W DOC AIRBUS | TSM A320F

Loss of Detection by Engine-2 Loop B

TASK 26-12-00-810-806-A
Loss of Detection by Engine-2 Loop B

1. Possible Causes
  • DET-FIRE, ENG 2 PYLON LOOP B [4WD2]
  • DET-FIRE, CORE VENT LOOP B [4001WD2]
  • DET-FIRE, CORE AGB LOOP B [4002WD2]
  • HARNESS-FIRE DET, ENG 2 PYLON LOOP B STUD A [41WD2]
  • HARNESS-FIRE DET, ENG 2 PYLON LOOP B STUD C [42WD2]
  • DET-FIRE, FAN LOOP B [4000WD2]
  • wiring
  • FDU-ENG2 [2WD2]
  • terminal-block
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 26-12-00-200-001
Visual Inspection of the Engine Fire Detection System
AMM 26-12-00-200-003
Visual Inspection of the Engine Fire Detection System
AMM 26-12-00-200-802
Visual Inspection of the Engine Fire Detection System
AMM 26-12-00-710-002
Operational Test of the Engine Fire and Overheat Detection with the Centralized Fault Display System (CFDS)
ASM 261201
AWM 261206
AWM 261208
AMM 26-12-15-000-041
Removal of the Fan Fire Detectors
AMM 26-12-15-000-042
Removal of the Fan Fire Detectors
AMM 26-12-15-400-041
Installation of the Fan Fire Detectors
AMM 26-12-15-400-042
Installation of the Fan Fire Detectors
AMM 26-12-16-000-001
Removal of the Pylon Fire Detectors
AMM 26-12-16-000-803
Removal of the Pylon Fire Detector
AMM 26-12-16-400-001
Installation of the Pylon Fire Detectors with the Tool (98D26203003000)
AMM 26-12-16-400-803
Installation of the Pylon Fire Detector
AMM 26-12-17-000-040
Removal of the Core Fire Detectors
AMM 26-12-17-000-041
Removal of the Core Fire Detectors
AMM 26-12-17-000-802
Removal of the Forward Fire/Overheat Detector
AMM 26-12-17-000-803
Removal of the Aft Fire/Overheat Detector
AMM 26-12-17-400-040
Installation of the Core Fire Detectors
AMM 26-12-17-400-041
Installation of the Core Fire Detectors
AMM 26-12-17-400-802
Installation of the Forward Fire/Overheat Detector
AMM 26-12-17-400-803
Installation of the Aft Fire/Overheat Detector
AMM 26-12-34-000-001
Removal of the Engine Fire-Detection Unit (FDU)
AMM 26-12-34-400-001
Installation of the Engine Fire-Detection Unit (FDU)
AMM 26-12-63-000-801
Removal of the Pylon Fire-Detector Harness
AMM 26-12-63-400-801
Installation of the Pylon-Fire Detector Harness
AWM 715175
AMM 78-36-51-400-040
Installation of the Thrust Reverser Half Door Opening Actuator
3. Fault Confirmation
Subtask 26-12-00-710-058-A
A. Test
   (1) Do the operational test of the engine fire and overheat detection from the Multipurpose Control and Display Unit (MCDU) AMM 26-12-00-710-002.
4. Fault Isolation
Subtask 26-12-00-810-210-B ** ON A/C NOT FOR ALL
A. If the test confirms the fault:
   (1) Do a visual inspection of the:
  • Engine-2-pylon loop-B fire-detector (4WD2),
  • Core-ventilation loop-B fire-detector (4001WD2)
  • Core-AGB loop-B fire-detector (4002WD2)
  • Engine-2-pylon fire-detector harnesses (41WD2) and (42WD2), AMM 26-12-00-200-802.
     (a) If one or more fire detector(s) is (are) damaged:
     (b) If there is no visual damage:
  • Do the trouble shooting given in Para 4.B.
Subtask 26-12-00-810-055-A ** ON A/C NOT FOR ALL
B. If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B:
   (1) If one or more fire detector(s) is (are) damaged:
   (2) If there is no visual damage, do a visual inspection of the engine 2 near the three fire detectors.
Make sure that:
     (a) There is no fuel or hydraulic leakage.
     (b) There is no air leakage at the connections of the bleed air duct.
     (c) The electrical cables are correctly connected.
     (d) The bend in the flex hose is outboard and away from the engine AMM 78-36-51-400-040.
   (3) If there is no visual damage, do a visual inspection for retention or worn contact of each pin of the terminal block 450VT2 AWM 261208. If necessary, replace the terminal block.
