CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
SPEECH COMMUNICATIONS
1. DESCRIPTION
This section covers the systems which utilize the voice to transmit and/or receive messages from air-to-air
or air-to-ground.
Serials 1005 thru 2015, 2016 & subs w/o Perspective Avionics: The speech communications system consists of two digitally-tuned integrated VHF communications (COM) transceivers. The tuning controls are
collocated with the NAV at the left side of the transceiver front panel. Frequency tuning is accomplished by
rotating the large and small concentric knobs to select a standby frequency and then transferring the frequency to the active window. The COM frequency display window is at the upper left corner of the transceiver display. Auto-tuning can be accomplished by entering a frequency from a menu.
The transceiver receives all narrow- and wide-band VHF communication transmissions transmitted within
a frequency range of 118.000 MHz to 136.975 MHz in 25.0 kHz steps (720 channels). For European operations, the COM can be operator configured for 8.33 kHz channel spacing (2280 channels).
The COM 1 antenna is located above the cabin on the airplane centerline. 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 COM1 and COM2 circuit breaker on the Avionics Essential Bus.
Serials 2016 & subs w/ Perspective Avionics: The speech communications system consists of two digitally
tuned VHF communications (COM) receivers integral to the Garmin GIA 63 integrated avionics unit. Frequency tuning is accomplished through either the Flight Management System (FMS) keyboard or through
the MFD or PFD display screens.
The transceiver receives all narrow- and wide-band VHF communication transmissions transmitted within
a frequency range of 118.000 MHz to 136.975 MHz in 25.0 kHz steps (760 channels). For European operations, the COM can be operator configured for 8.33 kHz channel spacing (3040 channels).
The COM 1 antenna is located above the cabin on the airplane centerline. The COM 2 antenna is located
below the cabin on the airplane centerline.
28 VDC for Integrated Avionics Unit 1 operation is supplied through the 7.5-amp COM 1 and 5-amp GPS
NAV GIA 1 circuit breakers on Essential Bus 1. 28 VDC for Integrated Avionics Unit 2 operation is supplied
through the 7.5-amp COM 2 and 5-amp GPS NAV GIA 2 circuit breakers on the Main Bus 2.
EFFECTIVITY:
All
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CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
2. MAINTENANCE PRACTICES
A. Garmin GNS 430 GPS/COM/NAV - Serials 1005 thru 2015, 2016 & subs w/o Perspective Avionics
The GNS 430 is an IFR certified VHF communications transceiver and Navigation Management System (NMS). The NMS includes GPS sensor, VOR/Localizer and Glideslope receivers. The GNS 430
includes two removable data cards, one with a Jeppesen data base, and second being a custom data
card. GPS signals are received by an internally mounted antennas. NAV/LOC/GS signals are received
by the VOR antenna. For installation and removal procedures refer to Dependent Position Determining. (Refer to 34-50)
B. Garmin GNC 420 GPS/COM - Serials 1005 thru 2015, 2016 & subs w/o Perspective Avionics
The GNC 420 is an IFR certified VHF communications transceiver and GPS sensor. The GNC 420
includes GPS sensor and two removable data cards, one with a Jeppesen data base, and second
being a custom data card. GPS signals are received by the low profile GA 56 antenna. For installation
and removal procedures refer to Dependent Position Determining. (Refer to 34-50)
C. Garmin GNC 250XL GPS/COM - Serials 1005 thru 2015, 2016 & subs w/o Perspective Avionics
The GNC 250XL is an VFR certified VHF communications transceiver and GPS sensor. The GNC
250XL includes a GPS sensor and removable data card. GPS signals are received by the low profile
GA 56 antenna. For installation and removal procedures refer to Dependent Position Determining.
(Refer to 34-50)
D. Garmin GIA 63W Integrated Avionics Unit - Serials 2016 & subs w/ Perspective Avionics
The GIA 63W Integrated Avionics Unit contains an IFR certified VHF communications transceiver and
Navigation Management System (NMS). The NMS includes a WAAS certified GPS receiver, VOR/ILS
localizer receiver, and ILS glideslope receiver. GPS signals are received by an internally mounted
antenna just aft of the windshield and an externally mounted antenna located on top of the fuselage.
NAV/LOC/GS signals are received by the VOR antenna. For installation and removal procedures refer
to Central Computers. (Refer to 31-40)
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EFFECTIVITY:
All