(2)  
For
the
applicable
ADIRS,
do
this
task:
ADIRS
BITE
Procedure,
34-21
TASK
801.

(3)  
If the maintenance message does not show on the CDU, and the status code does not show on the ISDU, then you corrected the fault.

(4)  
If the maintenance message shows on the CDU and the status code shows on the ISDU, then do the Fault Isolation Procedure below.

F.  Fault Isolation Procedure
(1)  For
the
applicable
DEU,
do
this
task:
CDS
BITE
Procedure,
31-62
TASK
801.

(a)  If the CDS BITE shows a DEU internal fault or an EFIS control panel fault in CURRENT STATUS, then go to the fault isolation task for the applicable CDS maintenance message to correct the fault.
1)  For
the
applicable
ADIRS,
do
this
task:
ADIRS
BITE
Procedure,
34-21
TASK
801.

2)  If the ADIRS maintenance message does not show on the CDU, and the status code does not show on the ISDU, then you corrected the fault.
(b)  If the CDS BITE does not show a DEU internal fault or an EFIS control panel fault, then continue.
(2) Replace the applicable ADIRU. These are the tasks: Air Data Inertial Reference Unit Removal, AMM TASK 34-21-01-000-801, Air Data Inertial Reference Unit Installation, AMM TASK 34-21-01-400-801.
(a)  If the test in the installation task for the ADIRU is satisfactory, then you corrected the fault.
-------------------------END OF TASK ---------------------------
824. Air/Ground Logic Invalid -Fault Isolation
A.  Description
(1)  
This task is for this maintenance message:

(a)  34-21038 AIR/GND LOGIC INVLD

(2)  
The maintenance message is identical for the left and right air data inertial reference systems (ADIRS). The left ADIRS maintenance message is shown on the ADIRS L BITE page on the control display unit (CDU). The right ADIRS maintenance message is shown on the ADIRS R BITE page on the CDU.

EFFECTIVITY

34-21 TASKS 823-824
SIL ALL
Page 245 D633A103-SIL Oct 15/2008

(3)  
The ADIRU receives the air/ground signal from the proximity switch electronics unit (PSEU) to determine the airplane is in air or on ground status. This message shows when the ADIRU receives an invalid air/ground signal from the PSEU.

(4)  
This fault causes the status code 38 to show on the inertial system display unit (ISDU).

B.  Possible Causes
(1)
Proximity switch electronics unit (PSEU), M2061

(2)
ADIRU, M1749 (left) or M1752 (right)

(3)
Wiring problem between the PSEU and the ADIRU

C.  Circuit Breakers
(1)  These are the primary circuit breakers related to the fault:
CAPT Electrical System Panel, P18-1
Row Col Number Name
E 5 C01009 ADIRU LEFT DC
E 7 C01007 ADIRU LEFT AC

CAPT Electrical System Panel, P18-2
Row Col Number Name
E 8 C00425 ADIRU LEFT EXC

F/O Electrical System Panel, P6-1
Row Col Number Name
C 14 C01008 ADIRU RIGHT AC
C 15 C00426 ADIRU RIGHT EXC
C 17 C01010 ADIRU RIGHT DC

D.  Related Data
(1)
(SSM 34-21)

(2)
(WDM 34-21-21)

(3)
(WDM 32-31-12)

E.  Initial Evaluation
(1)  
For
the
applicable
ADIRS,
do
this
task:
ADIRS
BITE
Procedure,
34-21
TASK
801.

　
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