ELT ELT406GPS Installation, Operating And Maintenance Manual Download

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1.3 System Description

ELT406GPS PN 51220-()products are type AF (automatic fixed beacons) and are equipped with
an internal GPS; Helicopter models PN 51220-H42 are equipped with a 5 axis G-switch module
that allows the ELT to be activated in a multi axes.

Certain functions of the different variants are described by the FAA in Notice 8150.3. “Non-
TSO’d functions”.
These “non-TSO’d” functions have the following characteristics:

•

Due to the nature of helicopter operations it is important to note that there is normally
operation in more than just the forward axis. The additional 5 axis “G” switch continues
to provide crash sensing in the axes other than “forward” at a nominal 12 “G” threshold.
This may change the performance specifications, software, hardware, environmental, or
qualification levels of the standard ELT 406 i.e. vibration etc.

•

A GPS receiver may be installed in the unit and will function independently of the base
unit. External power is required to operate the GPS system.

•

There are no changes to the installation and operating instructions or limitations. The
instructions for continued airworthiness (ICA) remain unchanged, for this non-TSO’d
function.

•

No additional failure modes or hazards introduced by use of the non-TSO’d functions
have been noted or anticipated.

•

None of these functions change any of the TSO’d functions of this unit.

The system has been designed to ensure that any inputs, whether shorts or opens in the harness or
any effect of electrostatic discharge (ESD) and connections to +28V or ground can cause the unit
to fail from automatic activation.

The only exception is the coax connected to the antenna.  It must remain connected and
undamaged to ensure proper functions after automatic activation. Any failure can be tested by
the pilot using the cockpit controller.  See section 6 for proper testing.

The RF output is through a single BNC connector. A second SMA connector is used between
the antenna and the unit for receiving real-time GPS information.  All functions are under
microprocessor control. Software is approved per the requirements of RTCA/DO-178B.

The battery pack consists of three D-size, LiMnO2 cells mounted on the rear cover of the unit.
See Sec 7 for detail on battery replacement. These are 5 year life expectancy batteries.  An
internal clock keeps up with actual battery use and alerts the pilot when there is less than the
minimum required battery life as specified by FAR 91.207(c).

406ELTs with GPS come with an antenna, remote switch, mounting plate, coaxes, and install
kits. Standard hardware and wiring are not supplied. See section 2.9 for details