CONTROL AND MONITORING - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
A Full Authority Digital Electronic Control system is contained in the ECB 59KD.
The ECB 59KD provides control for the operation and monitoring of the Auxiliary Power Unit (APU). It also provides the communication to the aircrafts other systems.
The ECB gives:

the control for the automatic operation of the APU,
the control for the APU at a constant speed,
the protection of the APU if a failure or an overload occurs,
the supply of pneumatic and shaft power,
the monitoring of the Line Replaceable Units (LRUs),
the tests on the APU system.

** ON A/C NOT FOR ALL

2. Component Location

Control and Monitoring - Component Location ** ON A/C NOT FOR ALL

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
4KD	RELAY-APU MAIN CTL	107VU	126	49-61-00
6KD	RELAY-APU AVAIL	103VU	126	49-61-00
14KD	P/BSW-APU/MASTER SW	25VU	210	49-61-00
59KD	ELECTRONIC CONTROL BOX		152	49-61-34

** ON A/C NOT FOR ALL

3. System Description

A. ECB

(1) The ECB is installed adjacent to the BULK cargo compartment on the right side, between FR58 and FR59. It is held in an ARINC 600-6 mounting rack.
The ECB provides full authority digital APU control from the start initialization, during the acceleration, at the governor speed to the shutdown. The ECB monitors the APU speed, the APU temperatures, the load compressor air flow, and other critical parameters based on signal inputs from the accessory sensors and the control switches. These data are used for the calculation and to continuously control:

the fuel flow,
the IGV position,
the bleed control valve position.

The ECB also controls the subsequent systems:

the starter motor,
the igniters,
the fuel control shutoff valve,
the air intake flap.

The ECB communicates with the aircraft systems through the ARINC 429 busses.
The subsequent LRUs are controlled by separate torque motor currents:

the fuel control assembly,
the IGV actuator,
the bleed control valve.

** ON A/C NOT FOR ALL

4. Power Supply

ECB Supply - Schematic ** ON A/C NOT FOR ALL

The battery bus 301PP supplies 28VDC to the ECB 59KD through the circuit breaker ECB SPLY 1KD and the relay APU MAIN 4KD. The 28VDC supply for the APU MAIN relay is through the circuit breaker APU CTL 2KD. The ECB continuously monitors its internal voltages and starts an APU shutdown if a voltage failure occurs (that would result in an unsafe operation of the APU).
The aircraft power supply allows the ECB 59KD to continue to control the APU during short power interruptions on the battery busbar 301PP. It will do this when the APU speed is more than 95 %.
The PMG supply installed in the cooling fan (Ref. AMM D/O 49-52-00-00) allows the ECB 59KD to continue to control the APU during short power interruptions on the battery busbar 301PP. It will do this when the APU speed is more than 70%.

** ON A/C NOT FOR ALL

5. Interface

A. Aircraft (A/C) Input Signals to the ECB 59KD

------------------------------------------------------------------------

INPUT SIGNAL SIGNAL

------------------------------------------------------------------------

Master Switch/Stop Ground

Start 28 V DC

Environmental Control System (ECS) ARINC 429 BUS

Main Engine Start (MES) 28 V DC

Emergency Shutdown Ground

Bleed Control Valve Operation Ground

Air/ground Signal Ground for ground

condition

A/C Parameter and Centralized Fault ARINC 429 BUS

Display System (CFDS)

Start Contactor Monitor Signal Open/28 V/ground

TSO/JAR Configuration Open/Ground

for TSO Configuration

A320/A321 PIN A320 Open/A321 Closed

Air Intake Actuator BITE Signals 2 x 28 V DC

APU Fuel LP Valve Open/Ground for enabled

(1) A/C Sensors connected to the ECB 59KD:

low fuel pressure switch 5030 QM,
generator oil-temperature sensor,
air-intake position switches.

B. ECB 59KD Output Signals to the A/C

--------------------------------------------------------------------

LOAD

OUTPUT SIGNAL SIGNAL STEADY CONDITION

STATE

--------------------------------------------------------------------

APU AVAILABLE 28 V DC 150 mA

Start Contactor 28 V DC 1 A

Back-Up Start Contactor 28 V DC 1 A

APU Fault 28 V DC 50 mA

Start in Progress 28 V DC 50 mA

Bleed Control Valve 28 V DC 10 mA (Ref. 49-51-51)

(open position)

APU Main Relay Ground 100 mA

Air Intake Actuator 28 V DC 1.6 A (Ref. 49-16-51)

(open CMD)

Air Intake Actuator 28 V DC 1.6 A (Ref. 49-16-51)

(close CMD)

APU Fuel LP Valve 28 V DC 200 mA (Ref. 26-22-00)

APU System Bus ARINC 429

(1) ECB 59KD Output Signals to APU loads:

fuel solenoid,
fuel servo valve,
ignition unit driver,
inlet guide vanes servo valve,
de-oil solenoid,
bleed control valve servo valve,
oil level RTD,
pressure transducer excitation,
IGV and bleed control valve LVDT,
oil filter and LOP switches.

(2) APU Input Signals to the ECB 59KD:

EGT (T5) chromel-alumel thermocouples (redundant),
monopole transducer (APU speed) (redundant),
oil temperature sensor,
low-oil pressure switch,
load-compressor inlet temperature sensor,
load-compressor discharge temperature sensor,
inlet pressure transducer (P2),
load-compressor delta pressure transducer (DELTA P),
load-compressor discharge static pressure-transducer (PT),
inlet-guide vane actuator-position (LVDT),
starter voltage sensor,
oil filter bypass switch,
engine ID module
bleed control valve position LVDT,
redundant speed from PMG,
oil level sensor,
PMG power supply.

