each passenger/crew door and one for each emergency exit. They have:
  • A plastic case housing
  • A lens
  • A number of LEDs.
(8) Wall-mounted exit-marking signs 90WL1 thru 90WL8 have:
  • A plastic case housing
  • A lens
  • A number of LEDs.
There is one for each passenger/crew door and one for each emergency exit.
(9) Wall-mounted exit-marking signs 95WL1 thru 95WL10 have:
  • A plastic case housing
  • A lens
  • A number of LEDs.
There is one for each passenger/crew door and one for each emergency exit.
F. System Control
(1) The EMER EXIT LT switch 4WL on the overhead panel 25VU is a 3-position double-pole toggle switch. The positions are ON, OFF and ARM. It is used to switch the emergency lighting system on or off. The emergency lighting comes on automatically when the toggle switch is selected to ARM, if the battery busbar power fails.
The toggle switch must be pulled to make a selection. This prevents accidental system selection.
(2) The emergency lighting system comes on when the LIGHT EMER pushbutton switch on the forward attendant panel 120RH is pushed. The pushbutton switch contains an integral light.
(3) The NO SMOKING switch 190RH on the overhead panel 25VU controls the relay 8WL in the relay box 103VU. The relay 8WL switches the exit signs on or off.
(4) EMER EXIT LT switch 4WL on overhead panel 25VU is a 3-position double-pole toggle switch. The positions are ON, OFF and ARM. It sets the emergency lighting system to on or off. The emergency lighting comes on automatically when the toggle switch is set to ARM, if there is a failure of the battery busbar power.
The toggle switch must be pulled to make a selection. This prevents accidental system selection.
(5) The emergency lighting system comes on when the LIGHT EMER pushbutton switch on Flight Attendant Panel (FAP) 120RH is pushed. The pushbutton switch has an internal light.
(6) NO SMOKING switch 190RH on overhead panel 25VU controls relay 8WL in relay box 103VU through the CIDS. Relay 8WL sets the exit signs on or off.
(7) EMER EXIT LT switch 4WL on overhead panel 25VU is a 3-position double-pole toggle switch. The positions are ON, OFF and ARM. It is used to set the emergency lighting system to on or off. The emergency lighting comes on automatically when the toggle switch is set to ARM, if there is a failure of the battery busbar power.
The toggle switch must be pulled to make a selection. This prevents accidental system selection.
(8) The emergency lighting system comes on when the EMER button on Flight Attendant Panel (FAP) 120RH is pushed. The button has a light.
(9) EXIT switch 190RH on overhead panel 25VU controls relay 8WL in relay box 103VU. Relay 8WL sets the exit signs to on or off.
(10) EMER EXIT LT switch 4WL, on overhead panel 25VU, is a 3-position double-pole toggle switch. The positions are ON, OFF and ARM. It sets the emergency lighting system to on or off. The emergency lighting comes on automatically when the toggle switch is set to ARM, if there is a failure of the battery busbar power.
The toggle switch must be pulled to make a selection. This prevents accidental system selection.
(11) The emergency lighting system comes on when the EMER button on Flight Attendant Panel (FAP) 120RH is pushed. The button has a light.
(12) No PED switch 190RH, on overhead panel 25VU, controls relay 8WL in relay box 103VU through the CIDS. Relay 8WL sets the exit signs to on or off.
G. Photoluminescent Floor Path-Marking-System
(1) The photoluminescent strips have no electrical power supply and are self-luminescent. They are charged by the cabin lights. The charging and discharging time can be increased and decreased by the related conditions:
  • Length of time of the charging
  • Light intensity during the charging
  • Color filter film (if installed).
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6. Operation
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Schematic ** ON A/C NOT FOR ALL

