(a) Do a Repair Confirmation below.
G. Repair Confirmation
(1) On the ADIRU MSU, set the IRS switch to NAV.
(a) Make sure the IRS DC FAIL light is not on.
-------------------------END OF TASK ---------------------------
EFFECTIVITY SIL ALL 34-21 TASK 842
D633A103-SIL BOEING PROPRIETARY -Copyright # Unpublished Work -See title page for details Page 281 Oct 15/2010
801. HDG Flag Shows on RMI -Fault Isolation
A. Description
(1)
This task is for this observed fault:
(a) The HDG flag shows on the radio magnetic indicator (RMI).
(2)
The HDG flag shows when RMI receives an invalid signal from air data inertial reference unit (ADIRU).
(3)
The HDG flag is located on the top center of the RMI.
B. Possible Causes
(1)
Left ADIRU, M1749.
(2)
Right ADIRU, M1753.
(3)
RMI, N185.
(4)
Wiring between the RMI and the ADIRUs.
C. Initial Evaluation
(1)
Make sure the ADIRUs are aligned and in the NAV mode.
(2)
Make sure the heading source select switch on the instrument switching module is in the normal position.
(3)
If the HDG flag does not show on the RMI, then you corrected the fault.
(4)
If the HDG flag shows on the RMI, then do the Fault Isolation Procedure below.
D. Fault Isolation Procedure
(1)
Set the heading source select switch on the instrument switching module to the BOTH ON R position.
(2)
If the HDG flag does not show on the RMI, then there is a fault in the left ADIRU or wiring problem between the left ADIRU and the RMI. Do these steps to isolate the fault:
(a)
Set the heading source select switch on the instrument switching module to the BOTH ON L or normal position.
(b)
Do
the
left
ADIRU
BITE
procedure
(34-21
TASK
801).
(c)
If there is a fault that relates to the inertial reference module or the ADIRU internal fault, then do the FIM task to clear that message.
1) If the HDG flag does not show on the RMI, then you corrected the fault.
(d)
If there is no fault message that relates to the inertial reference module or the ADIRU internal fault, then continue.
(e)
Do this check of the wiring between the left ADIRU and the RMI: 1) Remove the left ADIRU. To remove it, do this task: Air Data Inertial Reference Unit Removal, AMM TASK 34-21-01-000-801. 2) Remove the RMI. To remove it, do this task: Radio Magnetic Indicator (RMI) Removal,
AMM TASK 34-22-01-000-801. 3) Do a wiring check between these pins of connectors D3679 and D3687B:
D3679 D3687B
pin41 ------------------pinG7 pin42 ------------------pinG8
EFFECTIVITY SIL ALL 34-22 TASK 801
D633A103-SIL BOEING PROPRIETARY -Copyright # Unpublished Work -See title page for details Page 201 Jun 10/2006
4) If you find a problem with the wiring, then do these steps: a) Repair the wiring. b) Re-install the ADIRU. To install it, do this task: Air Data Inertial Reference Unit
Installation, AMM TASK 34-21-01-400-801. c) Re-install the RMI. To install it, do this task: Radio Magnetic Indicator (RMI) Installation, AMM TASK 34-22-01-400-801. d) If the HDG flag does not show on the RMI, then you corrected the fault. 5) If you do not find a problem with the wiring, then do these steps: a) Re-install the ADIRU. To install it, do this task: Air Data Inertial Reference Unit Installation, AMM TASK 34-21-01-400-801. b) Install a new RMI. To install it, do this task: Radio Magnetic Indicator (RMI) Installation, AMM TASK 34-22-01-400-801. c) If the test in the installation task for the RMI is satisfactory, then you corrected the fault.
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