Garmin GFC 600H User manual

190-02081-03 January 2023 Revision 3
GFC 600H
Helicopter Flight Control System
Part 27 STC
Maintenance Manual
Contains Instructions for Continued Airworthiness
Rotorcraft Make, Model, Registration Number, and Serial Number and
accompanying STC configuration information in Appendix A must be
completed and retained with rotorcraft permanent records.

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page i
©2023 Garmin International or its subsidiaries
All Rights Reserved
Except as expressly provided herein, no part of this manual may be reproduced, copied, transmitted,
disseminated, downloaded or stored in any storage medium, for any purpose without the express prior
written consent of Garmin. Garmin hereby grants permission to download a single copy of this manual and
of any revision to this manual onto a hard drive or other electronic storage medium to be viewed and to
print one copy of this manual or of any revision hereto, provided such electronic or printed copy of this
manual or revision must contain the complete text of this copyright notice and provided further any
unauthorized commercial distribution of this manual or any revision hereto is strictly prohibited.
Garmin®, flyGarmin®, GFC® are registered trademarks of Garmin International or its subsidiaries.
GNS™, GDL™, GTN™ and GTX™ are trademarks of Garmin International or its subsidiaries. These
trademarks may not be used without the express permission of Garmin.
Windows® is a registered trademark of Microsoft Corporation in the United States and other countries.
All other product or company names that may be mentioned in this publication are trade names,
trademarks, or registered trademarks of their respective owners.
For aviation product support, visit www.flyGarmin.com.
For information regarding the Aviation Limited Warranty, refer to Garmin's website.
Garmin International, Inc.
1200 E. 151st Street Olathe, KS 66062 USA
Telephone: [phone]
Aviation Product Support: 866.739.5687
www.flyGarmin.com
Garmin (Europe) Ltd.
Liberty House
Bull Copse Road
Hounsdown Business Park
Southampton, SO40 9LR, UK
Telephone: [phone]
Fax: [phone]
Garmin AT, Inc.
2345 Turner Rd. SE
Salem, OR 97302 USA
Telephone: [phone]
Fax: [phone]

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page ii
INFORMATION SUBJECT TO EXPORT CONTROL LAWS
This document may contain information which is subject to the Export Administration Regulations (EAR) issued by the United
States Department of Commerce (15 CFR, chapter VII, subchapter C) and which 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.
This information in this document is subject to change without notice. For updates and supplemental information regarding the
operation of Garmin products visit www.flyGarmin.com.
SOFTWARE LICENSE AGREEMENT FOR GARMIN AVIATION PRODUCTS
The software embedded in your Garmin product (the "Licensed Software") is owned by Garmin International, Inc. ("Garmin" or
"us"). The Licensed Software is protected under copyright laws and international copyright treaties. The Licensed Software is
provided under this Software License Agreement (hereinafter the "Agreement") and is subject to the following terms and
conditions which are agreed to by End User ("Licensee", "you" or "your"), on the one hand, and Garmin and its licensors and
affiliated companies of Garmin and its licensors, on the other hand. The Licensed Software is licensed, not sold, to you. Garmin
and Licensee may be referred to individually as a "Party" or jointly as the "Parties."
IMPORTANT: CAREFULLY READ THIS ENTIRE AGREEMENT BEFORE USING THIS PRODUCT. INSTALLING,
COPYING, OR OTHERWISE USING THIS PRODUCT INDICATES YOUR ACKNOWLEDGMENT THAT YOU HAVE
READ THIS AGREEMENT AND AGREE TO ITS TERMS AND CONDITIONS. IF YOU DO NOT AGREE TO THESE
TERMS AND CONDITIONS, YOU MAY NOT USE THIS PRODUCT.
1. Definitions. The following capitalized terms shall have the meanings set forth below:
a. “Device” means any Garmin device that is delivered by or on behalf of Garmin to Licensee onto which the
Licensed Software is installed.
b. “Documentation” means Gamin's then-current instructional, technical or functional documentation relating to the
Devices or Licensed Software which is delivered or made available by Garmin in connection with this
Agreement.
c. “Licensed Software” means the software in binary executable form that is embedded in the
i. Devices and/or made available for use on the Devices via a software loader card.
d. “Permitted Purpose” means operating and using the Device on which the Licensed Software is installed for the
Device's intended use.
2. License.
a. License Grant. Subject to the terms and conditions of this Agreement and Licensee's compliance with the terms
and conditions of this Agreement, Garmin hereby grants to Licensee a limited, royalty-free, non-exclusive, non-
sublicenseable, non-transferable and revocable right and license to use and perform the Licensed Software as
installed on the Devices and the Documentation solely for the Permitted Purpose and only during the term of this
Agreement, provided that the Licensed Software may only be used by Licensee on Devices on which the
Licensed Software has been installed or otherwise made available by Garmin. Reservation of Rights. Garmin
retains exclusive ownership of all right, title and interest in and to the Licensed Software and Documentation. All
of Gamin's rights in and to the Licensed Software and Documentation not expressly licensed to Licensee under
Section 2.1 are expressly reserved for Garmin. Nothing contained in this Agreement shall be construed as
conferring by implication, acquiescence, or estoppel any license or other right upon Licensee. Without limiting
the foregoing, the Parties acknowledge and agree that this Agreement grants Licensee a license of the Licensed
Software under the terms of Section 2.1, and shall not in any manner be construed as a sale of the Licensed
Software or any rights in the Licensed Software.
3. Restrictions; Protection and Third Party Devices.
a. Prohibited Uses. Licensee shall not, shall not attempt to and shall not permit any third party to: (a) sublicense,
lease, loan, sell, resell, market, transfer, rent, disclose, demonstrate, or distribute the Licensed Software or
Documentation to any third party; (b) uninstall the Licensed Software from the Device on which it was originally
installed; (c) make any use of or perform any acts with respect to the Licensed Software or Documentation other
than as expressly permitted in accordance with the terms of this Agreement; (d) use the Licensed Software or
Documentation in any manner that violates any applicable law; (e) reproduce or copy the Licensed Software; (f)
modify, adapt, alter, translate, port, create derivative works of, reverse engineer, decompile or disassemble the

