Garmin GTX 345R, GTX 345, GTX 335 User manual

GTX 3X5 Part 27 AML

Maintenance Manual

Contains Instructions for Continued Airworthiness

for STC SR02124SE

Rotorcraft make, model, registration number, and serial

number and accompanying STC configuration information in

Appendix A must be completed and saved with rotorcraft

permanent records.

190-00734-21 February 2020 Revision 2

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For information regarding the Aviation Limited Warranty, refer to Garmin’s website.

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Telephone: [phone]
Aviation Dealer Technical Support Line (Toll Free): [phone]

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190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page A

RECORD OF REVISIONS

Revision Revision Date Revision Summary

1 11/11/16 Initial release of document.

2

2/17/20

Added new GTX 345 part numbers and added new helicopter
models. Corrected formatting errors.

CURRENT REVISION DESCRIPTION

Section Description

2.4

4.2 Updated wording and ODA STC Unit Administrator.

4.6

5.2 Updated GTX 3X5 Transponder Alert Flowcharts and added sheet 5.

A.3.4 Added EC-135T3 and EC-135P3 models.

Added GTX 345 NV Panel Mount and GTX 345 NV GPS Panel Mount to Table 2-2
Equipment Weights.

Added note to include straps and aluminum foil with measurement during electrical
bonding test.

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page B

INFORMATION SUBJECT TO EXPORT CONTROL LAWS

This document may contain information that is subject to the Export Administration Regulations (EAR)
issued by the United States Department of Commerce (15 CFR, Chapter VII, Subchapter C) and may not
be exported, released, or disclosed to foreign nationals inside or outside of the United States without first
obtaining an export license. A violation of the EAR may be subject to a penalty of up to 10 years
imprisonment and a fine of up to $1,000,000 under Section 2410 of the Export Administration Act of 1979.
Include this notice with any reproduced portion of this document.

Information in this document can change without notice. Go to Garmin’s website fly
updates and supplemental information about the operation of Garmin units.

DEFINITIONS OF WARNINGS, CAUTIONS, AND NOTES

WARNING

A Warning means that injury or death is possible if the instructions are not
obeyed.

CAUTION

A Caution means that damage to the equipment is possible.

NOTE

A Note provides more information.

WARNING

This product, its packaging, and its components contain chemicals known to the State of
California to cause cancer, birth defects, or reproductive harm. This notice is being provided
in accordance with California's Proposition 65. If you have any questions or would like
additional information, please refer to our website at www.garmin.com/prop65

Garmin.com for

.

WARNING

Perchlorate Material - special handling may apply.
Refer to www.dtsc.ca.gov./hazardouswaste/perchlorate

.

CAUTION

The GTX 335/345 units have a special anti-reflective coated display that is sensitive to
waxes and abrasive cleaners. CLEANERS CONTAINING AMMONIA WILL CAUSE
DAMAGE TO THE ANTI-REFLECTIVE COATING. Clean the display with a clean,
lint-free cloth, with a cleaner that is safe for anti-reflective coatings.

NOTE

Screen shots are intended to provide visual reference only. All information depicted in
screen shots, such as software file names, versions, and part numbers, is subject to change
and may not be up-to-date.

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page i

TABLE OF CONTENTS

1 INTRODUCTION..............................................................................................................................1-1

1.1 Content, Scope, and Purpose......................................................................................................1-2

1.2 Organization ...............................................................................................................................1-3

1.3 Applicability...............................................................................................................................1-4

1.4 Publications ................................................................................................................................1-4

1.5 Revision and Distribution...........................................................................................................1-4

1.6 Reference....................................................................................................................................1-5

2 SYSTEM DESCRIPTION.................................................................................................................2-1

2.1 GTX 335/335R...........................................................................................................................2-2

2.2 GTX 345/345R...........................................................................................................................2-4

2.3 Electrical Load Information .......................................................................................................2-6

2.4 Weight and Balance ...................................................................................................................2-7

2.5 Unit Storage................................................................................................................................2-8

3 GTX CONTROL AND OPERATION.............................................................................................3-1

3.1 GTX 335/345..............................................................................................................................3-2

3.2 GTX 335R/345R ........................................................................................................................3-5

3.3 GTX 3X5 Install Tool ................................................................................................................3-6

4 INSTRUCTIONS FOR CONTINUED AIRWORTHINESS.........................................................4-1

4.1 Applicability...............................................................................................................................4-2

4.2 Airworthiness Limitations..........................................................................................................4-3

4.3 Servicing Information ................................................................................................................4-4

4.4 Maintenance/Inspection Intervals ..............................................................................................4-5

4.5 Visual Inspection........................................................................................................................4-6

4.6 Electrical Bonding Test..............................................................................................................4-9