F Lavatory Auxiliary Lights - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Lights - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Lights - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Lights - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Light - Schematic ** ON A/C NOT FOR ALL
F Lavatory Auxiliary Light - Schematic ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Switching Logic Diagram ** ON A/C NOT FOR ALL
F Cabin Emergency Lighting - Switching Logic Diagram ** ON A/C NOT FOR ALL
A. Operation of the Emergency Lighting System
(1) The system is supplied with power when busbars 103XP-B and 801PP are energized and circuit breakers 1WL, 2WL and 3WL are closed.
With EMER EXIT LT switch 4WL and the LIGHT EMER pushbutton switch on forward attendant panel 120RH in the OFF positions the power-supply units control-line OFF is grounded. All lights and signs are off and the battery in each power-supply unit is on charge. EMER EXIT LT OFF annunciator light 5WL comes on.
(2) The system is supplied with power when busbars 103XP-B and 801PP are energized and circuit breakers 1WL, 2WL and 3WL are closed.
With EMER EXIT LT switch 4WL and the EMER pushbutton switch on flight attendant panel 120RH in the OFF positions the power-supply units control-line OFF is grounded. All lights and signs are off and the battery in each power-supply unit is on charge. EMER EXIT LT OFF annunciator light 5WL comes on.
(3) When on overhead panel 25VU NO SMOKING switch 190RH is in the ON position, independent of the landing gear position, the emergency power-supply units EXIT SIGN control line is grounded. The EXIT SIGN control line is also grounded when NO SMOKING switch 190RH is in the AUTO position with the landing gear extended. With a grounded EXIT SIGN control line the emergency lights come on.
(4) When on overhead panel 25VU EXIT switch 190RH is in the ON position, independent of the landing gear position, the emergency power-supply units EXIT SIGN control line is grounded. The EXIT SIGN control line is also grounded when EXIT switch 190RH is in the AUTO position and the landing gear is extended. With a grounded EXIT SIGN control line the emergency lights come on.
(5) When No PED switch 190RH, on overhead panel 25VU, is in the ON position, independent of the landing gear position, the emergency power-supply units EXIT SIGN control line is grounded. The EXIT SIGN control line is also grounded when No PED switch 190RH is in the AUTO position and the landing gear is extended. With a grounded EXIT SIGN control line the emergency lights come on.
(6) The emergency lights go off when the NO SMOKING switch 190RH is in the ON or OFF position. The ground signal is removed from the EXIT SIGN control line. The emergency lights also go off when the landing gear retracts and the NO SMOKING switch 190RH is in the AUTO position.
(7) The emergency lights go off when EXIT switch 190RH is in the OFF position. The ground signal is removed from the EXIT SIGN control line. The emergency lights also go off when the landing gear retracts and EXIT switch 190RH is in the AUTO position.
(8) The emergency lights go off when No PED switch 190RH is in the OFF position. The ground signal is removed from the EXIT SIGN control line. The emergency lights go off when the landing gear retracts and No PED switch 190RH is in the AUTO position.
(9) With EMER EXIT LT switch 4WL in the ARM position, the power-supply units control-line ARM is grounded. EMER EXIT LT OFF annunciator light 5WL goes off. If the power supply on 115VAC normal busbar 103XP fails, the cabin emergency lights and floor proximity lights (if installed) come on. The lights are supplied with power through the 28VDC/6VDC converter in each power-supply unit.
(10) If the 28VDC essential busbar voltage falls below 16VDC +/- 1VDC, the batteries in the power supply units provide the power supply and continue to supply the loads for at least 10 minutes.
(11) With EMER EXIT LT switch 4WL in the ON position, the power-supply units control-line ON is grounded. This control line also has a ground connection, when the LIGHT EMER pushbutton switch on forward attendant panel 120RH is pushed. In either case the cabin emergency lights, the exit signs, the escape hatch-handle lights and the floor proximity lights come on. The 28VDC/6VDC converter of the power supply units supply these loads as long as the 28VDC essential busbar power is available. If the essential busbar fails see above.
(12) With the EMER EXIT LT switch 4WL in the ON position, the emergency power-supply units control-line ON is grounded. This control line also has a ground connection, when the LIGHT EMER pushbutton switch on the forward attendant panel 120RH is pushed. In either case the cabin emergency lights, the exit signs and the wall-mounted exit-marking signs come on. The 28VDC/6VDC converter of the emergency power-supply units supply these loads as long as the 28VDC essential busbar power is available. If the essential busbar fails see above.
(13) With EMER EXIT LT switch 4WL in the ON position, the power-supply units control-line ON is grounded. This control line also has a ground connection, when the EMER pushbutton on Flight Attendant Panel (FAP) 120RH is pushed. In either case the cabin emergency lights, the exit signs and the floor proximity lights come on. The 28VDC/6VDC converter of the emergency power-supply units supply these loads as long as the 28VDC essential busbar power is available. If the essential busbar fails see above.
(14) With EMER EXIT LT switch 4WL in the ON position, the emergency power-supply units control-line ON is grounded. This control line also has a ground connection, when the EMER button on Flight Attendant Panel (FAP) 120RH is pushed. In each condition the cabin emergency lights, the exit signs and the wall-mounted exit-marking signs come on. The 28VDC/6VDC converter of the emergency power-supply units supply these loads as long as the 28VDC essential busbar power is available. If the essential busbar has a failure see above.
(15) With EMER EXIT LT switch 4WL in the ON position, the power-supply units control-line ON is grounded. This control line also has a ground connection, when the EMER button on Flight Attendant Panel (FAP) 120RH is pushed. In each condition the cabin emergency lights, the exit signs, the escape hatch-handle lights and the wall-mounted exit-marking signs come on. The 28VDC/6VDC converter of the emergency power-supply units supply these loads as long as the 28VDC essential busbar power is available. If the essential busbar has a failure see above.
(16) With the passenger/crew doors open and the escape slides armed, that does not include the switch positions, the integral lights in the related escape slides come on.
With the emergency exit hatches removed and the escape slides released, that does not include the switch positions, the integral lights in the related escape slides and two overwing lights at these hatches come on.
(17) With the passenger/crew doors or the emergency exit doors open and the escape slides armed, independent of switch positions, the integral lights in the respective escape slides come on.
(18) With essential busbar 401PP energized and circuit breaker 79WL closed, a 28VDC auxiliary light comes on in each lavatory.
(19) In the event of excessive cabin depressurization, the exit marking signs and the exit location signs automatically come on.
(20) In the event of excessive cabin depressurization, the exit marking signs, the exit location signs and the emergency-escape hatch-handle lights automatically come on.
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7. BITE TEST
A. Emergency Lighting System
An electronic test circuit energizes when the TEST EMER LIGHT SYS membrane switch on programming and test panel 110RH (CIDS) is pushed. The test circuit supplies the ground for the emergency power-supply units control line TEST and, at the same time, the circuit for the SYS OK annunciator light.

