(4)
When the APU BLEED pushbutton switch 5HV is set to the ON position:
-the load control valve will open. The APU will then supply bleed air to the pneumatic system. The ECB controls the load control valve, which supplies the pneumatic system with bleed air. The EGT increases when a selection of pneumatic or electrical load, or both, is made. This is shown on the lower ECAM display unit of the Electronic Centralized Aircraft Monitoring (ECAM).
-With the engine speed at 95% rpm, the ECB will accept pneumatic and electrical demand signals. It computes the position of the IGVs and supplies the necessary pneumatic flow. The pneumatic and electrical loads together can cause the EGT to increase more than the set temperature limit. If this occurs, the ECB commands the IGVs to move nearer to the closed position from the set position. This reduces the pneumatic load and makes the electrical load the primary load.
(5)
When the MASTER SW 14KD is set to the OFF position, a usual APU shutdown starts. The ECB closes the APU load control valve. Then the ECB removes the 'AVAIL' signal to the aircraft circuits. The AVAIL legend in the APU START pushbutton switch 2KA and AVAIL indications on the lower ECAM displays are then turned off. With the pneumatic loads removed and the bleed air supply no longer required, the APU goes into a cool-down cycle (only if bleed air has been used).
-A decrease in the EGT shows on the APU page of the ECAM. After the cool-down cycle ends (from 0 to 120 s, as set), the ECB starts the shutdown.
-During the run-down cycle, when the engine speed is below 7% rpm, the ECB closes the air intake flap. Before it de-energizes itself, the ECB signals the aircraft circuits to:
-stop the fuel feed pump 4QC,
-close the FUEL LP VALVE 3QF.
The ECB continually monitors the APU operation and protection functions. If necessary, it shuts down the APU or gives a visual indication to the operator. When a malfunction occurs that could cause damage to the engine, the ECB automatically unloads the engine and starts a shutdown. The FAULT legend in the MASTER SW 14KD comes on. It will stay on until the MASTER SW 14KD is released to OFF.
4. Operational Characteristics___________________________
A. Operating Limits
(1)
Rated combination load at sea level 38 DEG.C (100 DEG.F) condition:
Bleed Load: Bleed flow = 0.97 Kg/s (128 lbs/min),
Bleed pressure = 3,1 bar (45psi),
Shaft load: 83KW (111.3 shp).
(2)
Turbine discharge temperature (governed speed, absolute maximum) 726 DEG.C (1339.5 DEG.F) approximately.
(3)
Turbine discharge temperature (at rated combination load) maximum 632 DEG.C (1170 DEG.F) approximately.
(4)
Turbine discharge temperature (during acceleration). (Ref. 49-61-00)
(5)
Output shaft speed: generator - 24239 rpm.
B. Fuel and Fuel Control System
NOTE : This is for general reference only. All fuel types approved in
____ your Flight Crew Operation Manual (FCOM) can be used in the APU.
----------------------------------------------------------------Fuel Specifications
----------------------------------------------------------------Jet A/Jet A1 ASTM D 1655 JP4 Mil-T-5624 Jet B ASTM D 1655 JP5 Mil-T-5624
-----------------------------------------------------------------
(1)
Fuel inlet pressure from 0.69 bar (10 psi) (min) above true vapour pressure to 3.5 bar (51.5 psi) (max).
(2)
Fuel inlet temperature from - 40 DEG.C (-40 DEG.F) to 54 DEG.C. (130 DEG.F).
(3)
Oil and Fuel leakage limits
-------------------------------------------------------------------------------Unit/Item Normal Maximum Remarks -------------------------------------------------------------------------------Plenum Drain zero zero Fuel leakage from drain
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