(1) Start procedure of APU Bleed-Air Supply The start sequence of the APU is complete when the APU acquires 95% speed (Ref. AMM 49-42-00). Above the acquired 95% speed the APU is obtainable for the supply of bleed-air and electrical power. An ECB 59KD logic, permits an APU speed decrease to 88% during normal APU operation before it automatically stops the bleed air. Information on the ECAM and the overhead panel shows that the APU is available : - on the EWD, (the green APU AVAIL indication comes on) - on the APU page of the SD, (the green AVAIL indication comes on) - on the APU overhead panel 25VU, (the green AVAIL legend on the APU
START P/ BSW 2KA comes on.
When the APU is available you can push the APU BLEED P/BSW on the
overhead panel 25VU to start the APU bleed-air supply.
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APU Bleed Indicating Figure 013
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When you push the APU BLEED P/BSW :
-
the blue ON legend on the P/BSW comes on
-
the P/BSW sends a signal to the BMC
-
the BMC starts a test of the sensing elements on the APU bleed-air duct and the left wing bleed-air ducts. If the test is correct the BMC tells the ECB to open the APU bleed load valve.
NOTE : If the BMC 1 finds a leak in the APU bleed-air ducts, while
____ there is a Main Engine Start (MES) signal from the engines, it ignores the leak signal and tells the ECB to open the APU bleed load valve.
(2) Stop of the APU Bleed-Air Supply To stop the APU bleed-air supply you push the APU BLEED P/BSW again:
-
the blue ON legend on the APU BLEED P/BSW goes off,
-
the APU BLEED P/BSW removes the ground signal from the BMCs,
-
the BMCs send an OFF signal to the ECB,
-
the ECB stops the supply of electrical power to the solenoid of the APU bleed load valve,
-
the APU bleed load valve closes and stops the bleed air supply,
- on the BLEED and APU pages of the SD, the green APU bleed-valve symbol is shown in the closed position.
NOTE : If an APU emergency shutdown or an APU automatic shutdown
____ occurs, the APU bleed air supply stops automatically.
R **ON A/C 106-149, 211-299, 301-399, 401-499,
R **ON A/C 106-149, 211-299, 401-499,
(Ref. Fig. 001)
**ON A/C 301-399,
(Ref. Fig. 001A)
R **ON A/C 106-149, 211-299, 301-399, 401-499,
(Ref. Fig. 002)
R 1EFF : ALL 1 36-12-00Page 39 1 1 Aug 01/05 1 1 1CES 1
A. APU Bleed-Air Supply-System (Ref. Fig. 013)
(1) Start procedure of APU Bleed-Air Supply The start sequence of the APU is complete when the APU acquires 95% speed (Ref. AMM 49-42-00 ). Above the acquired 95% speed the APU is obtainable for the supply of bleed-air and electrical power. An ECB 59KD logic, permits an APU speed decrease to 88% during normal APU operation before it automatically stops the bleed air. Information on the ECAM and the overhead panel shows that the APU is available : - on the EWD, (the green APU AVAIL indication comes on) - on the APU page of the SD, (the green AVAIL indication comes on) - on the APU overhead panel 25VU, (the green AVAIL legend on the APU
START P/ BSW 2KA comes on.
When the APU is available you can push the APU BLEED P/BSW on the
overhead panel 25VU to start the APU bleed-air supply.
When you push the APU BLEED P/BSW :
-
the blue ON legend on the P/BSW comes on
-
the P/BSW sends a signal to the BMC
-
the BMC starts a test of the sensing elements on the APU bleed-air duct and the left wing bleed-air ducts. If the test is correct the BMC tells the ECB to open the APU bleed valve.
NOTE : If the BMC 1 finds a leak in the APU bleed-air ducts, while
____ there is a Main Engine Start (MES) signal from the engines, it ignores the leak signal and tells the ECB to open the APU bleed valve.
(2) Stop of the APU Bleed-Air Supply To stop the APU bleed-air supply you push the APU BLEED P/BSW again:
-
the blue ON legend on the APU BLEED P/BSW goes off,
-
the APU BLEED P/BSW removes the ground signal from the BMCs,
-
the BMCs send an OFF signal to the ECB,
-
the ECB stops the supply of electrical power to the rotary actuator of the APU bleed control valve,
-
the APU bleed valve closes and stops the bleed air supply,
- on the BLEED and APU pages of the SD, the green APU bleed-valve symbol is shown in the closed position.
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