Emergency power-supply units 10WL thru 13WL start the following tests:
  • Internal logic circuits
  • Battery charging and monitoring circuits
  • 28VDC power supply
  • 115VAC power supply
  • External loads
  • Internal loads.

If there are no failures, the emergency power-supply unit completes the test signal loop. When the test loops of all emergency power-supply units are complete, the test circuit is complete and the SYS OK annunciator light comes on.

An electronic test circuit energizes when the TEST EMER LIGHT SYS membrane switch on programming and test panel 110RH (CIDS) is pushed. The test circuit supplies the ground for the emergency power-supply units control line TEST and, at the same time, the circuit for the SYS OK annunciator light.

Emergency power-supply units 10WL thru 15WL start the following tests:
  • Internal logic circuits
  • Battery charging and monitoring circuits
  • 28VDC power supply
  • 115VAC power supply
  • External loads and
  • Internal loads.

If there are no failures, the emergency power-supply unit completes the test signal loop. When the test loops of all emergency power-supply units are complete, the test circuit is complete and the SYS OK annunciator light comes on.

Each EPSU has two different integrated BITE functions:
  • A system test
  • A battery capacity test.
The EPSUs have an interface to the CIDS to read the BITE results of a system test and a battery capacity test.
(1) System Test
The system test monitors the subsequent functions:
  • A short circuit on each output
  • An overvoltage on each output
  • The output voltage of the battery pack
  • The battery heating device
  • The proper function of the EPSU logic and switching circuits
  • If the connected loads are in the pre-determined values.
The pre-determined resistance values are used as reference values.
The referenced values are stored in a memory of the EPSU electronic and monitoring circuits during a load programming (TEACH-IN) procedure. The procedure is accomplished as follows:
  • Disconnect EPSU from 28VDC aircraft power supply.
  • Remove EPSU battery.
  • Re-connect EPSU to 28VDC aircraft power supply.
  • Install EPSU battery.
During the system test each EPSU measure the resistance values of its connected loads. These measured values are compared with the reference values.
The system test has a limit of 60 seconds to prevent discharge of the battery pack.
(2) EPSU Test
The test signal loop of the emergency power-supply unit is not complete if there is a defect found during the tests. If the test circuit is not complete, the SYS OK annunciator light does not come on. The display of programming and test panel 110RH (CIDS) shows the messages:
  • EPSU UNIT
  • EPSU BATTERY
  • EPSU 28 VDC
  • EPSU 115 VAC
  • EPSU EXT LOAD
  • EPSU INT LOAD.