C. Explanations to the Parameter List
The parameter list is organized according to the connected ARINC 429 data buses.
The connected systems (e.g. FAC, ECU, EEC, etc.) and the corresponding ATA chapter numbers are stated in the header on the left side of each page of the parameter lists.
The columns are described as follows:

---------------------------------------------------------------

Column ! Description

---------------!-----------------------------------------------

1st ! EQ.SYS.LAB.SDI = Parameter number

SYS.LAB.SDI !

! System number: According to the system which is

! sending out the corresponding parameter:

! 1 for system one

! 2 for system two

! 3 for system three

! Label of the parameter, octal value

! according to ARINC 429.

! SDI states the Source/Destination Identifier

! which is used by the system for the

! corresponding parameter:

! 00 means SDI 00 (0)

! 01 means SDI 01 (1)

! 10 means SDI 10 (2)

! 11 means SDI 11 (3)

---------------!------------------------------------------------

2nd ! PARAMETER

PARAMETER ! Parameter name

---------------!------------------------------------------------

3rd ! RANGE

RANGE !

! Three different types of ranges are shown in

! this column:

! The first one, indicated by a 'W' (WORDRANGE),

! is related to the ARINC 429 data bus. This

! shows the maximum value of the parameter that

! can be transferred on the bus. This

! depends on the number of data bits (see

! column DATA BITS) and the resolution ('R') of

! the parameter (see column ACCURACY).

! The second one, with no specific indication,

! shows the normal operational range of the

! parameter.

! The third one is related to the ARINC 429

! Discrete Data Words. There are two states:

! 'bit status 0' or 'bit status 1'. They

! indicate the true condition of the

! corresponding data word bit position.

---------------!------------------------------------------------

4th ! ACCURACY

ACCURACY !

! Two different types of values are shown

! in this column:

! The first one, indicated by an 'R'

! (RESOLUTION) is related to the ARINC

! 429 data bus. It also shows the

! resolution of the data word. The second

! one, with no specific indication, shows

! the total accuracy of the parameter.

---------------!-----------------------------------------

5th ! SIGN BIT

SIGN BIT !

! This column shows whether a sign bit

! is available and in which bit position

! of the data word it is situated.

---------------!-----------------------------------------

6th ! DATA BITS

DATA BITS !

! Describes the number of data bits not

! including the sign bit. 'A' and a number

! means the discrete bit position in the

! ARINC 429 data word.

! For BCD coded data words the number of

! significant data digits is shown,

! indicated by '(1)'.

---------------!----------------------------------------------

7th ! UPD/sec

UPD/sec !

! This column shows how many times the

! parameter will be transmitted by the source

! system.

---------------!----------------------------------------------

8th ! CODE

CODE !

! BNR = binary data word

! BCD = binary coded decimal data word

! ISO = data word coded in ISO 5 Code

! DIS = discrete data word

! HEX = hexadecimal coded

! OCT = octal coded

! HYB = mixed code;

! e.g. : bit 11 to 16 DIS

! bit 17 to 28 BNR

---------------!----------------------------------------------

9th ! ALPHA CODING

ALPHA CODING !

! This column shows the mnemonic for the

! parameter (if available). By entering

! this code via the MCDU, the current

! parameter-value will be shown on the

! display. The value from both systems

! (if available) will be shown.

---------------!----------------------------------------------

10th ! This column shows the source origin, its

Source ! bus number, ATA Ref., and its label.

EQPT !

BUS NR !

ATA. REF !

CONV !

---------------!----------------------------------------------

D. ECB APU Parameter List EQPT: 7A

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

!07A.1.004.01 !Cooldown ! ! ! ! 3 !500 !BCD !PFAD ! ECB !

! !Timer !Bit 27-29 ! ! ! ! - ! ! ! !

! ! ! 0 = no ! ! ! !1000! ! ! !

! ! ! Cooldown ! ! ! !mSec! ! ! !

! ! ! 1 = 0 !Sec ! ! ! ! ! ! !

! ! ! 2 = 30 !Sec ! ! ! ! ! ! !

! ! ! 3 = 60 !Sec ! ! ! ! ! ! !

! ! ! 4 = 90 !Sec ! ! ! ! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.037.01 !APU status!Bit 11-29 ! ! ! 19 ! ! ! ! ECB !

! !----------!------------!----!----!----! ! ! !-------!

! !Bleed !bit status 1! ! ! 11 ! ! ! ! ECB !

! !Valve Open! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Bleed !bit status 2! ! ! 12 ! ! ! ! ECB !

! !Valve ! ! ! ! ! ! ! ! !

! !Closed ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Fuel Low !bit status 3! ! ! 13 ! ! ! ! ECB !

! !Pressure ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Air Intake!Always set ! ! ! 14 ! ! ! ! ECB !

! !Open !to 1 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Air Intake!bit status 1! ! ! 15 ! ! ! ! ECB !

! !Closed ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !EGT at !bit status 1! ! ! 16 ! ! ! ! ECB !

! !60 deg.F ! ! ! ! ! ! ! ! !

! !Below EGT ! ! ! ! ! ! ! ! !

! !Shutdown ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Auto !bit status 1! ! ! 17 ! ! ! ! ECB !

! !Shutdown ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Emergency !bit status 1! ! ! 18 ! ! ! ! ECB !

! !Shutdown ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !APU !bit status 1! ! ! 19 ! ! ! ! ECB !

! !Available ! ! ! ! ! ! ! ! !

! !(RTL) ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Low Oil !bit status 1! ! ! 20 ! ! ! ! ECB !

! !Level ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !MES mode !bit status 1! ! ! 21 !250 ! ! ! ECB !

! !& Bleed ! ! ! ! ! - ! ! ! !

! !Valve Open! ! ! ! !500 !DIS !ADW1 ! !

! !----------!------------!----!----!----!mSec! ! !-------!

! !APU Start !bit status 1! ! ! 22 ! ! ! ! ECB !

! !In ! ! ! ! ! ! ! ! !

