(2)
Closed Circuit Normally the avionics equipment is cooled with air in a closed circuit when:
-the aircraft is on the ground and the skin temperature is below +9 deg.C (+48.20 deg.F),
- or when the aircraft is in flight and the skin temperature is below +31 deg.C (+87.80 deg.F). In these conditions, the skin air inlet valve 15HQ, the skin air outlet valve 22HQ close. The skin exchanger outlet bypass valve 23HQ opens. In addition, the skin exchanger isolation valve 24HQ opens and the skin heat exchanger operates. Three pressure switches 17HQ, 19HQ and 30HQ at different places in the system, send a signal to the AEVC 10HQ when a decreasing pressure/airflow is detected. When this signal is received by the AEVC 10HQ, a warning message shows:
-
"VENT BLOWER FAULT" when a decreasing pressure/airflow is detected by the pressure switches 17HQ and 19HQ
-
"VENT EXTRACT FAULT" when a decreasing pressure/airflow is detected
by pressure switch 30HQ. At this time and according to the existing configuration, the pilot pushes in:
-
the Override (OVRD) pushbutton
-
the OVRD Blower pushbutton or
-
the OVRD Extract pushbutton or
-
the OVRD Blower and OVRD Extract pushbuttons
and the skin exchanger inlet bypass valve 16HQ closes.
The skin exchanger inlet bypass valve 16HQ opens when the pressure
switches detect a correct pressure/airflow in the system.
(3)
Partially Open Circuit The avionics equipment is cooled with air in a partially open circuit when the skin temperature is above +35 deg.C (+95.00 deg.F) and:
-
when the aircraft is on the ground (TLA above T/O),
-
when the aircraft is in flight.
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When the AEVC 10HQ receives a signal greater than +35 deg.C (+95.00
deg.F) from the skin temperature sensor 28HQ, this causes:
- the skin exchanger outlet bypass valve 23HQ to open,
- the skin air outlet valve 22HQ to partially open,
- the skin exchanger inlet bypass valve 16HQ to open.
The avionics equipment is then cooled with air conditioning system
and avionics compartment air coming into the system through the skin
exchanger outlet bypass valve 23HQ.
The air after cooling the equipment is directed overboard through the
skin air outlet valve 22HQ and to the forward underfloor area through
the skin exchanger inlet bypass valve 16HQ. When the skin temperature
drops below +31 deg.C (+87.80 deg.F), the system goes back to a
closed circuit configuration.
(4) Cockpit Supply Air
The avionics equipment is cooled with air tapped from the cockpit
supply duct when one of the following failure cases occurs:
(a) Extraction Low Flow
The AEVC 10HQ illuminates the FAULT legend on the EXTRACT
R pushbutton switch 14HQ if the pressure switch 30HQ detects low
R flow. On the ground, the ADIRU & AVNCS VENT caution light 25HQ
R comes on amber on the external power panel 108VU and the horn
R sounds. When this happens, the pushbutton switch must be released
R and the OVRD legend comes on. This causes the conditioned air
R inlet valve 21HQ and skin exchanger isolation valve 24HQ to open.
R All the other valves close.
(b) Blowing Low Flow/High Duct Temperature
The AEVC 10HQ illuminates the FAULT legend on the BLOWER
pushbutton switch 13HQ when one or both of the following occurs:
- if the pressure switch 17HQ (19HQ) detects low flow,
- if the temperature sensor 26HQ senses high duct temperature.
R On the ground, the ADIRU & AVNCS VENT caution light 25HQ comes on
R amber on the external power panel 108VU and the horn sounds.
When this happens, the pushbutton switch must be released and the
OVRD legend comes on. This causes the blower fan 20HQ to stop,
the conditioned air inlet valve 21HQ to open and the skin
exchanger isolation valve 24HQ to open. All the other valves
close.
(c) Smoke (Ref. 26-15-00)
If the smoke detector 1WA detects smoke, the AEVC 10HQ triggers
illumination of:
- the SMOKE legend of the GEN 1 LINE pushbutton switch on the
panel 21VU,
-the FAULT legends of the BLOWER and EXTRACT pusbutton switches on the panel 22VU. When this happens, the BLOWER pushbutton switch 13HQ and the EXTRACT pushbutton switch 14HQ must be released. and the OVRD legends come on. This causes the blower fan 20HQ to stop, the conditioned air inlet valve 21HQ to open and the skin air outlet valve 22HQ to partially open. All the other valves close and the air is directed overboard through the skin air outlet valve 22HQ. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：A320飞机维护手册 AMM AIR CONDITIONING 空调 1(150)