The EPSU UNIT message is shown when there is a failure in the internal logic circuits.
The EPSU BATTERY message is shown when there is a failure in the battery charging and monitoring circuits.
The EPSU 28 VDC or the EPSU 115 VAC messages are shown when there is a failure in the related power supply.
The EPSU EXT LOAD or the EPSU INT LOAD messages are shown when there are failures in the external and the internal loads. A failure is found when the resistance values of these loads are not in their given limits.
During the tests of the external and the internal loads and a load programming (TEACH-IN) procedure the emergency power-supply units switch on these loads. This tests and the TEACH-IN measure the resistance values of the loads.
The TEACH-IN calculates the resistance limits of the loads and stores their values in the memories of the emergency power-supply units.
Each emergency power-supply unit compares the measured values of the test with the stored limits of the TEACH-IN.

The TEACH-IN starts automatically when:
  • The 115VAC and the 28VDC power are available.
  • On forward attendant panel 120RH the LIGHT EMER pushbutton switch is in the released position.
  • On overhead panel 25VU EMER EXIT LT switch 4WL is in the OFF position.
  • On overhead panel 25VU NO SMOKING switch 190RH is in the OFF position.
  • The overwing emergency lights are off.
  • The emergency power-supply unit is installed on the A/C for the first time, or
    The battery was removed for more than 5 s and is then installed again.
(3) EPSU Test
The battery capacity test monitors:
  • If the capacity of each EPSU battery is sufficient enough to supply its emergency lights for at least 10 minutes.
  • If the loss of the capacity of each battery, between two consecutive battery capacity tests, is smaller than 0.40 Ah.
The battery capacity test requires up to three hours to be completed.
(4) EPSU Loads
External loads are:
  • The overwing emergency lights
  • The escape slide lights.

Internal loads are:
  • The cabin emergency lights
  • The escape hatch-handle lights
  • The exit location signs
  • The exit marking signs
  • The wall-mounted exit marking signs
  • The seat/wall-mounted emergency-lights
  • The seat/wall-mounted emergency-exit location-lights.

If there is a communication failure between the emergency power-supply units and programming and test panel 110RH (CIDS), the display of programming and test panel 110RH (CIDS) shows the message:
  • EPSU COMM.

NOTE: For detailed system information refer to 23-73-00.

The GND SCAN mode on programming and test panel 110RH (CIDS) gives the operator information on the status of the emergency power-supply units. After a failure message, the test buttons of the individual emergency power-supply units are pushed. A red LED shows the defective emergency power-supply units or the associated defective loads.
(5) EPSU Loads
External loads are:
  • The overwing emergency lights
  • The escape slide lights.

Internal loads are:
  • The cabin emergency lights
  • The escape hatch-handle lights
  • The exit location signs
  • The exit marking signs.

If there is a communication failure between the emergency power-supply units and programming and test panel 110RH (CIDS), the display of programming and test panel 110RH (CIDS) shows the message:
  • EPSU COMM.

NOTE: For detailed system information refer to 23-73-00.

The GND SCAN mode on programming and test panel 110RH (CIDS) gives the operator information on the status of the emergency power-supply units. After a failure message, the test buttons of the individual emergency power-supply units are pushed. A red LED shows the defective emergency power-supply units or the associated defective loads.
(6) EPSU Loads
External loads are:
  • The escape slide lights.

Internal loads are:
  • The cabin emergency lights
  • The exit location signs
  • The exit marking signs
  • The wall-mounted exit marking signs.

If there is a communication failure between the emergency power-supply units and the programming and test panel 110RH (CIDS), the display of the programming and test panel 110RH (CIDS) shows the message:
  • EPSU COMM.

NOTE: For detailed system information refer to 23-73-00.

