System Maintenance Manual

G1000 / GFC 700 System Maintenance Manual - 300/B300 Series King Air Page 2-3
190-00716-01 Revision 1
2.1.4 GCU 477 FMS Control Unit
The GCU 477 functions as the primary control interface to the GDU 1500 MFD. The GCU 477 provides
alphanumeric, softkey, and flight planning function keys used to interface with the G1000; the MFD does
not possess any knobs or controls other than softkeys. The GCU 477 is powered by No. 3 Triple Fed Bus.
The GCU 477 also provides the crew with the added functionality of tuning their receivers via the GCU as
well as the PFD. Detailed instructions regarding the controls are discussed in the G1000 Cockpit Reference
Guide.
Figure 2-4, FMS Controller
2.1.5 GTX 33( ) Extended Squitter Transponder (2)
The Garmin GTX 33( ) transponders communicates with the on-side GIA 63W through RS-232 digital
interface. This STC installation allows for installation of two GTX 33 non-diversity transponders, two
GTX 33D Diversity transponders, or one of each type. The units are mounted under the floor in the cabin
just aft of fuselage station 246.750. Power is provided by the No. 1 GTX 33( ) from Triple Fed Avionics
Bus. The No. 2 GTX 33( ) is powered from Left Gen Avionics Bus. Each GTX 33( ) transponder
interfaces with a transponder antenna mounted to the bottom of the fuselage. Each GTX33D diversity
transponder interfaces to a transponder antenna mounted to the top of the fuselage.
Figure 2-5, Transponder