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service bulletin

Garmin SB 26089A: GPS 175, GNC 355 and GNX 375 Software 3.30

RWAS Avionics Desk · 2026-07-17 · Garmin Service Bulletin 26089A

Mandatory compliance is required by January 29, 2027 for affected units at software version 3.22 or earlier.

Garmin AXIS flight displays installed in a certified-aircraft cockpit.

Garmin Service Bulletin 26089A calls for affected GPS 175, GNC 355 and GNX 375 navigators running main software version 3.22 or earlier to be upgraded to version 3.30 no later than January 29, 2027. Garmin classifies compliance as mandatory for the non-certified-aircraft installations covered by the bulletin.

Version 3.30 adds AXIS Flight Display support, radio control from GTN Xi, TXi and AXIS, coordinated Smart Alert popups, and several operational refinements. It also corrects the visual-approach vertical-guidance issue described in Service Alert 26050, improves navigator synchronization and preserves stored flight-plan catalog data during upgrade.

GNX 375 installations also receive transponder software version 2.90. Garmin estimates one hour of labor per installed unit and states that the modification is not warranty reimbursable.

The bulletin is specifically written for non-certified aircraft. It is not an owner/operator preventive-maintenance authorization for FAA-certified aircraft. RWAS can verify installed software, determine applicability and perform the update under the appropriate maintenance authority. Contact RWAS at (605) 299-8178.

For current pricing or installation scheduling, call RWAS at (605) 299-8178 or contact the service desk.