SLATS ELECTRICAL CONTROL AND MONITORING - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The electrical control and monitoring system of the slats has:

a manually operated slat/flap control lever
a Command Sensor Unit (CSU) 51CV
two Slat and Flap Control Computers (SFCC1 and SFCC2) 21CV, 22CV
two electrically controlled valve blocks 25CV(26CV) installed on the slats Power Control Unit (PCU) 6001CM (Ref. AMM D/O 27-84-00-00)
a Feedback Position Pick-Off Unit (FPPU) 28CV
two Asymmetry Position Pick-Off Units (APPU) 31CV(32CV)
two Wing Tip Brakes (WTB) 35CV(36CV).

The functions of the slats electrical control and monitoring system are:

to control the valve blocks electrically
to control the WTBs electrically
to receive data from and send data to the related systems
to monitor the power transmission for correct operation
to monitor the control system and power transmission for component failure
to monitor the inputs from and outputs to the related systems.

The system has a Built-In Test Equipment (BITE).

The slat/flap control lever controls the position of the slats. The CSU identifies the position of the slat/flap control lever and sends related signals to each SFCC. Each SFCC controls a valve block of a hydraulic motor, which is part of the slat PCU.

The two SFCCs monitor the operation of the transmission system. The FPPU (which is part of the slats PCU) and the two APPUs send signals to the SFCCs. They identify component failures of the transmission system and the control system. The Pressure-Off Brakes (POB) of the PCU and the WTBs stop and hold the transmission system when a failure occurs.

** ON A/C NOT FOR ALL

2. Component Location

Component Location

Slat System Electrical Equipment - Component Location

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
21CV	SLAT/FLAP CONTR.COMP.	85VU	127	27-51-34
** ON A/C NOT FOR ALL
21CV	SLAT/FLAP CONTR.COMP.	85VU	120	27-51-34
** ON A/C NOT FOR ALL
21CV	SLAT/FLAP CONTR.COMP.		120	27-51-34
** ON A/C NOT FOR ALL
22CV	SLAT/FLAP CONTR.COMP.	86VU	128	27-51-34
** ON A/C NOT FOR ALL
22CV	SLAT/FLAP CONTR.COMP.	86VU	120	27-51-34
** ON A/C NOT FOR ALL
22CV	SLAT/FLAP CONTR.COMP.		120	27-51-34
** ON A/C NOT FOR ALL
22CV	SLAT/FLAP CONTR.COMP.	85VU	120	27-51-34
** ON A/C ALL
25CV	VALVE BLOCK SLAT 1		147	27-84-53
26CV	VALVE BLOCK SLAT 2		148	27-84-53
28CV	FPPU-SLAT		148	27-81-19
** ON A/C NOT FOR ALL
31CV	POSITION PICK OFF UNIT	522UB	522	27-81-18
** ON A/C NOT FOR ALL
31CV	POSITION PICK OFF UNIT		522	27-81-18
** ON A/C NOT FOR ALL
32CV	POSITION PICK OFF UNIT	622UB	622	27-81-18
** ON A/C NOT FOR ALL
32CV	POSITION PICK OFF UNIT		622	27-81-18
** ON A/C NOT FOR ALL
35CV	WING TIP BRAKE	522UB	522	27-81-51
** ON A/C NOT FOR ALL
35CV	WING TIP BRAKE	575DB	575	27-81-51
** ON A/C NOT FOR ALL
35CV	WING TIP BRAKE		575	27-81-51
** ON A/C NOT FOR ALL
36CV	WING TIP BRAKE	622UB	622	27-81-51
** ON A/C NOT FOR ALL
36CV	WING TIP BRAKE	675DB	675	27-81-51
** ON A/C NOT FOR ALL
36CV	WING TIP BRAKE		675	27-81-51
** ON A/C NOT FOR ALL
51CV	CSU	114VU	210	27-51-17
** ON A/C NOT FOR ALL
51CV	CSU		220	27-51-17
** ON A/C NOT FOR ALL
51CV	CSU	114VU	220	27-51-17
** ON A/C ALL
90CV	RELAY-SLAT 1 FAULT	187VU	127	27-51-00
92CV	RELAY-SLAT 2 FAULT	188VU	128	27-51-00
94CV	RELAY-A/C ON GND	187VU	127	27-51-00
95CV	RELAY-A/C ON GND	187VU	127	27-51-00
96CV	RELAY-A/C ON GND	188VU	128	27-51-00

