DOC AIRBUS | AMM A320FAVIONICS COMPARTMENT SMOKE DETECTION - DESCRIPTION AND OPERATION
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** ON A/C NOT FOR ALL
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1. General
A. Definition
There are two types of smoke detection:
There are two types of smoke detection:
- the direct detection by the crew,
- the secondary detection by a smoke detector, which is a help.
B. Functions
The avionics-compartment smoke-detection system confirms that there is smoke in the avionics compartment.
The smoke detection system includes one smoke detector installed on the air extraction duct.
The smoke detector triggers the smoke warnings to the cockpit when the alarm threshold is reached.
When there is smoke, pneumatic and electrical procedures are started.
The avionics-compartment smoke-detection system confirms that there is smoke in the avionics compartment.
The smoke detection system includes one smoke detector installed on the air extraction duct.
The smoke detector triggers the smoke warnings to the cockpit when the alarm threshold is reached.
When there is smoke, pneumatic and electrical procedures are started.
2. Component Location
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3. System Description
When the smoke concentration is above the alarm threshold, the smoke detector triggers the smoke warnings in the cockpit:
** ON A/C NOT FOR ALL When the smoke concentration is above the alarm threshold, the smoke detector triggers the smoke warnings in the cockpit:
- on the EMER ELEC PWR section of the panel 21VU,
- on the VENTILATION section of the OVERHEAD CTL & IND panel 22VU,
- the MASTER CAUT light comes on,
- the warning message is shown on the lower ECAM display unit.
The aural warning sounds.
When this happens, you must push the VENTILATION/BLOWER pushbutton switch and the VENTILATION/EXTRACT pushbutton switch: the OVRD legends come on.
This causes the blower fan to stop, opens the conditioned-air inlet valve and opens the skin air-outlet valve not fully.
All other valves close and the air goes overboard through the skin air-outlet valve. The extract fan stays energized.
4. Power Supply
Avionics-Compartment Smoke-Detection System - Power supply ** ON A/C NOT FOR ALL
Avionics-Compartment Smoke-Detection System - Power supply ** ON A/C NOT FOR ALL
The smoke detection system gets the electrical power from the DC system of the aircraft.
Avionics-Compartment Smoke-Detection System - Power supply ** ON A/C NOT FOR ALL Avionics-Compartment Smoke-Detection System - Power supply ** ON A/C NOT FOR ALL The smoke detection system gets the electrical power from the DC system of the aircraft.
A. Circuit Breakers
The smoke detection system gets 28VDC through this circuit breaker:
The smoke detection system gets 28VDC through this circuit breaker:
| ------------------------------------------------------------------------------- |
| FIN PANEL/LOCATION DESIGNATION BUS ATA REF. |
| ------------------------------------------------------------------------------- |
| 5HQ 49VU D05 AIR COND/AVNCS VENT/CTL 401PP 21-26-00 |
| ------------------------------------------------------------------------------- |
5. Interface
The avionics-compartment smoke-detection system has an interface with the following systems:
** ON A/C NOT FOR ALL The avionics-compartment smoke-detection system has an interface with the following systems:
- Avionics Equipment Ventilation System (Ref. AMM D/O 21-26-00-00),
- Electrical Power: AC Main Generation (Ref. AMM D/O 24-22-00-00),
- Electrical Power: DC Ancillary Equipment (Ref. 24-68-00),
- Flight Warning Computer (FWC) (Ref. AMM D/O 31-52-00-00),
- Annunciator Light Test and Dimming (Ref. AMM D/O 33-14-00-00),
6. Component Description
Smoke Detector - Description ** ON A/C NOT FOR ALL
Smoke Detector - Description ** ON A/C NOT FOR ALL
Smoke Detector - Description ** ON A/C NOT FOR ALL
Smoke Detector - Description ** ON A/C NOT FOR ALL Smoke Detector - Description ** ON A/C NOT FOR ALL Smoke Detector - Description ** ON A/C NOT FOR ALL A. Smoke Detector FIN: 1-WA
The smoke detector includes:
The smoke detector includes:
- a protective box with air inlets and electrical connectors,
- an optical cell/card assembly.