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page iii
Licensed Software or Documentation or otherwise derive the source code or other proprietary information or
trade secrets from the Licensed Software; (g) remove, alter, or obscure any proprietary notices from the Licensed
Software or Documentation; (h) use the Licensed Software or Documentation to provide services to third parties
(such as business process outsourcing, service bureau applications or third party training); (i) use the Licensed
Software on any equipment, hardware or device other than a Device; or (j) export, re-export or otherwise
distribute, directly or indirectly, the Licensed Software or Documentation to a jurisdiction or country to which
the export, re- export or distribution of such Licensed Software or Documentation is prohibited by applicable
law.
b. Protection of Software and Documentation. Licensee shall use its best efforts to protect the Licensed Software
and Documentation from unauthorized access, distribution, modification, display, reproduction, disclosure or use
with at least the same degree of care as Licensee normally uses in protecting its own software and documentation
of a similar nature from unauthorized access, distribution, modification, display, reproduction, disclosure or use.
Licensee shall limit access to the Licensed Software and Documentation to only those employees of Licensee
who require access to the Licensed Software or Documentation for the Permitted Purpose and who have been
made aware of the restrictions set forth in this Agreement. Licensee shall take prompt and appropriate action to
prevent unauthorized use or disclosure of the Licensed Software and Documentation.
4. Term and Termination.
a. Term. The term of this Agreement shall commence on the Effective Date, and shall continue in perpetuity
thereafter, unless terminated earlier as provided in this Section 4.
b. Termination by Garmin. Garmin may immediately terminate this Agreement upon written notice to Licensee if
Licensee commits a material breach of this Agreement or breaches a material term of this Agreement.
c. Effect of Termination. Upon any termination of this Agreement for any Party: (a) Licensee shall immediately
cease all use of the Licensed Software and Documentation; (b) all rights and licenses granted to Licensee to the
Licensed Software and Documentation and Gamin's related obligations shall immediately terminate; and (c)
Sections 4.3, 5 and 6 shall survive.
5. Disclaimer; Limitations of Liability; Indemnity.
a. Disclaimer. To the maximum extent permitted by applicable law, the licensed software and documentation
(including any results to be obtained from any use of the licensed software and documentation) are provided “as
is” and “as available” with no warranties, guarantees or representations and neither Garmin nor its affiliates make
any representation, warranty or guarantee, statutory or otherwise, under law or from the course of dealing or
usage of trade, express or implied, including any warranties of merchantability, fitness for a particular purpose,
non-interference, non-infringement, title, or similar, under the laws of any jurisdiction. Garmin does not warrant
that the licensed software or documentation will meet licensee's requirements or that operation of the software
will be uninterrupted or error free. Licensee assumes the entire risk as to the quality and performance of the
licensed software and documentation. The licensed software is not intended for use in any nuclear, medical, or
other inherently dangerous applications, and Garmin disclaims all liability for any damage or loss caused by such
use of the licensed software.
b. Exclusion of damages; limitation of liability. Notwithstanding anything to the contrary herein, to the maximum
extent permitted by applicable law, under no circumstances and regardless of the nature of any claim shall
Garmin be liable to licensee for an amount in excess of USD $100, or be liable in any amount for any special,
incidental, consequential, punitive or indirect damages, loss of goodwill or profits, liquidated damages, data loss,
computer failure or malfunction, attorneys' fees, court costs, interest or exemplary or punitive damages, arising
out of or in connection with the use or performance or non-performance of the licensed software or
documentation, even if Garmin has been advised of the possibility of such loss or damages.
c. Indemnity. Licensee shall indemnify, defend and hold Garmin and its affiliates harmless against any and all
losses, claims, actions, causes of action, liabilities, demands, fines, judgments, damages and expenses suffered or
incurred by Garmin or its affiliated companies in connection with: (a) any use or misuse of the Licensed
Software or Documentation by Licensee or any third party in Licensee's reasonable control; or (b) Licensee's
breach of this Agreement.
6. General.
a. No Devices or Services. Licensee acknowledges and agrees that nothing in this Agreement shall be construed as
requiring Garmin to: (a) provide or supply the Devices or any other devices or hardware to Licensee; (b) grant
any licenses to any software other than the Licensed Software; or (c) provide any services, such as support,
maintenance, installation or professional services for the Licensed Software.
b. Non-Exclusive. Each Party's rights and obligations under this Agreement are non-exclusive. Garmin is not
precluded from marketing, licensing, providing, selling or distributing the Licensed Software or Documentation,
or any other products, software, documentation or services, either directly or through any third party.