! !Progress ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Class 2 !bit status 1! ! ! 23 ! ! ! ! ECB !

! !Fault ! ! ! ! ! ! ! ! !

! !Present ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Shutdown !bit status 1! ! ! 24 ! ! ! ! ECB !

! !Fault ! ! ! ! ! ! ! ! !

! !Inhibited ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !SPARE !Always set ! ! ! 25 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !One Pack !Always set ! ! ! 26 ! ! ! ! ECB !

! !Operation !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !SPARE !Always set ! ! ! 27 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !SPARE !Always set ! ! ! 28 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !SPARE !Always set ! ! ! 29 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.050.01 !APU Serial!W ! ! ! 19 !500 !BCD !ASN ! ECB !

! !Number !0 - 99999 ! - ! ! ! - ! ! ! !

! ! !R 1 ! ! ! !1000! ! ! !

! ! ! ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.110.01 !Inlet !W 128 ! ! 29 ! 7 !150 !BNR !LCIT ! ECB !

! !Temp. !-64 to +64 !deg.! ! ! - ! ! ! !

! ! !R 1 ! C ! ! !250 ! ! ! !

! ! !+/- 2.77 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.112.01 !Inlet !W 512 ! ! ! 9 !150 !BNR !P2A ! ECB !

! !pressure !0.058-14.852!psia! ! ! - ! ! ! !

! ! !R 0.058 ! ! ! !250 ! ! ! !

! ! !+/- 0.675 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.120.01 !EGT !W 2048 ! ! 29 ! 11 !250 !BNR ! ! ECB !

! !Overtemp. !1-1024 !deg.! ! ! - ! ! ! !

! !Limit !R 1 ! C ! ! !500 ! ! ! !

! ! !+/- 1 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.123.01 !Corrected !W 512 ! g/ ! ! 9 !150 !BNR !WB ! ECB !

! !bleed air !4-1024 !Sec ! ! ! - ! ! ! !

! !flow !R 4 ! ! ! !250 ! ! ! !

! ! !+/- 24g/Sec ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.130.01 !IGV !W 2048 ! ! ! 11 !150 !BNR !IGV ! ECB !

! !Position !0.043945-90 !deg.! ! ! - ! ! ! !

! ! !R 0.043945 ! ! ! !250 ! ! ! !

! ! !+/- 7% ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.131.01 !BCV !W 512 ! ! ! 9 !150 !BNR ! ! ECB !

! !Position !0.25-64 !% ! ! ! - ! ! ! !

! ! !R 0.25 ! ! ! !250 ! ! ! !

! ! !+/- 7% ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.132.01 !Operating !W 16384 ! ! ! 14 !250 !BNR !AHRI ! ECB !

! !hours !0 - 16383 ! h ! ! ! - ! ! ! !

! ! !R 1 ! ! ! !500 ! ! ! !

! ! !+/- 1 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.133.01 !Start !W 16384 ! ! ! 14 !250 !BNR !ACYI ! ECB !

! !cycles !0 - 16383 !Cy- ! ! ! - ! ! ! !

! ! !R 1 !cles! ! !500 ! ! ! !

! ! !+/- 1 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.135.01 !Operating !W 131072 ! ! ! 17 !250 !BNR ! ! ECB !

! !hours !0 - 131071 ! h ! ! ! - ! ! ! !

! ! !R 1 ! ! ! !500 ! ! ! !

! ! !+/- 1 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.136.01 !Start !W 131072 ! ! ! 17 !250 !BNR ! ! ECB !

! !cycles !0 - 131071 !Cy- ! ! ! - ! ! ! !

! ! !R 1 !cles! ! !500 ! ! ! !

! ! !+/- 1 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.144.01 !Vendor !W 2 ! ! ! 2 !500 !BNR ! ! ECB !

! !Identifier!0-3 ! - ! ! ! - ! ! ! !

! ! !R 1 ! ! ! !1000! ! ! !

! ! ! ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.145.01 !Fuel Servo!W 512 ! ! ! 9 !100 !BNR ! ! ECB !

! !Current !1-256 !mA ! ! ! - ! ! ! !

! ! !R 1 ! ! ! !200 ! ! ! !

! ! !+/- 1 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.146.01 !Spare ! ! ! ! 18 !500 ! ! ! ECB !

! !(Zeros) ! ! ! ! ! - ! ! ! !

! ! ! ! ! ! !1000! ! ! !

! ! ! ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.147.01 !Spare ! ! ! ! 19 !500 ! ! ! ECB !

! !(Zeros) ! ! ! ! ! - ! ! ! !

! ! ! ! ! ! !1000! ! ! !

! ! ! ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.165.01 !delta !W 512 ! ! ! 9 !150 !BNR ! ! ECB !

! !Pressure !0.07812-20 !psid! ! ! - ! ! ! !

! ! !R 0.07812 ! ! ! !200 ! ! ! !

! ! !+/- 0.875 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.166.01 !Bleed !W 1024 ! ! ! 10 !150 !BNR ! PT ! ECB !

! !pressure !0.116-59.408!psia! ! ! - ! ! ! !

! ! !R 0.116 ! ! ! !250 ! ! ! !

! ! !+/- 3.5 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.175.01 !EGT !W +/- 2048 ! ! 29 ! 11 !100 !BNR ! EGTA! ECB !

! ! !1-1024 ! ! ! ! - ! ! ! !

! ! !R 1 ! ! ! !200 ! ! ! !

! ! !EGT>215deg.C!deg.! ! !mSec! ! ! !

! ! !+/- 1.4% ! C ! ! ! ! ! ! !

! ! !EGT<215deg.C! ! ! ! ! ! ! !

! ! !+/- 3deg.C ! ! ! ! ! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.176.01 !RPM !W 256 ! ! ! 9 !100 !BNR ! NA ! ECB !

! ! !0.5-128% !rpm ! ! ! - ! ! ! !

