Ameri-King AK-451-ELT - Manual (Page 75)

75
3.2 OPERATION
The AK-451 ELT, Emergency Locator Transmitter, is a state of the art Micro
controller technology, long lasting, solid state based equipment. It is an extremely
reliable, highest standard of quality, designed to meet TSO-C126 and TSO-C91a
requirements for critical application.
Both ELT main unit and Remote Switch are self-powered by their own internal
batteries. Interface with aircraft electrical power system is not required.
With the main switch, located on the ELT main unit, set at "ARM" position, the AK-
451 ELT is automatically activated upon sensing a change of velocity of 4.5 ± 0.5
Feet/Second, along its longitudinal axis (Automatic Fixed-ELT (AF) Configuration).
It is also designed to be removed from the aircraft and used as a personal locating
device when it is necessary to leave the scene of the accident (Automatic Portable
ELT (AP) Configuration) and survival ELT(s) configuration.
In the event of a crash, the AK-451 activates automatically, and transmits the standard
swept tone on 243/121.5 MHz lasting until battery power is gone. This 243/121.5
MHz signal is mainly used to pinpoint the beacon during search and rescue
operations.
For the first 24 hours of operations, a 406 MHz signal is transmitted at 50-second
intervals. This transmission lasts 520 ms and contains identification data programmed
into the beacon and is received by COSPAS-SARSAT satellites. The aircraft
GPS/NAV latitude/longitude data position will also be transmitted (if GPS/NAV is
connected with the ELT). 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.
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 about a 1-2 km radius. If the GPS/NAV position data is
transmitted, the accuracy of the AK-451 will narrow to 22 meters (typically).
3.3
TRANSMITTER FUNTIONAL TEST
The ELT should be tested every month.