(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)  Do these steps from the CDU again to enter the present position:
(a)  Set the mode select switches on the inertial reference system (IRS) mode select unit (MSU) to the off position.
1) Make sure the ALIGN light are off.
NOTE: It can takes up to 30 seconds for the ALIGN light to turn off.
(b)  
Set the mode select switches on the inertial reference system (IRS) mode select unit (MSU) to the NAV position.

(c)  
Make sure the ON DC lights on the IRS MSU come on for a short time.

(d)  
Make sure the ALIGN lights on the IRS MSU come on.

(e)  
Do these steps to enter the latitude and longitude from a control display unit (CDU):

NOTE: CDU data lines that permit a selection are identified with a caret ( or >). The CDU has 12 line-select-keys (LSK). Six keys are on each side of the display. LSK 1L thru 6L are on the left side, and LSK 1R thru 6R are on the right side.
1) Push the INIT REF key on the CDU. 2) Push the LSK 6L adjacent to the < INDEX prompt on the CDU. a) Make sure the CDU shows the INIT/REF INDEX 1/1 page. 3) Push the LSK 2L adjacent to the < POS prompt on the CDU. a) Make sure the CDU shows the POS INIT 1/3 page. 4) Put the latitude and longitude data in the scratch pad line of the CDU.
NOTE: Do not put a space between the latitude and longitude. The format of the latitude and longitude data is as follows:
Latitude and longitude: XDDMM.MYDDDMM.M
* Where:
X is N or S for latitude
Y is E or W for longitude
D is the number of degrees

M is the number of minutes 5) Push the LSK 4R adjacent to the SET IRS POS > prompt on the CDU. a) Make sure the CDU shows the latitude and longitude below the SET IRS POS line.
(2)  
Do the repair confirmation below.

(a)  If the maintenance message shows on the CDU and the status code shows on the ISDU, then continue.

(3)  
Use the CDU to enter the present position again.

(4)  
Do the repair confirmation below.

(a)  If the maintenance message shows on the CDU and the status code shows on the ISDU, then continue.

(5)
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.

(6)  
If the test in the installation task for the ADIRU is satisfactory, then you corrected the fault.

(7)  
Do the repair confirmation below.

EFFECTIVITY SIL ALL  34-21 TASK 805 
D633A103-SIL BOEING PROPRIETARY -Copyright # Unpublished Work -See title page for details  Page 210 Oct 15/2008 

G.  Repair Confirmation
(1)  Do these steps:
(a)  Do
the
applicable
ADIRU
BITE
procedure
(34-21
TASK
801).

1)  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.
-------------------------END OF TASK ---------------------------
806. IR Data Invalid -Fault Isolation
A.  Description
(1)  
This task is for these maintenance messages:

(a)  34-21037 IR DATA 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.
　
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