. Tune a receiver (usually the aircraft radio) to 121.5 MHz.
. Turn the ELT aircraft panel switch to “ON”, wait for 3 sweeps on the receiver, which takes about 1 second, and then turn the switch back to the “ARM” (OFF) position while paying special attention of the LED activity upon entering the “ARM” (OFF) condition.
To pass the test, you must hear the 3 sweeps AND see the front panel light immediately begin to flash continuously. During the “ON” to “ARM” transition, the microprocessor in the ELT checks the “G-switch” (automatic activation switch) latching circuit, pins 5 & 12 on the D-sub connector at the ELT; the 406 MHz transmitter for proper RF output and a battery check. If the ELT is working properly, the sequence following entry to the “ARMED” (OFF) condition will result in the panel LED staying illuminated for approximately 1 second, then extinguishing.
Always perform the tests within the first 5 minutes after the hour. Notify any nearby control tower of your intensions, in accordance with AC 43.13, Section 12-22, Note 3. If outside of the US, always follow all local or national regulations for testing of ELTs.
121.5 MHz Test
Tune a receiver (usually the aircraft radio) to 121.5 MHz. Turn the ELT aircraft panel switch “ON” for about 1 second, then back to the “ARM” position. The receiver should voice about 3 audio sweeps.
At turn-off (back to ‘ARM’ state) the panel LED should present 1 pulse. If more are displayed, determine the problem from the list below.
Codes displayed with the associated conditions are as follows:
1 Flash – Indicates that the system is operational and that no error conditions were found.
Caution!
Do not allow test duration to exceed 5 seconds. A false alarm may be generated.
Any time the ELT is activated it is transmitting a 121.5 MHz distress signal. If the unit operates for approximately 50 seconds, a “live” 406 MHz distress signal is transmitted and is considered valid by the satellite system. Any time that the ELT is cycled from “ARM” to “ON” and then back to “ARM”, a 406 MHz signal is transmitted, however it is specially coded as a “self-test” signal that is ignored by the COSPAS-SARSAT satellites.
3 Flashes – Bad load detect. Detects open or short condition on the antenna output or cable. These problems can probably be fixed by the installer.
. Check that the RF cable is connected and in good condition. Perform continuity check of center conductor and shield. Check for a shorted cable.
. Check for intermittent connection in the RF cable. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：DESCRIPTION, OPERATION, INSTALLATION AND MAINTENANCE MANUAL ME406P ELT(30)
