(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.

 1EFF : ALL 1 21-26-00Page 43 1 1 Aug 01/04R 1 1 1CES 1

 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.
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：A320飛機維護手冊 AMM AIR CONDITIONING 空調 1(150)