Thommen CM20 User Operational Manual
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Thommen CM20 User Operational Manual

Digital chronometer
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User Operational Manual
CM20 Digital Chronometer
USER OPERATIONAL MANUAL
CM20 DIGITAL CHRONOMETER
Revision: 1.5
29/04//2022
THOMMEN AIRCRAFT EQUIPMENT AG
Hofackerstrasse 48, CH-4132 Muttenz, Switzerland

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  • Page 1 User Operational Manual CM20 Digital Chronometer USER OPERATIONAL MANUAL CM20 DIGITAL CHRONOMETER Revision: 1.5 29/04//2022 THOMMEN AIRCRAFT EQUIPMENT AG Hofackerstrasse 48, CH-4132 Muttenz, Switzerland...
  • Page 2 User Operational Manual CM20 Digital Chronometer INTENTIONALLY BLANK TITLE PAGE Page 2 29/04/2022 Revision: 1.5...
  • Page 3 User Operational Manual CM20 Digital Chronometer RECORD OF REVISIONS Rev. Date Reason for Revision Prepared Checked Approved NOV 4/2011 Initial Release JAN 9/2012 Format update JUN 12/2012 Content update AUG 20/2012 Layout corrections Ulrich Dembinski Document updated in new format with TAE NOV 30/2018 company address and logo.
  • Page 4 User Operational Manual CM20 Digital Chronometer INTENTIONALLY BLANK RECORD OF REVISIONS Page 2 29/04/2022 Revision: 1.5...
  • Page 5 User Operational Manual CM20 Digital Chronometer SERVICE BULLETIN LIST SB No. Subject Rev. Date SERVICE BULLETIN LIST Page 1 29/04/2022 Revision: 1.5...
  • Page 6 User Operational Manual CM20 Digital Chronometer INTENTIONALLY BLANK SERVICE BULLETIN LIST Page 2 29/04/2022 Revision: 1.5...
  • Page 7 User Operational Manual CM20 Digital Chronometer LIST OF EFFECTIVE PAGES SECTION PAGE REV. DATE SECTION PAGE REV. DATE Title Page 29/04/22 Introduction 29/04/22 29/04/22 29/04/22 29/04/22 29/04/22 Record of Revisions 29/04/22 29/04/22 Description and Operation 29/04/22 29/04/22 29/04/22 Service Bulletin List...
  • Page 8 User Operational Manual CM20 Digital Chronometer INTENTIONALLY BLANK LIST OF EFFECTIVE PAGES Page 2 29/04/2022 Revision:...

  • Page 9: Table Of Contents

    User Operational Manual CM20 Digital Chronometer TABLE OF CONTENTS RECORD OF REVISIONS SERVICE BULLETIN LIST LIST OF EFFECTIVE PAGES TABLE OF CONTENTS INTRODUCTION 1. Proprietary Notice 2. Purpose of this Manual 3. Manual Description 4. Revisions 5. Warnings, Cautions and Notes...
  • Page 10 User Operational Manual CM20 Digital Chronometer NVIS Emergency Procedures 3. Quick Reference Guide FAULT ISOLATION 1. General Malfunctions Troubleshooting TABLE OF CONTENTS Page 2 29/04/2022 Revision: 1.5...

  • Page 11: Introduction

    Neither this document nor the information disclosed herein or of a supplementary nature shall be reproduced or transferred to other documents or used or disclosed to others for manufacturing purposes, or for any other purposes, except as specifically authorized in writing by Thommen Aircraft Equipment AG (TAE). All rights are reserved.

  • Page 12: Warnings, Cautions And Notes

    The Document / Equipment Defect Report (on the next page) gives the customer and/or Approved Service Facility 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.
  • Page 13 User Operational Manual CM20 Digital Chronometer 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...

  • Page 14: List Of Abbreviations

    User Operational Manual CM20 Digital Chronometer List of Abbreviations Abbreviation Description Air Transport Association Battery CM20 Digital Chronometer, Type CM20 Component Maintenance Manual Defect Error Elapsed Time Elapsed Timer Down Flight Time Flight Timer Alarm INSOP Installation and Operating Manual...

  • Page 15: Description And Operation

    It has the purpose to provide clock and timer capabilities in aviation cockpit applications. 1.2 Function Description The CM20 has a three-line negative image liquid crystal display (LCD). The top line shows the UTC; the middle and bottom lines show the selected additional function.

  • Page 16: Limitations

    CM20 Digital Chronometer 1.3 Limitations The CM20 is vibration tested in accordance with category U2 of section 8.0 of RTCA/DO- 160F, curves F and F1, without shock mounts. The CM20 can therefore be installed in a helicopter or a fixed wing aircraft.

  • Page 17: Operation

    CM20 Digital Chronometer Operation 2.1 General When electrical power is switched ON, the CM20 enters a self-test routine. During this time, all display segments are turned on for about five seconds, as shown below. Figure 2 - Display Self-test During normal mode of operation, the CM20 cycles between the different display pages by pressing the MODE button.
  • Page 18 User Operational Manual CM20 Digital Chronometer Figure 3 - Display Page Selection DESCRIPTION AND OPERATION Page 4 29/04/2022 Revision: 1.5...