4.7 Additional Instructions...............................................................................................................4-9

5 TROUBLESHOOTING ....................................................................................................................5-1

5.1 GTX General Troubleshooting...................................................................................................5-2

5.2 GTX Failure Annunciations.......................................................................................................5-4

5.3 Connector Pinout Information..................................................................................................5-14

6 UNIT REMOVAL AND RE-INSTALLATION..............................................................................6-1

6.1 GTX 3X5....................................................................................................................................6-2

6.2 Transponder Antenna ...............................................................................................................6-17

6.3 Traffic Annunciator (If Installed).............................................................................................6-17

7 SOFTWARE.......................................................................................................................................7-1

7.1 Software Check ..........................................................................................................................7-2

7.2 GTX 3X5/3X5R Software Update .............................................................................................7-4

8 SYSTEM CONFIGURATION AND CHECKOUT .......................................................................8-1

8.1 Overview ....................................................................................................................................8-2

8.2 System Checkout........................................................................................................................8-2

8.3 Configuration .............................................................................................................................8-2

8.4 GTX Test....................................................................................................................................8-3

9 SYSTEM RETURN TO SERVICE..................................................................................................9-1

9.1 Maintenance Records .................................................................................................................9-1

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page ii

APPENDIX A INSTALLATION-SPECIFIC INFORMATION ........................................................A-1

A.1 Rotorcraft-Specific Information................................................................................................A-2

A.2 Equipment Interfaced to the GTX.............................................................................................A-4

A.3 GTX 3X5 Airframe-Specific Installation................................................................................A-11

A.4 GTX 3X5 Configuration Log..................................................................................................A-28

A.5 GTX 335/335R Configuration Log.........................................................................................A-29

A.6 GTX 345/345R Configuration Log.........................................................................................A-30

APPENDIX B ELECTRICAL BONDING PROCEDURES............................................................... B-1

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page iii

LIST OF FIGURES

Figure 2-1 GTX 335 or GTX 335R Interface Summary ........................................................................2-3

Figure 2-2 GTX 345 or GTX 345R Interface Summary ........................................................................2-5

Figure 3-1 GTX 335/345 Front Panel ....................................................................................................3-2

Figure 3-2 GTN 7XX Transponder Control ...........................................................................................3-5

Figure 3-3 GTN 6XX Transponder Control ...........................................................................................3-5

Figure 3-4 USB A and USB B Connectors ............................................................................................3-6

Figure 3-5 GTX 3X5/3X5R State Page ..................................................................................................3-7

Figure 3-6 GTX 3X5/3X5R Status Page ................................................................................................3-8

Figure 3-7 GTX 3X5/3X5R Configuration Group .................................................................................3-9

Figure 3-8 GTX 3X5/3X5R Diagnostics Group ..................................................................................3-10

Figure 3-9 GTX 3X5/3X5R Product Data Group ................................................................................3-11

Figure 5-1 GTX Transponder Troubleshooting (All Models) ................................................................5-3

Figure 5-2 GTX 3X5 Transponder Alerts ..............................................................................................5-4

Figure 5-3 GTX 3X5 Install Tool Failure/Fault Messages ....................................................................5-9

Figure 5-4 Rear View, Connector J3251 ..............................................................................................5-14

Figure 5-5 Rear View, Connector J3252 ..............................................................................................5-16

Figure 6-1 GTX 3X5 Connector Kits .....................................................................................................6-2

Figure 6-2 GTX 3X5 without GPS Backplate Assembly .......................................................................6-3

Figure 6-3 GTX 3X5 with GPS Backplate Assembly ............................................................................6-4

Figure 6-4 GTX 3X5 Vertical Mount without GPS, Backplate Assembly ............................................6-5

Figure 6-5 GTX 3X5 Vertical Mount with GPS, Backplate Assembly .................................................6-6

Figure 6-6 GTX 3X5 Vertical Mount with TNC XPDR Backplate Assembly ......................................6-7

Figure 6-7 Panel-Mounted GTX 3X5 Transponder .............................................................................6-10

Figure 6-8 GTX 3X5R Remote Transponder with Horizontal Mount .................................................6-12

Figure 6-9 GTX 3X5R Remote Transponder with Vertical Mount .....................................................6-14

Figure 6-10 Garmin Altitude Encoder with Backplate Assembly ..........................................................6-16

Figure 6-11 Traffic Annunciator Installation .........................................................................................6-18

Figure 7-1 GTX 3X5 Start-Up Screen ....................................................................................................7-2

Figure 7-2 GTX 3X5 Product Data Page ...............................................................................................7-2

Figure 7-3 GTN 6XX/7XX System Page ...............................................................................................7-3

Figure 7-4 Install Tool Dialog Box ........................................................................................................7-4

