Thommen AD20 - Non Critical or Tolerable Failures; Fig. 2-7 Indication of Non - Critical or Tolerable Failures

REVUE THOMMEN AG
CH-4437 Waldenburg
AD20 Standby Altimeter
Page 34 of 72
07-Sep-2009 Document No: AD-INSOP-800 Revision: 1.6
NOTE:
If a non critical BIT allows to continue operation but invalid values would lead to wrong calculations
ARINC 429 labels is marked as “failure warning” (SSM).
If any error is indicated on LCD at startup the lighting is activated before the instrument goes into idle
mode.
Dashes will be indicated if no valid data can be displayed
The REVUE THOMMEN AD20 Standby Altimeter has the ability to find possible failures via extensive
built in test (BIT) functions. To read the BIT history the AD20 Standby Altimeter can be connected via
the RS232 serial data interface to PC. The failure codes are then uploaded with the maintenance
Software.
NOTE: Refer to Appendix II for Failure codes and its descriptions
2.4.3.2 Non critical or tolerable Failures
Non Critical Failures are indicated by the lower three digits of the altitude display showing altering
‘E r r’ and altitude.
Fig. 2-7 Indication of Non-critical or tolerable Failures
The instrument operation will continue and the ARINC 429 communication will mark invalid labels as
“failure warning”.