** ON A/C NOT FOR ALL

3. System Description

A. Mechanical Input

The slat/flap control lever is installed in the cockpit on panel 114VU. There are five possible positions for the lever (identified as 0,1,2,3 and FULL). The lever position to the related flight phase, flap angle and the slat angle is as follows:

The slat/flap control lever is installed in the cockpit on panel 114VU. There are five possible positions for the lever (identified as 0,1,2,3 and FULL).
The lever position to the related flight phase, flap angle, inboard and outboard tab angle and the slat angle is as follows:

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

LEVER FLAP SLAT

POSITION FLIGHT PHASE ANGLE (deg) ANGLE (deg)

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

0 Cruise 0 0

1* Hold (Lowspeed) 0 18

1* Take-off 10 18

2 Take-off 15 22

3 Take-off /Approach 20 22

FULL Land 35 27

* Flap auto-command function

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

LEVER FLAP SLAT

POSITION FLIGHT PHASE ANGLE (deg) ANGLE (deg)

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

0 Cruise 0 0

1* Hold (Lowspeed) 0 18

1* Take-off 10 18

2 Take-off 15 22

3 Take-off /Approach 20 22

FULL Land 40 27

* Flap auto-command function

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

LEVER FLIGHT FLAP TAB TAB SLAT

POSITION PHASE ANGLE ANGLE ANGLE ANGLE

INBOARD OUTBOARD

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

0 Cruise 0 0 0 0

1* Take-off 0 0 0 18

1* Take-off/Approach 10 5.4 6.2 18

2 Take-off/Approach 14 8.4 9.7 22

3 Take-off/Approach 21 13.6 15.8 22

FULL Land 25 16.1 19.1 27

* Flap auto-command function

NOTE: The flap, tab and slat angles are in degrees.

The slat/flap control lever has two baulks. One baulk between position 1 and 2, and one between position 3 and FULL. The baulks prevent a one-movement-change of the lever position from FULL to 0. The lever turns a shaft which moves the input shaft of the CSU through spur gears.

B. Electrical Control

Slats Electrical Control - Schematic

The CSU is installed in the cockpit, immediately below the slat and flap control lever on the panel 114VU. The CSU changes the mechanical signals from the control lever into electrical signals to the SFCC1 and SFCC2.

The two SFCCs are installed in racks in the forward avionics compartment. The SFCCs have power supplies with no relation between them. Each SFCC has the same function and includes one flap channel and one slat channel. The slat channels each control one of the two valve blocks on the slats PCU. Each valve block has its own different hydraulic supply (Ref. AMM D/O 27-84-00-00).
There are three solenoid valves at each valve block. For the low speed mode, the SFCCs energize the retract/extend solenoid valves and the POB solenoid. For the high speed mode, the SFCCs energize the extend solenoid valve and the POB solenoid. The POB solenoid permits the release of the POB of the hydraulic motor (Ref. AMM D/O 27-84-00-00).

An FPPU, which is attached to the PCU, sends signals on the position of the slat transmission to the two SFCCs. The PCU gearbox moves the FPPU.
The FPPU has two synchro transmitters, which are the same. One sends signals to the SFCC1, the other one to the SFCC2.

C. Wing Tip Brake (WTB) Control

Wing Tip Brake (WTB) Control - Schematic

The WTB is an electro-hydraulic pressure-on brake. It is installed near the end of the transmission system in each wing. The WTBs stop and hold the transmission if the SFCCs find some given types of failures. Each WTB has two solenoid valves. Each solenoid valve controls one part of a WTB. The WTBs have different hydraulic supplies. The Blue hydraulic system supplies one solenoid valve and the Green hydraulic system supplies the other solenoid valve.

Power is supplied to the WTB solenoids through the SFCCs. Each SFCC supplies and controls one solenoid on each WTB. When the WTBs operate, the transmission locks. The circuit can only be reset (set back) on the ground through the Centralized Fault Display System (CFDS). The two SFCCs control the LH and the RH WTB.

D. Monitoring

Slat Transmission Monitoring - Schematic

The two SFCCs monitor the slat system continuously for failures in:

the operation of the power transmission system
the Line Replaceable Units (LRU)
the input and output signals
the power supplies.

Failures in the slat system will not give, but may lead to class 1 level 3 warnings which are generated by the Electronic Centralized Aircraft Monitoring (ECAM) system.

