Thommen CM20 User manual

Installation and Operating Manual
CM20
Digital Chronometer
THOMMEN AIRCRAFT EQUIPMENT AG
H ofackerstrasse 48, CH-4132 Muttenz, Switzerland
INSTALLATION AND OPERATING MANUAL
CM20 DIGITAL CHRONOMETER
ATA 31-22-10
Revision: 1.8
29/04/2022

Installation and Operating Manual
CM20 Digital Chronometer
31-22-10
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TITLE PAGE
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Installation and Operating Manual
CM20 Digital Chronometer
RECORD OF REVISIONS
Revision: 1.8
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RECORD OF REVISIONS
Rev. Date Reason for Revision Prepared Checked Approved
1.0 FEB 2/2012 Initial Issue T. Rolls - T. Balazs
1.1 FEB 9/2012 Different paragraphs updated T. Balazs - T. Balazs
1.2 MAR 19/2012 Illustrations updated T. Balazs - T. Balazs
1.3 MAR 19/2012 Table “Preparation” removed T. Balazs - T. Balazs
1.4 MAY 31/2012
Environmental Quality Test cat. ZN (DO-160F,
Sect. 19) added; Bonding bolt modified (from
M4 to M5)
T. Balazs - T. Balazs
1.5 MAY 26/2014 Type identification drawing corrected T. Balazs - T. Balazs
1.6 DEC 2/2016
Thommen Logo and address changed.
Page layout Changed.
Minor Editing changes.
ATA Format included
A. Anwar - S. Jaquier
1.7 OCT 15/2018 Battery replacement procedure added to Page
Block 201. M. Sreetharanathan - A. Anehila
1.8 APR 29/2022
Document reformatted.
MID number removed (1515).
DIP switch information either changed or
removed in order to retract authorisation of the
customer to change the settings.
General corrections and improvements. J. Garrett G. Schaffner A. Savin

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CM20 Digital Chronometer
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SERVICE BULLETIN LIST
SB No. Subject Rev. Date

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Installation and Operating Manual
CM20 Digital Chronometer
LIST OF EFFECTIVE PAGES
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LIST OF EFFECTIVE PAGES
SECTION PAGE REV. DATE SECTION PAGE REV. DATE
Title Page 1 29/04/22 Description and Operation 1 29/04/22
2 29/04/22 2 29/04/22
3 29/04/22
4 29/04/22
5 29/04/22
Record of Revisions 1 29/04/22 6 29/04/22
2 29/04/22 7 29/04/22
8 29/04/22
9 29/04/22
10 29/04/22
Service Bulletin List 1 29/04/22 11 29/04/22
2 29/04/22 12 29/04/22
List of Effective Pages 1 29/04/22
2 29/04/22
Table of Contents 1 29/04/22
2 29/04/22
3 29/04/22
4 29/04/22
Introduction 1 29/04/22
2 29/04/22
3 29/04/22
4 29/04/22
5 29/04/22
6 29/04/22

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CM20 Digital Chronometer
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LIST OF EFFECTIVE PAGES
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SECTION PAGE REV. DATE SECTION PAGE REV. DATE
Fault Isolation 101 29/04/22 Removal / Installation 401 29/04/22
102 29/04/22 402 29/04/22
403 29/04/22
404 29/04/22
Maintenance Practices 201 29/04/22
202 29/04/22
203 29/04/22 Adjustment / Test 501 29/04/22
204 29/04/22 502 29/04/22
205 29/04/22
206 29/04/22
207 29/04/22
208 29/04/22 Inspection / Check 601 29/04/22
209 29/04/22 602 29/04/22
210 29/04/22
211 29/04/22
212 29/04/22
213 29/04/22
214 29/04/22

Installation and Operating Manual
CM20 Digital Chronometer
TABLE OF CONTENTS
Revision: 1.8
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31-22-10
Page 1
TABLE OF CONTENTS
RECORD OF REVISIONS 1
SERVICE BULLETIN LIST 1
LIST OF EFFECTIVE PAGES 1
TABLE OF CONTENTS 1
INTRODUCTION 1
1. Purpose of this Manual 1
2. Manual Description 1
3. Revisions 1
4. Warnings, Cautions and Notes 2
4.1 Warnings 2
4.2 Cautions 2
4.3 Notes 2
5. Technical Support 3
6. Installer Responsibility 3
7. Maintenance 3
8. Document/Equipment Feedback 3
9. List of Abbreviations 5
DESCRIPTION AND OPERATION 1
1. General 1
1.1 Introduction 1
1.2 Equipment Identification 1
1.3 Specifications and Standards 2
1.4 Environmental Specifications 4
1.5 Operational Limitations, Range and Tolerances 5
2. Description 6
2.1 Physical Description 6
2.2 Electrical Description 7
2.3 Weight and Balance 7
2.4 Materials 7
2.5 Surface Finish 7
2.6 Push Buttons 8
2.7 Display Area 8
2.8 Lighting Description 9
2.9 Software 9
3. Operation 10
3.1 Functional Description 10
3.2 Operation Modes 11
3.3 Night Vision Operation 11
3.4 Continued Airworthiness 11
FAULT ISOLATION 101
1. General 101
2. Error Codes 101
MAINTENANCE PRACTICES 201
1. Installation and Design Considerations 201

