**ON A/C ALL
(3) Leak Detection
When an overheat sensing element finds a leak:
-
the BMCs receive a leak signal,
-
the BMCs prepare this signal and send an OFF signal to the ECB,
-
the ECB removes the electrical power from the APU bleed-valve solenoid,
-
the APU bleed valve closes and stops the bleed air supply,
-
the amber FAULT legend in the APU BLEED P/BSW comes on,
-
the amber MASTER CAUT lights come on,
-a single chime is heard,
- on the EWD:
AIR
APU BLEED LEAK
-APU BLEED .......................OFF is shown, - on the BLEED and APU pages of the SD, the APU bleed-valve symbol is
shown in the closed position.
When you push the APU BLEED P/BSW:
-the ON legend in the APU BLEED P/B goes off,
- on the EWD:
STATUS
INOP SYS
APU LEAK
is shown.
**ON A/C 001-049, 051-060, 101-102,
B. Crossbleed System (Ref. Fig. 012, 014) A crossbleed valve is installed in the crossbleed duct in the unpressurized area. The crossbleed valve is equipped with two electrical motors which can both actuate the butterfly plate in the opening or closing positions. One motor is used in the automatic mode, the other in the manual mode. Each motor includes a 'brake system' which locks the butterfly in position if the electrical power supply is cut off.
(1) Automatic Control The crossbleed valve selector-switch 3HV is usually in the AUTO position. In this position the coil of the crossbleed-valve auto-control relay 4HV is connected to the normal bus 206PP. When you push the APU BLEED pushbutton-switch 5HV to the ON position the BMCs send a ground signal to the crossbleed-valve auto-control relay 4HV if:
1EFF : ALL 1 36-12-00Page 41 1 1 Aug 01/05R 1 1 1CES 1
Crossbleed Valve - Indicating Figure 014
1EFF : 1 1R 1CES ALL 1 11 1 36-12-00 Page 42 Aug 01/05
-the APU bleed load valve is in the fully open position,
-there is no leak warning (the leak warning will be ignored during
the main engine start). The crossbleed-valve auto-control relay 4HV supplies electrical power to the crossbleed valve motor 1 and the crossbleed valve opens. On the BLEED page of the SD the green crossbleed-valve symbol is shown in the open position.
R **ON A/C 106-149, 211-299, 301-399, 401-499,
B. Crossbleed System
R **ON A/C 106-149, 211-299, 401-499,
(Ref. Fig. 012)
**ON A/C 301-399,
(Ref. Fig. 012A)
R **ON A/C 106-149, 211-299, 301-399, 401-499,
(Ref. Fig. 014) A crossbleed valve is installed in the crossbleed duct in the unpressurized area. The crossbleed valve is equipped with two electrical motors which can both actuate the butterfly plate in the opening or closing positions. One motor is used in the automatic mode, the other in the manual mode. Each motor includes a 'brake system' which locks the butterfly in position if the electrical power supply is cut off.
(1) Automatic Control The crossbleed valve selector-switch 3HV is usually in the AUTO position. In this position the coil of the crossbleed-valve auto-control relay 4HV is connected to the normal bus 206PP. When you push the APU BLEED pushbutton-switch 5HV to the ON position the BMCs send a ground signal to the crossbleed-valve auto-control relay 4HV if:
-the APU bleed control valve is in the fully open position,
-there is no leak warning (the leak warning will be ignored during
the main engine start). The crossbleed-valve auto-control relay 4HV supplies electrical power to the crossbleed valve motor 1 and the crossbleed valve opens.
On the BLEED page of the SD the green crossbleed-valve symbol is shown in the open position. The crossbleed relay 7HV monitors the crossbleed valve in the fully open position to prevent a complete pack shut down in flight due to a wrong EIU - signal, if the crossbleed valve is in the closed position, only one pack instead of both closes.
**ON A/C 001-049, 051-099, 101-105, 151-199, 201-210,
Post SB 21-1121 For A/C 001-049,051-060,101-102,
B. Crossbleed System (Ref. Fig. 012, 014) A crossbleed valve is installed in the crossbleed duct in the unpressurized area. The crossbleed valve is equipped with two electrical motors which can both actuate the butterfly plate in the opening or closing positions. One motor is used in the automatic mode, the other in the manual mode. Each motor includes a 'brake system' which locks the butterfly in position if the electrical power supply is cut off.
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