The ECAM system shows class 1, level 1 and level 2 cautions to the flight crew (Ref. AMM D/O 31-50-00-00). The SFCCs supply failure data to the ECAM system through:

the System Data Acquisition Concentrators (SDAC)
the Flight Warning Computers (FWC)
the Display Management Computers (DMC) (Ref. AMM D/O 31-62-00-00).

The ECAM gives a Maintenance Status Reminder for class 2 failures.

The SFCCs supply all the related data of failures to the Centralized Fault Display System (CFDS).

(1) Monitoring of the Power Transmission Systems

The SFCCs monitor the power transmission system for these failures:

asymmetry (a position difference between the two APPUs)
runaway (a position difference between the APPUs and the FPPU)
uncommanded movement (a movement in the wrong direction, or a movement away from the last set position)
overspeed (the faster movement of one or more PPUs)
system jam
half speed
low hydraulic pressure
control valve position.

To monitor the power transmission system, the SFCCs compare the CSU signals with the position data. The SFCCs receive the position data from:

the two APPUs
the FPPU
the valve blocks.

(2) LRU Monitoring

The SFCCs monitor these LRUs for failures:

SFCC1 and SFCC2
the CSU
the two WTBs
the two APPUs
the FPPU
the valve blocks of the slat PCU.

The SFCCs keep the data related to the failures in their memories.

(3) Monitoring of Input and Output Signals

The SFCCs monitor these input and output signals:

the ARINC 429 inputs from other systems
the ARINC 429 inputs from the cross-computer link (other SFCC)
the installation coding
the operation mode codings
the ground inhibit
the ARINC 429 outputs (wraparound)

If the above signals are not in the specified limits, the SFCCs keep the data related to the failure in its memory. The SFCCs transmit the data to the CFDS.

Other discrete inputs are:

the Aircraft On Ground (AOG) discrete
the WTB-arm input.

(4) Monitoring of Power Supplies

The SFCCs monitor these power supplies:

the SFCC DC Supply
the WTB DC Supply
the synchro excitation power generated by the SFCCs
the LVDT synchro excitation power generated by the SFCCs.

If the voltage is not in the specified limits, the SFCCs keep the data related to the failure in its memory.
The SFCCs transmit the data to the CFDS. If the SFCC DC supply or the synchro excitation power is not in the specified limits, the flight crew get a failure indication.

** ON A/C NOT FOR ALL

4. Power Supply

Power Supply Distribution - Schematic

The electrical power supplies for the slat control and monitoring system are:

the essential bus 401PP
the normal bus 202PP
the battery buses 701PP and 702PP.

The essential bus 401PP supplies:

the SFCC1 slat channel
the related PCU solenoids
the synchro and LVDT excitation voltages.

The battery bus 701PP supplies the WTB solenoids related to the SFCC1.

The normal bus 202PP supplies:

the SFCC2 slat channel
the related PCU solenoids
the synchro and LVDT excitation voltages.

The battery bus 702PP supplies the WTB solenoids related to the SFCC2.

If the WTBs are operated, the battery buses keep the solenoids energized during a SFCC power failure.

** ON A/C NOT FOR ALL

5. Interfaces

Slat System Components - Interfaces

Slat System Interfaces - Data to Other Systems ** ON A/C NOT FOR ALL

Slat System Interfaces - Data from Other Systems

** ON A/C NOT FOR ALL

6. Component Description

A. Refer to (Ref. 27-51-00) for data on:

the Slat and Flap Control Lever
the CSU
the SFCC.

B. Valve Block

Valve Block

The valve block is the same as the valve block of the flaps PCU. Refer to (Ref. 27-51-00) for data on the valve block.

C. Feedback Position Pick-off Unit (FPPU)

Feedback Position Pick-off Unit

The slats FPPU is the same as the flaps FPPU. Refer to (Ref. AMM D/O 27-51-00-00) for data on the FPPU.

D. Asymmetry Position Pick-off Unit (APPU)

Asymmetry Position Pick-Off Unit

The two APPUs are the same as, and interchangeable with, the FPPU. Refer to (Ref. AMM D/O 27-51-00-00) for data on the FPPU.

E. Adapter Plate

Adapter Plate

An adapter plate, attached to the wing structure, connects the APPU to the slat transmission system.

F. Wing Tip Brake

Wing Tip Brake

The slats WTB is the same as the flaps WTB. Refer to (Ref. AMM D/O 27-51-00-00) for data on the WTB.