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page iv
c. Assignment. Licensee may not assign this Agreement or any of its rights, interests or obligations hereunder
without the prior written consent of Garmin. Any purported assignment in violation of this Section 6.3 shall be
null and void. Subject to the foregoing, this Agreement shall be binding upon and shall inure to the benefit of the
Parties and their respective successors and permitted assigns and transferees.
d. Feedback and Data. Licensee may from time to time provide feedback, comments, suggestions, questions, ideas,
or other information to Garmin concerning the Licensed Software or Documentation or Gamin's products,
services, technology, techniques, processes or materials ("Feedback"). Garmin may in connection with any of its
products or services freely use, copy, disclose, license, distribute and otherwise exploit such Feedback in any
manner without any obligation, payment, royalty or restriction whether based on intellectual property rights or
otherwise.
e. Governing Law. The validity, interpretation and enforcement of this Agreement will be governed by the
substantive laws, but not the choice of law rules, of the state of Kansas. This Agreement shall not be governed by
the 1980 UN Convention on Contracts for the International Sale of Goods.
f. Legal Compliance. You represent and warrant that (i) you are not located in a country that is subject to a U.S.
Government embargo, or has been designated by the U.S. Government as a “terrorist supporting” country, and
(ii) you are not listed on any U.S. Government list of prohibited or restricted parties.
g. Injunctive Relief. The Parties acknowledge and agree that irreparable damage would occur if any provision of
this Agreement was not performed in accordance with its specific terms or was otherwise breached and as such,
the Parties will be entitled to an injunction or injunctions to prevent breaches of this Agreement and to enforce
specifically the performance of the terms and provisions of this Agreement without proof of actual damages, this
being in addition to any other remedy to which any Party is entitled at law or in equity.
h. Amendments and Waivers. This Agreement may be amended and any provision of this Agreement may be
waived, provided that any such amendment or waiver will become and remain binding upon a Party only if such
amendment or waiver is set forth in a writing by such Party. No course of dealing between or among any persons
having any interest in this Agreement will be deemed effective to modify, amend or discharge any part of this
Agreement or any rights or obligations of any Party under or by reason of this Agreement. No delay or failure in
exercising any right, power or remedy hereunder will affect or operate as a waiver thereof; nor will any single or
partial exercise thereof or any abandonment or discontinuance of steps to enforce such a right, power or remedy
preclude any further exercise thereof or of any other right, power or remedy. The rights and remedies hereunder
are cumulative and not exclusive of any rights or remedies that any Party would otherwise have.
i. Severability. The provisions of this Agreement will be severable in the event that for any reason whatsoever any
of the provisions hereof are invalid, void or otherwise unenforceable, any such invalid, void or otherwise
unenforceable provisions will be replaced by other provisions which are as similar as possible in terms to such
invalid, void or otherwise unenforceable provisions but are valid and enforceable and the remaining provisions
will remain valid and enforceable to the fullest extent permitted by applicable law, in each case so as to best
preserve the intention of the Parties with respect to the benefits and obligations of this Agreement.
j. No Third-Party Beneficiaries. This Agreement is solely for the benefit of the Parties and does not confer on third
parties any remedy, claim, reimbursement, claim of action or other right in addition to those existing without
reference to this Agreement.
k. Entire Agreement. This Agreement shall constitute the entire agreement between Garmin and you with respect to
the subject matter hereof and will supersede all prior negotiations, agreements and understandings of Garmin and
you of any nature, whether oral or written, with respect to such subject matter.
l. Interpretation. In this Agreement: (a) headings are for convenience only and do not affect the interpretation of
this Agreement; (b) the singular includes the plural and vice versa; (c) the words 'such as', 'including',
'particularly' and similar expressions are not used as, nor are intended to be, interpreted as words of limitation;
(d) a reference to a person includes a natural person, partnership, joint venture, government agency, association,
corporation or other body corporate; a thing includes a part of that thing; and a party includes its successors and
permitted assigns; and (e) no rule of construction applies to the disadvantage of a Party because that Party was
responsible for the preparation of this Agreement. Any translation of this Agreement from English is provided as
a convenience only. If this Agreement is translated into a language other than English and there is a conflict of
terms between the English version and the other language version, the English version will control.

