W DOC AIRBUS | TSM A320F

Loss of the Signal from the Tachometer (Wheel 1) to the BSCU

TASK 32-42-00-810-817-A
Loss of the Signal from the Tachometer (Wheel 1) to the BSCU

1. Possible Causes
  • DRIVE ASSY-TACHOMETER,WHEEL 1 [2681GM]
  • BSCU [10GG]
  • TACHOMETER-WHEEL 1 [19GG]
  • wiring
  • SEC-2 [1CE2]
  • SEC-3 [1CE3]
  • wiring from the tachometer (19GG) pins A/A and A/C to the BSCU (10GG) pins AB/5K, AB/5J
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 27-94-34-000-001
Removal of the SEC
AMM 27-94-34-400-001
Installation of the SEC
AMM 32-41-11-000-006
Removal of the MLG Wheel
AMM 32-41-11-400-006
Installation of the MLG Wheel
AMM 32-42-00-720-002
Functional Test of the Tachometers and the Anti-Skid System with the Normal Braking System ON
AMM 32-42-00-720-003
Functional Test of the tachometers with the AIDS.
ASM 324202
AMM 32-42-34-000-001
Removal of the Braking/Steering Control Unit (BSCU)
AMM 32-42-34-400-001
Installation of the Braking/Steering Control Unit (BSCU)
AMM 32-42-57-000-001
Removal of the Tachometer
AMM 32-42-57-400-001
Installation of the Tachometer
AMM 32-42-68-000-003
Removal of the MLG Tachometer-Drive
AMM 32-42-68-400-003
Installation of the MLG Tachometer-Drive
TSM TASK 32-42-00-03
NORMAL BRAKING - TASK SUPPORTING DATA
3. Fault Confirmation
Subtask 32-42-00-720-054-A ** ON A/C NOT FOR ALL
A. Test
Do the functional test of the tachometer AMM 32-42-00-720-002 or AMM 32-42-00-720-003.
Subtask 32-42-00-720-054-B ** ON A/C NOT FOR ALL
A. Do a Check to Know if the Fault Message is Spurious or Not.
   (1) If you find all of the conditions that follow, the fault message is spurious:
     (a) Do a check of the last five entries in the aircraft logbook and make sure that these ECAM warnings are not shown:
  • BRAKES AUTO BRK FAULT/BRAKE RELEASED
  • BRAKES RELEASED.
     (b) Do a check of the Post Flight Report (PFR):
       1 Make sure that the PFR gives the ECAM warning:
  • BRAKES AUTO BRK FAULT/BRAKE RELEASED, or
  • BRAKES RELEASED.
NOTE: If the PFR gives also the message SEC2 OR INPUT OF WHEEL TACHOMETER or SEC3 OR INPUT OF WHEEL TACHOMETER, it is necessary to do the related troubleshooting procedure.
     (c) Make sure that the TROUBLE SHOOTING DATA (TSD) gives the fault code 850 32-42-00-03 TSM TASK 32-42-00-03.
     (d) Make sure that the REFERENCE SPEED is more than 100 kts in the TSD, page 1/2 32-42-00-03 TSM TASK 32-42-00-03.
4. Fault Isolation
Subtask 32-42-00-810-066-A ** ON A/C NOT FOR ALL
A. If the test does not confirm the fault:
   (1) Do a visual inspection of the tachometer drive mechanism and make sure that:
  • The tachometer drive shaft moves freely.
  • The splines of the tachometer drive shaft are in the correct condition.
  • The splines of the tachometer hubcap or the splines of the debris guard (if brake fans are installed) are in the correct condition.
NOTE: The functional test of the tachometer can be correct although the splines are worn.
   (2) If the tachometer drive is damaged:
   (3) If the tachometer hubcap or the debris guard (if brake fans are installed) is damaged:
Subtask 32-42-00-810-066-B ** ON A/C NOT FOR ALL
A. Confirmation of the type of failure on the TROUBLE SHOOTING DATA of the BSCU:
   (1) If the TROUBLE SHOOTING DATA gives fault code 850:
  • Refer to Para. B.
   (2) If the TROUBLE SHOOTING DATA gives fault code 858, 868 or 878:
  • Refer to Para. C.
Subtask 32-42-00-810-253-A ** ON A/C NOT FOR ALL
B. Do a check to know if the fault message is spurious or not.
