W DOC AIRBUS | TSM A320F

Failure of the Mechanic Call Horn During a Smoke Detection in the Avionics Compartment on Ground

TASK 21-26-00-810-835-A
Failure of the Mechanic Call Horn During a Smoke Detection in the Avionics Compartment on Ground

1. Possible Causes
  • HORN-MECH CALL [15WC]
  • wiring between the relay (4WC) and the mechanic call horn (15WC)
  • wiring between the pin A/X2 of the relay (4WC) and the first terminal block
  • diode module 1800VD
  • wiring between the pin A/D of the relay (12KS2) and the pins A/28 and A/29 of the diode module 1800VD
  • RELAY-OIL LOW PRESS AND GROUND, ENG1 (12KS1)
  • RELAY-OIL LOW PRESS AND GROUND, ENG2 (12KS2)
  • wiring between the pin A/8 of the relay (12KS2) and the pin A/D of the relay (12KS1)
  • wiring between the pin A/8 of the relay (12KS1) and the pin A/A2 of the relay (9HQ)
  • RELAY-HORN CONTROL (9HQ)
  • diode module 1160VD
  • wiring between the pin A/A1 of the relay (9HQ) and the pin A/11 of the diode module 1160VD
  • wiring between the pin A/A of the relay (8WC) and the pin A/26 of the diode module 1160VD
  • RELAY-HORN SPLY RESET (8WC)
  • wiring between the pin A/1 of the relay (8WC) and the first terminal block
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
ASM 212600
AMM 21-26-00-710-003
Operational Check of Smoke Configuration Control Circuit
ASM 234200
AMM 23-42-21-000-001
Removal of the Mechanic Call Horn
AMM 23-42-21-400-001
Installation of the Mechanic Call Horn
3. Fault Confirmation
Subtask 21-26-00-710-110-A
A. Test
   (1) Do an operational test of the control circuit of the smoke configuration AMM 21-26-00-710-003.
     (a) Make sure that the mechanic call horn operates correctly.
4. Fault Isolation
Subtask 21-26-00-810-088-A
A. If the mechanic call horn does not operate correctly:
  • on the VENTILATION section of the panel 22VU, release the EXTRACT and the BLOWER pushbutton switches
  • on the overhead control and indicating panel 21VU, push the CALLS/MECH pushbutton switch
  • make sure that the mechanic call horn operates correctly.
   (1) If the mechanic call horn does not operate correctly:
  • make sure that the CALLS/MECH pushbutton switch is pushed, and do a check for:
    . ground at the pin A/X2 of the horn supply relay (4WC)
    . ground at the pin (-) of the mechanic call horn (15WC)
    . 28VDC at the pin A/A1 of the horn supply relay (4WC)
    . 28VDC at the pin (+) of the mechanic call horn (15WC)
    ASM 234200.
     (a) If there is a ground signal and 28VDC:
     (b) If there is no ground signal and 28VDC:
  • repair the wiring between the relay (4WC) and the mechanic call horn (15WC).
       1 If the fault continues:
  • repair the wiring between the pin A/X2 of the relay (4WC) and the first terminal block.
   (2) If the mechanic call horn operates correctly:
  • do a check for ground at the pin A/D of the ENG2 oil low pressure and ground relay (12KS2) ASM 212600.
     (a) If there is no ground signal:
  • replace the diode module 1800VD .
       1 If the fault continues:
  • repair the wiring between the pin A/D of the relay (12KS2) and the pins A/28 and A/29 of the diode module 1800VD.
     (b) If there is a ground signal:
  • do a check for ground at the pin A/A2 of the horn control relay (9HQ) ASM 212600.
       1 If there is no ground signal:
  • do a check of the RELAY-OIL LOW PRESS AND GROUND, ENG1 (12KS1) and the RELAY-OIL LOW PRESS AND GROUND, ENG2 (12KS2)
  • replace them if necessary.
         a If the fault continues:
  • repair the wiring between the pin A/8 of the relay (12KS2) and the pin A/D of the relay (12KS1).

    - If the fault continues:
    . repair the wiring between the pin A/8 of the relay (12KS1) and the pin A/A2 of the relay (9HQ).
       2 If there is a ground signal:
  • do a check for ground at the pin A/A of the horn supply-reset relay (8WC) ASM 212600 and ASM 234200.
         a If there is no ground signal:
  • replace the RELAY-HORN CONTROL (9HQ).

    - If the fault continues:
    . replace the diode module 1160VD .

    - If the fault continues:
    . repair the wiring between the pin A/A1 of the relay (9HQ) and the pin A/11 of the diode module 1160VD.

    - If the fault continues:
    . repair the wiring between the pin A/A of the relay (8WC) and the pin A/26 of the diode module 1160VD.
         b If there is a ground signal:
  • do a check for ground signal at the pin A/X2 of the relay (4WC) ASM 234200.

    - If there is no ground signal:
    . replace the RELAY-HORN SPLY RESET (8WC).

    - If the fault continues:
    . repair the wiring between the pin A/1 of the relay (8WC) and the first terminal block.
Subtask 21-26-00-710-111-A
B. Do the operational test given in Para. 3.
[Rev.8 from Aug 2018] 2026.04.04 04:24:39 UTC
"AVIABRAIN" 2025