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page v
Record of Revisions
Change Description
Revision Revision Date Description
1 02/05/2020 Initial release.
2 04/28/2020 Minor change to include GMU 44B.
3 01/13/2023 Minor change to update Collective Position Sensor adjustment.
Section Description of Change
4.1 Updated statement to be compliant with FAA regulations.
6.7 Updated Figure 6-18 Collective Position Sensor Adjustment with improved rigging
instructions.

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page vi
DEFINITIONS OF WARNINGS, CAUTIONS, AND NOTES
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. For questions or additional
information, please refer to www.garmin.com/prop65.
WARNING
Perchlorate Material - special handling may apply,
Refer to www.dtsc.ca.gov./hazardouswaste/perchlorate.
NOTE
All screen shots used in this document are current at the time of publication. Screen shots
are intended to provide visual reference only. All information depicted in screen shots,
including software file names, versions, and part numbers, is subject to change and may
not be up to date.
WARNING
Warnings indicate that personal injury or death is possible if the instructions are
disregarded.
CAUTION
Cautions indicate that damage to the equipment is possible if the instructions
are disregarded.
NOTE
Notes provide additional information.

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page vii
TABLE OF CONTENTS
1 INTRODUCTION .............................................................................................................................1-1
1.1 Purpose ......................................................................................................................................1-2
1.2 Scope .........................................................................................................................................1-2
1.3 Applicability ..............................................................................................................................1-2
1.4 Revision and Distribution ..........................................................................................................1-2
1.5 Terminology ..............................................................................................................................1-3
1.6 Reference Documents ...............................................................................................................1-5
2 SYSTEM DESCRIPTION ................................................................................................................2-1
2.1 GFC 600H Flight Control System Functions ............................................................................2-2
2.2 System Overview ......................................................................................................................2-3
2.3 Power Requirements ...............................................................................................................2-16
3 CONTROL AND OPERATION ......................................................................................................3-1
3.1 GMC 605H Mode Controller ....................................................................................................3-2
3.2 Garmin Displays (G500H Installations) ....................................................................................3-6
3.3 GMC 605H Configuration Mode ............................................................................................3-10
4 INSTRUCTIONS FOR CONTINUED AIRWORTHINESS ........................................................4-1
4.1 Airworthiness Limitations .........................................................................................................4-2
4.2 Servicing Information ...............................................................................................................4-3
4.3 Maintenance Intervals ...............................................................................................................4-5
4.4 Visual Inspection .......................................................................................................................4-6
4.5 Electrical Bonding Check ..........................................................................................................4-8
4.6 Magnetic Field Updates ............................................................................................................4-8
4.7 Servo Arm Torque Check .........................................................................................................4-9
5 TROUBLESHOOTING ...................................................................................................................5-1
5.1 General Troubleshooting ...........................................................................................................5-2
5.2 GMC 605H Mode Controller ....................................................................................................5-4
5.3 GRS 79H or GSU 75H ADAHRS and GMU 44( ) Magnetometer ........................................5-10
5.4 Connectors ...............................................................................................................................5-14
6 EQUIPMENT REMOVAL AND RE-INSTALLATION ..............................................................6-1
6.1 GMC 605H Mode Controller ....................................................................................................6-3
6.2 GFS 83 Servo ............................................................................................................................6-5
6.3 GSU 75H ADAHRS ................................................................................................................6-19
6.4 GRS 79H AHRS ......................................................................................................................6-22
6.5 GMU 44( ) Magnetometer .......................................................................................................6-24
6.6 GTP 59 OAT Probe .................................................................................................................6-29
6.7 Collective Position Sensor ......................................................................................................6-31
6.8 Configuration Module Replacement .......................................................................................6-35
7 CONFIGURATION AND CHECKOUT ........................................................................................7-1
7.1 GMC 605H Mode Controller ....................................................................................................7-2
7.2 GFS 83 Servos ...........................................................................................................................7-3
7.3 Collective Position Sensor ........................................................................................................7-5
7.4 GSU 75H ADAHRS ..................................................................................................................7-6
7.5 GRS 79H AHRS ........................................................................................................................7-8
7.6 GMU 44( ) Magnetometer .........................................................................................................7-8
7.7 Post-Installation Calibration ......................................................................................................7-9
7.8 GFC 600H System Configuration ...........................................................................................7-21