** ON A/C NOT FOR ALL

7. Operation/Control and Indicating

Slats - Normal Operation

A. Normal Operation
System Requirements

For the normal operation of the slats:

energize the aircraft electrical network
close the circuit breakers 5CV, 7CV, 9CV and 11CV
pressurize the Blue hydraulic system for the slat system 1 and the Green hydraulic system for the slat system 2.

NOTE: For safety, the circuit breakers 9CV and 11CV have a red guard installed to prevent incorrect operation during flight. To open the circuit breakers it is necessary to remove the applicable red guard first.

(1) Manual Control

The slat and flap control lever controls the position of the slats. When the lever is moved to a new position, the slats move to the indicated slat angle.

NOTE: The slats will not move when the slat and flap control lever moves from position 2 to 3 , or 3 to 2. As a function of the lever position, the flaps can move.

B. Electrical Control

The CSU sends discrete signals to the slat channel of each SFCC. At the same time, the CSU sends discrete signals for the flap position to the flap channel. The switch pattern of the CSU changes when the control lever moves. This causes the SFCC to get different signals (Ref. Table 2). Each slat channel receives signals from two sets of the 5-track switches in the CSU. For a correct signal, each channel must receive the same detent pattern from the two sets of switches.

For a permitted out-of-detent pattern, each channel must receive the same out-of-detent pattern from the two sets of switches.
If a different configuration occurs, it is a CSU failure.

The CSU sends discrete signals to the slat channel of each SFCC. At the same time, the CSU sends discrete signals for the flap position to the flap channel. The switch pattern of the CSU changes when the control lever moves. This causes the SFCC to get different signals (Ref. Table 2). Each slat channel receives signals from two sets of the 5-track switches in the CSU. For a correct signal, each channel must receive the same detent pattern from the two sets of switches.

For a permitted out-of-detent pattern, each channel must receive the same out-of-detent pattern from the two sets of switches.

A CSU failure is given as one of the two that follows:

a CSU pattern being other than a valid selection or out-of-detent
the CSU is seen to move directly from 0 to Full or from Full to 0 without going through positions 1, 2 or 3. This failure is called a CSU disadjust if it is confirmed by the other SFCC.

C. Table

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

LEVER

POSITION 0 1 2 3 FULL

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

TRACK 1 XXXXX XXXXX

TRACK 2 XXXXXXXXXXX

TRACK 3 XXXXXXXXXX

TRACK 4 XXXXXXXXXXX

TRACK 5 XXXXXXXXXXXXX

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

SLAT ANGLE 0 18 22 22 27

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

FLAP ANGLE 0 10 15 20 35

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

Lever Position and Switch Pattern

Table 2

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

LEVER

POSITION 0 1 2 3 FULL

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

TRACK 1 XXXXX XXXX

TRACK 2 XXXXXXXXXXX

TRACK 3 XXXXXXXXXX

TRACK 4 XXXXXXXXXXXX

TRACK 5 XXXXXXXXXXXXX

_______________________________________________________________________________

SLAT ANGLE 0 18 22 22 27

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

FLAP ANGLE 0 10 15 20 40

Lever Position and Switch Pattern

Table 2

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

LEVER

POSITION 0 1 2 3 FULL

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

TRACK 1 XXXXX XXXXX

TRACK 2 XXXXXXXXXXX

TRACK 3 XXXXXXXXXX

TRACK 4 XXXXXXXXXXX

TRACK 5 XXXXXXXXXXXXX

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

SLAT ANGLE 0 18 22 22 27

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

FLAP ANGLE 0 10 14 21 25

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

TAB INB'D 0 5.4 8.4 13.6 16.1

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

TAB OUT'D 0 6.2 9.7 15.8 19.1

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

Lever Position and Switch Pattern

Table 2

D. SFCC Memory
The SFCC memory keeps the last correct signal, which controls the slat and flap position. The SFCCs compare a new CSU signal with the slat position signal which comes from the FPPU. If a change of slat angle is necessary, the PCU solenoids get electrical power. The slats move towards the new position (Ref. 27-54-00). When the position data from the FPPU is the same as the CSU signal, the slats stop.

NOTE: Slat and flap movement always obeys the last correct control lever movement. For example, when the lever moves from position 3 to FULL, the slats will extend in the direction of the FULL position. If the lever returns to position 3 before the slats reach position FULL, the direction of slat movement changes and the slats move back to position 3.

