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P/N 11934-S22
Section 9
Cirrus Design
Supplements
SR20
VHF NAV is powered by 28 VDC through the Avionics Master
Switch and the 5-amp GPS2 circuit breaker on the Avionics
Non-essential Bus. 28 VDC for transceiver operation is
supplied through the Avionics master Switch and the 7.5-amp
COM2 circuit breaker on the Avionics Non-Essential Bus.
GNS 430 Integrated GPS/NAV/COM System
This airplane is equipped with a GNS 430 integrated GPS navigator,
NAV receiver, and COM transceiver. The GPS navigator consists of a
GPS receiver, a navigation computer, and a Jeppeson NavData
database all contained in the GNS 430 control unit mounted in the
center console. The GPS is designated ‘GPS 1.’ A VHF NAV receiver
and tuner for receiving VHF Omnirange (VOR), Localizer (LOC), and
Glideslope (G/S) is also integrated into the control unit. The NAV
receiver is designated ‘NAV 1.’ Additionally, a VHF communications
receiver, designated ‘COM 1,’ is also integrated into the unit. All tuning
and display controls for the GPS, NAV, and COM are located in the
GNS 430 control/display in the center console. The following
paragraphs describe the GPS, NAV, and COM functions of this unit.
For a complete description, as well as full operating instructions,
refer
to the Garmin GNS 430 Pilot’s Guide and Reference
.
GPS Navigator
The Garmin GNS 430 GPS navigator is the primary system (GPS 1),
is IFR certified, and is coupled to the airplane’s HSI (or HSI) and MFD.
Normally, the second GPS Navigator provides backup and is approved
for VFR use only. If the second GPS is also a Garmin 430, it will be
coupled to the CDI and is also approved for IFR use. The Garmin GPS
430 is capable of providing IFR enroute, terminal, and approach
navigation with position accuracies better than 15 meters. The system
utilizes the Global Positioning System (GPS) satellite network to derive
the airplane’s position (latitude, longitude, and altitude) and the
altitude digitizer to enhance the altitude calculation. The GPS 1
antenna is located beneath the cabin roof along the airplane centerline
and the GPS 2 antenna is located under the glareshield. All GPS
navigator controls and functions are accessible through the GNS 430
front control panel located in the center console. The panel includes
function keys, power switches, MSG and Nav status annunciators,
color LCD display, two concentric selector knobs on each panel, and a
Revision 2: 08-15-07