   (1) If the two conditions that follow occur at the same time, the fault is spurious:
     (a) Do a check of the last five flight entries in the aircraft logbook:
  • Make sure that there are no other BRAKES AUTO BRK FAULT/BRAKE RELEASED or other BRAKES RELEASED ECAM warnings in the last five flights.
     (b) Make sure that the REFERENCE SPEED is more than 100 kts in the TROUBLE SHOOTING DATA page 1/2 32-42-00-03 TSM TASK 32-42-00-03.
   (2) If the fault is spurious:
     (a) Do a reset of the BSCU [10GG] : set the A/SKID & N/W STRG switch to OFF, then to ON, on landing gear control and indicating panel 402VU.
   (3) If the fault is not spurious:
  • Refer to Para. C.
Subtask 32-42-00-810-246-A ** ON A/C NOT FOR ALL
C. If the test confirms the fault:
   (1) Do a visual inspection of the tachometer drive mechanism and make sure that:
  • The tachometer drive shaft moves freely and the splines of the tachometer drive shaft are in the correct condition.
  • The splines of the tachometer hubcap or the splines of the debris guard (if brake fans are installed) are in the correct condition.
     (a) If the tachometer drive shaft is damaged or the splines of the tachometer drive shaft are not in the correct condition:
     (b) If the tachometer hubcap or the debris guard (if brake fans are installed) is damaged:
     (c) If the tachometer drive mechanism is not damaged:
   (2) If the fault continues:
  • Do a check of the wiring ASM 324202 between:
    . Pin A/A of the TACHOMETER-WHEEL 1 [19GG] and pin AB/5K of the BSCU [10GG]
    . Pin A/C of the TACHOMETER-WHEEL 1 [19GG] and pin AB/5J of the BSCU [10GG]
     (a) If the wiring is not correct:
  • Repair the wiring .
     (b) If the wiring is correct:
   (3) If the fault continues:
   (4) If the fault continues:
Subtask 32-42-00-720-055-A ** ON A/C NOT FOR ALL
D. Do the functional test given in Para. 3.A.
Subtask 32-42-00-810-246-B ** ON A/C NOT FOR ALL
E. Do the functional test of the tachometer AMM 32-42-00-720-002 or AMM 32-42-00-720-003.
   (1) If the test does not confirm the fault:
     (a) Do a visual inspection of the tachometer drive mechanism and make sure that:
  • The tachometer drive shaft moves freely.
  • The splines of the tachometer drive shaft are in the correct condition.
  • The splines of the tachometer hubcap or the splines of the debris guard (if brake fans are installed) are in the correct condition.
NOTE: The functional test of the tachometer can be correct although the splines are worn.
     (b) If the tachometer drive is damaged:
     (c) If the tachometer hubcap or the debris guard (if brake fans are installed) is damaged:
   (2) If the test confirms the fault:
     (a) Do a visual inspection of the tachometer drive mechanism and make sure that:
  • The tachometer drive shaft moves freely.
  • The splines of the tachometer drive shaft are in the correct condition.
  • The splines of the tachometer hubcap or the splines of the debris guard (if brake fans are installed) are in the correct condition.
     (b) If the tachometer drive is damaged:
     (c) If the tachometer hubcap or the debris guard (if brakes fans are installed) is damaged:
     (d) If the tachometer drive mechanism is not damaged:
     (e) If the fault continues:
     (f) If the fault continues:
     (g) If the fault continues:
     (h) If the fault continues:
Subtask 32-42-00-720-055-B ** ON A/C NOT FOR ALL
F. After the subsequent flight, make sure that the fault does not continue.
[Rev.8 from Aug 2018] 2026.04.04 04:31:32 UTC
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