Figure 7-5 GTX 3X5 Install Tool Software Upload Page ......................................................................7-5

Figure A-1 Rotorcraft-Specific Information ..........................................................................................A-2

Figure A-2 Interfaced Equipment Table ................................................................................................A-5

Figure B-1 Aluminum Tape Joint .......................................................................................................... B-2

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page iv

LIST OF TABLES

Table 1-1 Reference Documentation ....................................................................................................1-4

Table 2-1 GTX Electrical Load .............................................................................................................2-6

Table 2-2 Equipment Weights ..............................................................................................................2-7

Table 4-1 Maintenance/Inspection Intervals .........................................................................................4-5

Table 5-1 J3251 Pinout .......................................................................................................................5-14

Table 5-2 J3252 Pinout .......................................................................................................................5-16

Table 5-3 GTX 3X5/3X5R Encoded Altitude Pin Assignments ........................................................5-17

Table 5-4 GTX 3X5/3X5R Discrete Outputs ......................................................................................5-18

Table 5-5 GTX 3X5/3X5R Configurable Output Pins .......................................................................5-18

Table 5-6 GTX 3X5/3X5R Discrete Inputs ........................................................................................5-19

Table 5-7 GTX 3X5/3X5R Configurable Input Pins ..........................................................................5-19

Table 5-8 GTX 3X5/3X5R RS-232 Connections ...............................................................................5-20

Table 5-9 GTX 3X5/3X5R ARINC 429 Connections ........................................................................5-20

Table 5-10 GTX 3X5/3X5R RS-422 Connections ...............................................................................5-20

Table 5-11 GTX 345/345R HSDB Connections ...................................................................................5-21

Table 6-1 GTX 3X5 Connector Kit ......................................................................................................6-2

Table 6-2 Standard Mount Backplate (P/N 011-02976-00 and -01) .....................................................6-3

Table 6-3 Vertical Mount Backplate (P/N 011-02976-10) ...................................................................6-5

Table 6-4 Vertical Mount Backplate (P/N 011-02976-11) ...................................................................6-6

Table 6-5 Vertical Mount Backplate (P/N 011-02976-12) ...................................................................6-7

Table 6-6 GTX 3X5 Transponder Parts List .........................................................................................6-9

Table 6-7 Garmin Altitude Encoder Kit (P/N 011-03080-00) ............................................................6-16

Table 6-8 Traffic Annunciator Installation .........................................................................................6-18

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page v

1 INTRODUCTION

1.1 Content, Scope, and Purpose ............................................................................................................1-2

1.2 Organization......................................................................................................................................1-3

1.3 Applicability .....................................................................................................................................1-4

1.4 Publications.......................................................................................................................................1-4

1.5 Revision and Distribution.................................................................................................................1-4

1.6 Reference ..........................................................................................................................................1-5

1.6.1 Terminology...............................................................................................................................1-5

1.6.2 Acronyms ...................................................................................................................................1-5

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 1-1

1.1 Content, Scope, and Purpose

This document provides Instructions for Continued Airworthiness (ICA) of the GTX 3X5 with ADS-B
functionality installed and compliant to ADS-B Out Version 2 under AML STC SR02124SE. This document
satisfies the requirements for continued airworthiness as defined by 14 CFR Part 27.1529 and 14 CFR Part 27
Appendix A. Information in this document is required to maintain the continued airworthiness of the GTX 3X5.

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 1-2

1.2 Organization

The following outline briefly describes the organization of this manual:

Section 2: System Overview

 Equipment features
 Electrical load information
 Weight and balance

Section 3: Control and Operation

 Controlling the GTX
 Using the GTX 3X5 Install Tool

Section 4: Instructions for Continued Airworthiness

 Applicability
 Airworthiness limitations
 Service information
 Maintenance intervals
 Bonding test

Section 5: Troubleshooting

 General troubleshooting
 Failure annunciations
 Connector pinout information

Section 6: Unit Removal and Re-Installation

 Removal and re-installation of the GTX
 Removal and re-installation of the Garmin Altitude Encoder
 Removal and re-installation of the transponder antenna
 Removal and re-installation of the traffic annunciator (if installed)

Section 7: Software

 Software check
 Software update

Section 8: System Configuration and Checkout

 System checkout
 Configuration
 GTX tests

Section 9: System Return to Service Procedure

 Maintenance records

Appendix A: Rotorcraft-Specific Information

 Rotorcraft-specific information form
 Equipment interfaced to the GTX
 Wire routing
 Configuration logs

Appendix B: Special Bonding Procedures

 Surface preparation
 Aluminum tape repair and replacement considerations

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 1-3

1.3 Applicability

This document applies to all rotorcraft with the GTX 3X5 installed in accordance with STC SR02124SE.
Modification of a rotorcraft by this Supplemental Type Certificate (STC) obligates the rotorcraft operator
to implement the specific maintenance practices and/or airworthiness limitations provided in this
document. This is in addition to the rotorcraft’s existing approved maintenance, inspection, and
airworthiness limitations programs.

