INDICATING - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General

ECAM Display Units ** ON A/C NOT FOR ALL

The indicating system monitors the APU speed and the Exhaust Gas Temperature (EGT).
You can also see on the Multipurpose Control & Display Unit (MCDU) the unservicable LRUs and test results for the APU system.

** ON A/C NOT FOR ALL

2. System Description

ECAM Display Units ** ON A/C NOT FOR ALL

A. Power Indicating
The power indicating system monitors the APU speed in revolutions per minute (rpm). Two speed sensors transmit a signal to the ECB 59KD. The ECB 59KD gives a speed signal to the Electronic Instrument System (EIS). The EIS shows the APU speed in percent on the APU system page at the lower ECAM display unit.

B. Temperature Indicating
The temperature indicating system monitors the APU Exhaust Gas Temperature (EGT). Two rakes, each with two thermocouples, transmit a signal to the ECB 59KD. The ECB 59KD gives a EGT signal to the Electronic Instrument System (EIS). The EIS shows on the APU page at the lower ECAM display unit the APU EGT in DEG. C.

C. Built-In Test Equipment (BITE)
The Electronic Control Box (ECB) 59KD has a Built-In Test Equipment (BITE) task. This is a function which provides fault detection, component protection, fault information and repair verification for the APU and the ECB itself.
The ECB performs th BITE task in three routines:

the Power Up Test (PUT),
the In Operation Test (IOT),
the Self Test (SET).

The ECB transmits the data to the Centralized Fault Display-System (CFDS) (Ref. 31-30-00), if selected on the Multipurpose Control and Display Units (MCDUs) which are the interface for selection and indication of the data.

D. APU Life Data
You can also select the APU life data on the MCDUs for indication. The APU life data are:

the APU Serial Number,
the APU Operating Hours,
the APU Cycles.

The APU life data are stored in the ECB and the DMU (Ref. AMM D/O 31-00-00-00). The APU serial number is hardwired in the encoder, which is installed on the APU.

** ON A/C NOT FOR ALL

3. Operation/Control and Indicating

ECAM Display Units ** ON A/C NOT FOR ALL

A. System Display
During usual operation, the APU system page is shown on the lower ECAM display unit in one of these modes:

the manual mode,
the flight phase related mode,
the advisory automatic mode,
the failure related automatic mode.

(1) Manual Mode
In the manual mode, operation of the APU button (on the ECAM control panel 11VU on the pedestal) shows the APU system page on the lower ECAM display unit.

(2) Flight Phase Related Mode
The flight phase related mode operates, when the other modes are not set. The ECAM system shows the system page related to the applicable flight phase the aircraft is in.
The APU system page is shown when these conditions are applicable:

the aircraft is in the flight phase 1 or phase 2,
the MASTER SW 14KD is set to the ON position.

The APU system page will stay on unless it is cancelled by another mode until:

the APU speed is more than 95 % for 15 s.
the MASTER SW 14KD is set to OFF.

(3) Advisory Automatic Mode
The advisory automatic mode operates when one of the following conditions occurs:

the APU operates and the EGT is less than 60 DEG. C (140 DEG. F) from the overtemperature schedule,
a LOW OIL LEVEL is detected,
the air intake flap is not fully closed within 3 minutes of the MASTER SW selection to the OFF position.

The related indication flashes for as long as the condition exists.

(4) Failure Related Automatic Mode
The failure related automatic mode, automatically shows the system page, when the operation limit is at a warning level. It also gives a warning message on the ECAM (upper display unit) engine/warning page.

B. Indications of Operating Parameters
The operating parameters of the APU are shown on the APU system display page of the ECAM. The parameters shown are:

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FUNCTION TYPICAL TEXT DISPLAY TYPE

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1. Title APU Text

2. APU available AVAIL Text

3. Bleed Valve Position open/closed Graphics

4. Bleed Pressure BLEED 35 psi Digital Readout

5. Exhaust Gas Temperature 557 DEG. C Analog Display and

Digital Readout

6. APU Speed 100 % Analog Display and

Digital Readout

7. Generator Frequency 400 Hz Digital Readout

8. Generator Voltage 115 V Digital Readout

9. Generator Load 26 % Digital Readout

C. Status Display
The status display of the APU system is shown on the ECAM (lower display unit) status page. It tells the flight crew the status of the APU system.
The status page is set automatically or manually.

(1) Automatic Status Display
The status page is set automatically immediately after a correction procedure is done. The warning is also cleared on the engine/warning page (upper display unit) of the ECAM.

(2) Manual Status Display
When the STATUS (STS) button on the ECAM control panel 11VU is operated, the status page is shown.

D. Warning and Caution

(1) Warning Messages
The warning messages are shown on the ECAM (upper display unit - lower third area). At the same time the related system page is shown on the lower ECAM display unit. The warning message includes:

the system failure,
a correction procedure instruction,
possible limits to the system.

If there are no system failures, memo messages replace the warning messages. The memo message shows the flight crew which functions and systems are in temporary use.

(2) Master Warning and Caution

(a) A MASTER WARN and a MASTER CAUT, annunciator lights (attention getters), are installed on panel 130 VU (right glareshield) and on panel 131 VU (left glareshield). They come on, to give the flight crew a visual indication, that a failure (related to a warning or a caution) has occured.

(b) An APU fire, will cause the red MASTER WARN annunciator lights to come on (flash), together with a 'repetitive chime' (aural warning).
An APU system failure, will cause the amber MASTER CAUT annunciator lights to come on (flash), together with a 'single chime' (aural warning).

(3) Correction Procedure

(a) When you operate one of the two MASTER WARN pushbutton switches (with the MASTER WARN annunciator lights on):

both the MASTER WARN annunciator lights go off,
the 'repetitive chime' (aural warning) stops.

(b) When you operate one of the two MASTER CAUT pushbutton switches (with the MASTER CAUT annunciator lights on):

both the MASTER CAUT annunciator lights go off.

the warning message on the upper ECAM display unit goes off,
the APU system status page shows on the lower ECAM display unit.

[Rev.10 from 2021] 2026.04.01 01:31:54 UTC