E. Slat Alpha Lock/Speed Baulk

The Air Data/Inertial Reference Units (ADIRU) supply corrected angle-of-attack (alpha) and computed air speed (CAS) data to the SFCC. The SFCC use the data to prevent slat retraction at high alpha and/or low CAS. Slat retraction is not possible if:

the alpha is more than 8.5 deg.
the CAS is less than 148 knots.

The function resets if alpha decreases below 7.6 deg. or CAS increases over 154 knots.

Alpha lock/speed baulk is not possible if:

the slat retraction is set before alpha is more than 8.5 deg. or CAS less than 148 knots
the aircraft is on the ground with CAS below 60 knots.

When the function is active, the ECAM shows the message A-Lock (cyan, pulsing) below the slat position indication (Ref. AMM D/O 27-85-00-00).

The Air Data/Inertial Reference Units (ADIRU) supply corrected angle-of-attack (alpha) and computed air speed (CAS) data to the SFCC. The SFCC use the data to prevent slat retraction at high alpha and/or low CAS. Slat retraction is not possible if:

the alpha is more than 8.5 deg.
the CAS is less than 148 knots.

The function resets if alpha decreases below 7.6 deg. or CAS increases over 154 knots.

Alpha lock/speed baulk is not possible if:

the slat retraction is set before alpha is more than 8.5 deg. or CAS less than 148 knots
the aircraft is on the ground with CAS below 60 knots.

When the function is active, the ECAM shows the message A LOCK (green, flashing) above the slat position indication (Ref. AMM D/O 27-85-00-00).

The Air Data/Inertial Reference Units (ADIRU) supply corrected angle-of-attack (alpha) and computed air speed (CAS) data to the SFCC. The SFCC use the data to prevent slat retraction at high alpha and/or low CAS. Slat retraction is not possible if:

the alpha is more than 8.0 deg.
the CAS is less than 165 knots.

The function resets if alpha decreases below 7.1 deg. or CAS increases over 171 knots.

Alpha lock/speed baulk is not possible if:

the slat retraction is set before alpha is more than 8.0 deg. or CAS less than 165 knots
the aircraft is on the ground with CAS below 60 knots.

When the function is active, the ECAM shows the message A LOCK (green, flashing) above the slat position indication (Ref. AMM D/O 27-85-00-00).

F. Operation of the Wing Tip Brake

Wing Tip Brake Logic

The WTBs lock the transmission system if some given types of failure occur that requires it to lock the WTBs.

(1) If one or the other lane of the slat channel finds a failure:

the lane arms its own WTB circuits
the other channel receives a WTB-arm discrete signal.

(2) If one or the other lane in the second slat channel also finds the failure:

the lane arms its own WTB circuits
the first channel receives a WTB-arm discrete signal.

When the SFCCs receive a WTB-arm signal they energize the related WTB solenoid valves. The WTBs lock the transmission system.
If one SFCC does not operate, the other SFCC receives a WTB-arm signal automatically. If the other SFCC finds some given types of failure, one solenoid valve on each WTB gets electrical power.

(3) Reset

The WTB can only be reset on the ground through the CFDS.

G. Monitoring for Failure Conditions

(1) Monitoring of the Power Transmission System
The SFCCs monitor:

the slat position data from the APPUs and the FPPU
the rate of change of the slat position data
the selected position from the CSU.

The SFCCs use this data to find:

an asymmetry
a runaway
an uncommanded movement
an overspeed.

(2) System Jam

The SFCC will find a system jam if the system speed is below 2% nominal for more than 4 seconds.

When the SFCCs find a system jam:

the valve block solenoids on the PCU are de-energized
the POBs are applied and stop their related hydraulic motors
the SFCCs give a class 1 level 2 caution and the ECAM display unit shows a failure message.

If the SFCCs receive a new correct CSU signal, the SFCCs go back to their normal operation.
If there is low hydraulic pressure, the SFCCs stop system jam monitoring.

(3) LRU Monitoring

(a) SFCC1 and SFCC2

Each lane of each slat channel receives output signals from the other lane in the same channel. Each lane compares these signals with its own output signals. If there is a difference for more than 320 milliseconds and minor failure steps are taken:

the solenoids on the related valve block are de-energized
the POBs lock their related hydraulic motor
the other channel receives a WTB-arm signal
the SFCCs give a class 1 level 1 caution and the ECAM display unit shows a failure message
the slats operate at half speed.