! ! !R +/- 0.5% ! ! ! !200 ! ! ! !

! ! !+/- 0.5 % ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.246.01 !Generator !W 256 ! ! 29 ! 8 !250 !BNR ! ! ECB !

! !oil !-128 to 128 !deg.! ! ! - ! ! ! !

! !Temp. !R 1 ! C ! ! !500 ! ! ! !

! ! !+/- 2.77 ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.247.01 !Oil Sump !W 256 ! ! 29 ! 8 !250 !BNR ! OTA ! ECB !

! !Temp. !-128 to 128 !deg.! ! ! - ! ! ! !

! ! !R 1 ! C ! ! !500 ! ! ! !

! ! !+/- 2.77 ! ! ! !mSec! ! ! !

!-----------------------------------------------------------------------------!

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

!07A.1.351.01 !LRU Fault !Bits 11-29 ! ! ! 19 ! ! ! ! ECB !

! !#1 ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !LCD !bit status: ! ! ! 11 ! ! ! ! ECB !

! !Pstatic !1= failed ! ! ! ! ! ! ! !

! !Sensor !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !LCD !bit status: ! ! ! 12 ! ! ! ! ECB !

! !Delta P !1= failed ! ! ! ! ! ! ! !

! !Sensor !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Sensor !bit status: ! ! ! 13 ! ! ! ! ECB !

! !Speed #1 !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Sensor !bit status: ! ! ! 14 ! ! ! ! ECB !

! !Speed #2 !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Not Used !Always set ! ! ! 15 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !GBX oil !bit status: ! ! ! 16 ! ! ! ! ECB !

! !Temp RTD !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Fuel !bit status: ! ! ! 17 ! ! ! ! ECB !

! !Servo !1= failed ! ! ! ! ! ! ! !

! !Valve !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Bleed !bit status: ! ! ! 18 ! ! ! ! ECB !

! !Control !1= failed ! ! ! ! ! ! ! !

! !Valve !0= OK ! ! ! ! ! ! ! !

! !Servo ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !EGT !bit status: ! ! ! 19 ! ! ! ! ECB !

! !sensor #1 !1= failed ! ! ! !500 ! ! ! !

! ! !0= OK ! ! ! ! - !DIS ! ! !

! !----------!------------!----!----!----!1000! ! !-------!

! !EGT !bit status: ! ! ! 20 !mSec! ! ! ECB !

! !sensor #2 !1= failed ! ! ! ! ! ! ! !

! ! !2= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !IGV !bit status: ! ! ! 21 ! ! ! ! ECB !

! !Actuator !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Ignition !bit status: ! ! ! 22 ! ! ! ! ECB !

! !unit/ !1= failed ! ! ! ! ! ! ! !

! !exciter !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !GBX !bit status: ! ! ! 23 ! ! ! ! ECB !

! !De-oiling !1= failed ! ! ! ! ! ! ! !

! !Valve !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Gen. oil !bit status: ! ! ! 24 ! ! ! ! ECB !

! !temp !1= failed ! ! ! ! ! ! ! !

! !RDT !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !ECS demand!bit status: ! ! ! 25 ! ! ! ! ECB !

! !signal !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Not Used !Always set ! ! ! 26 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !LOP !bit status: ! ! ! 27 ! ! ! ! ECB !

! !switch !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !P2 sensor !bit status: ! ! ! 28 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !ECB !bit status: ! ! ! 29 ! ! ! ! !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.352.01 !LRU Fault !Bits 11-29 ! ! ! 19 ! ! ! ! ECB !

! !#2 ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Low oil !bit status: ! ! ! 11 ! ! ! ! ECB !

! !level !1= failed ! ! ! ! ! ! ! !

! !sensor !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! ! Spare !bit status: ! ! ! 12 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! ! Spare !bit status: ! ! ! 13 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !LCIT !bit status: ! ! ! 14 ! ! ! ! ECB !

! !sensor !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Main fuel !bit status: ! ! ! 15 ! ! ! ! ECB !

! !valve !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Main start!bit status: ! ! ! 16 ! ! ! ! ECB !

! !contactor !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Back-up !bit status: ! ! ! 17 ! ! ! ! ECB !

! !start !1= failed ! ! ! ! ! ! ! !

! !contactor !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !APU S/N !bit status: ! ! ! 18 ! ! ! ! ECB !

! !encoder !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Aircraft !bit status: ! ! ! 19 !500 ! ! ! ECB !

! !ID pin !1= failed ! ! ! ! - !DIS ! ! !

! !coding !0 = OK ! ! ! !1000! ! ! !

! !----------!------------!----!----!----!mSec! ! !-------!

! !Air intake!bit status: ! ! ! 20 ! ! ! ! ECB !

! !actuator !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !BCV LVDT !bit status: ! ! ! 21 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !IGV LVDT !bit status: ! ! ! 22 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Air intake!bit status: ! ! ! 23 ! ! ! ! ECB !

! !actuator !1= failed ! ! ! ! ! ! ! !

! !switches !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !10V press.!bit status: ! ! ! 24 ! ! ! ! ECB !

! !pressure !1= failed ! ! ! ! ! ! ! !

! !reference !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Oil !bit status: ! ! ! 25 ! ! ! ! ECB !

! !scavenge !1= failed ! ! ! ! ! ! ! !

! !and lube !0= OK ! ! ! ! ! ! ! !

! !filter ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !bit status: ! ! ! 26 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !bit status: ! ! ! 27 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !bit status: ! ! ! 28 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !bit status: ! ! ! 29 ! ! ! ! ECB !

! ! !1= failed ! ! ! ! ! ! ! !

! ! !0= OK ! ! ! ! ! ! ! !

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

!07A.1.353.01 !LRU Fault !Bits 11-29 ! ! ! 19 ! ! ! ! ECB !

! !#3 ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !No flame !bit status 1! ! ! 11 ! ! ! ! ECB !