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page viii
8 RETURN-TO-SERVICE ..................................................................................................................8-1
8.1 Maintenance Records ................................................................................................................8-2
8.2 Configuration Mode Functional Checkout ................................................................................8-2
8.3 Normal Mode Functional Checkout ..........................................................................................8-3
APPENDIX A INSTALLATION-SPECIFIC INFORMATION ....................................................A-1
A.1 General Installation Information ..............................................................................................A-2
A.2 Interfaced Equipment ...............................................................................................................A-3
A.3 Configuration Log ....................................................................................................................A-5

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page ix
LIST OF FIGURES
Figure 2-1 System Function Diagram ....................................................................................................2-6
Figure 2-2 GMC 605H Mode Controller ...............................................................................................2-7
Figure 2-3 GMC 605H System Interface Overview ..............................................................................2-8
Figure 2-4 GFS 83 Servo (-11 Variant) ...............................................................................................2-10
Figure 2-5 GFS 83 Servo (-00 Variant) ...............................................................................................2-10
Figure 2-6 GSU 75H, GMU 44, GMU 44B, and GTP 59 Sensors ......................................................2-12
Figure 2-7 GRS 79H ............................................................................................................................2-12
Figure 2-8 GTP 59 OAT Probe ............................................................................................................2-13
Figure 2-9 GMU 44 and GMU 44B Magnetometers ...........................................................................2-14
Figure 2-10 Collective Position Sensor .................................................................................................2-15
Figure 3-1 GMC 605H Normal Mode Operation ..................................................................................3-3
Figure 3-2 FCS Switches .......................................................................................................................3-4
Figure 3-3 Yaw Switch ..........................................................................................................................3-5
Figure 3-4 G500H Alerts and Annunciations Layout ............................................................................3-6
Figure 3-5 GMC 605H Configuration Mode Navigation ....................................................................3-10
Figure 3-6 GMC 605H Configuration Mode Layout ...........................................................................3-11
Figure 3-7 GMC 605H Configuration Mode Map ...............................................................................3-12
Figure 3-8 GDU Configuration Mode Home Screen ...........................................................................3-14
Figure 3-9 System Management Page .................................................................................................3-15
Figure 4-1 Armature Installation (P/N 011-03367-11) ........................................................................4-10
Figure 4-2 Shear Fuse Installation .......................................................................................................4-12
Figure 5-1 Rear View of GMC 605H Backplate .................................................................................5-14
Figure 5-2 GMC 605H P6051/P6052 Connectors ...............................................................................5-14
Figure 5-3 GFS 83 P831-P/R/Y Connector .........................................................................................5-17
Figure 5-4 GSU 75H J751 Connector ..................................................................................................5-18
Figure 5-5 GSU 79H J791 Connector ..................................................................................................5-20
Figure 5-6 GMU 44 J441 Pigtail Connector ........................................................................................5-22
Figure 5-7 GMU 44B Connector .........................................................................................................5-23
Figure 5-8 Collective Position Sensor P6053 Connector ....................................................................5-24
Figure 6-1 Location of GFC 600H System Components ......................................................................6-2
Figure 6-2 GMC 605H Installation ........................................................................................................6-3
Figure 6-3 GFS 83 Pitch and Roll Servo Installation ............................................................................6-6
Figure 6-4 GFS 83 Yaw Servo Installation ...........................................................................................6-8
Figure 6-5 Pitch Control Push-Rod Adjustment ..................................................................................6-11
Figure 6-6 Roll Control Push-Rod Adjustment ...................................................................................6-12
Figure 6-7 Yaw Control Push-Rod Adjustment ..................................................................................6-13
Figure 6-8 Pitch and Roll Clutchless Servo Output Arm and Shear Fuse Installation ........................6-16
Figure 6-9 Yaw Clutched Servo Output Arm and Shear Fuse Installation .........................................6-17
Figure 6-10 GSU 75H Installation .........................................................................................................6-19
Figure 6-11 Pitot and Static Connections ..............................................................................................6-21
Figure 6-12 GRS 79H Installation .........................................................................................................6-22
Figure 6-13 GMU 44 Installation on (Existing) Flux Valve Support ....................................................6-25
Figure 6-14 GMU 44 Installation with Universal Mount ......................................................................6-26
Figure 6-15 GMU 44B Installation ........................................................................................................6-27
Figure 6-16 GTP 59 OAT Probe Installation .........................................................................................6-29
Figure 6-17 Collective Position Sensor .................................................................................................6-32
Figure 6-18 Collective Position Sensor Adjustment ..............................................................................6-33
Figure 6-19 GMC 605H Configuration Module Installation .................................................................6-35

