Input Program Pins

The system select program pin input sets the system modulation rate and system identification. The modulation rate for the RA 1 system is 145Hz, the RA 2 system is 155Hz.

The aircraft installation delay (AID) program pin is grounded to the 57 feet selection. This calibrates the system so that the radio altitude is 0 feet at touchdown. It makes an allowance for these conditions:

· Length of the antenna cables

· Fuselage to ground distance

· Flare angle.

When grounded, the continuous data program pin selects noninterrupted RA data output at all times.

RA SYSTEM - FAULT DETECTION

BITE Module

The built-in test equipment (BITE) module monitors the circuits in the RA receiver/transmitter for faults. The flight fault memory stores the number of faults for each flight leg. Shop personnel use the automatic test equipment (ATE) connector to read the fault memory contents.

Test

A test switch on the front of the RA receiver/transmitter starts an RA self-test. LEDs show the results of the self-test.

The self-tests do a check of these:

· Receiver/transmitter internal status

· ARINC 429 output transmitters status

· Antennas and coaxial cables.

The flight control computers (FCCs) supply a test inhibit signal to the receiver/transmitters. This prevents an RA test when the FCC is in the approach mode.

RA SYSTEM - FRONT PANEL BITE

Test

The front panel BITE test only operates when the airplane is on the ground.

Momentarily push the test switch on the front of the RA receiver/transmitter to start a self test. Monitor the front panel for these results:

· Time = 0 seconds - all front panel LEDs come on red

· Time = 2 seconds - LRU STATUS LED changes to green

· Time = 4 seconds - all front panel LEDs go off

· Time = 6 seconds - applicable LEDs come on to show a normal (green) or fault (red) condition

· Time = 36 seconds - Front panel LEDs go off.

Дата добавления: 2015-11-14