   (4) If there is no visual damage, swap the pins that follow:
  • The pins B and D of the terminal block 450VT2 section 1 with the pins D and A of the terminal block 450VT2 section 2 AWM 261206 and AWM 261208.
     (a) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B again:
  • Swap back the pins B and D of the terminal block 450VT2 section 1 with the pins D and A of the terminal block 450VT2 section 2.
  • Repair the wiring from the terminal block 450VT2 section 2 to the engine 2 Fire Detection Unit (FDU) (2WD2) AWM 261208.
     (b) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP A:
  • Swap back the pins B and D of the terminal block 450VT2 section 1 with the pins D and A of the terminal block 450VT2 section 2.
  • Swap the pins of the terminal block 450VT2 section 1 of the engine 2 pylon loop A fire detector (3WD2) with the pins of the terminal block 450VT2 section 2 of the engine 2 pylon loop B fire detector (4WD2) AWM 261206 and AWM 261208.
  • Continue with the subsequent step.
     (c) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP A:
  • Swap back the pins of the fire detector (3WD2) with the pins of the fire detector (4WD2).
  • Do a check and if necessary, repair the wiring from the terminal block 450VT2 section 2 to the fire detector (4WD2) AWM 261208.
       1 If the wiring is correct and if the fault continues:
     (d) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B again:
  • Swap back the pins of the fire detector (3WD2) with the pins of the fire detector (4WD2).
  • Swap the pins of the terminal block 450VT2 section 1 of the core loop A fire detector (4001WD1) with the pins of the terminal block 450VT2 section 2 of the core loop B fire detector (4001WD2) AWM 261206 and AWM 261208.
  • Continue with the subsequent step.
     (e) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP A:
  • Swap back the pins of the fire detector (4001WD1) with the pins of the fire detector (4001WD2).
  • Do a check and if necessary, repair the wiring from the terminal block 450VT2 section 2 to the fire detector (4001WD2) AWM 261208.
       1 If the wiring is correct and if the fault continues:
     (f) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B again:
  • Swap back the pins of the fire detector (4001WD1) with the pins of the fire detector (4001WD2).
  • Swap the pins of the terminal block 450VT2 section 1 of the fan loop A fire detector (4000WD1) with the pins of the terminal block 450VT2 section 2 of the fan loop B fire detector (4000WD2) AWM 261206 and AWM 261208.
  • Continue with the subsequent step.
     (g) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP A:
  • Swap back the pins of the fire detector (4000WD1) with the pins of the fire detector (4000WD2).
  • Do a check and if necessary, repair the wiring from the terminal block 450VT2 section 2 to the fire detector (4000WD2) AWM 261208.
       1 If the wiring is correct and if the fault continues:
     (h) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B again:
  • Swap back the pins of the fire detector (4000WD1) with the pins of the fire detector (4000WD2).
  • Continue with the subsequent step.
   (5) If the fault continues:
  • Disconnect the connector 2WD2-B from the engine 2 FDU (2WD2).
  • On the connector, on the wiring side, make sure that the equivalent resistance value between pins J and K is between 1425 ohms and 1575 ohms ASM 261201.
     (a) If the equivalent resistance value is not correct and is:
  • Between 2137 ohms and 2363 ohms: there is one defective detector.
  • Between 4275 ohms and 4725 ohms: there are two defective detectors.
  • Infinite: there is either three defective detectors or a defective wiring.
       1 Disconnect the electrical harness from the three loop B fire detectors.
       2 On the responder of each detector, make sure that the resistance value is between 4275 ohms and 4725 ohms ASM 261201 between:
. Pins A and D for the engine 2 pylon loop B fire detector (4WD2) and the fan loop B fire detector (4000WD2)
. Pins A and C for the core loop B fire detector (4001WD2).
         a If the resistance value is not correct:
         b If the resistance value is correct:
  • Do a check and repair the wiring of the FIRE DET I/P (LOOP B) from the engine 2 FDU (2WD2) to the three loop B fire detectors ASM 261201.
     (b) If the equivalent resistance value is correct:
       1 If the fault continues:
  • Disconnect the electrical harness from the three loop B fire detectors.
  • To do the insulation of the fire detector, refer to the table below for the correct voltage values.