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page x
Figure 6-20 GRS 79H or GSU 75H Configuration Module Installation ...............................................6-36
Figure 7-1 Rotorcraft Position Example ..............................................................................................7-15
Figure 8-1 Audio Test Page ...................................................................................................................8-2

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page xi
LIST OF TABLES
Table 1-1 Reference Documents ............................................................................................................1-5
Table 2-1 Servo Program Pins and Configuration ...............................................................................2-11
Table 2-2 GFC 600H Electrical Loads .................................................................................................2-16
Table 3-1 GMC 605H Normal Mode Key Descriptions ........................................................................3-2
Table 3-2 Description of GMC 605H Normal Mode Operation ............................................................3-3
Table 3-3 GFC 600H Switch Function ...................................................................................................3-4
Table 3-4 Description of GDU FCS Annunciation Bar .........................................................................3-6
Table 3-5 GMC 605H Configuration Mode Navigation ......................................................................3-11
Table 3-6 GMC 605H Configuration Mode Layout .............................................................................3-11
Table 4-1 Periodic Maintenance Intervals ..............................................................................................4-5
Table 4-2 Existing Electrical Bonding Requirement (Milliohm) ...........................................................4-8
Table 4-3 Repaired Electrical Bonding Requirement (Milliohm) ..........................................................4-8
Table 5-1 General Troubleshooting Guide .............................................................................................5-2
Table 5-2 GMC 605H LED Indicators ...................................................................................................5-4
Table 5-3 GMC 605H CAS Troubleshooting ........................................................................................5-4
Table 5-4 GMC 605H Configuration Mode (Post-Install Procedures) Test Faults ................................5-7
Table 5-5 General Troubleshoot Guide for AHRS/ADC Install Tool .................................................5-10
Table 5-6 ADC Field Calibration Troubleshooting ..............................................................................5-10
Table 5-7 Post-Install Procedures Troubleshooting .............................................................................5-11
Table 5-8 Upload and Download Troubleshooting ..............................................................................5-13
Table 5-9 P6051 Connector Pinout ......................................................................................................5-15
Table 5-10 P6052 Connector Pinout ......................................................................................................5-16
Table 5-11 P831 Connector Pinout ........................................................................................................5-17
Table 5-12 J751 Connector Pinout .........................................................................................................5-19
Table 5-13 J791 Connector Pinout .........................................................................................................5-21
Table 5-14 J441 Connector Pinout .........................................................................................................5-22
Table 5-15 J442 Connector Pinout .........................................................................................................5-23
Table 5-16 P6053 Connector Pinout ......................................................................................................5-24
Table 6-1 BoM for Pitch and Roll Servo Installation .............................................................................6-5
Table 6-2 BoM for Yaw Servo Installation ............................................................................................6-7
Table 7-1 Airspeed Test Points ..............................................................................................................7-7
Table 7-2 Post-Installation Calibrations ...............................................................................................7-10
Table 7-3 Magnetic Interference Test Sequence Example ...................................................................7-13
Table 7-4 Heading Verification ............................................................................................................7-18
Table A-1 Garmin Equipment ................................................................................................................A-3
Table A-2 Other Equipment ...................................................................................................................A-4

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page 1-1
1 INTRODUCTION
1.1 Purpose..............................................................................................................................................1-2
1.2 Scope.................................................................................................................................................1-2
1.3 Applicability .....................................................................................................................................1-2
1.4 Revision and Distribution .................................................................................................................1-2
1.5 Terminology......................................................................................................................................1-3
1.6 Reference Documents.......................................................................................................................1-5