  • Page 19: Local Time (Lt)

    CM20 Digital Chronometer 2.4.1 Local Time (LT) The first mode entered by CM20 is Local Time. The middle line displays the local time, the bottom line statically displays ‘LT’. Depending on the configuration setting, the local time can be displayed in 12-hour or 24-hour format.

  • Page 20: Set Page

    User Operational Manual CM20 Digital Chronometer 2.4.2 LT Set Page The UTC and Local Time can be manually set. Use the RESET button to switch to the desired field to be set (e.g., UTC hours, LT hours, etc.) and increase the value with the START/STOP button.

  • Page 21: Flight Time (Ft)

    User Operational Manual CM20 Digital Chronometer 2.4.3 Flight Time (FT) Once airborne, the current flight time is automatically increased. The middle line displays the time elapsed since flight beginning; the bottom line statically displays ‘FT’. The activation signal depends on the configuration setting.

  • Page 22: Maintenance Timer In Hours (Mth)

    User Operational Manual CM20 Digital Chronometer 2.4.4 Maintenance Timer in Hours (MTH) Similar to the FT page, this is information about accumulated flight hours. The counter is automatically increased upon activation of FLIGHT discrete and shows the total amount of flight time.

  • Page 23: Flight Timer Alarm (Fta)

    The FTA is very helpful in this situation. Simply set the FTA to the desired time before or during the flight. CM20 will launch an alarm when this time point is reached. The alarm can be in visible or audible form, depending on the aircraft configuration.

  • Page 24: Flight Timer Alarm (Fta) Set Page

    User Operational Manual CM20 Digital Chronometer 2.4.6 Flight Timer Alarm (FTA) Set Page Setting the FTA value is very similar to setting the Local Time. There are only two things which need to be considered when setting the FTA: the FTA value must be greater than zero (00:00:00) and greater than the Flight Timer, otherwise the alarm cannot be set.

  • Page 25: Elapsed Timer (Et)

    Figure 11 - Elapsed Timer An initial press on the START/STOP button starts the counter. A second press on the START/STOP button freezes the displayed value, while CM20 continues to count in the background. Another press on the same button updates the display.
  • Page 26 User Operational Manual CM20 Digital Chronometer Figure 12 - Setting Elapsed Timer Pressing the RESET button for approximately 2 seconds restarts the counter if not stopped previously, otherwise it simply resets it. The figure above shows the functional behaviour. The MODE button switches to the Elapsed Timer Down display page.

  • Page 27: Elapsed Timer Down (Etd)

    User Operational Manual CM20 Digital Chronometer 2.4.8 Elapsed Timer Down (ETD) A second alarm can be launched after an arbitrary delay set by Elapsed Timer Down. This countdown alarm is independent of the flight time. It is manually triggered. The timer allows a maximum value of 99:59:59 hours to count down. The middle line displays the current ETD value, the bottom line statically displays ‘ETD’.

  • Page 28: Elapsed Timer Down (Etd) Set Page

    User Operational Manual CM20 Digital Chronometer 2.4.9 Elapsed Timer Down (ETD) Set Page Set the ETD in the same way as the FT Alarm. Use the RESET and START/STOP buttons to navigate to different units and to increase their values.

  • Page 29: Alarms

    CM20 Digital Chronometer 2.4.10 Alarms The CM20 can have two types of alarm: FTA and ETD. Each alarm is accompanied by an alarm annunciator and a visible or audible alarm output. An alarm can have three states: Alarm NOT Set, Alarm Set and Alarm Activated.

  • Page 30: User Programmable Modes

    Different display illumination behaviour can be applied to the CM20. The modification can be performed by an operator only. In a default configuration, the Day Mode luminance is constant. When switching the cockpit panel to Night Mode, the luminance of CM20 display can be dimmed to adapt it to ambient instruments. 2.8 NVIS The CM20, when operated in night mode, fulfils the conditions defined for NVIS, Type I, Class B.

  • Page 31: Quick Reference Guide

    Top Line Middle Line Alarm Annunciator Bottom Line START/STOP MODE RESET • Start/stop timer • Switch to next • (re)set values • Increase value display page Figure 17 - CM20 Front View DESCRIPTION AND OPERATION Page 17 29/04/2022 Revision: 1.5...
  • Page 32 User Operational Manual CM20 Digital Chronometer Figure 18 - Display Page Sequence DESCRIPTION AND OPERATION Page 18 29/04/2022 Revision: 1.5...

  • Page 33: Fault Isolation

    Table 101 – Warning Messages 1.2 Troubleshooting If an unexpected error occurs during the operation of the CM20, the clock will be stopped. The top and middle lines will statically display ‘--:--' and ‘--:--:--' respectively. The bottom line will display ‘ERR:<Code>’.
  • Page 34 User Operational Manual CM20 Digital Chronometer INTENTIONALLY BLANK FAULT ISOLATION Page 102 29/04/2022 Revision: 1.5...

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