If the failure resets within 5 seconds, the channel returns to its normal operation. The SFCCs cancel the caution and the WTB-arm signal. If the failure is still there after 5 seconds then a major failure step is taken:

the SFCC arms the WTB for the defective channel.

The major failure step is also taken if 10 minor failures occur within 3 minutes.

If there is a failure in the two slat channels:

the solenoids on the two valve blocks are de-energized
the POBs lock their related hydraulic motor
the WTB for the two channels lock the transmission system
the SFCCs give a class 1 level 2 caution and the ECAM display unit shows a failure message
the slats do not operate until reset on the ground.

(b) CSU

The SFCCs monitor the CSU signals for the correct detent or out-of-detent switch patterns.

If the SFCCs receive an incorrect pattern for more than 0.5 seconds:

the solenoids on the related valve block are de-energized
the POBs lock their related hydraulic motor
the SFCCs give a level 1 caution and the ECAM display unit shows a failure message.

If the SFCCs receive an out-of-detent pattern for more than 10 seconds:

the SFCCs give a class 1 level 2 caution after the slats are at the last set position
the ECAM display unit shows a failure message.

If a CSU disadjust failure is detected:

the solenoids on the two valve blocks are de-energized
the POBs lock their related hydraulic motor
each channel arms its own WTB and sends a WTB-arm signal to the other channel
the WTBs lock the transmission system
the SFCCs give a class 1 level 2 caution and the ECAM display unit shows a failure message
the slats do not operate until reset on the ground.

(c) WTB

Each slat channel monitors its related WTB solenoids for open circuit or short circuit. If there is a failure with the correct WTB power available:

the ECAM display unit shows a failure message.

(d) PPU

If one slat channel finds failures because of PPU differences, but does not receive the WTB-arm signal from the other channel:

the SFCC will find a failure in one synchro of the related PPU
the solenoids on the related valve block are de-energized
the POBs lock their related hydraulic motor
the related channel arms its WTB
the other channel receives the WTB-arm signal
the SFCCs give a class 1 level 1 caution and the ECAM display unit shows a failure message
the slats operate at half speed.

(e) Valve Blocks

1 LVDT

Each slat channel monitors its related LVDT for the correct operation. If there is a failure, the SFCCs memory keeps the related data and sends it to the CFDS. If the failure stops the operation of the motor:

the SFCCs give a class 1 level 1 caution and the ECAM display unit shows a failure message
the slats operate at half speed.

2 Solenoid Valves

Each slat channel monitors the position of the solenoid valves on its related valve block. The slat channels use the signals from the LVDT to compare the position of the control valve with that commanded. If a valve does not close after a signal:

the channel will not try to drive the motor when the SFCC gets DC power
the SFCCs give a class 1 level 1 caution and the ECAM display unit shows a failure message
the slats operate at half speed.

3 Hydraulic Pressure

Each slat channel monitors the hydraulic pressure available to move its related motor. It uses signals from the LVDT to compare the position of the control valve with that commanded (Ref. AMM D/O 27-54-00-00). If there is low pressure:

the SFCCs give a class 1 level 1 caution and the ECAM display unit shows a failure message
the slats operate at half speed.

When hydraulic pressure goes back to its normal condition:

the SFCCs and the ECAM system cancel the class 1 level 1 caution and the failure message
the slats operate at normal speed.

If low pressure is detected the SFCCs stop system jam monitoring.

(f) Hydraulic Motors

Each slat channel monitors the transmission system for half speed operation when there is a hydraulic motor jam. The half speed monitor operates only when the valves of the two valve blocks are in the full speed position. If the slat movement is slower than the minimum speed for two-motor operation:

the SFCCs give a class 1 level 1 caution after 8 seconds and the ECAM display unit shows a failure message
the slats operate at half speed.

When the aircraft is on the ground, half speed monitoring stops.

(4) Monitoring of Input and Output Signals

(a) ARINC 429 Inputs from other Systems

Each slat channel monitors ARINC 429 inputs from the Air Data/Inertial Reference Unit (ADIRU).

(b) ARINC 429 Input from Cross-Computer Link

Each slat channel monitors the other slat channel for the correct operation. If there is no data for more than 10 seconds, the CFDS gets a failure message.

all ARINC 429 outputs, for that channel, change to no computed data
the CFDS gets a failure message.