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page 1-2
1.1 Purpose
This document is designed for use by the installing agency of the Garmin GFC 600H Flight Control
System (FCS) as a Maintenance Manual (MM) and Instructions for Continued Airworthiness (ICA) to
satisfy the requirements for continued airworthiness as defined by 14 CFR Part 27.1529 and 14 CFR
Part 27 Appendix A. This manual includes a description of the GFC 600H FCS and maintenance
information required by the operator to adequately maintain the GFC 600H FCS.
1.2 Scope
This document details maintenance and provides Instructions for Continued Airworthiness (ICA) for the
Garmin GFC 600H Flight Control System (FCS) installed in accordance with STC SR02647SE.
1.3 Applicability
This document applies to all rotorcraft with the GFC 600H FCS installed in accordance with STC
SR02647SE. Maintenance information provided in this document must be included in the operator's
Aircraft Maintenance Manual and operator's Aircraft Scheduled Maintenance Program, if applicable, for
all rotorcraft modified by this STC.
1.4 Revision and Distribution
This manual is required for maintaining the continued airworthiness of the GFC 600H FCS. When this
manual is revised, every page will be revised to indicate the current revision level. Garmin dealers may
obtain the latest revision of this manual on the Garmin Dealer Resource Center. Dealers are notified of
manual revision changes via Garmin Service Bulletin posted to the Dealer Resource Center.
Owner/operators may obtain the latest revision of this manual from www.flyGarmin.com or by contacting
a Garmin dealer.

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page 1-3
1.5 Terminology
The following acronyms and abbreviations are used in this manual:
AC: Advisory Circular FTR: Force Trim Release
AD: Airworthiness Directive GDC: Garmin Air Data Computer
ADAHRS: Air Data & Attitude Heading
Reference System
GDU: Garmin Display Unit
ADC: Air Data Computer GFC: Garmin Flight Control
ADTS: Air Data Test Set GFS: Garmin Force-Trim Servo
AHRS: Attitude Heading Reference System GMA: Garmin Marker Audio (audio panel)
ALT: Altitude GMC: Garmin Mode Controller
ALTS: Altitude Preselect GMU: Garmin Magnetometer Unit
AMM: Aircraft Maintenance Manual GNS: Garmin Navigation System (radio)
AP: Autopilot GPS: Global Positioning System
APR: Approach GRS: Garmin attitude Reference System
ARINC: Aeronautical Radio, Incorporated GS: Glide Slope
ATT: Attitude Mode GSPD: Ground Speed Mode
CAN: Controller Area Network GSU: Garmin Sensor Unit
CAS: Crew Alerting System GTN: Garmin Touch Navigator (radio)
CCW: Counter Clockwise GTP: Garmin Temperature Probe
CDI: Course Deviation Indicator GTX: Garmin Transponder
CFR: Code of Federal Regulations HDG: Heading
COMM: Communication Radio HFCS: Helicopter Flight Control System
CPL: Couple Flight Director HSI: Horizontal Situation Indicator
DISC: Disconnect HSDB: High Speed Data Bus
ECO: Engineering Change Order IAS: Indicated Air Speed
EFIS: Electronic Flight Instrumentation
System
ICA: Instructions for Continued
Airworthiness
EL: Equipment List IFR: Instrument Flight Rules
EMI: Electro Magnetic Interference IGRF: International Geomagnetic Reference
Field
ESD: Electro-Static Discharge ILS: Instrument Landing System
FAA: Federal Aviation Administration LMTQ: Limit Que Mode
FCS: Flight Control System LOC: Localizer
FD: Flight Director LRU: Line Replaceable Unit
FPGA: Field Programmable Gate Array LVDT: Linear Variable Differential
Transformer
FPM: Flight Path Marker LVL: Level Mode

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page 1-4
MIN: Minimum SCAS: Stability and Control Augmentation
System
MM: Maintenance Manual SNSR: Sensor
N/A: Not Applicable STC: Supplemental Type Certificate
NAV: Navigation SW: Software
NVIS: Night Vision Imaging System SYS: System
OAT: Outside Air Temperature TAT: Total Air Temperature
OBS: Omni-Bearing Selector TSO: Technical Standard Order
ODA: Organization Designation
Authorization
USB: Universal Serial Bus
PC: Personal Computer VDC: Volts of Direct Current
PFD: Primary Flight Display VFR: Visual Flight Rules
PFT: Pre-flight Test VHF: Very High Frequency
POT: Positional Sensor VLOC: Vertical Localizer
PTRM: Pitch Trim VNAV: Vertical Navigation
PWR: Power VNE:Velocity Never Exceed
Rev: Revision VOR: VHF Omni Directional Radio Range
RFMS: Rotorcraft Flight Manual Supplement VS: Vertical Speed
SAS: Stability Augmentation System WAAS: Wide Area Augmentation System
SBAS: Satellite Based Augmentation System

