Textron Aviation Cessna 172S NAV III Skyhawk SP, Information Manual

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CESSNA SECTION 3
MODEL 172S NAV III EMERGENCY PROCEDURES
KAP 140 AUTOPILOT
U.S.
ELECTRICAL POWER SUPPLY SYSTEM
MALFUNCTIONS
(Continued)
INSUFFICIENT RATE OF CHARGE
(Continued)
Main battery life can be extended by setting the MASTER switch (ALT
and BAT) to OFF and operating the equipment on the ESS BUS from
the standby battery. The standby battery is only capable of providing
power for systems on the essential bus and cannot provide power for
transponder (XPDR) operation. Main battery life should be extended,
when practical, for possible later operation of the wing flaps and use of
the landing light (at night).
NOTE
The LOW VOLTS annunciator can come on when the
engine is operated at low RPM with a high electrical load.
The LOW VOLTS annunciator will usually go off when the
engine is operated at higher RPM for greater alternator
system output. Make sure that the M BATT AMPS
indication shows positive (+) current at the higher RPM.
172SPHAUS-05 3-37
For
Training
Purposes
Only