1.4 Publications

In addition to this manual, the following documents are recommended to perform maintenance based on
the installed and interfaced equipment. It is the responsibility of the owner/operator to ensure the latest
applicable versions of these documents are used during operation, servicing, or maintenance of the
rotorcraft.

Table 1-1 Reference Documentation

Document Garmin P/N Applicable Sections

GTX 3X5 Part 27 AML STC Equipment List

GTN 625/635/650 Pilot’s Guide

GTN 725/750 Pilot’s Guide

005-00734-A5 All

190-01004-03 2.1 and 15.3.2

190-01007-03 2.1 and 16.3.2

1.5 Revision and Distribution

This document is required for maintaining the continued airworthiness of the rotorcraft. Garmin Dealers
may obtain the latest revision of this document at the Garmin Dealer Resource Center

Dealers are notified of manual revision changes by way of a Garmin Service Bulletin.

Owner and operators may obtain the latest revision of this document at flyGarmin.com
Garmin dealer. Garmin contact information is available at flyGarmin.com

.

website.

or by contacting a

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 1-4

1.6 Reference

1.6.1 Terminology

Except where specifically noted, references made to the GTX 3X5 will apply to the GTX 335/335R/345/
345R. ADS-B or ADS-B Out refers to Version 2 ADS-B Out only. ADS-B In refers to TIS-B traffic and
FIS-B weather received from ground stations over UAT, as well as ADS-B and ADS-R traffic targets
received directly over 1090 MHz or UAT.

Throughout this document, references will be made to metallic rotorcraft. For the purposes of this manual,
metallic rotorcraft will be those with an aluminum skin. Nonmetallic rotorcraft refers to all other rotorcraft
(e.g., rotorcraft with composite skin).

Unless otherwise stated, all units of measure are in US standard units.

The term squitter refers to a burst or broadcast of data that is transmitted periodically by a Mode S
transponder without interrogation.

1.6.2 Acronyms

AC: Advisory Circular HAT: Height Above Terrain

ADC: Air Data Computer ICA: Instructions for Continued Airworthiness

ADS-B: Automatic Dependent Surveillance -

Broadcast

AHRS: Attitude Heading Reference System I/O: Input/Output

AML: Approved Model List MFD: Multifunction Display

ATC: Air Traffic Control PED: Portable Electronic Device

ATCRBS: Air Traffic Control Radar Beacon System SBAS: Satellite-Based Augmentation System

EGNOS: European Geostationary Navigation

Overlay Service

ES: Extended Squitter SRM: Structural Repair Manual

FAA: Federal Aviation Administration STC: Supplemental Type Certificate

FIS-B: Flight Information System-Broadcast TAS: Traffic Advisory System

GAE: Garmin Altitude Encoder TCAS: Traffic Alert and Collision Avoidance

GNS: Garmin Navigation System TIS: Traffic Information Service

GNSS: Global Navigation Satellite System TSO: Technical Standard Order

GPS: Global Positioning System UAT: Universal Access Transceiver

GTN: Garmin Touchscreen Navigator VSWR: Voltage Standing Wave Ratio

GTX: Garmin Transponder WAAS: Wide Area Augmentation System

ICAO: International Civil Aviation Organization

SPI: Special Position Identifier

System

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
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2 SYSTEM DESCRIPTION

2.1 GTX 335/335R .................................................................................................................................2-2

2.2 GTX 345/345R .................................................................................................................................2-4

2.3 Electrical Load Information..............................................................................................................2-6

2.4 Weight and Balance..........................................................................................................................2-7

2.5 Unit Storage ......................................................................................................................................2-8

Garmin GTX 3X5 units operate on radar frequencies receiving ground radar or TCAS interrogations. The
GTX transmits a coded response of pulses to ground-based radar on a frequency of 1090 MHz. Each unit
has IDENT capability and replies to ATCRBS Mode A, Mode C, and Mode S All-Call interrogation. GTX
345/345R units include ADS-B In, which provides TIS-B and FIS-B data via UAT and 1090 MHz. GTX
3X5 units offer an optional Garmin Altitude Encoder to meet the required barometric pressure altitude
source and an optional internal GPS/SBAS source to meet the required GNSS position source integrity for
ADS-B Out.

The Garmin transponders approved by this STC are the family of GTX 3X5 transponders.