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page 1-5
1.6 Reference Documents
In addition to this manual, the following documents are recommended for performing maintenance on the
GFC 600H FCS. 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 GFC 600H FCS.
All of the documents listed in Table 1-1 are available for download on the Garmin Dealer Resource Center.
Table 1-1 Reference Documents
Document Title Garmin P/N
GFC 600H Part 27 STC Installation Manual 190-02081-00
GFC 600H AFCS Installation, Airbus Helicopters AS350 B2/B3 190-02081-01
GFC 600H Pilot’s Guide 190-02081-04
Rotorcraft Flight Manual Supplement for Garmin GFC 600H Flight Control System 190-02081-02

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page 2-1
2 SYSTEM DESCRIPTION
2.1 GFC 600H Flight Control System Functions ...................................................................................2-2
2.2 System Overview..............................................................................................................................2-3
2.2.1 Attitude Hold (ATT) ..................................................................................................................2-3
2.2.2 Helicopter Electronic Stability and Protection (H-ESP) ............................................................2-4
2.2.3 Flight Director Modes ................................................................................................................2-5
2.2.4 GMC 605H AFCS Mode Controller ..........................................................................................2-7
2.2.5 GFS 83 Force Trim Servo ..........................................................................................................2-9
2.2.6 Sensors .....................................................................................................................................2-11
2.3 Power Requirements.......................................................................................................................2-16

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page 2-2
2.1 GFC 600H Flight Control System Functions
The GFC 600H FCS is a 2-axis flight control system with an optional 3rd axis (Yaw). The GFC 600H
utilizes a parallel servo installed in each control axis to provide force trim, attitude hold, and autopilot
functions as follows.
The functionality provided by the GFC 600H is dependent upon the interfaced equipment.

190-02081-03 GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3 Page 2-3
2.2 System Overview
The GFC 600H is a digital helicopter flight control system (HFCS) which provides attitude hold, force
feedback and coupled flight to flight director modes. The overall system capabilities are dependent upon
the interfaced equipment; however, each installation offers the same core functions.
2.2.1 Attitude Hold (ATT)
The system uses aircraft attitude, rates, and acceleration data to stabilize the aircraft and hold a reference
attitude. ATT is lowest level mode of operation and ATT is the default mode when engaging the system.
When engaging the system at low speeds, the system may engage into groundspeed (GSPD) hold if the
installation is equipped with a Garmin GTN navigator. Availability of ATT is dependent upon dual AHRS
sensor availability. Air data or GPS data is required for the AHRS to initialize, but these data sources are
not necessary for continued operation in flight.
Control forces are in detent (i.e., forces are minimized on the controls) when the reference attitude is
achieved. The system provides a force feedback to the pilot in the form of a spring gradient such that forces
increase as the aircraft deviates from the reference attitude. If the pilot pushes on the controls such that the
system detects that the pilot is hands-on, an out of detent annunciation is displayed on the GMC 605H and
Garmin GDU to indicate that the system is not able to maintain its control objective because the pilot is
hands-on.
When trimmed to a level roll attitude, the system will make small corrections to maintain and stabilize an
aircraft heading.
When holding a pitch attitude at higher airspeeds speeds, the GFC 600H system will also help stabilize and
maintain airspeed.
When initially engaging the system, the GFC 600H system will set the reference attitude to the current
attitude, provided they system was not engaged through the LVL function.
The pilot can adjust the pitch/roll attitude control reference by pressing the force trim release (FTR) switch
or by using the TRIM switch.
For installations with a yaw axis, the yaw heading reference is reset when the pilot presses through the
forces on the pedals and releases. The yaw axis reference can only be adjusted in hover. When the pedals
are released, the new heading reference will be set to the current aircraft heading.
Sub-functions and capabilities of attitude hold are as follows:
Hover Assist
In hover assist, the system stabilizes the aircraft to a zero groundspeed reference. Hover assist is
automatically engaged when the aircraft groundspeed approaches zero. If equipped with an optional yaw
servo, the yaw axis will maintain aircraft heading within this flight envelope. The heading reference is
adjusted by simply flying through the pedals to a new heading.
Groundspeed Hold
Like hover assist, groundspeed hold operates in the low speed flight regime. Groundspeed hold is uniquely
annunciated as “GSPD” on the GMC 605H display. This mode allows for a longitudinal and lateral
groundspeed to be selected and maintained by the flight control system. Just like ATT, the GSPD reference
can be adjusted with the FTR switch and the TRIM switch.