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

Page: 262 / 490

SECTION 7 CESSNA
AIRPLANE AND SYSTEM DESCRIPTION MODEL 172S NAV III
KAP 140 AUTOPILOT
U.S.
ELECTRICAL SYSTEM
(Continued)
ELECTRICAL SYSTEM MONITORING AND
ANNUNCIATIONS
(Continued)
LOW VOLTAGE ANNUNCIATION (Continued)
The ALT FIELD circuit breaker may open on occasion during normal
engine starts due to transient voltages. Provided that normal alternator
output is resumed after the ALT FIELD circuit breaker is reset, these
occurrences are considered nuisance events. If the ALT FIELD circuit
breaker opens after reset, do not close again. Repeated occurrences
indicate a problem with the electrical system that must be corrected by
a qualified maintenance technician before flight.
HIGH VOLTAGE ANNUNCIATION
The HIGH VOLTS annunciator will come on when main or essential bus
voltage is above 32.0 volts. This warning annunciation is an indication
that the alternator is supplying too high of a voltage. The ALT MASTER
switch should immediately be positioned to OFF (refer to Section 3,
Emergency Procedures, HIGH VOLTS ANNUNCIATOR COMES ON).
In the event a HIGH VOLTS condition occurs, the ACU will
automatically open the ALT FIELD circuit breaker, removing alternator
field current and stopping alternator output. The HIGH VOLTS
annunciator is a warning that the ACU automatic alternator shutdown
circuit is not operational and an action from the pilot is required to
position the ALT MASTER to OFF.
(Continued Next Page)
172SPHAUS-05
7-56
For
Training
Purposes
Only