GTX 3X5 units all provide ADS-B Out functionality. GTX 345/345R units provide ADS-B In.
GTX 3X5 models include:

 GTX 335

 GTX 345

 GTX 335R

 GTX 345R

Automatic Dependent Surveillance-Broadcast (ADS-B) technology improves situational awareness and
flight safety. A Garmin transponder with ADS-B capabilities will automatically transmit position, velocity,
and heading information to other aircraft and ground stations. The current air traffic control system
depends on a transponder request for pertinent aircraft information; whereas ADS-B provides automatic
transmission of aircraft information without a request.

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 2-1

2.1 GTX 335/335R

GTX 335/335R units are panel or remote-mounted units that have Mode S with ADS-B Out extended
squitter capability. The panel-mounted unit contains an integrated display, while the remote-mounted unit
requires an interface to a control source for normal operation and functionality.

GTX 335/335R units have these features:

 Mode S transponder

 ADS-B Out capability

 Optional internal GNSS receiver

 Optional GAE pressure sensor module

 Entry of squawk code and flight ID

 Show squawk code and flight ID

 Show pressure altitude

 Show outside air temp

 Show density altitude

 Show flight timers

 Audio output

 TIS-A traffic output to a compatible display

The transponder provides an ADS-B Out failure message to alert the crew that the unit has a degraded
ADS-B system.

GTX 335/335R units interface through these:

 ARINC 429

 RS-232

 Gray code

 Discrete I/O

Figure 2-1 provides a summary of the interfaces provided for the GTX 335 or GTX 335R. For interfaces
approved by this STC, refer to GTX 3X5 Part 27 AML STC Installation Manual.

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 2-2

GTX 335/335R

GPS Antenna

GPS Source

Audio Panel

Bottom Antenna

GTX 3X5 with GPS only

OR

GTX 335R

Control

Power/Ground

Altitude Source

Heading Source

Air Data Source

Secondary GPS

Existing LRUNew LRU

Legend

Optional Interfaces

Required Interfaces

Garmin Altitude

Encoder

OR

Temperature

External Ident

External Standby

Traffic System

For XPDR cross-talk

Required if HAT is

Not Available

Collective Switch

Radar Altitude

Source

OR

Aircraft Battery

Keep Alive input from aircraft battery
source for internal G PS o nly

Figure 2-1 GTX 335 or GTX 335R Interface Summary

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 2-3

2.2 GTX 345/345R

GTX 345/345R units are panel or remote-mounted units that supply Mode S with ADS-B Out extended
squitter and UAT and 1090 receivers for ADS-B In capabilities. The panel-mounted unit has an integrated
display, while the remote-mounted unit requires an interface to a control source for normal operation and
functionality.

GTX 345/345R units have these features:

 Mode S transponder

 ADS-B Out capability

 ADS-B In capability with built-in 1090 MHz and UAT receivers

 Optional internal GNSS receiver

 Optional GAE pressure sensor module

 Entry of squawk code and flight ID

 Show squawk code and flight ID

 Show pressure altitude

 Show outside air temp

 Show density altitude

 Show flight timers

 Audio output

 Bluetooth interface to show weather and traffic on portable devices

The transponder provides an ADS-B failure message to alert the crew that the unit has a degraded ADS-B
(In or Out) system.

GTX 345/345R units interface through these:

 HSDB

 ARINC 429

 RS-232

 RS-422

 Gray code

 Discrete I/O

Figure 2-2 provides a summary of the interfaces provided for the GTX 345 or GTX 345R. For interfaces
approved by this STC, refer to GTX 3X5 Part 27 AML STC Installation Manual.

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 2-4

TAS/TCAS I

Traffic Sensor

ADS-B Traffic
FIS-B Display

Bluetooth

Device

GTX 345/345R

GPS Antenna

GPS Source

Audio Panel

Bottom Antenna

GTX 3X5 with GPS only

OR

GTX 345R

Control

Power/Ground

Altitude Source

Heading Source

Air Data Source

Secondary GPS

Existing LRUNew LRU

Legend

Optional Interfaces

Required Interfaces

Bluetooth

External Traffic

Annunciator

For NO display Install

Garmin Altitude

Encoder

OR

Keep Alive input from aircraft battery
source for internal GPS only

Temperature

External Ident

External Standby

Required if HAT is

Not Available

Collective Switch

Radar Altitude

Source

OR

Aircraft Battery

Figure 2-2 GTX 345 or GTX 345R Interface Summary

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 2-5

2.3 Electrical Load Information

Table 2-1 contains electrical load information for the GTX. Circuit protection for the GTX is located
within the rotorcraft’s avionics circuit protection and is labeled “XPDR.” Appendix A contains details
specific to the load changes for the installation.

