Test Indications
Push the TEST switch to start the test. The LRU STATUS, CONTROL FAIL, and ANTENNA FAIL indicators show red for three seconds. Then, the LRU STATUS indicator shows green and the other indicators show red for three more seconds.
Then, all indicators go off for three seconds.
Then, the transceiver shows the result of the test for 30 seconds. If the LRU STATUS indicator is green and the CONTROL FAIL and ANTENNA FAIL indicators are not on, then the test result is good. If an indicator is red, then there is a failure.
The red LRU STATUS indicator comes on if there is a failure of the VHF transceiver. The red CONTROL FAIL indicator comes on if there is a failure of the signal from the control panel or the ACARS management unit. The red ANTENNA FAIL comes on if there is a failure of the antenna or the wiring between the transceiver and the antenna.
Radio Communication Panel bite Indication
When you push the VHF switch on the radio communication panel (RCP), the display usually shows a VHF radio frequency. If the built-in test equipment in the RCP senses a failure, you see one of these displays:
Inop inop
If the RCP receives no signal from the VHF transceiver, both displays show INOP. This occurs for these conditions:
There is no VHF transceiver
The VHF transceiver has no power
The VHF transceiver can not send ARINC 429 data to the RCP
The RCP does not receive the ARINC 429 data from the VHF transceiver
Wiring from the VHF transceiver to the RCP is bad.
If the RCP receives the FAIL WARN signal from the VHF transceiver, both displays show FAIL. This occurs when the BITE in the VHF transceiver senses that the transceiver has a failure.
If the RCP has a failure, the active display shows PANEL and the standby display shows FAIL.
