Mandatory: For all aircraft that have a G500/G600 Integrated Flight Deck System interfaced to a KFC 275 or KFC 325 autopilot system that includes altitude capture (ALTC) mode and vertical speed (VS) control from the G500/G600 Primary Flight Display (PFD).
Optional: For all other aircraft, this STC Service Bulletin may be incorporated at the owner’s discretion.
GAD 43e Expansion Board software version 2.31 updates the King KAS 297B and King KAS 297C #1/#2 Altitude Preselect communication protocols to fix an issue where an interfaced KFC 275 or KFC 325 autopilot could be provided with erroneous pitch commands. This software version resolves the issue described in Garmin Service Advisory 1555.
GAD 43e units installed under the G500/G600 Part 23 AML STC SA02153LA-D are affected.