Table 2-1 GTX Electrical Load

Unit Characteristic

GTX 335

GTX 335, GPS

GTX 345

GTX 345, GPS

GTX 335/345, GPS Input current, GPS KEEP ALIVE

Input current, typical 0.57 A 0.29 A

Input current, maximum 0.86 A 0.43 A

Input current, typical 0.72 A 0.36 A

Input current, maximum 1.22 A 0.61 A

Input current, typical 0.72 A 0.36 A

Input current, maximum 1.30 A 0.65 A

Input current, typical 1.07 A 0.54 A

Input current, maximum 1.43 A 0.72 A

65 µA typical 20 µA typical

85 µA maximum 40 µA maximum

Specification

14 VDC 28 VDC

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
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2.4 Weight and Balance

Update the rotorcraft Equipment List to indicate any items that are added, removed, or relocated. Each
change must include the date and the name and certificate number of the person making the entry.
Table 2-2 contains equipment weights.

Table 2-2 Equipment Weights

Kit P/N Description

010-01214-01 GTX 335 Panel Mount 2.8 / 1.27

010-01214-21 GTX 335 NV Panel Mount 2.8 / 1.27

010-01214-41 GTX 335 GPS Panel Mount 2.9 / 1.32

010-01216-01 GTX 345 Panel Mount 3.1 / 1.41

010-01216-41 GTX 345 GPS Panel Mount 3.2 / 1.45

010-01216-21 GTX 345 NV Panel Mount 3.1 / 1.41

010-01216-61 GTX 345 NV GPS Panel Mount 3.2 / 1.45

010-01215-01 GTX 335 Remote 2.5 / 1.13

010-01217-01 GTX 345 Remote 2.9 / 1.32

Weight

(lbs/kg)

010-01215-41 GTX 335 GPS Remote 2.7 / 1.22

010-01217-41 GTX 345 GPS Remote 3.0 / 1.36

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
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2.5 Unit Storage

The GTX 3X5 transponder unit is qualified for an operating temperature range of -55 ºC to +85 ºC.
Recommended unit storage temperatures (uninstalled) are between 10 ºC and 35 ºC.

190-00734-21 GTX 3X5 Part 27 AML Maintenance Manual
Rev. 2 Page 2-8

3 GTX CONTROL AND OPERATION

3.1 GTX 335/345 ....................................................................................................................................3-2

3.2 GTX 335R/345R...............................................................................................................................3-5

3.3 GTX 3X5 Install Tool.......................................................................................................................3-6

3.3.1 State Page ...................................................................................................................................3-7

3.3.2 Status Page .................................................................................................................................3-8

3.3.3 Configuration Group ..................................................................................................................3-9

3.3.4 Diagnostics Group....................................................................................................................3-10

3.3.5 Product Data Group..................................................................................................................3-11

3.3.6 Software Upload Group ...........................................................................................................3-11

Control and operation of GTX 335/345 units occurs through the front panel of the GTX. Control and
operation of remote-mounted GTX 335R/345R units is handled through the external interface provided via
the GTN 6XX/7XX. ADS-B In information from the GTX 345 can be displayed through the external
interface provided via the GTN 6XX/7XX or GNS 400W/500W series. Figure 3-2 and Figure 3-3 show the
transponder control pages.

Important Codes

NOTE

The selected identification code must be entered carefully (either the one assigned by air
traffic control for IFR flight or an applicable VFR transponder code).

1200 VFR code for any altitude in the US (refer to ICAO standards)

7000 VFR code commonly used in Europe (refer to ICAO standards)

7500 Hijack code (rotorcraft is subject to unlawful interference)

7600 Loss of communications

7700 Emergency

Avoid selecting code 7500 and all codes in the 7600-7777 range. These codes trigger special emergency
alerts in ATC monitoring facilities. A rotorcraft’s transponder code is used for ATC tracking purposes;
therefore, be careful when making routine code changes.

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3.1 GTX 335/345

Figure 3-1 GTX 335/345 Front Panel

Function Selection Keys

NOTE

If the transponder is in the ON or ALT operating mode, the transponder becomes an active
part of the Air Traffic Control Radar Beacon System (ATCRBS). The transponder
responds to interrogations from TCAS-equipped rotorcraft.

The function selection keys are:

OFF Powers off the GTX 3X5.

STBY Selects the Standby mode. Pressing the STBY key when the GTX 335/345 is powered off

automatically powers the unit on in Standby mode. When in Standby mode, the transponder
does not reply to interrogations (but new codes can be entered) and a “SBY” indication
appears on the display.

ON Selects the On mode, which generates Mode A and Mode S replies, but Mode C altitude

reporting is inhibited. Pressing the ON key when the GTX 335/345 is powered off
automatically powers on the unit in Mode A and will transmit a squawk code when
interrogated. ADS-B Out will not return barometric altitude as it switches to GPS altitude in
this mode. Interrogations are indicated by the reply symbol (®). The replies do not include
altitude information.

