Aviation Alerts and Advisories

Service Bulletin 1382: GTR 225/GNC 255 Software Upgrade to Display Software Version 2.02

20 December 2013  / Service Document Notifications /

CERTIFICATION APPROVAL: TSO Authorization (see Approval section of SSB1382 for details)


Mandatory: This Software Service Bulletin must be accomplished for installations utilizing the NMEA RS 232 interface to an external EFIS/PFD, excluding G500/G600 systems.

Optional: For all other installations, this Software Service Bulletin may be incorporated at the owner’s discretion and is not warranty reimbursable.


Display Software Version 2.02 contains the following changes from Version 2.01:

  • Added improvements to the display’s auto-contrast to react more efficiently with temperature changes
  • Sets the GNC 255’s RS-232 NMEA output bearing flag to invalid when tuned to a localizer

The following service documents have been resolved:

  • Corrected issue with the GNC 255’s RS-232 Serial Port configured to ‘NMEA’ and outputting incorrect CDI deviation data over the RS-232 NMEA interface when tuned to a VOR and the TO/FROM flag indicates FROM (Service Advisor 1380, Service Bulletin 1379)


Refer to ASDN1382


This software service bulletin describes the process for upgrading the GTR 225/GNC 255 Series Unit’s Display Software to Version 2.02.