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1.1 Possibilities of Installation 201
1.2 Installation Features and Options 201
1.3 Electrical Connectors 202
1.4 Master-Slave Configuration 204
1.5 Mounting Requirements 205
1.6 ARINC Mounting Clamp Installation Procedure 206
1.7 Software Updates 207
1.8 Electrical Bonding 207
1.9 Power Supply 207
2. Installation Features and Option Settings 208
2.1 DIP Switches 208
2.2 Timer Start Switch Signal (Discrete Signal Input) 209
2.3 Active-High 209
2.4 Active-Low 209
2.5 Lighting Control Signal 210
2.6 Lighting Mode Switch (Discrete Signal Input) 211
2.7 Alarm 211
3. Storage 212
3.1 Storage Facility Conditions 212
3.2 Handling, Transport and Storage 212
4. Battery Replacement 213
REMOVAL / INSTALLATION 401
1. Removal 401
1.1 References 401
1.2 Special Tools and Equipment 401
1.3 Consumable Materials 401
1.4 Expendable Parts 401
1.5 Preparation 401
1.6 Procedure 401
1.7 Close-up 401
2. Installation 403
2.1 References 403
2.2 Special Tools and Equipment 403
2.3 Consumable Materials 403
2.4 Expendable Parts 403
2.5 Preparation 403
2.6 Procedure 404
2.7 Close-up 404
ADJUSTMENT / TEST 501
1. General 501
2. Operational Test 501
2.1 References 501
2.2 Special Tools and Equipment 501
2.3 Consumable Materials 501
2.4 Expendable Parts 501

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2.5 Preparation 501
2.6 Procedure 501
INSPECTION / CHECK 601
1. General 601
2. Inspection / Check 601
2.1 References 601
2.2 Special Tools and Equipment 601
2.3 Consumable Materials 601
2.4 Expendable Parts 601
2.5 Preparation 601
2.6 Procedure 601

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Installation and Operating Manual
CM20 Digital Chronometer
INTRODUCTION
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INTRODUCTION
1. Purpose of this Manual
This Installation and Operating Manual (INSOP) gives a description of the CM20 Digital
Chronometer and the necessary procedural steps to remove/install, inspect and maintain the
equipment. It also gives the mechanical and electrical characteristics to make sure that it is
compatible with the aircraft.
For detailed operating instructions, refer to the User Operational Manual (CM20-USOM).
For repair procedures, refer to the Component Maintenance Manual (CM20-CMM),
ATA 31-22-10.
Only Thommen Aircraft Equipment AG are permitted to repair the CM20 Digital Chronometer.
2. Manual Description
The page blocks in this manual comply with the Air Transport Association of America (ATA)
specification i2200.
3. Revisions
Thommen Aircraft Equipment AG (TAE) gives the customers (that have a product guarantee)
a complete revised manual when a change is included in a manual. The Record of Revisions
section gives the reason for the changes done in the current revision.
A documentation revision service (with a customer portal) is also available for customers that
have instruments/devices no longer covered by a product guarantee. This can be useful when
an upgrade to the instrument/device can improve the operational life and/or reliability of older
products.
The documentation revision service also includes the necessary Service Bulletins that
upgrade/modify the device.

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CM20 Digital Chronometer
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4. Warnings, Cautions and Notes
4.1 Warnings
WARNING: WARNINGS ARE GIVEN IN THE RELEVANT PAGE BLOCKS TO TELL
PERSONNEL ABOUT SOMETHING THAT CAN CAUSE INJURY TO THEM.
WARNINGS ARE GIVEN IMMEDIATELY BEFORE THE APPLICABLE TEXT
TO WHICH THEY REFER.
4.2 Cautions
CAUTION: CAUTIONS ARE GIVEN IN THE RELEVANT PAGE BLOCKS TO TELL
PERSONNEL ABOUT SOMETHING THAT CAN CAUSE DAMAGE TO THE
EQUIPMENT. CAUTIONS ARE GIVEN IMMEDIATELY BEFORE THE TEXT TO
WHICH THEY REFER.
4.3 Notes
NOTE: Notes give helpful information to the personnel doing the task. Notes are included
before or after the text to which they refer.

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5. Technical Support
Please contact Thommen Aircraft Equipment AG at the address given below for technical
support.
THOMMEN AIRCRAFT EQUIPMENT AG
Hofackerstrasse 48
CH-4132 Muttenz
Switzerland
Phone: [phone]
Email: tech-s[email protected]
Internet: www.thommen.aero
6. Installer Responsibility
The installer is responsible for the correct installation of the equipment. This includes the
mechanical and electrical configuration and compatibility with the aircraft.
All installation personnel must be fully qualified and approved to do the work procedures given
in this Installation and Operating Manual (INSOP).
7. Maintenance
Only Thommen Aircraft Equipment AG (or an approved service facility) are authorised to
perform maintenance tasks not given in this manual.
8. Document/Equipment Feedback
The Document / Equipment Defect Report (on the next page) gives the customer a way to
inform Thommen Aircraft Equipment AG about any defects regarding the equipment or
discrepancies in the technical documentation. This feedback will help Thommen Aircraft
Equipment AG to make continued improvements to the equipment and/or the technical
documentation.