(d) Operation Mode Coding

Each slat channel monitors its operation mode coding inputs. If they find an incorrect coding:

the ARINC 429 slat and flap system status changes to no computed data
the solenoids on the related valve block are de-energized
the POBs lock their related hydraulic motor
the related channel arms its WTB
the other channel receives the WTB-arm signal
the SFCCs give a class 1 level 1 caution and the ECAM display unit shows a failure message
the slats operate at half speed.

If the channel receives the WTB-arm signal from the other channel:

the WTBs lock the transmission system
the SFCCs give a class 1 level 2 caution and the ECAM display unit shows a failure message.

Reset is only possible on the ground.

(e) ARINC 429 Outputs (Wraparound)

Each slat channel monitors its ARINC 429 outputs. Wraparound inputs get the output data. If there is a difference, the related output stops and the CFDS gets a failure message.

(5) Monitoring of Power Supplies

(a) SFCC DC Supply

Each slat channel monitors its primary 28V DC supply and its internal secondary power supply. If the primary power supply goes below 15V DC, or the internal secondary power supply does not operate:

the solenoids on the related valve block are de-energized
the POB locks the related motor
the other channel receives the WTB-arm signal
the SFCCs give a class 1 level 1 caution and the ECAM display unit shows a failure message
the slats operate at half speed.

NOTE: The failed channel does not arm the WTB in case of interruption of all aircraft DC power. This is to stop the WTB locking the system at the same time when the DC power fails.

(b) WTB DC Supply

Each slat channel monitors the special power supply for its WTB. If the WTB power input goes below 15V DC:

the ECAM display unit shows a failure message
the CFDS gets a failure message.

(c) Synchro Excitation Power

Each slat channel monitors the correct synchro excitation power. The internal secondary DC power supplies the synchro excitation power. If the voltages or frequency are not correct:

the solenoids on the related valve block are de-energized
the POB locks the related motor
the channel arms the related WTB
the other channel receives a WTB-arm signal
the SFCCs give a class 1 level 1 caution and the ECAM display unit shows a failure message
the slats operate at half speed.

If the synchro excitation power goes back to the correct value, the slats will operate as normal. If the other channel receives the WTB-arm signal:

the WTBs lock the transmission system
the SFCCs give a class 1 level 2 caution and the ECAM display unit shows a failure message.

Reset is only possible on the ground.

H. Failure Table

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

MONITORED ECAM MESSAGE WARNING MOTOR SYSTEM

FAILURE ------------------------------ STATUS STATUS

E/W CRT SYS/STATUS CRT

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

Asymmetry. FLT CTL INOP SYS CAUTION The two Stopped.

Runaway. SLATS LOCKED SLATS CAT 3 + stopped No reset

Overspeed. WING TIP BRK ON Single in flight

Uncommanded MAX SPEED... chime

movement.

CSU MAX SPEED ... LDG DIST=x1.1*

mechanical CAT 2 ONLY

failure

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

System FLT CTL INOP SYS CAUTION The two Stopped.

jam. SLATS FAULT CAT 3 SLATS + stopped Reset if

The two Slat MAX. SPEED... LOG DIST... Single failure

Channels SLATS LEVER... CAT 2 ONLY chime disapp-

failed ...RECYCLE INCREASED FUEL ears

CONSUMP

CSU failure

(valid out-

of-detent

for more than

10 seconds)

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

Slats not in CONFIG WARNING

T.O. SLATS NOT IN +

config. T.O. CONFIG CIRC

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

MONITORED ECAM MESSAGE WARNING MOTOR SYSTEM

FAILURE ------------------------------ STATUS STATUS

E/W CRT SYS/STATUS CRT

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

Slat Channel FLT CTL SLATS SLOW Stopped 1/2

failure SLATS SYS 1(2) speed

CSU failure FAULT

(invalid

pattern)

PPU Synchro.

LVDT.

Valve Block

Solenoid.

Low hydraulic

pressure.

Operation

Mode Coding.

SFCC DC

supply

synchro excitation supply.

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

Hydraulic SLATS SLOW Stopped 1/2

Motor jam speed

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

WTB supply. FLT CTL

WTB solenoid SLAT TIP BRK FAULT

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

ARINC 429

Input/Output.

Installation

Coding

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

* Depending on the slat and flap position.

I. Parameter List
Refer to 27-51-00 for data on the parameter list.

** ON A/C NOT FOR ALL

8. BITE

Not Applicable

[Rev.10 from 2021] 2026.04.01 06:56:19 UTC