The GND SCAN mode on programming and test panel 110RH (CIDS) gives the operator information on the status of the emergency power-supply units. After a failure message, the test buttons of the individual emergency power-supply units are pushed. A red LED shows the defective emergency power-supply units or the associated defective loads.
B. Emergency Lighting Batteries
The code for the battery capacity test is selected on programming and test panel 110RH (CIDS) and the display shows the message BATTERY CAPACITY TEST ACTIVE. An electronic test circuit energizes when the TEST EMER LIGHT BAT membrane switch on programming and test panel 110RH (CIDS) is pushed. The integral light in this membrane switch comes on. The test circuit connects a 28 VDC positive for emergency power-supply units 10WL thru 13WL control line TEST and completes, at the same time, the circuit for the BAT OK annunciator light. If all batteries have full capacity, the test circuit is complete and the BAT OK annunciator light comes on.

If the annunciator light does not come on, the display of programming and test panel 110RH (CIDS) shows the message EPSU BAT CAP. The message EPSU BAT CAP indicates that one or more batteries of emergency power-supply units 10WL thru 13WL is/are defective.

NOTE: For detailed system information refer to 23-73-00.

The GND SCAN mode on programming and test panel 110RH (CIDS) gives the operator information on the status of the emergency power-supply units. After a failure message the test buttons of the individual emergency power-supply units are pushed. A red LED indicates the defective emergency power-supply units or the defective batteries.
The code for the battery capacity test is selected on programming and test panel 110RH (CIDS) and the display shows the message BATTERY CAPACITY TEST ACTIVE. An electronic test circuit energizes when the TEST EMER LIGHT BAT membrane switch on the programming and test panel 110RH (CIDS) is pushed. The integral light in this membrane switch comes on. The test circuit connects a 28 VDC positive for emergency power-supply units 10WL thru 15WL control line TEST and completes, at the same time, the circuit for the BAT OK annunciator light. If all batteries have full capacity, the test circuit is complete and the BAT OK annunciator light comes on.

If the annunciator light does not come on, the display of programming and test panel 110RH (CIDS) shows the message EPSU BAT CAP. The message EPSU BAT CAP indicates that one or more batteries of emergency power-supply units 10WL thru 15WL is/are defective.

NOTE: For detailed system information refer to 23-73-00.

The GND SCAN mode on the programming and test panel 110RH (CIDS) gives the operator information on the status of the emergency power-supply units. After a failure message the test buttons of the individual emergency power-supply units are pushed. A red LED indicates the defective emergency power-supply units or the defective batteries.
C. Description
The EPSUs and the CIDS use a RS232 interface for the data exchange of both BITE functions. You can start the two different BITE functions only on the ground with a related CFDS/MCDU test menu page. Additionally the start of the battery capacity test is code protected against inadvertent action, because the batteries are discharged during the battery capacity test.
The EPSUs only accept the test start commands when the subsequent conditions are fulfilled:
  • Aircraft on ground
  • All emergency lights OFF
  • 28 V DC available
  • 115 V AC available
  • Control switch 'EMER EXIT LT' 4WL in OFF position
  • Pushbutton 'EMER' on the FAP in OFF position
  • Control switch 'NO SMOKING' 190RH in OFF position.
The EPSUs and the CIDS use a RS232 interface for the data exchange of both BITE functions. You can start the two different BITE functions only on the ground with a related CFDS/MCDU test menu page. Additionally the start of the battery capacity test is code protected against inadvertent action, because the batteries are discharged during the battery capacity test.
The EPSUs only accept the test start commands when the subsequent conditions are fulfilled:
  • Aircraft on ground
  • All emergency lights OFF
  • 28 VDC available
  • 115 VAC available
  • Control switch 'EMER EXIT LT' 4WL in OFF position
  • Pushbutton 'EMER' on the FAP in OFF position
  • Control switch 'EXIT' 190RH in OFF position.
The EPSUs and the CIDS use a RS232 interface for the data exchange of both BITE functions. You can start the two different BITE functions only on the ground with a related CFDS/MCDU test menu page. Additionally the start of the battery capacity test is code protected against inadvertent action, because the batteries are discharged during the battery capacity test.
The EPSUs only accept the test start commands when the subsequent conditions are fulfilled:
  • Aircraft on ground
  • All emergency lights OFF
  • 28 VDC available
  • 115 VAC available
  • Control switch 'EMER EXIT LT' 4WL in OFF position
  • Pushbutton 'EMER' on the FAP in OFF position
  • Control switch 'No PED' 190RH in OFF position.
(1) System Test
F EPSU System Test - MCDU Start Menu ** ON A/C NOT FOR ALL
F MCDU Failure Page (1/2) ** ON A/C NOT FOR ALL
F MCDU Failure Page (2/2) ** ON A/C NOT FOR ALL

