DOC AIRBUS | TSM A320FFailure of the Thrust Reverser Actuator LVDT A on Engine 2, Channel A
1. Possible Causes
NOTE: This task is to troubleshoot the Clear Language Message (CLM) REV LVDT CHA/HC/EEC2. The fault acronyms
listed in the fault confirmation section below will help you to focus on the correct cause of this CLM.
· LVDT-THRUST REV UPPER L ACTUATOR ( 4004KS )
· 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 71-13-00-410-010 Closing of the Fan Cowls 437AL(447AL),438AR(448AR)
Ref. AMM 71-50-00-210-010 Wire Harness Visual Inspection - All Power Plant Electrical Cables
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 73-25-16
Ref. AMM 78-30-00-440-012 Re-activation of the Thrust Reverser Hydraulic Control Unit (HCU) after
Ground Maintenance
Ref. AMM 78-31-00-710-041 Operational Test of the Thrust Reverser System with the CFDS
Ref. AMM 78-32-00-410-010 Closing of the Thrust Reverser Halves
Ref. AMM 78-32-48-000-010 Removal of the C-Duct Non-Locking Actuator
Ref. AMM 78-32-48-400-010 Installation of the C-Duct Non-Locking Actuator
70-00-00-03-13 STANDARD PRACTICES - ENGINE - GENERAL - TASK SUPPORTING
DATA
Failure of the Thrust Reverser Actuator LVDT on Engine 2, Channel A SHEET 1
Figure 78(IAE)-30-00-991-02500-A / SHEET 1/1 - Failure of the Thrust Reverser Actuator LVDT on
Engine 2, Channel A not printed, as per printing preferences
3. Fault Confirmation
Subtask 78-30-00-860-142-A
A. Job Set-up
(1) Energize the aircraft electrical circuits
Ref. AMM 24-41-00-861-002 .
(2) On the overhead panel 50VU, release the ENG FADEC GND PWR 2 pushbutton switch to the ON
position.
Subtask 78-30-00-710-246-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 CFDS Message Decoding and read the scheduled maintenance report to identify the fault
acronym (for A5 engines) related to the CLM (Ref. TSM 70-00-00-03) .
(2) If the readout gives fault acronym REVLFF (for A5 engines) in FADEC 2A, do the operational test
of the thrust reverser system with CFDS (through FADEC 2A) Ref. AMM 78-31-00-710-041 . This is
followed by the CFDS Message Decoding to read the scheduled maintenance report to identify the
fault acronym (for A5 engines) related to the CLM (Ref. TSM 70-00-00-03) .
(a) If the test gives the fault acronym REVLFF (for A5 engines) in FADEC 2A, or there are two or
more occurrences in fault history, continue with fault isolation Para 4.A.
(b) If the test does not give the fault acronym REVLFF (for A5 engines), and there is no history of
faults, send the engine back to service.
(3) If the readout gives the fault acronym REVXCW (for A5 engines) in FADEC 2A, do the operational
test of the thrust reverser system with CFDS (through FADEC 2A) Ref. AMM 78-31-00-710-041 . This
is followed by the CFDS Message Decoding to read the scheduled maintenance report to identify the
fault acronym related to the CLM (Ref. TSM 70-00-00-03) .
NOTE: The fault acronym REVXCW is applicable only to A5 engines.
(a) If the test gives the fault acronym REVXCW in FADEC 2A, or there are two or more occurrences
in fault history, continue with fault isolation Para 4.B.
(b) If the test does not give the fault acronym REVXCW, and there is no history of faults, send the
engine back to service.
4. Fault Isolation
(Ref. Fig. Failure of the Thrust Reverser Actuator LVDT on Engine 2, Channel A SHEET 1)
Subtask 78-30-00-810-165-A
A. Fault Isolation for Fault Acronym REVLFF (for A5 engines)
· The Thrust Reverser Upper Left Actuator LVDT signal feedback failed in channel A.
· This is caused by an open, short to ground, or a wire to wire short in this circuit.
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 EEC connector (4000KS-J4) to the thrust reverser upper
left actuator (4004KS) 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 wire chafing.
4 If a problem is found with the harness, repair or replace as necessary Ref. ASM 73-25-16.
(b) If no problems were found with the harness, disconnect electrical connector (4004KS-A) from the
thrust reverser upper left actuator (4004KS) 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.
(c) Do this electrical check of the channel A LVDT circuit in the thrust reverser upper left actuator
Ref. ASM 73-25-16.