! !----------!------------!----!----!----! ! ! !-------!

! !Surge/ !bit status 1! ! ! 12 ! ! ! ! ECB !

! !Reverse ! ! ! ! ! ! ! ! !

! !Flow ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Loss DC !Always set ! ! ! 13 ! ! ! ! ECB !

! !power !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !High oil !bit status 1! ! ! 14 ! ! ! ! ECB !

! !tempera- ! ! ! ! ! ! ! ! !

! !ture ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 15 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 16 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Air intake!bit status 1! ! ! 17 ! ! ! ! ECB !

! !actuator ! ! ! ! ! ! ! ! !

! !failure ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !High gen. !bit status 1! ! ! 18 ! ! ! ! ECB !

! !oil tempe-! ! ! ! ! ! ! ! !

! !rature ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !True !bit status 1! ! ! 19 !250 ! ! ! ECB !

! !emergency ! ! ! ! ! - !DIS ! ! !

! !stop ! ! ! ! !500 ! ! ! !

! !----------!------------!----!----!----!mSec! ! !-------!

! !Overtempe-!bit status 1! ! ! 20 ! ! ! ! ECB !

! !rature ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Sensor !bit status 1! ! ! 21 ! ! ! ! ECB !

! !failure ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !No accele-!bit status 1! ! ! 22 ! ! ! ! ECB !

! !ration ! ! ! ! ! ! ! ! !

! !underspeed! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Start time!Always set ! ! ! 23 ! ! ! ! ECB !

! !exceeded !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Overspeed !bit status 1! ! ! 24 ! ! ! ! ECB !

! !----------!------------!----!----!----! ! ! !-------!

! !ECB !bit status 1! ! ! 25 ! ! ! ! ECB !

! !failure ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Low oil !bit status 1! ! ! 26 ! ! ! ! ECB !

! !pressure ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Loss of !bit status 1! ! ! 27 ! ! ! ! ECB !

! !speed ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Not Used !Always set ! ! ! 28 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 29 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.356.01 !CFDS fault!Bits 9-31 ! ! ! 23 !50 !ISO ! ! !

! !transmis- ! ! ! ! ! - ! ! ! !

! !sion word ! ! ! ! !250 ! ! ! !

! ! ! ! ! ! !mSec! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

!07A.1.274.01 !ECB Input !Bits 11-29 ! ! ! 19 ! ! ! ! ECB !

! !check ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Bleed !bit status 1! ! ! 11 ! ! ! ! ECB !

! !activated ! ! ! ! ! ! ! ! !

! !signal ! ! ! ! ! ! ! ! !

! !received ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 12 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Start !bit status 1! ! ! 13 ! ! ! ! ECB !

! !contact !when active ! ! ! ! ! ! ! !

! !monitor ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Inlet flap!bit status 1! ! ! 14 ! ! ! ! ECB !

! !actuator !when ! ! ! ! ! ! ! !

! !movement !movement ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 15 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Air/ground!bit status: ! ! ! 16 ! ! ! ! ECB !

! ! !1= Ground ! ! ! ! ! ! ! !

! ! !0= Air ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !A320/A321 !bit status: ! ! ! 17 ! ! ! ! ECB !

! !ID #1 !1= A321 ! ! ! ! ! ! ! !

! ! !0= A320 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !A320/A321 !bit status: ! ! ! 18 ! ! ! ! ECB !

! !ID #2 !1= A321 ! ! ! ! ! ! ! !

! ! !0= A320 ! ! ! !500 ! ! ! !

! !----------!------------!----!----!----! - !DIS ! !-------!

! !Starter !bit status: ! ! ! 19 !1000! ! ! ECB !

! !motor !1= A321 ! ! ! !mSec! ! ! !

! !voltage !0= A320 ! ! ! ! ! ! ! !

! !<5 VDC ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !MES signal!bit status 1! ! ! 20 ! ! ! ! ECB !

! !received ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Inlet flap!bit status 1! ! ! 21 ! ! ! ! ECB !

! !actuator ! ! ! ! ! ! ! ! !

! !is open ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Inlet flap!bit status 1! ! ! 22 ! ! ! ! ECB !

! !actuator ! ! ! ! ! ! ! ! !

! !is closed ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !APU Stop !bit status 1! ! ! 23 ! ! ! ! ECB !

! !Master ! ! ! ! ! ! ! ! !

! !switch off! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Emergency !bit status 1! ! ! 24 ! ! ! ! ECB !

! !stop ! ! ! ! ! ! ! ! !

! !received ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !START !bit status 1! ! ! 25 ! ! ! ! ECB !

! !switch ! ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 26 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 27 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 28 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

! !----------!------------!----!----!----! ! ! !-------!

! !Spare !Always set ! ! ! 29 ! ! ! ! ECB !

! ! !to 0 ! ! ! ! ! ! ! !

!-----------------------------------------------------------------------------!

E. Alpha Call-Up List

-------------------------------------------------------------------------------

ALPHA PARAMETER NAME UNIT

CALL-UP NUMBER

-------------------------------------------------------------------------------

PFAD 7A.1.004.01 Cooldown timer Sec

ADW1 7A.1.037.01 APU Status

ASN 7A.1.050.01 APU Serial Number

LCIT 7A.1.110.01 Load Compressor Inlet deg. C

P2A 7A.1.112.01 Inlet Pressure bar

7A.1.120.01 EGT limit deg. C

WB 7A.1.123.01 Bleed Air Flow Kg/sec

IGV 7A.1.130.01 IGV Position deg.

