Thommen AD20 - Critical Failure Indication; Power Failure; Fig. 2-8 Indication of Critical Failures

REVUE THOMMEN AG
CH-4437 Waldenburg
AD20 Standby Altimeter
Page 35 of 72
07-Sep-2009 Document No: AD-INSOP-800 Revision: 1.6
2.4.3.3 Critical Failure Indication
Critical Failures are indicated by the lower three digits of the altitude display showing steady ‘E r r’.
Fig. 2-8 Indication of Critical Failures
The pointer will stopp at its current position and the instrument is set to idle mode. The ARINC 429
communication shall mark all labels as “failure warning”.
In case of a Critical Failure (operation stopped) the Failure Code number is displayed in the lower
part of LCD section. This condition requires depot level maintenance.
NOTE: Refer to Appendix II for Failure codes and its descriptions
2.4.3.4 Power Failure
In case of total power fail or switching off the instrument’s power supply the instrument will
• set the warning flag valid discrete output to invalid (WFVOUTD)
• switch off lighting
• switch off ARINC 429 interface
• set the LCD blank
• leave pointer in current position