1 Make sure that contacts 1, 2, 3 and 4 are not shorted to ground.
2 Make sure that contacts 1, 2, 3 and 4 are not shorted to other contacts in the connector.
3 Make sure the resistance from contact 1 to contact 2 is between 460 and 688 ohms.
4 Make sure the resistance from contact 3 to contact 4 is between 364 and 555 ohms.
5 If a problem is found, remove and replace the LVDT-THRUST REV UPPER L
ACTUATOR ( 4004KS ) Ref. AMM 78-32-48-000-010 and Ref. AMM 78-32-48-400-010 .
(d) If no problems were found, 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.
(e) 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.
Thrust Reverser Actuator LVDT Circuit Channel A Harness
Thrust Reverser Actuator (4004KS) EEC (4000KS)
(4004KS-A) (4000KS-J4)
Contacts Contacts
3 N
4 f
2 g
1 h
3 If a problem is found with the harness, repair or replace as necessary Ref. ASM 73-25-16.
(f) Install all the removed connectors Ref. AMM 70-23-15-912-010 .
(g) Do the test for this fault, listed in Para 3 for fault confirmation.
1 If the test does not give the fault acronym REVLFF (for A5 engines), send the engine back to
service.
2 If the test gives the fault acronym REVLFF (for A5 engines), remove and replace the LVDTTHRUST
REV UPPER L ACTUATOR ( 4004KS ) Ref. AMM 78-32-48-000-010 and Ref.
AMM 78-32-48-400-010 .
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 .
Subtask 78-30-00-810-185-A
B. Fault Isolation for Fault Acronym REVXCW (for A5 engines only)
· The thrust reverser upper left actuator LVDT signal in channel A does not agree with the signal in
channel B. This is caused by an open, short to ground, or a wire to wire short in this circuit.
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 EEC connector (4000KS-J4) to the thrust reverser upper
left actuator (4004KS) 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 wire chafing.
4 If a problem is found with the harness, repair or replace as necessary Ref. ASM 73-25-16.
(b) If no problems were found with the harness, disconnect electrical connector (4004KS-A) from the
thrust reverser upper left actuator (4004KS) 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.
(c) Do this electrical check of the channel A LVDT circuit in the thrust reverser upper left actuator
Ref. ASM 73-25-16.
1 Make sure that contacts 1, 2, 3 and 4 are not shorted to ground.
2 Make sure that contacts 1, 2, 3 and 4 are not shorted to other contacts in the connector.
3 Make sure the resistance from contact 1 to contact 2 is between 460 and 688 ohms.
4 Make sure the resistance from contact 3 to contact 4 is between 364 and 555 ohms.
5 If a problem is found, remove and replace the LVDT-THRUST REV UPPER L
ACTUATOR ( 4004KS ) Ref. AMM 78-32-48-000-010 and Ref. AMM 78-32-48-400-010 .
(d) If no problems were found, 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.
(e) 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.
Thrust Reverser Actuator LVDT Circuit Channel A Harness
Thrust Reverser Actuator (4004KS) EEC (4000KS)
(4004KS-A) (4000KS-J4)
Contacts Contacts
3 N
4 f
2 g
1 h
3 If a problem is found with the harness, repair or replace as necessary Ref. ASM 73-25-16.
(f) Install all the removed connectors Ref. AMM 70-23-15-912-010 .
(g) Do the test for this fault, listed in Para 3 for fault confirmation
1 If the test does not give the fault acronym REVXCW, send the engine back to service.
2 If the test gives the fault acronym REVXCW, remove and replace the LVDT-THRUST
REV UPPER L ACTUATOR ( 4004KS ) Ref. AMM 78-32-48-000-010 and Ref.
AMM 78-32-48-400-010 .
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 78-30-00-860-143-A
A. Put the aircraft back to its initial configuration.
(1) Make sure that the thrust reverser halves 461AL and 462AR are closed Ref.
AMM 78-32-00-410-010 .
(2) Activate the thrust reverser HCU Ref. AMM 78-30-00-440-012 .
(3) Make sure that the fan cowls 447AL and 448AR are closed Ref. AMM 71-13-00-410-010 .
(4) On the ECAM control panel, set the UPPER DISPLAY and LOWER DISPLAY potentiometers to OFF.
Ref. AMM 31-60-00-860-002 .
(5) On the panel 50VU, push the ENG FADEC GND PWR 2 pushbutton switch.
(6) De-energize the aircraft electrical circuits
Ref. AMM 24-41-00-862-002 .
(7) Remove the warning notice(s). [Rev.6 from Feb 2017] 2026.04.04 04:38:08 UTC