Troubleshooting guide

ARTEX AIRCRAFT SUPPLIES, INC. 570-1600
In addition, for the first 24 hours of operation, a 406 MHz signal is transmitting at 50-second
intervals. This transmission lasts 440 ms and contains identification data programmed into the
beacon and is received by COSPAS-SARSAT satellites. The transmitted data is referenced in a
database (maintained by the national authority responsible for ELT registration) and used to
identify the beacon and owner.
1.6.1 Accuracy
Doppler positioning is employed using both 121.5 MHz and 406 MHz signals. Position accuracy
of the 121.5 MHz signal is within an area of approximately 15-20 km radius about the
transmitter. Due to the better signal integrity of the 406 MHz, its location accuracy is within a 3
km radius.
1.6.2 Switch Operation
In a crash, an acceleration activated crash sensor (G-switch) turns the ELT ‘ON’ automatically
when the ELT experiences a change in velocity (or deceleration) of 4.5 fps ±0.5 fps. Activation
is also accomplished by means of the cockpit mounted remote switch or the switch on the ELT.
To deactivate the ELT set either switch to the ‘ON’ position, then back to ‘ARM’.
The ELT does not have an ‘OFF’ position. Instead, a jumper between two pins on the front D-
sub connector must be in place for the G-switch to activate the unit. The jumper is installed on
the mating half of the connector so that when the connector is installed, the beacon is armed.
This allows the beacon to be handled or shipped without ‘nuisance’ activation (front connector
removed).
NOTE: The ELT can still be manually activated using the local switch on the front of the
ELT. Care should be taken when transporting or shipping the ELT to not move
the switch or allow packing material to become lodged such as to toggle the
switch.
In the ME406HM, activation is also accomplished by any of the 5 auxiliary “G” switches at a
nominal 12 “G” level.
1.6.3 Self-Test mode
Upon turn-off, the ELT automatically enters a self-test mode that transmits a 406 MHz test
coded transmission that monitors certain system functions before returning to the ‘ARM’ mode.
The transmission is ignored by any satellite that receives this signal, but the ELT requires it to
check output power and correct frequency. If the ELT is left activated for approximately 50
seconds or greater, a distress signal is generated that is accepted by the satellites.
In addition to 121.5 and 406 MHz signal integrity, other operating parameters are checked
during the self-test. Error codes are then generated if other problems are found. The error
codes are displayed by a series of “blinks” of the ELT LED, remote LED and audio indicator. See
paragraph 4.4.9,
Installed Transmitter Test , for more details and a description of the error
codes.
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