Loss of the MCDU1 Data Detected by the ATSU

TASK 46-21-00-810-810-A
Loss of the MCDU1 Data Detected by the ATSU

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 22-82-12-000-001	Removal of the MCDU
AMM 22-82-12-400-002	Installation of the MCDU
AMM 46-21-00-740-001	BITE Test of the ATIMS
ASM 462105
AMM 46-21-34-000-001	Removal of the Air Traffic Service Unit (ATSU)
AMM 46-21-34-400-001	Installation of the Air Traffic Service Unit (ATSU)

3. Fault Confirmation
Subtask 46-21-00-740-068-A

A. Test
(1) Do the BITE test of the ATIMS AMM 46-21-00-740-001.

4. Fault Isolation
Subtask 46-21-00-810-059-A

A. If the test gives the maintenance message MCDU1(3CA1)/ATSU1(1TX1):

(1) If the fault continues:

(a) If the fault continues:

remove the MCDU 1 and the ATSU
do a check and repair the wiring of the MCDU TRANSMITTER BUS : between pins A/27,28 of the MCDU 1 and pins AA/7E,7F of the ATSU ASM 462105
install the MCDU 1 and the ATSU.

Subtask 46-21-00-740-069-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:34:18 UTC