Cessna SkyHawk SP 172S NAV III 2005 Pilot Operating Handbook page 89

SECTION 3
EMERGENCY PROCEDURES
CESSNA
MODEL 172S NAV III
SYSTEM SUPPLY ELECTRICAL POWER
MALFUNCTIONS
(Continued)
IF LOW VOLTS ANNUNCIATOR REMAINS ON (Continued)
NOTE
• The Main Battery supplies electrical power to the
Main and Essential Buses until M BUS VOLTS
decreases below 20 volts. When M BUS VOLTS
falls below 20 volts, the Standby Battery System
will automatically supply electrical power to the
Essential Bus for at least 30 minutes.
• Select COM1 MIC and NAV1 on the audio panel
and tune to the active frequency before setting
AVIONICS BUS 2 to OFF. If COM2 MIC and
NAV2 are selected when AVIONICS BUS 2 is set
to OFF, the COM and NAV radios cannot be
tuned.
i.
COM1 and NAV1 - TUNE TO ACTIVE
FREQUENCY
j. COM1 MIC and NAV1 - SELECT (COM2 MIC
and NAV2 will be inoperative once AVIONICS
BUS 2 is selected to OFF)
NOTE
GMA 1347 Audio Panel
NAV2
GDU 1040 MFD
When AVIONICS BUS 2 is set to OFF, the following
items will not operate:
KAP 140 Autopilot
COMM2
GTX 33 Transponder
k. AVIONICS Switch (BUS 2) - OFF (KEEP ON if in
clouds)
I
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13-18 U.S.
172SPHAUS-03