General Description; Introduction; Equipment Description - Garmin GMA 347 Installation Manual

1

GENERAL DESCRIPTION

1.1

Introduction

This manual presents mechanical and electrical installation requirements for installing the Garmin
GMA 347 Audio Panel. The GMA 347 can be installed into a variety of airframes by means of an STC,
TC or Field Approval. Each airframe installation may vary. Use only approved data for specific
installation instructions in a particular aircraft. After installation of the GMA 347, FAA Form 337 must
be completed by an appropriately certificated agency to return the aircraft to service.
1.2

Equipment Description

The operation of cellular telephones or other cellular mobile devices aboard aircraft while
airborne is prohibited by FCC rules. Due to the potential for interference with onboard
systems, the operation of cellular communication devices while onboard an aircraft that is
on the ground is subject to (FAA) 14 CFR 91.21.
(FCC) 47 CFR 22.925 prohibits airborne operation of cellular telephones installed in or
carried aboard aircraft. Cellular telephones must not be operated aboard any aircraft
while the aircraft is off the ground. When any aircraft leaves the ground, all cellular
telephones on board that aircraft must be turned off.
Cellular telephones that are on, even in a monitoring state, can disrupt GPS performance.
The Garmin GMA 347 is a horizontally oriented panel-mounted audio control panel and marker beacon
system. The system delivers reliability and versatility for all audio controlling functions. LED-
illuminated pushbuttons and logical panel layout allow audio selection of NAV, COM. LED annunciator
brightness is adjusted to an appropriate level for ambient cockpit light conditions automatically by
photocell dimming. Key brightness is controlled manually with the radio lighting dimming bus. A
failsafe circuit connects the pilot's left headset channel and microphone directly to COM 1 in case power
is interrupted or the unit is turned off.
The Garmin GMA 347 Audio Panel incorporates a microcontroller for processing front panel key
commands, annunciator control, input/output functions, and communication.
The GMA 347 includes a six-position intercom system (ICS) with electronic cabin noise de-emphasis,
two stereo music inputs, and combined pilot, copilot, and passenger volume controls. The intercom
provides four selectable modes of isolation (All, Crew, Pilot, Copilot). A pilot-selectable cabin speaker
output can be used to listen to the selected aircraft radios or to broadcast PA announcements. The PA
function is pilot selectable.
The GMA 347 provides a digital voice recorder with playback capability. Recording is automatic when a
COM signal is received. Playback is controlled by pressing the PLAY button or a remote mounted
switch.
GMA 347 Installation Manual
190-00325-01
CAUTION
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Revision A