(c)
True airspeed (TAS) data does not show on the captain’s EFIS display.

B.  Possible Causes
(1)
Loose AOA vane ground wire in ground stud

(2)
ADM sensor

(3)
Wiring between the ADIRUs and the DEU 1

(4)
Left ADIRU, M1749

(5)
DEU 1, M1808

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
D 5 C01359 DISPLAY DEU 1 PRI
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 10 C01361 DISPLAY DEU 1 HOLDUP

D.  Related Data
(1)
(SSM 34-21-14)

(2)
(SSM 34-21-24)

(3)
(WDM 34-21-14)

EFFECTIVITY

34-21 TASKS 826-827
SIL ALL
Page 254 D633A103-SIL Oct 15/2008

(4) (WDM 34-21-24)
E.  Initial Evaluation
(1)  Do these steps to prepare for initial evaluation and fault isolation:
(a)  
Make sure the DISPLAY switch on the P5 panel is in the AUTO position.

(b)  
Make sure the left ADIRU is aligned and in the NAV mode.

(c)  
Make sure the R IRS switch on the mode select unit is in the OFF position.

(d)  
Open these circuit breakers and install safety tags:

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

(2)  If the observed fault shows on the captain’s EFIS display, then do the Fault Isolation Procedure below.
(a)  Remove the safety tags and close these circuit breakers:
F/O Electrical System Panel, P6-1
Row Col Number Name
C 15 C00426 ADIRU RIGHT EXC
C 17 C01010 ADIRU RIGHT DC

(3)  If the observed fault does not show on the captain’s EFIS display, then there was an intermittent fault.
(a)  Remove the safety tags and close these circuit breakers:
F/O Electrical System Panel, P6-1
Row Col Number Name
C 15 C00426 ADIRU RIGHT EXC
C 17 C01010 ADIRU RIGHT DC

F. Fault Isolation Procedure
(1)  
Do the air data inertial reference system self-test in this task: Air Data Inertial Reference System -Operational Test, AMM TASK 34-21-00-710-801.

(a)  
If static or pitot ADM test is unsatisfactory, then do these steps.

1) Replace the static and/or pitot ADM as appropriate, these are the tasks: Pitot Air Data Module Removal, AMM TASK 34-21-04-000-801, Pitot Air Data Module Installation, AMM TASK 34-21-04-400-801, Static Air Data Module Removal, AMM TASK 34-21-04-000-802, Static Air Data Module Installation, AMM TASK 34-21-04-400-802. a) If static and/or pitot ADM test is satisfactory, then you corrected the fault. b) If the test is unsatisfactory, then continue.

(b)  
If the test is satisfactory, then continue.

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

(a)  
If there is a left ADIRS fault message that shows on the CDU, then go to the FIM task to clear that message.

(b)  
After you clear the left ADIRS maintenance messages, if the observed fault does not show on the captain’s EFIS display, then you corrected the fault.

(c)  
After you clear the left ADIRS maintenance messages, if the observed fault continues to show on the captain’s EFIS display, then continue.
　
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