(a)
In case the ECB receives an 'APU EMERGENCY STOP'-command for a minimum of 50ms, the following sequence occurs:
-the ECB 59KD shuts down the APU immediately (no cool-down cycle),
-when the APU speed has decreased to below 7%, the ECB 59KD transmits a 'FLAP CLOSE'-command to the air intake flap actuator,
-the air intake flap actuator moves the flap into the 'CLOSE'-position within approximately 20s.
-when the air intake flap actuator reaches its end position 'extended' (flap in 'CLOSED'-position), a 'FLAP CLOSED'-signal is transmitted back to the ECB 59KD.
(b)
After the MASTER SW has been set to the 'off'-position, the following sequence occurs:
-the APU main relay 4KD is de-energized,
-electrical power is disconnected from the ECB.
(3)
Air Intake Flap Does Not Fully Open (Class 1 Fault)
(a) If the ECB 59KD Build-In Test Equipment (BITE) completes the Power Up Test (PUT) and does not receive a 'FLAP OPEN'-signal within 30 seconds of transmitting the 'OPEN FLAP'-command, the following procedure occurs:
-
the ECB interrupts the APU start procedure,
-
the ECB transmits a 'FLAP CLOSE'-command to the air intake flap actuator,
APU Air Intake - Electrical Schematic
Figure 002 (SHEET 1)
CES
APU Air Intake - Electrical Schematic
Figure 002 (SHEET 2)
CES
-the air intake flap actuator moves the flap into the 'CLOSED'-position within approximately 20s,
-when the air intake flap actuator reaches its end position 'extended' (flap in 'CLOSED'-position), a 'FLAP CLOSED'-signal is transmitted back to the ECB 59KD.
(b) After the MASTER SW has been set to the 'off'-position, the following sequence occurs:
-the APU main relay 4KD is de-energized,
-electrical power is disconnected from the ECB.
C. Built-In Test Equipment (BITE) of the ECB 59KD
(1)
The BITE of the ECB automatically monitors the APU and the APU system control and isolates any component malfunctions. The ECB will shutdown the APU when:
-
the air intake flap actuator does not supply a 'FLAP OPEN'-signal to the ECB. This will occur only when a signal has not been received for 0.5s and the APU speed is more than 7%,
-
the air intake flap does not open within 30s of driver start by the ECB 59KD,
-
the air intake flap does not close within 30 s after driver start by the ECB,
-electrical power disconnected from the APU.
(2)
When the APU is in operation and the BITE detects a malfunction, the following sequence occurs:
-
the ECB will shut the APU immediately down (no cool-down cycle),
-
the amber FAULT legend in the MASTER SW comes on and stays on,
-a caution
'APU AUTO SHUT DOWN
-MASTER SW ...................... OFF
is shown on the lower part of the ECAM upper display unit (Ref.
49-70-00).
(3)
When the MASTER SW is set to the 'off'-position, the following
sequence of operation occurs:
-
the amber FAULT legend in the MASTER SW goes off,
-
the ECB transmits a 'FLAP CLOSE'-command to the air intake flap actuator,
-
the air intake flap actuator operates to close the air intake flap within 20s.
-when the air intake flap actuator reaches its end position 'extended' (flap in 'CLOSED'-position), a 'FLAP CLOSED'-signal is transmitted back to the ECB.
-the APU MAIN relay de-energizes,
-electrical power is disconnected from the ECB.
D. Indications (Ref. 49-70-00)
(1)
If the air intake flap does not move to the fully open position within 30s, a Class 1 Fault will occur. APU AUTO SHUT DOWN occurs and the subsequent indications are given:
(a)
a continuous amber FAULT legend in the MASTER SW.
(b)
Glareshield panel 131VU (130VU) MASTER CAUT annunciator lights:
-steady amber MASTER CAUT annunciator lights,
-single chime.
(c)
On the ECAM upper display unit:
-an amber caution 'APU AUTO SHUT DOWN - MASTER SW OFF' shows on the lower part of the Engine/Warning page,
-INOP SYS - APU is shown on the ECAM status page,
-no APU AVAIL indication is given on the ECAM lower display unit.
(2)
When an APU EMERGENCY SHUT DOWN occurs on the ground (because an APU EMERGENCY STOP ground signal has been received by the ECB 59KD), indications are given on:
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