2) If the maintenance message shows on the CDU, then continue.
-------------------------END OF TASK ---------------------------
803. IR Failure -Fault Isolation
A.  Description
(1)  
This task is for this maintenance message:

(a) 34-21002 IR FAIL

(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.

(3)  
The IR function calculates inertial altitude, present position, groundspeed, heading and attitude etc.

(4)  
The message 34-21002 shows when the ADIRU detects an internal fault of the IR. The IR fault also causes the status code 02 to show on the inertial system display unit (ISDU) and the FAULT light on the mode select unit (MSU) to come on.

B.  Possible Causes
(1) ADIRU, M1749 (left) or M1752 (right).
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 34-21-11)

(2)
(WDM 34-21-11)

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

(2)  
If other maintenance messages are shown on the CDU along with the 34-21002 message, then do the corrective tasks to remove those maintenance messages first.

EFFECTIVITY

34-21 TASKS 802-803
SIL ALL
Page 207 D633A103-SIL Oct 15/2008

(a)  
After you clear the correlated maintenance messages, if the maintenance message 34-21002 does not show on the CDU, the status code 02 does not show on the ISDU, and the FAULT light on the MSU goes off, then you corrected the fault.

(b)  
After you clear the correlated maintenance messages, if the maintenance message 34-21002 continues to show on the CDU, the status code 02 shows on the ISDU, and the FAULT light on the MSU stays on, then do the Fault Isolation Procedure below.

F. Fault Isolation Procedure
(1) 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)  
For
the
applicable
ADIRS,
do
this
task:
ADIRS
BITE
Procedure,
34-21
TASK
801.

(b)  
If the maintenance message does not show on the CDU, the status code does not show on the ISDU, and the FAULT light on the MSU does not come on, then you corrected the fault.

-------------------------END OF TASK ---------------------------
804. Excessive Motion During Alignment -Fault Isolation
A.  Description
(1)  
This task is for this maintenance message:

(a)  34-21003 EXCESSIVE MOTION

(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.
　
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