(1) Protective box
The protective box is a cylindrical box made of aluminium alloy. It is made of two half shells:
The protective box is a cylindrical box made of aluminium alloy. It is made of two half shells:
(a) One half shell with:
- two connectors (only one used),
- the cell/card assembly,
- and the identification plate.
(b) Another half shell which is connected to the outside by air inlets.
(2) Optical cell/card assembly
The optical cell/card assembly includes:
The optical cell/card assembly includes:
(a) An optical measurement chamber
A black plastic light labyrinth on which is placed a light emmitting diode (light source) and a receiving photodiode (light receiver). This constitutes the optical measurement chamber.
A black plastic light labyrinth on which is placed a light emmitting diode (light source) and a receiving photodiode (light receiver). This constitutes the optical measurement chamber.
(b) A Printed Circuit Board (PCB)
The Printed Circuit Board (PCB) which analyses and processes the data supplied by the optical measurement chamber. A wire harness is soldered to the PCB.
The Printed Circuit Board (PCB) which analyses and processes the data supplied by the optical measurement chamber. A wire harness is soldered to the PCB.
(3) Protective box
The protective box is a cylindrical box made of two half-shells:
The protective box is a cylindrical box made of two half-shells:
(a) One half-shell that has:
- Two connectors (only one used)
- The cell/card assembly and
- The identification plate.
(b) The other half-shell has air inlets.
(4) Optical cell/PCB assembly
The optical cell/PCB assembly includes:
The optical cell/PCB assembly includes:
(a) An optical measurement chamber
The optical cell is made of a plastic light-labyrinth on which a light emitting diode (light source) and a receiving photodiode (light receiver) are installed.
The optical cell is made of a plastic light-labyrinth on which a light emitting diode (light source) and a receiving photodiode (light receiver) are installed.
(b) A Printed Circuit Board (PCB)
The PCB makes an analysis of the data from the optical measurement chamber and processes it. A wire harness is soldered to the PCB.
The PCB makes an analysis of the data from the optical measurement chamber and processes it. A wire harness is soldered to the PCB.
B. Principle
Smoke Detector - Description ** ON A/C NOT FOR ALL
Smoke Detector - Description ** ON A/C NOT FOR ALL
Smoke Detector - Description ** ON A/C NOT FOR ALL
The smoke detector is of the photo-electrical type. The smoke detection is based on the scattered light principle.
The heart of the smoke detector is an optical measurement chamber that screens external parasite light but optimally detects light colored and dark smoke particles.
The light source (IR LED), the light trap (or light stop) and the light receiver (photodiode) are arranged in such a way that the light from the emitter cannot directly reach the receiver. Only when smoke particles are present in the optical path, some of the scattered light reaches the photoreceiver and produces an electrical signal. A labyrinth enables the light trap to be efficient and prevent false alarms due to parasite light.
The IR LED periodically transmits brief light pulses (0.4 ms) into the measurement chamber.
The wavelength of the light is 880 nm (near infrared) in order to optimise the detection efficiency.
When smoke particles are present in the optical path, the photodiode receives scattered light and converts it into an electrical signal, to be processed by the electronics.
Smoke Detector - Description ** ON A/C NOT FOR ALL Smoke Detector - Description ** ON A/C NOT FOR ALL Smoke Detector - Description ** ON A/C NOT FOR ALL The smoke detector is of the photo-electrical type. The smoke detection is based on the scattered light principle.
The heart of the smoke detector is an optical measurement chamber that screens external parasite light but optimally detects light colored and dark smoke particles.
The light source (IR LED), the light trap (or light stop) and the light receiver (photodiode) are arranged in such a way that the light from the emitter cannot directly reach the receiver. Only when smoke particles are present in the optical path, some of the scattered light reaches the photoreceiver and produces an electrical signal. A labyrinth enables the light trap to be efficient and prevent false alarms due to parasite light.
The IR LED periodically transmits brief light pulses (0.4 ms) into the measurement chamber.
The wavelength of the light is 880 nm (near infrared) in order to optimise the detection efficiency.
When smoke particles are present in the optical path, the photodiode receives scattered light and converts it into an electrical signal, to be processed by the electronics.
7. Operation/Control and Indicating
A. Operation in Warning Configuration
The alarm output (discrete signal) is activated when the alarm threshold is reached.