P/N
Voltage to apply
S700Y0883 (7101-05-1050-575-9)
S702Y0420 (8862-01-1150-707-9)
S702Y0443 (8862-101-1150-707-9)
250 VDC Max
7827-03, 7827-02
S700Y0840 (5421-10-932-430-8)
S702Y0202 (5421-14-932-430-8)
7702-02, 7702-03, 7702-04
250 VDC
473873-2, 473873-8
10-1050
N/A
12134-00
3601-91
45 VDC
  • On the responder of each detector, make sure that the insulation resistance value is higher than 20 Megohms ASM 261201:
    . Between pin A and the responder metal casing and between pin D and the responder metal casing for the engine 2 pylon loop B fire detector (4WD2) and the fan loop B fire detector (4000WD2)
    . Between pin A and the responder metal casing and between pin C and the responder metal casing for the core loop B fire detector (4001WD2).
         a If the insulation resistance value is not correct:
         b If the insulation resistance value is correct:
  • Do a check and repair the wiring of the FIRE DET I/P (LOOP B) from the engine 2 FDU (2WD2) to the three loop B fire detectors ASM 261201.
Subtask 26-12-00-810-055-C ** ON A/C NOT FOR ALL
B. If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B:
   (1) If one or more fire detector(s) is (are) damaged:
   (2) If there is no visual damage, do a visual inspection of the engine 2 near the three fire detectors.
Make sure that:
     (a) There is no fuel or hydraulic leakage.
     (b) There is no air leakage at the connections of the bleed air duct.
     (c) The electrical cables are correctly connected.
     (d) The bend in the flex hose is outboard and away from the engine AMM 78-36-51-400-040.
   (3) If there is no visual damage, do a visual inspection for retention or worn contact of each pin of the terminal block 450VT2 AWM 261208. If necessary, replace the terminal block.
   (4) If there is no visual damage, swap the pins that follow:
  • The pins B and D of the terminal block 450VT2 section 1 with the pins D and A of the terminal block 450VT2 section 2 AWM 261206 and AWM 261208.
     (a) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B again:
  • Swap back the pins B and D of the terminal block 450VT2 section 1 with the pins D and A of the terminal block 450VT2 section 2.
  • Repair the wiring from the terminal block 450VT2 section 2 to the engine 2 Fire Detection Unit (FDU) (2WD2) AWM 261208.
     (b) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP A:
  • Swap back the pins B and D of the terminal block 450VT2 section 1 with the pins D and A of the terminal block 450VT2 section 2.
  • Swap the pins of the terminal block 450VT2 section 1 of the engine 2 pylon loop A fire detector (3WD2) with the pins of the terminal block 450VT2 section 2 of the engine 2 pylon loop B fire detector (4WD2) AWM 261206 and AWM 261208.
  • Continue with the subsequent step.
     (c) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP A:
  • Swap back the pins of the fire detector (3WD2) with the pins of the fire detector (4WD2).
  • Do a check and if necessary, repair the wiring from the terminal block 450VT2 section 2 to the fire detector (4WD2) AWM 261208.
       1 If the wiring is correct and if the fault continues:
     (d) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B again:
  • Swap back the pins of the fire detector (3WD2) with the pins of the fire detector (4WD2).
  • Swap the pins of the terminal block 450VT2 section 1 of the core loop A fire detector (4001WD1) with the pins of the terminal block 450VT2 section 2 of the core loop B fire detector (4001WD2) AWM 261206 and AWM 261208.
  • Continue with the subsequent step.
     (e) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP A:
  • Swap back the pins of the fire detector (4001WD1) with the pins of the fire detector (4001WD2).
  • Do a check and if necessary, repair the wiring from the terminal block 450VT2 section 2 to the fire detector (4001WD2) AWM 261208.
       1 If the wiring is correct and if the fault continues:
     (f) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B again:
  • Swap back the pins of the fire detector (4001WD1) with the pins of the fire detector (4001WD2).
  • Swap the pins of the terminal block 450VT2 section 1 of the fan loop A fire detector (4000WD1) with the pins of the terminal block 450VT2 section 2 of the fan loop B fire detector (4000WD2) AWM 261206 and AWM 261208.
  • Continue with the subsequent step.
     (g) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP A:
  • Swap back the pins of the fire detector (4000WD1) with the pins of the fire detector (4000WD2).
  • Do a check and if necessary, repair the wiring from the terminal block 450VT2 section 2 to the fire detector (4000WD2) AWM 261208.
       1 If the wiring is correct and if the fault continues:
     (h) If the test gives the maintenance message CHECK ENG 2 FIRE LOOP B again:
  • Swap back the pins of the fire detector (4000WD1) with the pins of the fire detector (4000WD2).
  • Continue with the subsequent step.
   (5) If the fault continues:
  • Disconnect the connector 2WD2-B from the engine 2 FDU (2WD2).
  • On the connector, on the wiring side, make sure that the equivalent resistance value between pins J and K is between 1425 ohms and 1575 ohms ASM 261201.
