B737
MAINTENANCE MANUAL
EFFECTIVITY
Post ELT STC ST03081AT
23-24-00
PAGE 001
JAN 02/07
EMERGENCY LOCATOR TRANSMITTER SYSTEM
DESCRIPTION AND OPERATION
1. General
A.
The ARTEX C406-1 series ELT’s are a “third generation ELT,” transmitting on 121.5, 243.0 and
406.025 MHz. The ELT’s are designed to meet or exceed the requirements of TSO C91a, TSO
C126 and the mandatory automatic ELT requirements of FAR Part 91. The ELT meets the
requirements of Canadian Aviation Regulation (CAR) Part V, Subpart 51, Airworthiness Manual
Section 551.104. In addition, these ELT’s are designed to meet the requirements of Eurocae ED-
62.
B.
The C406-1 series ELT’s employ a completely new transmitter which features higher output
power and a more integrated design. The 121.5/243.0 MHz section of the transmitter is
contained in a module with the 406.025 MHz transmitter. The top circuit board contains the
microprocessor that controls the module and all ELT functions. The C406-1 is a single output
ELT, unlike previous models of ARTEX 406 MHz ELT’s.
C.
The ELT automatically activates during a crash and transmits the standard swept tone on 121.5
and 243.0 MHz. Every 50 seconds for 520 milliseconds (long message protocol) the 406.025
MHz transmitter turns on. During that time an encoded digital message is sent to the satellite.
The information contained in that message is shown below:
• Serial Number of the Transmitter or Aircraft ID
• Country Code
• I.D. Code
• Position Coordinates (when coupled to an ARTEX ELT/NAV Interface unit [453-6500]).
D.
The 406.025 MHz transmitter will operate for 24 hours and then shuts down automatically. The
121.5/243.0 MHz transmitter will continue to operate until the unit has exhausted the battery
power which typically will be at least 72 hours.
E.
The ELT/NAV Interface unit (if installed) allows the ELT to communicate with the aircraft’s
navigation system and receive position data (longitudinal and latitude) which the ELT will transmit
in the event of a crash. Programming the ELT with the 24 bit long message protocol allows the
ELT to be automatically programmed by the ELT/NAV interface with the aircraft’s 24 bit address.
The ELT/NAV interface unit must be strapped (binary “1” bits tied to ground) with the same 24 bit
address as the ICAO or mode S transponder system 24 bit address. This gives the ELT the
ability to be moved from one aircraft to another without the need for manual reprogramming of
the ELT. This is advantageous for fleet operators since the ELT/NAV interface unit will
automatically reprogram the ELT with the new aircraft’s 24 bit address identification.
F.
The ARTEX DGL-a dongle allows the operator to easily program aircraft 24-bit (Long Message
Protocol) address into a compatible ELT. The DGL-1 comes attached to the top cover. The top
cover and dongle remain with the aircraft. When an ELT is installed, the DGL-1 reprograms the
ELT with the aircraft’s 24 bit address. The operation of the dongle is fully automatic. When
aircraft power is applied, the DGL-1 verifies the ELT is programmed to the 24 bit address stored
in the dongle. If the addresses match, the DGL-1 shuts down. If there is no match, the DGL-1
reprograms the ELT to the 24 bit address stored in the dongle and then shuts down.
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