7A.1.131.01 Flow diverter current feedback A

AHRI 7A.1.132.01 Operating Hours (APU) hr

ACYI 7A.1.133.01 Start Cycles (APU) cycles

AHRI 7A.1.135.01 Operating Hours (APU) hr

ACYI 7A.1.136.01 Start Cycles (APU) cycles

7A.1.144.01 Vendor ID

7A.1.145.01 Fuel Servo Current Feedback A

7A.1.165.01 Delta Pressure bar

PT 7A.1.166.01 Bleed Air Pressure bar

EGTA 7A.1.175.01 EGT (APU) deg. C

NA 7A.1.176.01 RPM APU % rpm

7A.1.246.01 Generator Oil Temperature deg. C

OTA 7A.1.247.01 APU Oil Sump Temp. deg. C

7A.1.274.01 ECB input Check

7A.1.351.01 LRU Fault 1

7A.1.352.01 LRU Fault 2

7A.1.353.01 LRU Fault 3

7A.1.356.01 CFDS Fault Transmission Word

** ON A/C NOT FOR ALL

6. Component Description

A. Electronic Control Box (ECB) FIN: 59-KD

APU Control - Schematic ** ON A/C NOT FOR ALL

(1) The ECB 59KD is a microprocessor-based digital control-system. The Intel 80C186 Central Processing Unit (CPU) processes the program data kept in an Erasable Programmable Read Only Memory (EPROM) mounted in an OBRM. The program gives the control and internal tests of the system. A Random Access Memory (RAM) keeps:

the results of temporary calculations (such as fuel schedules and speed rate commands) that change continuously,
the operational and test status flags,
the software computational temporary data.

The 80C186 CPU also transmits data through the ARINC 429 Bus of the ECB and the RS232 interface.

(2) The ECB 59KD is a fully digital electronic controller that does the primary part of the APU system logic. The ECB will do this for all modes of engine operation. These include self-tests, protective shutdowns and continuous monitoring of these APU functions:

(a) Start Sequence,

(b) Start,

(d) Operation Temperature - EGT,

(e) Shutdown Sequence,

(f) Automatic Shutdown,

(g) Bleed Air.

B. Speed Control

(1) There are three consecutive programmes used to supply and meter the fuel during starting.

Manifold Fill Algorithm,
Open Loop Control,
Acceleration Close Control Loop.

(a) Manifold Fill Algorithm - General
During engine start up, the ECB controls the output of the fuel servo-valve to implement the manifold fill algorithm. The control is an open loop schedule based on the rotation speed and which ends when a given quantity of fuel is delivered to the manifold.

(b) Open Loop Fuel Control - General
This fuel programme replaces the manifold fill algorithm when the flow delivered has reached either 0.02 or 0.032lbm, depending on condition. It is a programme based on ambient pressure and temperature. It can be considered as the basic fuel flow needed to obtain the correct ignition in the combustion chamber.

(c) Acceleration Closed Control Loop - General
This control loop takes place from N greater than 15% and DELTA EGT greater than 166 deg. C until N = 95%.
This programme gives a rapid acceleration of the engine during start and avoids overtemperature and surge. The programme determines a flow rate against acceleration and EGT limit.

(2) Starting State - Fuel Control

(a) Manifold Fill Algorithm - Operation
The flow rate is made proportional to a single engine parameter (fuel flow in pph function of speed).

(b) Open Loop Fuel Control - Operation
The flow rate is a first function of the rotation speed and then it is affected by a correction factor. The correction factor is a function of the inlet pressure and temperature parameters.

the actual acceleration is checked against the acceleration set point to determine a first fuel flow datum.
the actual EGT is checked against an EGT reference value (value function of the speed N) so as to determine another fuel flow datum.
the system selects automatically the lowest of the two fuel flow datums calculated (datum LEAST selector).
the selected fuel flow datum is then checked against the minimum and maximum flow rates. The minimum and maximum flow values are determined automatically as a function of the inlet pressure and temperature and speed.
the digital value of the calculated fuel flow datum is then transformed into an analog intensity signal (D/A function).

(d) Speed Control Loop - Operation
The fuel flow is metered as follows:

The actual speed is checked against a speed set point (100%) so as to calculate a fuel flow datum
The fuel flow datum is then checked against fuel limits (min. and max.) which vary according to the inlet pressure and temperature parameters
Finally, the digital calculated fuel flow is changed into an analog intensity signal to supply the fuel metering servo valve.

C. IGV Control

(1) The ECB 59KD implements a current signal (ISV) in relation to the EGT and to other parameters such as Aircraft Type, MES or ECS, pressure and temperature parameters (OAT, OAP). This current signal is sent to the servo-valve which causes the angular displacement of the spill valve that controls the leak rate of the potentiometric jet.
The servo-valve then delivers to the actuator a modulated fuel pressure in relation to the ISV signal. The actuator spool valve is subjected on one side to the modulated fuel pressure and on the other side to the normal fuel pressure.
When the modulated fuel pressure varies, it creates a difference of pressure between the two sides of the spool valve that moves and drives the actuator piston. The linear voltage differential transducer sends the spool valve position signal to the ECB to control the operation of the actuator.
The piston displacement causes the displacement of the arm of the rack and pinion system which rotates. This rotation causes the rotation of the IGVs through their sector gears.
The load compressor then supplies compressed air to the aircraft pneumatic system or passes it to the exhaust system dependant on the cockpit selection and operating conditions.
The position of the actuator is fed back to the ECB by a Linear Voltage Differential Transformer (LVDT) located inside the spool valve.

(2) APU Starting
During APU start the IGVs are closed to reduce the load on the compressor.

(a) In Flight Operation
During flight operation, the opening or closing of the IGVs depends on the system demands. If the EGT exceeds the limits the IGVs automatically move towards the closed position to reduce the load on the compressor. IGV control failure will automatically move the IGVs to the closed position.