     (a) If the equivalent resistance value is not correct and is:
  • Between 2137 ohms and 2363 ohms: there is one defective detector.
  • Between 4275 ohms and 4725 ohms: there are two defective detectors.
  • Infinite: there is either three defective detectors or a defective wiring.
       1 Disconnect the electrical harness from the three loop B fire detectors.
       2 On the responder of each detector, make sure that the resistance value is between 4275 ohms and 4725 ohms ASM 261201 between:
. Pins A and D for the engine 2 pylon loop B fire detector (4WD2) and the fan loop B fire detector (4000WD2)
. Pins A and C for the core loop B fire detector (4001WD2).
         a If the resistance value is not correct:
         b If the resistance value is correct:
  • Do a check and repair the wiring of the FIRE DET I/P (LOOP B) from the engine 2 FDU (2WD2) to the three loop B fire detectors ASM 261201.
     (b) If the equivalent resistance value is correct:
       1 If the fault continues:
  • Disconnect the electrical harness from the three loop B fire detectors.
  • To do the insulation of the fire detector, refer to the table below for the correct voltage values.
P/N
Voltage to apply
S700Y0883 (7101-05-1050-575-9)
S702Y0420 (8862-01-1150-707-9)
S702Y0443 (8862-101-1150-707-9)
250 VDC Max
7827-03, 7827-02
S700Y0840 (5421-10-932-430-8)
S702Y0202 (5421-14-932-430-8)
7702-02, 7702-03, 7702-04
250 VDC
473873-2, 473873-8
10-1050
N/A
12134-00
3601-91
45 VDC
  • On the responder of each detector, make sure that the insulation resistance value is higher than 20 Megohms ASM 261201:
    . Between pin A and the responder metal casing and between pin D and the responder metal casing for the engine 2 pylon loop B fire detector (4WD2) and the fan loop B fire detector (4000WD2).
    . Between pin A and the responder metal casing and between pin C and the responder metal casing for the core loop B fire detector (4001WD2).
         a If the insulation resistance value is not correct:
         b If the insulation resistance value is correct:
  • Do a check and repair the wiring of the FIRE DET I/P (LOOP B) from the engine 2 FDU (2WD2) to the three loop B fire detectors ASM 261201.
Subtask 26-12-00-810-055-D ** ON A/C NOT FOR ALL
B. If the test confirms the fault:
  • Disconnect connector 2WD2-B from the engine 2 FDU (2WD2).
  • On the connector, on the wiring side, do a check of the equivalent resistance value between pins B/J and B/K, ASM 261201.
   (1) If the resistance value is between 3078 ohms and 3402 ohms:
  • Do a check of the wiring between the engine-2-pylon loop-B fire-detector (4WD2) and the first terminal block, AWM 261208.
     (a) If the wiring is not correct:
  • Disconnect the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2) from the engine-2-pylon loop-B fire-detector (4WD2).
  • On the responder, make sure that the resistance value is between 4275 ohms and 4725 ohms between pins A/A and A/C, ASM 261201.
       1 If the resistance values are out of the specified limits:
       2 If the resistance values are in the specified limits:
  • Do a continuity test of the wiring of the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2), AWM 261208.

         a If there is no continuity:
         b If there is continuity:
  • Do a check and repair the wiring between first terminal-block and the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2), AWM 261208.
  • Connect the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2) to the engine-2-pylon loop-B fire-detector (4WD2).
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).

     (b) If the wiring is correct:
  • Connect the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2) to the engine-2-pylon loop-B fire-detector (4WD2).
  • Do a check of the wiring between the first terminal-block and the core-AGB loop-B fire-detector (4002WD2), AWM 715175.
       1 If the wiring is not correct:
  • Repair it.
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).
       2 If the wiring is correct:
         a If the fault continues:
   (2) If the resistance value is between 4275 ohms and 4725 ohms:
  • Do a check of the wiring between, AWM 261208 and AWM 715175:
    . Pin A/C of the core-ventilation loop-B fire-detector (4001WD2) and the first terminal-block
    . Pin A/A of the core-ventilation loop-B fire-detector (4001WD2) and the first terminal-block
    . Pin A/C of the core-AGB loop-B fire-detector (4002WD2) and the first terminal-block
    . Pin A/A of the core-AGB loop-B fire-detector (4002WD2) and the first terminal-block.
     (a) If the wiring is not correct:
  • Replace it (them).
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).
     (b) If the wiring is correct:
   (3) If the resistance value is between 6469.5 ohms and 7150.5 ohms:
  • Do a check of the wiring between the engine-2-pylon loop-B fire-detector (4WD2) and the first terminal-block, AWM 261208.