As the smoke detector operates in autonomous mode, the corresponding warnings are directly triggered by means of relays to the cockpit.
The alarm output (discrete signal) is activated when the alarm threshold is reached.
As the smoke detector operates in autonomous mode, the corresponding warnings are directly triggered by means of relays to the cockpit.
B. Indicating
When the alarm threshold is reached, the smoke detector triggers the following warnings:
Avionics-Compartment Smoke-Detection System - Indicating and Test ** ON A/C NOT FOR ALL
Avionics-Compartment Smoke-Detection System - Indicating and Test ** ON A/C NOT FOR ALL
The single chime (SC) sounds.
When the alarm threshold is reached, the smoke detector triggers the following warnings:
Avionics-Compartment Smoke-Detection System - Indicating and Test ** ON A/C NOT FOR ALL Avionics-Compartment Smoke-Detection System - Indicating and Test ** ON A/C NOT FOR ALL - on the EMER ELEC PWR section of the overhead panel 21VU
. the SMOKE legend of the GEN 1 LINE pushbutton switch comes on,
- on the VENTILATION section of the overhead panel 22VU
. the FAULT legends of the BLOWER and EXTRACT pushbutton switches come on,
- the MASTER CAUT light comes on,
- a warning message is shown on the lower ECAM display unit.
The single chime (SC) sounds.
NOTE: When smoke concentration decreases below the alarm threshold, the smoke detector returns to the initial state.
C. Control
(1) Smoke Procedure
The list of the necessary actions during the smoke procedure comes into view automatically on the lower ECAM display unit while the SMOKE warnings are triggered.
When these actions are completed, the related lines are cancelled automatically on the lower ECAM display unit (See ATA Ref. 31-51-00).
The procedure below must be applied:
The list of the necessary actions during the smoke procedure comes into view automatically on the lower ECAM display unit while the SMOKE warnings are triggered.
When these actions are completed, the related lines are cancelled automatically on the lower ECAM display unit (See ATA Ref. 31-51-00).
The procedure below must be applied:
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| DISPLAY ACTIONS |
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| AVIONICS SMOKE LAND ASAP |
| . IF PERCEPTIBLE SMOKE : |
| . Smoke from avionics compartment is |
| detected directly by the crew. |
| - OXY MASK/GOGGLES........ON |
| . Make sure crew members can speak to control |
| tower each other. Do not use the interphone |
| position to keep the interference of the |
| oxygen-mask breathing noise to a minimum. |
| - CAB FANS...............OFF |
| . To keep smoke off the cockpit and the |
| cabin. |
| - BLOWER................OVRD |
| - EXTRACT...............OVRD |
| . Avionics ventilation is provided by air |
| conditioning system and extracted |
| overboard: Valve F opening, valve B partial |
| opening, valves A, E and D closing. |
| Blower fan (A) stopping, extract fan (B) |
| remains energized. |
| . IF SMOKE AFTER 5MN00S: |
| . An electrical procedure is applied to |
| eliminate the cause of the smoke if the |
| smoke emission persists more than 5 mn. |
| - EMERG ELEC GEN 1 LINE..OFF |
| . GEN 1 LINE contactor opens. GEN 1 remains |
| in operation and supplies one fuel pump in |
| each wing tank. AC BUS 1 is supplied by |
| GEN 2 through bus tie contactor. |
| - EMER ELEC PWR.......MAN ON |
| . The Ram Air Turbine (RAT) is extended and |
| the emergency generator is connected to |
| the aircraft network. |
NOTE: If smoke disappears within 5 mn, restore normal ventilation.
8. BITE Test
A. Built-In Test Equipment (BITE)
Avionics-Compartment Smoke-Detection System - Indicating and Test ** ON A/C NOT FOR ALL
Avionics-Compartment Smoke-Detection System - Indicating and Test ** ON A/C NOT FOR ALL
The smoke detector is tested by the AEVC upon manual test indication from the MCDU (see. ATA Ref. 21-26-00).
Avionics-Compartment Smoke-Detection System - Indicating and Test ** ON A/C NOT FOR ALL Avionics-Compartment Smoke-Detection System - Indicating and Test ** ON A/C NOT FOR ALL The smoke detector is tested by the AEVC upon manual test indication from the MCDU (see. ATA Ref. 21-26-00).