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P/N 11934-S38
Section 9
Cirrus Design
Supplements
SR20
Section 7 - Systems Description
• Note •
This section provides general description and aircraft
integration information for the Garmin GNC 420W and GNS
430W 400W-Series Navigators. For detailed descriptions and
operational instructions,
refer to the Garmin 400W-Series
GPS Navigator Pilot's Guide and Reference, P/N 190-00356-
00, Revision A or later revision
GNC 420W
The GNC 420W, designated as the secondary navigator (GPS 2), is a
GPS Navigator and VHF communications transceiver. The GPS
Navigator consists of a GPS receiver, a navigation computer, and a
Jeppeson NavData database all contained in the GNC 420W control
unit mounted in the center console. Additionally, a VHF
communications receiver, designated COM 2, is also integrated into
the unit.
GPS Navigator
The GNC 420W navigator is coupled to the airplane’s CDI. The GPS 2
antenna is located on top of the fuselage slightly aft of the rear window
along the airplane centerline. The navigator is powered by 28 VDC
through the 5-amp GPS2 and 7.5-amp COM 2 circuit breakers on the
Avionics Non-Essential Bus.
Communication (COM) Transceiver
The GNC 420W includes a digitally-tuned integrated VHF
communications (COM) transceiver. The COM 2 antenna is located
below the cabin on the airplane centerline.
28 VDC for transceiver operating is controlled through the Avionics
Master Switch and supplied through the 7.5-amp COM 2 circuit
breaker on the Avionics Non-Essential Bus.
Revision 02: 10-29-13