STATIC INVERTER/ILS PROCESSOR B Standby Attitude Reference System Component Location Figure 1
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(2)
The static inverter converts the 28 volts dc into three phase, 115-volt ac, 400 Hz power, which is required by the vertical gyro. The static inverter also provides 28 volts dc to the gyro warning flag motor for flag operation.
(3)
The ILS processor provides 28 volts dc to the G/P and LAT warning flag motors for flag operation. The ILS processor also uses the 28 volts dc as an input for an internal power supply that produces | 15 volts dc and + 5 volts dc. The | 15 volts dc is used for the glide path and lateral deviation bar control and the + 5 volts dc is for ILS processor internal circuitry power.
B. Gyro Operation
(1) The gyro utilizes a spinning pendulum and counterweight device to automatically erect the gyro at turn on. The normal rate of erection is three degrees per minute. A caging knob on the front face of the indicator is used to mechanically accelerate the erection process. Pulling the caging knob and holding it for a few seconds will stabilize the display sphere to the zero pitch and zero roll position. After power is removed, the indicator requires at least nine minutes to come to rest.
C. Gyro Warning Flag Operation
(1)
The GYRO warning flag is driven by a motor 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 the gyro rotor speed is too low or high the switch will be opened and the flag will be pulled into view.
(4)
The flag will be pulled into view when there is a failure in the gyro power circuity or the gyro valid signal voltage drops below 2 volts dc.
D. ILS Operation
(1)
The ILS processor receives ARINC 429 digital glide path and lateral data from the left ILS receiver. The processor converts this data into an anolog output voltage to drive the deviation bars in the indicator.
(2)
The input ILS data is first checked for parity. The data is then converted from serial to parallel data. It is checked for validity and correct labeling (glide path and lateral). Then the data is converted to analog data in the D/A converter.
(3)
If the parity, validity and labeling are correct the analog signals are gated to the glide path and lateral deviation bar galvanometers in the indicator.
(4)
If parity or labeling checks fail the corresponding G/P and LAT warning flag will appear. For invalid data the corresponding devation bar will be retracted and the failure flag will come into view.
(5)
Glide path deviation is displayed by a horizontal bar. The deviation bar moves up and down with the respect to the scale marks on the vertical deviation bar.
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(6)
Lateral deviation is displayed by a vertical bar. The deviation bar moves laterally with respect to the scale marks on the horizontal deviation bar.
(7)
ILS functions are controlled by the mode select switch located in the lower left-hand corner of the indicator front face. The three selectable modes operate as follows:
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