(2023) Service Bulletin 23037 Rev B: GPS 175/GNX™ 375/GNC® 355 Main Software Version 3.21 and GNX 375 Transponder Board Software Version 2.80

PRODUCTS AFFECTED:

GPS 175, GNC 355, and GNX 375 products listed below with Main Software Version 3.20 and earlier are affected:

Table 1. Products Affected

CERTIFICATION AUTHORIZATION:

TSO Authorization

TSO Authorization does not provide installation airworthiness approval. Separate installation airworthiness approval is required for type-certified aircraft. Notification of revision to any Garmin STC(s) will be provided under a separate service bulletin.

COMPLIANCE:

Recommended: Compliance with Service Bulletin 23037 is recommended for the models listed in Table 1.

PURPOSE:

GPS 175/GNX 375/GNC 355 Main Software Version 3.21 contains the following changes from Main Software Version 3.20:

• Corrected an issue where some 1090ES ADS-B and ADS-R surface targets may erroneously appear as directional on the GNX 375
• Improved flight plan importing from a PED
• Added option to set the CDI Scale on the GNC 355

GPS 175/GNX 375/GNC 355 Main Software Version 3.21 contains the following changes from Main Software Version 3.12:

• Added support to use Fuel data from G500(H)/G600/G700 TXi and GI 275 EIS units on the Fuel Planning Page
• Added support for the following RS-232 Fuel formats for fuel data to display on the Fuel Planning Page:
  
  • FADC Format 1
  • Fuel Format 1
  • Fuel Format 2

NOTE
This feature requires settings to be entered in configuration mode: Setup > Interfaces > RS-232.

• Flight plan waypoints that are used for transitions are now displayed in gray text on the flight plan page
• Route waypoint types have been expanded to include fly-over waypoints
• User waypoint were expanded to support user airports
• Added Crossfill support for sharing flight plan information between two Garmin navigators: GPS 175, GNC 355, GNX 375, GTN (v6.72), and GTN Xi (v20.30)

NOTE
This feature requires settings to be entered in configuration mode: Setup > Interfaces > Cross-Side Navigator.

• Added support GPS 175 and GNC 355 to receive ADS-B traffic and weather data from a GNX 375

NOTE
This feature requires settings to be entered in configuration mode: Setup > Interfaces > ADS-B SRC.

• ON GNX 375 OAT user data fields now display when OAT temp probe is installed
• Fixed an issue where users were receiving “ABORT APPROACH” messages when flying LNAV+V approaches
• Fixed an issue with Label 100 in GAMA output formats to allow GDU 620 to change the CDI from GPS to VOR
• Fixed an issue with tuning the GNC 355 COM radio from the G3XT. The MapMx Format 2 interface now sends the correct COM channel spacing value
• Expanded flight plan feature to allow removing a hold at the final approach fix
• Improved the accuracy of the internal AHRS processing for calculating attitude (pitch and roll) provided to a portable electronic device

WARRANTY INFORMATION:

For GPS 175 and GNC 355 products, this modification is reimbursable under the original Garmin factory warranty.

For GNX 375 products, this modification is warranty reimbursable with a deadline of October 31, 2023.