Invalid Display

The amber ADF fail flags show in the lower corners of the display when there is a failure of the ADF receivers. The ADF flags show in the same location for the expanded display.

ADF SYSTEM - FRONT PANEL BITE

Test

Push the test switch on the front of the ADF receiver to start the test. The test results show on the LED status indicators on the front of the receiver.

When you push the test switch, the receiver does a check of the internal receiver operation and the interface with the ADF control panel. The self test lasts 30 seconds. This is the test sequence that shows on the LED status indicators:

· 0 to 2 seconds - the LRU status and control fail LEDS come on red

· 2 to 4 seconds - the LRU status LED changes to green and the control fail LED remains red

· 4 to 12 seconds - the LRU status and control fail LEDs go off

· 12 to 42 seconds - the test results show on the LED status indicators.

For test results, the LRU status LED comes on green if there are no LRU faults or red if any faults occur. The control fail LED stays off if the ADF control panel input signal is valid or comes on red if there is no input from the ADF control panel or if the input signal is invalid.

Test

To see the ADF test sequence, select VOR or APP on the EFIS control panel mode selector.

A maintenance person must be in the E/E compartment to start the test from the front of the ADF receiver.

During the first two seconds of the test, the receiver output goes to a fail condition. The pointer goes out of view and the amber ADF flag shows momentarily.

For the next two seconds, the receiver output goes to an NCD condition. During this time, the amber ADF flag goes out of view and the pointer stays out of view.

Next, the test display shows and the pointer goes to a test position of 135 degrees from the heading lubber line until the end of test.

NOTE: The graphic shows a test of ADF receiver 1. For a dual system, the test is the same for ADF receiver 2.

ADF SYSTEM - SELF-TEST