ALT Altitude mode is automatically selected when the rotorcraft becomes airborne using the unit’s

Air/Ground logic or when the ALT key is pressed. Pressing the ALT key when the
GTX 335/345 is powered off automatically powers on the unit in Altitude Reporting mode.
While the rotorcraft is on the ground and in ALT mode, the transponder does not allow
Mode A and Mode C replies, but it does permit acquisition squitter and replies to Mode S
interrogations.

While the rotorcraft is in ALT mode and airborne, it will generate Mode A, Mode C, and
Mode S replies, as well as transmit acquisition and extended squitter, including ADS-B Out.

All transponder interrogations are indicated by the reply symbol (®).

IDENT Pressing the IDENT key activates the Special Position Identification (SPI) pulse for

18 seconds, identifying the transponder return from others on an air traffic controller’s screen.
During the IDENT period, the word “IDENT” appears in the upper-left corner of the display.

VFR Sets the transponder code to the pre-programmed VFR code selected in Configuration mode

(set to 1200 at the factory). Pressing the VFR key again restores the previous identification
code.

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FUNC In Normal mode, pressing the FUNC key changes the subpage group shown on the right side

of the display. Subpages include Flight ID, Pressure Altitude, Flight Time, Altitude Monitor,
System Count Up, and Count Down Timers. In Configuration mode, it steps through the
function pages.

ENT Confirms entry for selected item and moves the cursor to the next editable item, or function

selection, in configuration and normal operation. Starts and stops the altitude monitor, count
up, count down, and flight timers.

CRSR Selects changeable fields in configuration and normal operation. Initiates entry of the starting

time for the count down timer and cancels transponder code entry. Holding the CRSR key
during power-up will place the unit into a Ground Test mode that forces the rotorcraft into an
airborne status for testing purposes.

CLR Resets the count up, count down, and flight timers. Cancels the previous key press during code

selection, count down entry, or flight ID entry. Used in Configuration mode to scroll through
the function pages.

8 Used as a scroll-up key to navigate through page groups in Normal and Configuration mode.

9 Used as a scroll-down key to navigate through page groups in Normal and Configuration

mode.

Code Selection

Code selection is entered with eight keys (0 through 7) providing 4,096 active identification codes.
Pushing one of these keys begins the code selection sequence. The new code is not activated until the
fourth digit is entered. Pressing the CLR key moves the cursor back to the previous digit. Pressing the
CLR key when the cursor is on the first digit of the code, or pressing the CRSR key during code entry,
removes the cursor and cancels data entry, restoring the previous code. The numbers 8 and 9 are not used
for code entry, only for flight ID entry, count down time, rotorcraft tail number entry, and data selection in
Configuration and Normal mode.

Configuration Mode

To enter Configuration mode, press and hold the ENT key, then energize the unit. To exit Configuration
mode, press and hold the OFF key until the unit de-energizes.

 To cycle through the pages, press the FUNC key

 To access items on the page, press the CRSR key

 To cycle through the selections of an item on the page, press the 8 or 9 key

 To scroll up or down on the page when nothing is selected, press the 8 or 9 key

 To move within the page, press the ENT key

 To move to previous selection on the page, press the CLR key

 To exit the page, press the FUNC key

GTX 3X5 units may also be configured using the GTX 3X5 Install Tool. For configuration using the
GTX 3X5 Install Tool, refer to Section 3.3.

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Function Display

FLIGHT ID If Allow Pilot to Edit Flt ID is configured to YES, the flight ID can be changed

by the pilot at any time in Normal mode. This allows the pilot/crew to enter
the specific flight ID for transmission to ATC interrogations.

UP COUNTER Timer controlled by ENT and CLR keys.

DOWN COUNTER Timer controlled by ENT, CLR, and CRSR keys. The initial count down time

is entered with the 0 through 9 keys.

FLIGHT TIMER Displays the flight time, controlled by the ENT key or by one of four airborne

sources (squat switch, GPS ground speed recognition, air data airspeed
recognition, or altitude increase), as configured during installation. The timer
begins when the GTX 3X5 determines that the rotorcraft is airborne.

TRIP TIMER Timer controlled by ENT and CLR keys.

PRESSURE ALT Displays the altitude data supplied to the GTX 3X5 in feet, hundreds of feet

(flight level), or meters, depending on configuration.

ALT MONITOR Controlled by ENT key. Activates a voice alarm and warning annunciator

when altitude limit is exceeded.

SAT/DALT Displayed when the GTX 3X5 is configured with temperature input. Displays

Static Air Temperature and Density Altitude.

CONTRAST/OFFSET Contrast is controlled by the 8 and 9 keys.

