7-72
P/N 11934-003
Section 7
Cirrus Design
Airplane Description
SR20
outside typical operating parameters. The MFD and PFD receive the
voltage signals via the DAU as measured directly off the Main and
Essential Buses.
In the event Main Bus voltage is less than 24.5v or exceeds 32.0v the
MFD will display “Check Main Bus” in a yellow advisory box in the
lower right corner of the MFD.
In the event Essential Bus voltage is less than 24.5v or exceeds 32.0v
the MFD will display “Check Main Bus” in a red advisory box in the
lower right corner of the MFD.
Alternator 1 and Alternator 2 ampere output are shown as text in the
electrical data block located in the mid-right section of the MFD. The
MFD and PFD receive the amp signals via the DAU as derived from
current transducers located in the MCU.
In the event Alternator 1 or Alternator 2 ampere output is less than 2
amps for 20 seconds or more, the MFD will display “Check ALT 1” or
“Check ALT 2” respectively, in a yellow advisory box in the lower right
corner of the MFD.
28 VDC for the digital instrument operation is supplied through the 2-
amp ANNUN / ENGINE INST circuit breaker on the Essential Bus.
Ammeter Select Switch
Serials 1268 through 1581:
The AMMETER SELECT switch on the
instrument panel is used to select the desired source of electrical
current flow to be indicated on the ammeter. The switch has three
positions: ALT 1, BATT, and ALT 2. The BATT position indicates BAT
1 current flow only. Selecting one of the switch positions will cause the
amperage output from that device to be displayed on the ammeter.
Serials 1582 and subsequent:
Main and Essential Bus voltages are
displayed on the MFD and PFD, therefore, no ammeter select switch
is necessary.
Low-Volts Warning Light
The airplane is equipped with a red LOW VOLTS warning light in the
annunciator panel located on the left side of the instrument panel. A
voltage sensor in the (MCU) monitors voltage on the Essential Bus
Revision A5
Summary of Contents for SR20
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Page 22: ...2 2 P N 11934 003 Section 2 Cirrus Design Limitations SR20 Placards 2 21 Revision A6 ...
Page 308: ...9 2 P N 11934 003 Section 9 Cirrus Design Supplements SR20 Intentionally Left Blank Reissue A ...