(a)  
OFF - Horizontal and vertical deviation bars and G/P and LAT warning flags are retracted out of view.

 (b)  
APP - The ILS processor drives the deviation bars for front course approach.

 (c)  
B/CRS - The ILS processor reverses the vertical deviation bar deflection for back course approach.

 E. ILS Warning Flag Operation
 (1)  
The ILS warning flags are driven by motors to the out of view position. When the motor is de-energized a spring brings the flag into view.

 (2)  
A transistor switch controls when the motor is energized. During normal operation the switch will be closed and the flag will be out of view.

 (3)  
When a fault occurs the ILS processor logic will open the switch and the flag will be pulled into view.

 F. Control
 (1)  To place the standby attitude/ILS system in operation, the following steps are required.
 (a)  
Provide electrical power (Ref 24-22-00).

 (b)  
Position APP mode select switch on standby attitude/ILS indicator to OFF.

 (c)  
Close the following overhead circuit breaker panel P7 circuit breakers: 1) 7A6 NAV RADIO ILS L 2) 7B24 STBY INSTR ILS IND 3) 7B25 STBY INSTR ATTD IND

 (d)  
Pull caging knob when GYRO warning flag retracts and hold until display stabilizes in the zero pitch and zero roll position.

 (e)  
Gently release the caging knob.

 (f)  
Wait six minutes and verify that pitch and roll indications are |1 degree of airplane attitude.

 (g)  
Verify that G/P and LAT flags and horizontal and vertical deviation bars are retracted out of view.

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

ATTITUDE DISPLAY
28V TO GYRO FLAG MOTOR
28V DC MAIN
1
BATTERY  INPUTGYRO
BUS C749
POWER CURRENT
STDBY ATTITUDE

GYRO
INDICATOR

PROTECTION SENSING
GYRO ROLL
SINE POWER FLAG
PRE-AMP FOLLOWER
DRIVE INVERTER
QUADRATURE
POWER PITCH
SINE WAVE
SUPPLY OSCILLATOR
(DC)
28V DC
STBY BUS

GYRO
C10050
STDBY ILS

COSINE POWER
115V, 400HZPRE-AMP FOLLOWER
INDICATOR
O
3 ,AC P11 OVERHEAD CIRCUIT
VOLTAGE GYRO BREAKER PANEL REGULATOR
CAGE OVERCURRENT
MECH'M PROTECTION
STATIC INVERTER
ILS PROCESSOR28V AC GYRO
POWER PROCESSOR CAGE
GYRO SUPPLY
POWER
POWER SUPPLY KNOB
CAGE INPUT
SUPPLY
(DC)
B/CRSPROTECTION
FAILURE
15V, 5V, MODE
28VMONITOR APP
SELSW
A
OFF
DATA REGISTER
DATA

MODE SEL DISCRETEBUS
SERIAL STORAGE PARALLEL
DATA BUS IN OUT
NO. 2 INTERFACE
LAT G/P LABEL LABEL
G/P DEV PARITY 28V
LAT DEV  TEST
1
APP
B620 LEFT ILS RECEIVER
DATA TEST TEST
OFF
VALIDITY
APP B/CRS
TEST
M
G/P
VALID

G /
P 28V
T
D/A
A
MODE
L
CONVERTER
A
SELECT G/P LAT
FLAG
1 VALID LAT G/P
RETRACT RETRACT
LAT 15V
FLAG
G/P
POINTER
GALVO

15V
NOTES:
B/CRS
1

LAT
FLAGS ARE DRIVEN BY TORQUE
SWITCHING
MOTORS TO THE OUT OF VIEW

POINTERGALVO
POSITION. WHEN MOTOR IS
DE-ENERGIZED SPRING BRINGS
FLAG INTO VIEW.

B339 STATIC INVERTER/ILS PROCESSOR UNIT 5V AC PILOT'S PANELLIGHTS POWER
WWWWW (33-11-00)
N138 STANDBY ATTITUDE/ILS INDICATOR
Standby Attitude Reference System Schematic
Figure 2

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 FAULT ISOLATION/MAINT MANUAL
STANDBY ATTITUDE REFERENCE SYSTEM
　
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