(b) The relationship between % actuator position and guide vane angle is as below where 100% means fully open:

Actuator Position % IGV Angle (degrees)
00.0 82
22.9 60
43.7 40
64.6 20
85.4 00
95.8 -10
100.0 -14

D. Surge Control
The ECB 59KD controls the Bleed Control Valve (BCV) (8051KM) to prevent surge of the APU load compressor. The valve is of the butterfly type and has a compressed air inlet and two exits, one to exhaust,the other to the aircraft system. The flap diverts the air to the aircraft system when open and exhaust when closed.
The ECB receives electrical signals from sensors through transducers from delta P and static pressure (Ps) at the discharge of the load compressor.
The pressure sensors are assembled as one unit and are mounted on the air inlet plenum. Should delta P and static pressure fall below a defined value, the bleed control valve will start to close to prevent surge. If surge or reverse flow occurs, the ECB will command the bleed valve to close. If the surge continues and the BCV cannot be closed, the ECB will initiate APU shutdown. Failure of the transducers or the analog/digital converters will cause the ECB to close the valve and allow the compressed air to discharge to exhaust.

E. De-Oil Logic
De-oiling is done independent of the oil temperature at each shutdown commencing at 90% speed. When both speed sensors (8060KM1) and (8060KM2) have failed, the de-oil valve is energized 2 seconds after the fuel solenoid is de-energized.
De-oiling is performed at each start commencing 1.5 seconds after the back-up start contactor is energized until 55% speed is reached.

F. Protective Shutdowns

(1) An APU shutdown may be due to the following conditions.

(a) Overspeed
An overspeed shutdown occurs when the speed is more than 105%. The speed is detected by two electromagnetic sensors located on the reduction gearbox casing and in front of a common target gear.
To provide full redundancy for overspeed protection, one phase of the PMG is used to check the speed. When the speed reaches more than 107% the fuel solenoid is de-energized.
In case of detection of a speed injection test failure, both primary channels or watchdog circuit failure, a restart will not be possible for safety reasons.

(b) Overtemperature
Overtemperature shutdown occurs when EGT exceeds the following limits.

DURING STARTING PHASE

SPEED TEMP LIMIT TEMP LIMIT TEMP LIMIT

(from 25000 up to 34000ft (above 34000ft.)

during 9.5 sec to confirmation)

0 426 deg C 426 deg C 426 deg C

10 788 deg C 788 deg C 788 deg C

20 899 deg C 899 deg C 899 deg C

30 899 deg C 899 deg C 899 deg C

50 853 deg C 853 deg C 899 deg C

60 --- deg C --- deg C 899 deg C

80 788 deg C 788 deg C 843 deg C

100 670 deg C 670 deg C 760 deg C

DURING STEADY STATE (APU available)

T inlet (deg C) I EGTSD (deg C)

-----------------------+-------------------------

-5 I 640

33 I 682

EGT shutdown if EGT = EGTSD for 4.5 sec

EGT shutdown if EGT +60 deg C = EGTSD

(c) Low Oil Pressure (LOP)
APU shutdown occurs when the low oil pressure switch (8091KM) input to the ECB indicates LOP after the APU has reached 95 % speed.

(d) High Oil Temperature (HOT)
APU shutdown occurs when the RTD detects a gearbox temperature above 275 deg.F (135.00 deg.C) or a gearbox temperature failure in conjunction with a generator oil temperature in excess of 320 deg.F (160.00 deg.C)

(e) No Flame
APU shutdown occurs when the EGT does not rise at least 100 deg.F (37.78 deg.C), 6 seconds after the APU reaches 5 % speed.

(f) No Acceleration
APU shutdown occurs if:

failure to crank,
The APU speed fails to reach 3% within 2 seconds after main start contactor is energized.
When the main start contactor is energized and starter motor voltage is less than 5.0VDC, the main and back-up contactor outputs do not indicate failed then, t delay = 12 seconds otherwise t delay = zero. For temperatures between 70 deg.F (21.11 deg.C) and -40 deg.F (-40.00 deg.C), linear interpolation is used.

(g) Low acceleration rate:
When the APU speed fails to maintain 0.1% per second rate of acceleration, acceleration failure will only be invoked after 5% speed and combustor light off has been achieved.

(h) Deceleration during start sequence:
This occurs during engine speed deceleration at a rate greater than or equal to 1.6% per second for 3 consecutive seconds.

(i) Surge/Reverse Flow
Reverse flow APU shutdown occurs when the load compressor delta P/Ps drops below the minimum acceptable limit when the surge control algorithm has commanded the bleed control valve to the maximum surge free position.

(j) Generator high oil temperature
APU shutdown occurs when the generator oil temperature RTD detects an oil temperature above 365 deg.F (185.00 deg.C)

(k) Loss of DC power
APU shutdown occurs when a voltage of less than 15.5VDC for more than
230 m secs is detected at the ECB power supply.

(l) Underspeed
APu shutdown occurs when the APU speed drops below 95% after establishing a ready to load condition.

(m) Loss of speed
APU shutdown occurs if both speed sensors fail.

(n) Sensor failure
APU shutdown occurs after the following failures:
both thermocouples, or
both oil temperature RTDs, or
low oil pressure switch and oil level RTD, or
low oil pressure switch and low oil level.

(o) Air intake not open
APU shutdown occurs if the air intake actuator (4015KM) fails with the air intake flap in the not fully open position.

(p) ECB failure
APU shutdown occurs when the following failures in the ECB are detected.
Backup overspeed circuit failure,
both speed injection test failure.

(2) Alternate values for failed sensors
The ECB 59KD programmes alternate values for certain failed LRUs to keep the APU available. The LRU failures and alternate actions are listed as follows:

------------------------------------------------------------------------------

FAILED LRU ACTION

------------------------------------------------------------------------------

Gearbox oil temperature For high oil temperature shutdown a generator

oil temperature greater than 320 deg.F (160 deg.C)

has to be detected.

Generator oil temperature In the event of sensor failure, the generator is

still protected by the gearbox high oil temperature

limit.

Inlet air temperature For fuel adjustments, the following default

values are used:

Max fuel limit: T inlet = -65 deg.F (-54 deg.C),

P inlet = 14.7 psia.

