DOC AIRBUS | TSM A320FFailure of the Master LPC Bleed Actuator on Engine 2
1. Possible Causes
NOTE: This task is to troubleshoot the Clear Language Message (CLM) 2.5 BLD ACT/HC/EEC2. The fault acronyms
listed in the fault confirmation section below will help you to focus on the correct cause of this CLM.
· wiring
· ACTUATOR-MASTER, LPC BLEED ( 4021KS )
· EEC ( 4000KS )
2 Job Set-up Information
A. Referenced Information
REFERENCE DESIGNATION
Ref. AMM 24-41-00-861-002 Energize the Aircraft Electrical Circuits from the External Power
Ref. AMM 24-41-00-862-002 De-energize the Aircraft Electrical Circuits Supplied from the External
Power
Ref. AMM 31-60-00-860-002 EIS Stop Procedure
Ref. AMM 70-23-15-912-010 Connection of Electrical Connectors
Ref. AMM 71-50-00-210-010 Wire Harness Visual Inspection - All Power Plant Electrical Cables
Ref. AMM 73-22-00-710-040 Operational Test of the FADEC SYSTEM on the Ground
Ref. AMM 73-22-34-000-010 Removal of the Electronic Engine Control (EEC)
Ref. AMM 73-22-34-400-010 Installation of the Electronic Engine Control (EEC)
Ref. ASM 73-25-18
Ref. AMM 75-31-42-000-010 Removal of the Low Pressure Compressor (LPC) Bleed-Master Actuator
Ref. AMM 75-31-42-400-010 Installation of the Low Pressure Compressor (LPC) Bleed-Master Actuator
Ref. AMM 78-30-00-440-012 Re-activation of the Thrust Reverser Hydraulic Control Unit (HCU) after
Ground Maintenance
70-00-00-03-13 STANDARD PRACTICES - ENGINE - GENERAL - TASK SUPPORTING
DATA
Master LPC Bleed Actuator SHEET 1
Figure 75(IAE)-30-00-991-00100-D / SHEET 1/1 - Master LPC Bleed Actuator not printed, as per
printing preferences
3. Fault Confirmation
Subtask 75-30-00-860-054-A
A. Job Set-up
(1) Energize the aircraft electrical circuits
Ref. AMM 24-41-00-861-002 .
(2) On the ENG section of the maintenance panel 50VU, select FADEC GND PWR 2 pushbutton switch
to the ON position.
Subtask 75-30-00-710-193-A
B. Identify the Test for Fault Confirmation.
NOTE: Troubleshooting can start immediately without doing the fault confirmation if this CLM was shown
in multiple flight or ground legs.
(1) Do the Centralized Fault Display System (CFDS) message decoding and read the scheduled
maintenance report to identify the fault acronym related to the CLM (Ref. TSM 70-00-00-03) .
(2) If the readout gives the fault acronym B25XCF in FADEC 2A or FADEC 2B, do an operational test of
FADEC system on the ground for fault confirmation Ref. AMM 73-22-00-710-040 :
(a) If the test gives the fault acronym B25XCF or there are two or more occurrences in fault history,
continue with fault isolation Para. 4.C.
(b) If the test does not give the acronym B25XCF and there is no history of faults, send the engine
back to service.
4. Fault Isolation
(Ref. Fig. Master LPC Bleed Actuator SHEET 1)
Subtask 75-30-00-810-054-A
A. Fault Isolation for Fault Acronym B25XCF
The LPC bleed actuator-master (4021KS) position signal does not agree with the signal from the opposite
channel. This crosscheck fault (XCF) is caused by an open, short to ground or a wire to wire short in this
circuit. This fault will always be set in both channels.
NOTE: After each step that is done during this procedure, you can do the steps in Para. 3. to make sure
the fault is corrected.
NOTE: Disconnection and connection of the electrical connectors can correct this fault.
(1) Do the steps that follow:
(a) Visually examine the harness from the channel A EEC connector (4000KS-J4) to the 2.5 bleed
actuator (4021KS) Ref. AMM 71-50-00-210-010 :
1 Look for harness damage.
2 Look for loose or damaged connectors.
3 Look for loose or damaged backshells.
NOTE: Loose backshells must be disassembled and examined for internal wiring chafing.
4 If a problem is found with the harness, repair or replace as necessary.
(b) Visually examine the harness from the channel B EEC connector (4000KS-J10) to the 2.5 bleed
actuator (4021KS) Ref. AMM 71-50-00-210-010 :
1 Look for harness damage.
2 Look for loose or damaged connectors.
3 Look for loose or damaged backshells.
NOTE: Loose backshells must be disassembled and examined for internal wiring chafing.
4 If a problem is found with the harness, repair or replace as necessary.
(c) If no problems were found with the harness, disconnect electrical connector (4021KS-A) from the
2.5 bleed actuator (4021KS) Ref. AMM 71-50-00-210-010 . Examine the male and female parts
of the connection:
1 Examine pins and sockets (contacts) for alignment and damage.
2 Look for contacts pushed rearward into the connector face.
3 Look for ovalized sockets in the connector.
NOTE: This can be done by inserting a harness connector pin into each socket. You must
feel friction when you insert and remove the pin.