When you start the system test via a CFDS/MCDU test page action the CIDS transmit the 'EPSU SYS TEST' data word through the related DEU-Bs to the EPSUs. When the 'EPSU SYS TEST' data word is accepted the EPSUs are set to the system test mode.
When the EPSUs can start the system test the status message 'TEST IN PROGRESS' is send to the CIDS. The system test will be completed within approximately 60 seconds. When the system test is completed the test results are sent to the CIDS and shown as a test result message on the CFDS/MCDU.
When the EPSUs cannot start the system test the reason for not starting the system test is sent to the CIDS and shown as a status message on the CFDS/MCDU.
(2) Battery Capacity Test
F EPSU Battery Capacity Test - MCDU Menu Pages (1/2) ** ON A/C NOT FOR ALL
F EPSU Battery Capacity Test - MCDU Menu Pages (2/2) ** ON A/C NOT FOR ALL

You can start the battery capacity test via a CFDS/MCDU test page action. The test start procedure is protected against accidental operation with a code. When the EPSUs accept the code you can start the battery capacity test and the EPSUs are set to the battery capacity test mode. The status message 'EPSU BAT CAP TEST IN PROGRESS' is sent to the CFDS/MCDU.
Before the main battery capacity test starts a system test is automatically done. If there is a system failure the battery capacity test is stopped.

When the battery capacity test is started during high environmental temperature conditions, e.g. Aircraft in sunlight without Air Conditioning and the battery temperature exceeds more than 45 deg.C, the test is delayed.
When the temperature falls to a normal day profile, the normal battery test cycle continuous. The message on the MCDU remains for information.
The maximum time for a delayed battery capacity test is 24 hours. After a delay of more than 24 hours, the battery capacity test is stopped.
D. Operation
(1) System Test
You can start the system test of the emergency lighting system when you select the 'CIDS' main menu through the 'CFDS SYSTEM REPORT TEST' menu page. In the 'CIDS' main menu you have to select the 'SYSTEM TEST' menu page. When you push the 'EPSU SYS TEST' line select key of the 'SYSTEM TEST' menu the 'EPSU SYS TEST' menu comes on and shows the subsequent data:
  • Initial conditions of starting the system test
  • < START
  • < RETURN.
When you set the 'START' line key and the system test starts, the message 'TEST IN PROGRESS XXs' comes on. When the system test cannot start, a status message shows the reason for not start the test.
When the system test is completed, a test result message comes on.
(2) Battery Capacity Test
You can start the 'EPSU BAT CAP TEST' of the emergency lighting system, when you select the 'CIDS' main menu through the 'CFDS SYSTEM REPORT TEST' menu page. When you push the 'EPSU BAT CAP TEST' line key, the 'EPSU BAT CAP TEST 1/2' page comes on and shows the subsequent data:
  • A CAUTION message
  • Initial conditions to start the test
  • < RETURN.
When you push the 'NEXT PAGE' line key the CIDS requests the status of all EPSUs and the message 'IN PROGRESS XXs' comes on during the waiting time.
After approximately XXs the 'EPSU BAT CAP TEST 2/2' page comes on and shows the subsequent data:
  • A CAUTION message
  • A request to enter the access code
  • START TEST
  • TEST RESULT.
As long as the correct code is not entered and there are no test results of a previous test available there are no '<' prompts in front of the 'START TEST' and 'TEST RESULT' messages.
When you enter the code, the '<' prompt comes on in front of the 'START TEST' message. Now you can push the 'START TEST' line key and the '< CONFIRM START OF TEST' message comes on. Push the 'CONFIRM START OF TEST' line key and the battery capacity test starts. The message 'TEST IN PROGRESS 3HR' comes on.
When the battery capacity test cannot start, a status message shows the reason for not start the test.
After approximately 3 hours, when the battery capacity is completed, a test result message or a status message comes on.
[Rev.10 from 2021] 2026.04.01 05:36:33 UTC
"Aviabrain" 2025