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INTRODUCTION
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DOCUMENT / EQUIPMENT DEFECT REPORT
Aircraft Type Serial No. Manual No. Operator
Date Reported By Contact Details
Document / Equipment:
Description of Defect:
Corrective action taken to continue operation:
Please send to:
THOMMEN AIRCRAFT EQUIPMENT AG
Hofackerstrasse 48
CH-4132 Muttenz
Switzerland
Telephone: [phone]
Email: tech-[email protected]

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9. List of Abbreviations
Abbreviation Description
AMM Aircraft Maintenance Manual
ARINC Aeronautical Radio Incorporated
ATA Air Transport Association of America
AWG American Wire Gauge
CG
Centre of Gravity
CMM
Component Maintenance Manual
CM20 CM20 Digital Chronometer
DIP Dual In-line Package
EASA European Union Aviation Safety Agency
EEC European Economic Community
EPROM Erasable Programmable Read-Only Memory
ERR
Error
ET
Elapsed Timer
ETD Elapsed Timer Down
FAA Federal Aviation Administration
FED-STD Federal Standard
FT Flight Timer
FTA
Flight Timer Alarm
HIRF
High Intensity Radiated Fields
INSOP
Installation and Operating Manual
I/O Input/Output
LCD Liquid Crystal Display
LCS Lighting Control Signal
LT Local Time
MFD
Manufactured
MID
Master Identification Number
MIL Military
MOD Modification (also Mode)
MoO Mode of Operation
MTBF Mean Time Before Failure
MTH Maintenance Timer in Hours
NRB
NVIS Radiance Requirements for Class B Equipment
NVIS
Night Vision Imaging System
P/N Part Number
PWM Pulse-Width Modulation
REV Revision

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INTRODUCTION
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Abbreviation Description
RH Relative Humidity
RMS
Root Mean Square
RS
Recommended Standard
RST
Reset
RTCA Radio Technical Commission for Aeronautics
RX Receive
SAE Society of Automotive Engineers
SB Service Bulletin
SER No
Serial Number
ST/SP
Start/Stop
TAE Thommen Aircraft Equipment AG
TX Transmit
USOM User Operational Manual
UTC Universal Time Coordinated
VAC
Volts Alternating Current
VDC
Volts Direct Current
WoW
Weight-on-Wheels

Installation and Operating Manual
CM20 Digital Chronometer
DESCRIPTION AND OPERATION
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DESCRIPTION AND OPERATION
1. General
1.1 Introduction
The Description and Operation (page block 1) of this manual gives a description of the
functionality and operation of the CM20 Digital Chronometer.
The CM20 Digital Chronometer is a Thommen Aircraft Equipment digital chronometer, type
CM20, from a production line ‘Aircraft Clocks and Chronographs’.
The CM20 Digital Chronometer is a precision, multi-functional digital chronometer that shows
the time and has various timer functions. It is normally installed in the aircraft cockpit, on the
instrument panel.
1.2 Equipment Identification
The equipment identification and qualification labels on the CM20 Digital Chronometer comply
with the requirements of MIL-STD-130 and Sub-part Q of EASA Part 21.
Each CM20 Digital Chronometer has an identification label (showing equipment identification
data) and a qualification label (showing qualification and electrical/mechanical data), attached
to the left and right sides of the housing.
Figure 1 – Identification and Qualification Labels

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1.3 Specifications and Standards
The CM20 Digital Chronometer complies with the latest civil and military avionic standards, as
shown in the following tables:
Reference Description
EASA/Part 21
EC/Commission Regulation (EC) No 1702/2003 Annex Part 21 -
Certification of aircraft and related products, parts and appliances,
and of design and production organizations
EASA/Part 21
Sub-part K
Parts and Appliances Airworthiness
FAA/AC 20-94A Digital Clock Installation in Aircraft
FAA/AC 20-158
The Certification of Aircraft Electrical And Electronic Systems for
Operations in the High Intensity Radiated Fields (HIRF)
Environment
Table 1 – Certification Standards
Reference Description
MIL-C-81774 Military Specification, General Requirements for Aircraft Control
Panel
MIL-P-7788 Panel, Information, Integrally Illuminated
MIL-STD-810 Environmental Test Method and Engineering Guidelines
MIL-STD-1472 Human Engineering
MIL-STD-3009 Lighting, Aircraft, Night Vision Imaging System (NVIS) Compatible
MIL-HDBK-217 Reliability Prediction of Electronic Equipment
MIL-STD-130 Identification Marking
Table 2 – MIL Standards