4 Repair as necessary.
(d) Do this electrical check of the channel A Linear Variable Differential Transducer (LVDT) circuit in
the 2.5 bleed actuator (4021KS) Ref. ASM 73-25-18:
1 Make sure that contacts A, B, C and D are not shorted to ground.
2 Make sure that contacts A, B, C and D are not shorted to other contacts in the connector.
3 Make sure the resistance from contact A to contact B is between 700 and 800 ohms.
4 Make sure the resistance from contact C to contact D is between 300 and 400 ohms.
5 If a problem is found, remove and replace the ACTUATOR-MASTER, LPC
BLEED ( 4021KS ) , Ref. AMM 75-31-42-000-010 and Ref. AMM 75-31-42-400-010 .
(e) Do this electrical check of the channel B LVDT circuit in the 2.5 bleed actuator (4021KS) Ref.
ASM 73-25-18:
1 Make sure that contacts F, G, K and E are not shorted to ground.
2 Make sure that contacts F, G, K and E are not shorted to other contacts in the connector.
3 Make sure the resistance from contact F to contact G is between 700 and 800 ohms.
4 Make sure the resistance from contact K to contact E is between 300 and 400 ohms.
5 If a problem is found, remove and replace the ACTUATOR-MASTER, LPC
BLEED ( 4021KS ) , Ref. AMM 75-31-42-000-010 and Ref. AMM 75-31-42-400-010 .
(f) If no problems were found with the 2.5 bleed actuator (4021KS), disconnect electrical connector
(4000KS-J4) from the EEC (4000KS) Ref. AMM 71-50-00-210-010 . Examine the male and
female parts of the connection:
1 Examine pins and sockets (contacts) for alignment and damage.
2 Look for contacts pushed rearward into the connector face.
3 Look for ovalized sockets in the connector.
NOTE: This can be done by inserting a harness connector pin into each socket. You must
feel friction when you insert and remove the pin.
4 Repair as necessary.
(g) Do this electrical check of the LVDT wiring in the channel A harness. Look for:
1 Wire to wire shorts and shorts to ground:
· Wire to wire short check: measure resistance between wires. If resistance is below
100000 (100K) ohms, then the wires are shorted and must be repaired.
· Wire to ground short check: measure resistance between wire and engine metal or
ground. If resistance is below 100000 (100K) ohms, then the wire is shorted to ground and
must be repaired.
2 Continuity:
· Continuity check: measure resistance between ends of same wire. If resistance is more
than 10 ohms, then the wire must be repaired.
NOTE: An incorrectly wired harness can cause this problem. When you test these circuits,
make sure the contacts are installed in the correct positions in each connector as
specified in the wiring diagram.
2.5 Bleed Actuator LVDT Circuit Channel A Harness
2.5 Bleed Actuator (4021KS) EEC (4000KS)
(4021KS-A) (4000KS-J4)
Contacts Contacts
A q
B r
C M
D e
3 If a problem is found with the harness, repair or replace as necessary Ref. ASM 73-25-18.
(h) If no problems were found, disconnect electrical connector (4000KS-J10) from the EEC (4000KS)
Ref. AMM 71-50-00-210-010 . Examine the male and female parts of the connection:
1 Examine pins and sockets (contacts) for alignment and damage.
2 Look for contacts pushed rearward into the connector face.
3 Look for ovalized sockets in the connector.
NOTE: This can be done by inserting a harness connector pin into each socket. You must
feel friction when you insert and remove the pin.
4 Repair as necessary.
(i) Do this electrical check of the LVDT wiring in the channel B harness. Look for:
1 Wire to wire shorts and shorts to ground:
· Wire to wire short check: measure resistance between wires. If resistance is below
100000 (100K) ohms, then the wires are shorted and must be repaired.
· Wire to ground short check: measure resistance between wire and engine metal ground. If
resistance is below 100000 (100K) ohms, then the wire is shorted to ground and must be
repaired.
2 Continuity:
· Continuity check: measure resistance between ends of same wire. If resistance is more
than 10 ohms, then the wire must be repaired.
NOTE: An incorrectly wired harness can cause this problem. When you test these circuits,
make sure the contacts are installed in the correct positions in each connector as
specified in the wiring diagram.
2.5 Bleed Actuator LVDT Circuit Channel B Harness
2.5 Bleed Actuator (4021KS) EEC (4000KS)
(4021KS-A) (4000KS-J10)
Contacts Contacts
F q
G r
K M
E e
3 If a problem is found with the harness, repair or replace as necessary Ref. ASM 73-25-18.
(j) Install all removed connectors Ref. AMM 70-23-15-912-010 .
(k) Do the test for this fault, listed in Para. 3. for fault confirmation.
1 If the test does not give the fault acronym B25XCF, send the engine back to service.
2 If the test gives the fault acronym B25XCF, remove and replace the ACTUATOR-MASTER,
LPC BLEED ( 4021KS ) , Ref. AMM 75-31-42-000-010 and Ref. AMM 75-31-42-400-010 .
3 If this fault continues, remove and replace the EEC ( 4000KS ) , Ref.
AMM 73-22-34-000-010 and Ref. AMM 73-22-34-400-010 .
5. Close-up
Subtask 75-30-00-860-055-A
A. Put the aircraft back to its initial configuration.
(1) Activate the thrust reverser HCU Ref. AMM 78-30-00-440-012 .
(2) On the ECAM control panel, set the UPPER DISPLAY and LOWER DISPLAY potentiometers to OFF.
Ref. AMM 31-60-00-860-002 .
(3) On the ENG section of the maintenance panel 50VU, push the FADEC GND PWR 2 pushbutton
switch.
(4) De-energize the aircraft electrical circuits
Ref. AMM 24-41-00-862-002 .
(5) Remove the warning notice(s). [Rev.6 from Feb 2017] 2026.04.04 04:37:15 UTC