Textron Cessna C172S PIM, Pilot Operating Handbook

Page: 98 / 322

SECTION 3 CESSNA
EMERGENCY PROCEDURES MODEL 172S NAV III
GFC 700 AFCS
U.S.
ELECTRICAL POWER SUPPLY SYSTEM 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
When AVIONICS BUS 2 is set to OFF, the following items
will not operate:
k. AVIONICS Switch (BUS 2) - OFF (KEEP ON if in clouds)
9. Land as soon as practical.
NOTE
Make sure a successful landing is possible before
extending flaps. The flap motor is a large electrical load
during operation.
Autopilot Audio Panel
COMM 2 NAV 2
Transponder MFD
172SPHBUS-00
3-20