BACKLIGHT/OFFSET This page is only displayed if photocell backlighting mode is selected in

Configuration mode. Backlighting is controlled by the 8 and 9 keys.

MESSAGES Alerts crew of transponder faults, fails, and advisory messages. “MSG”

appears when a message is generated. CRSR and ENT keys access messages
for acknowledgment and viewing.

BLUETOOTH This page is only shown on the GTX 345 when configured for Bluetooth at

installation. When selected, it allows PEDs to pair to the GTX 345 and device
management to show ADS-B In data.

INTERNAL GPS This page displays Lat/Long accuracy, number of connected satellites,

horizontal figure of merit, whether the unit is using internal GPS, and overall
status.

1090ES TX CTRL This is only displayed when the unit is configured for 1090ES Out Control in

Configuration mode to be Pilot Set. Once configured, this can be highlighted
by the CRSR key, changed by the 8 and 9 keys, and selected by ENT key.
Turns the extended squitter function on or off.

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3.2 GTX 335R/345R

Figure 3-2 and Figure 3-3 show the GTX control pages associated with the GTN 6XX/7XX. Refer to the
specific pilot’s guide and cockpit reference guide for details regarding control and function. Part numbers
for these documents are listed in Table 1-1.

Figure 3-2 GTN 7XX Transponder Control

Figure 3-3 GTN 6XX Transponder Control

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3.3 GTX 3X5 Install Tool

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NOTE

If the GTX 3X5/3X5R is configured to interface with a display control unit, the display
control unit must be turned off or in Configuration mode prior to running the GTX 3X5
Install Tool.

NOTE

The GTX 3X5 Install Tool pages shown within this manual reflect GTX 3X5 Install Tool
version 2.05. Some differences in operation may be observed when comparing information
in this manual to later versions of the install tool.

The GTX 3X5 Install Tool is available for download from the Garmin Dealer Resource Center
GTX 3X5 Install Tool requires a computer with available USB 2.0 ports and Microsoft Windows XP or
later.

A USB A-to-B cable is required to interface between a computer and the GTX 3X5/3X5R. For additional
details, refer to Figure 3-4. To use the GTX 3X5 Install Tool:

1. Remove power from the GTX 3X5/3X5R.

2. Remove power from the display control unit or verify it is in Configuration mode.

3. Connect the USB cable between the GTX 3X5 and the computer.

4. Energize the GTX 3X5/3X5R and run the GTX 3X5 Install Tool.

Figure 3-4 USB A and USB B Connectors

The install tool is used to check equipment status, load software, and configure the unit.

To place a GTX 3X5/3X5R unit in Configuration mode:

1. In the Unit Mode window, change “Normal Mode” to “Configuration Mode.”

2. Click the Set key.

. The

Green boxes indicate a function operating correctly. Red boxes indicate a failure. Yellow boxes indicate a
fault or warning. Gray boxes indicate the presence of a message.

The bottom of the install tool displays unit information, such as software version, connection status, and
unit mode. The tool will annunciate if alerts, faults, failures, or warnings exist. The menu bar at the top of
the install tool has a GTX key and a Help key. The GTX key provides the following options:

• Save configuration

• Load configuration

• Reset configuration

• Push configuration from install tool to configuration module

• Exit

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The Help key provides the following information:

• Part number

• Version number

• Copyright statement

• Software license agreements

3.3.1 State Page

The State page of the GTX 3X5 Install Tool reports the current mode of the GTX 3X5/3X5R, Flight ID,
Squawk Code, and Pressure Altitude. Mode selections include Ground Test and Traffic Test modes.
Standby and Operate test modes are also provided for TCAS.

Figure 3-5 GTX 3X5/3X5R State Page

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3.3.2 Status Page

The Status page reports failures, faults, warnings, and pilot alerts. Information such as whether there is a
configuration module present is also displayed.

Figure 3-6 GTX 3X5/3X5R Status Page

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3.3.3 Configuration Group

The Configuration group contains the following pages:

 Aircraft page – allows the configuration of basic aircraft configuration and flight ID settings

 Airframe page – allows the configuration of basic airframe configuration and operational options

settings

 Unit page – allows the configuration of identification code, unit options, and display options

 Interfaces page – allows the configuration of serial, A429, discretes, and HSDB settings

 Sensors page – allows the configuration of Garmin Altitude Encoder, GPS, internal AHRS, and

additional sensors

 Audio page – allows the configuration of audio options and alerts

 Display page – allows the configuration of display and key backlight, photocell and lighting bus

curves, and default offsets

NOTE

All configurable settings must match the GTX System Configuration Log retained in the
rotorcraft permanent records.

Figure 3-7 GTX 3X5/3X5R Configuration Group

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