     (a) If the wiring is not correct:
  • Disconnect the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2) from the engine-2-pylon loop-B fire-detector (4WD2).
  • On the responder, make sure that the resistance value is between 4275 ohms and 4725 ohms between pins A/A and A/C, ASM 261201.
       1 If the resistance values are out of the specified limits:
       2 If the resistance values are in the specified limits:
  • Do a continuity test of the wiring of the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2), AWM 261208.

         a If there is no continuity:
         b If there is continuity:
  • Do a check and repair the wiring between the first terminal-block and the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2), AWM 261208.
  • Connect the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2) to the engine-2-pylon loop-B fire-detector (4WD2).
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).

     (b) If the wiring is correct:
  • Connect the engine-2-pylon fire-detector harnesses (41WD2) and (42WD2) to the engine-2-pylon loop-B fire-detector (4WD2).
  • Do a check of the wiring between the first terminal-block and the core-ventilation loop-B fire-detector (4001WD2), AWM 261208 and AWM 715175.
       1 If the wiring is not correct:
  • Repair it.
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).
       2 If the wiring is correct:
         a If the fault continues:
   (4) If the resistance value is infinite:
     (a) Do a check of the wiring between, AWM 261208:
  • Pin B/K of the connector 2WD2-B and the first terminal-block
  • Pin B/J of the connector 2WD2-B and the first terminal-block.
       1 If the wiring is not correct:
  • Repair it (them).
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).
       2 If the wiring is correct:
  • Do a check of the wiring between, ASM 261201:
    . Pin B/K of the connector 2WD2-B and pin A/C of the core-ventilation loop-B fire-detector (4001WD2)
    . Pin B/J of the connector 2WD2-B and pin A/A of the core-ventilation loop-B fire-detector (4001WD2)
    . Pin B/K of the connector 2WD2-B and pin A/C of the core-AGB loop-B fire-detector (4002WD2)
    . Pin B/J of the connector 2WD2-B and pin A/A of the core-AGB loop-B fire-detector (4002WD2)
    . Pin B/K of the connector 2WD2-B and pin A/C of the engine-2-pylon loop-B fire-detector (4WD2)
    . Pin B/J of the connector 2WD2-B and pin A/A of the engine-2-pylon loop-B fire-detector (4WD2).
         a If the wiring is not correct:
  • Repair it (them).
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).
         b If the wiring is correct:
   (5) If the resistance value is between 225 ohms and 1312.1 ohms:
  • Do a visual check for water on all the connections:
     (a) If there is water:
  • Clean the connection(s).
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).
     (b) If there is no water:
  • On the responder of the engine-2-pylon loop-B fire-detector (4WD2), apply 45VDC voltage and make sure that the insulation resistance value is more than 100 Mohms.
       1 If the insulation resistance value is not correct:
       2 If the insulation resistance value is correct:
         a On the responders of the core-AGB loop-B fire-detector (4002WD2) and of the core-ventilation loop-B fire-detector (4001WD2), apply voltage between 15VDC and 28VDC and make sure that the insulation resistance value is more than 100 Mohms:
   (6) If the resistance value is between 0 ohms and 178 ohms:
  • On the responders, do a check of the equivalent resistance value between, ASM 261201:
    . Pin A/C and A/A of the core-ventilation loop-B fire-detector (4001WD2)
    . Pin A/C and A/A of the core-AGB loop-B fire-detector (4002WD2)
    . Pin A/C and A/A of the engine-2-pylon loop-B fire-detector (4WD2).
     (a) If the resistance values are null:
     (b) If the resistance values are corrects:
  • Do a check of the wiring between, ASM 261201:
    . Pin A/C of the core-ventilation loop-B fire-detector (4001WD2) and the first terminal-block
    . Pin A/A of the core-ventilation loop-B fire-detector (4001WD2) and the first terminal-block
    . Pin A/C of the core-AGB loop-B fire-detector (4002WD2) and the first terminal-block
    . Pin A/A of the core-AGB loop-B fire-detector (4002WD2) and the first terminal-block
    . Pin A/C of the engine-2-pylon loop-B fire-detector (4WD2) and the first terminal-block
    . Pin A/A of the engine-2-pylon loop-B fire-detector (4WD2) and the first terminal-block.
       1 If the wiring is not correct:
  • Repair it (them).
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).
       2 If the wiring is correct:
  • Replace the terminal-block .
  • Connect connector 2WD2-B to the engine 2 FDU (2WD2).
Subtask 26-12-00-710-059-A
C. Do the test given in Para. 3.
[Rev.8 from Aug 2018] 2026.04.04 04:27:06 UTC
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