Min fuel limit: T inlet = 50 deg.F (10 deg.C),

P inlet = 3 psia.

For acceleration and EGT set point:

P inlet = 3 psia.

PID control gains at steady state speed control:

P inlet = 7.3 psia.

T inlet = 70 deg.F (21 deg.C).

Cold junction RTD The last cold junction is used if the ECB is

powered after failure and no valid cold junction

value is available.

Default value is 70 deg.F (21 deg.C).

** ON A/C NOT FOR ALL

7. Operation/Control and Indicating

Starting - Acceleration Closed Control Loop ** ON A/C NOT FOR ALL

A. APU Start

(1) Energize the 28VDC battery busbar 301PP and close the subsequent circuit breakers:

the ECB SPLY 1KD,
the APU CTL 2KD.

(2) Set the MASTER SW pushbutton switch 14KD to the ON position.

the ON legend in the switch comes on,
the ECB energizes through the relay APU MAIN 4KD,
the ECB starts the power-up test,
the APU fuel LP valve actuator 3QF energizes and opens the APU fuel LP valve 14QM,
the APU fuel-feed pump element 4QC and control is armed,
the air intake flap opens,
the start system is energized.

(3) When the APU START pushbutton switch 2KA is pushed to ON, the ON legend in the switch comes on. The automatic start cycle starts (Ref. AMM D/O 49-42-00-00).

(4) When the automatic start cycle ends, the engine reaches governed speed and is ready to load. The ECB transmits an 'AVAIL' signal to the related aircraft systems. When this occurs the ON legend in the APU START switch goes off and the AVAIL light comes on.

(5) The fine-speed circuit in the ECB and the proportional governors, keep the speed constant at the correct speed. The fine-speed circuit sends a signal to the fuel control unit which increases or decreases the fuel flow as necessary.

B. APU Normal Shutdown

(1) When the MASTER SW pushbutton switch 14KD is set to the off position,

if the bleed-air is not in operation, the ECB immediately starts the shutdown sequence.
if the bleed-air is in operation, the ECB transmits a signal to close the bleed-air valve. When the pneumatic load is removed, the APU goes into a cool-down cycle. This shows on the Electronic Centralized Aircraft Monitoring (ECAM) system page as a decrease in EGT. After the cool-down cycle ends (up to 120 s) the shutdown sequence starts.

(2) Shutdown Sequence
When the ECB starts the APU shutdown sequence:

the AVAIL on the lower ECAM display unit disappears,
the AVAIL legend in the START pushbutton switch goes off,
the APU shuts down,
the APU fuel LP valve actuator 3QF closes,
the APU fuel-feed pump element 4QC and the control is de-energized,
the air intake flap closes when the speed is less than 7%,
the control and protection system de-energizes and resets when the speed is less than 7% and the air intake flap is closed.

C. Automatic Shutdown

(1) The ECB 59KD keeps the shutdown information (faulty units and cause of the APU shutdown) in its memory.

(2) An overspeed test signal of 109% is generated for 50 ms. If the overtemperature test is done, this test (overspeed) is delayed for 3.5 s The overspeed signal is put into the analog 'highest wins' logic and starts the APU shutdown (the APU fault signal is stopped). If after 20 s the speed is more than 85%, a shutdown circuit fault is recorded and all power is disconnected:

the AVAIL on the lower ECAM display unit disappears,
the AVAIL legend in the START pushbutton switch goes off,
the MASTER CAUT lights come on with a single chime,
the upper ECAM display unit shows:
APU AUTO SHUT DOWN
MASTER SW ....................... OFF
the FAULT legend in the MASTER SW pushbutton switch comes on,
the APU shuts down without a time delay,
the APU fuel LP valve actuator 3QF closes,
the APU fuel-feed pump element 4QC and the control is de-energized,
the air intake flap closes when the speed is less than 7%,
the control and protection system de-energizes and resets when the speed is less than 7% and the air intake flap is closed,
when the MASTER SW is set to the off position, the FAULT legend goes off.

D. Environmental Control System (ECS)
The ECS mode operates when the APU BLEED pushbutton switch is pushed and the air conditioning packs are in operation. Then the Air Conditioning System Controller (ACSC) sends the ECS demand through the ARINC 429 bus to the ECB (Ref. AMM D/O 21-63-00-00). This sets the Inlet Guide Vanes (IGV) position in proportion to the ECS demand signal.

E. Main Engine Start (MES)
The MES mode operates when the APU BLEED pushbutton switch is pushed and a main engine start is initiated (Ref. AMM D/O 73-25-00-00). Then the FADEC sends a signal to the ECB. This sets the IGV position in a fixed position in proportion to the inlet temperature and the T5 trim schedule.
When the engine starter valve closes, the FADEC removes the MES signal to the ECB and the ECB switches back to the normal operation mode.

** ON A/C NOT FOR ALL

8. BITE Test

A. BITE Test
The BITE tests the three subsequent BITE modes:

the Power Up Test (PUT),
the In Operation Test (IOT),
the self test if started from the MCDU.

(1) Power-Up Test (PUT)
The PUT starts if the subsequent signals are available:

the power up initialization is complete and
the APU speed is below 7 % or
the start signal received for more than 60 seconds.

During the PUT the drivers and the loads are tested for open and short. The switches are tested for their position and the sensor signals are compared to their limits.

(2) In Operation Test (IOT)
The IOT tests all LRUs which are necessary for the APU operation. The IOT starts after the PUT.

(3) Self Test
The self test is similar to the power-up test. It is optional when:

the test is manual started from the MCDU,
the APU speed is less than 7%.

(4) Built In Test Equipment (BITE)
For the indication of the report and test pages on the MCDU refer to the chapter 49-73-00 Analyzers.

[Rev.10 from 2021] 2026.04.01 01:31:38 UTC