Textron Cessna C172S PIM, Руководство по эксплуатации для пилотов

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CESSNA SECTION 7
MODEL 172S NAV III AIRPLANE AND SYSTEM DESCRIPTION
GFC 700 AFCS
U.S.
ELECTRICAL SYSTEM
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ELECTRICAL SYSTEM MONITORING AND
ANNUNCIATIONS
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LOW VOLTAGE ANNUNCIATION
A signal from the ACU, located inside the power distribution module,
provides the trigger for a red LOW VOLTS annunciation shown on the
PFD. LOW VOLTS is displayed when the main bus voltage measured
in the power distribution module is below 24.5 volts. The LOW VOLTS
warning annunciation is an indication that the alternator is not supplying
the power that is required by the airplane. If the conditions causing the
LOW VOLTS warning can not be resolved, nonessential electrical loads
should be eliminated and the flight should be terminated as soon as
practicable.
NOTE
During low RPM operation, with a high electrical load on the
system, such as during a low RPM taxi, the LOW VOLTS
annunciation may come on, the bus voltage values may
turn red, and main battery ammeter discharge indications
may occur. Under these conditions, increase RPM or
decrease electrical loads to reduce demand on the battery.
In the event an overvoltage condition (or other alternator fault) occurs,
the ACU will automatically open the ALT FIELD circuit breaker,
removing alternator field current and stopping alternator output. The
main battery will then supply current to the electrical system as shown
by a discharge (negative number) on the M BATT ammeter. The LOW
VOLTS annunciator will come on when the system voltage drops below
24.5 volts. Set the ALT FIELD circuit breaker to the ON position (push
in) to energize the ACU. If the warning annunciation goes out and the
main battery (M BATT) ammeter indicates positive current, normal
alternator charging has resumed. If the annunciator comes on again, or
the ALT FIELD circuit breaker opens again, an alternator malfunction
has occurred. If the circuit breaker opens again, do not SET it to the ON
position again. Have a qualified technician determine the cause and
correct the malfunction. Turn off nonessential electrical loads and land
as soon as practicable.
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172SPHBUS-00 7-55