Low Voltage Annunciation; Circuit Breakers And Fuses - Cessna 172S Skyhawk Information Manual

CESSNA
MODEL 172S
SECTION 7
AIRPLANE
&
SYSTEMS DESCRIPTION
LOW VOLTAGE ANNUNCIATION
The low voltage warning annunciator is incorporated in thel
annunciator panel and activates when voltage falls below 24.5 volts.
If low voltage is detected, the red annunciation VOLTS will flash for
approximately 10 seconds before illuminating steadily. The pilot
cannot turn off the annunciator.
In the event an overvoltage condition occurs, the alternator
control unit automatically opens the AL T FLD circuit breaker-,I
removing alternator field current and shutting off the alternator. Th91
battery will then supply system current as shown by a discharge
rate on the ammeter. Under these conditions, depending on
electrical system load, the low voltage warning annunciator will
illuminate when system voltage drops below normal. The alternator
control unit may be reset by resetting the circuit breaker. If the 10~
voltage warning annunciator extinguishes, normal alternato
charging has resumed; however, if the annunciator illuminate
again, a malfunction has occurred, and the flight should b
terminated as soon as practicable.
NOTE
Illumination of the low voltage annunciator and ammeter I
discharge indications may occur during low RPM conditions
with an electrical load on the system, such as during a low
RPM taxi. Under these conditions, the light will go out at
higher RPM.
CIRCUIT BREAKERS AND FUSES
All circuit breakers inside the airplane are of the "push to reset"
or "switch/breaker" type. The power distribution module uses spade
type (automotive style) fuses and one glass type fuse (controlling
the clock).
Spare fuses for the power distribution module are located inside
the module. If one of the spare fuses is used, a replacement spare
should be obtained and reinstalled before the next flight.
Revision 4 7-35