P/N 11934-003
3A-9
Cirrus Design
Section 3A
SR20
Abnormal Procedures
System Malfunctions
Alternator Failure
Steady illumination of either ALT caution light in the annunciator panel
indicates a failure of the corresponding alternator. The most likely the
cause of the alternator failure is a wiring fault, a malfunctioning
alternator, or a malfunctioning control unit. Usually, electrical power
malfunctions are accompanied by an excessive rate of charge or a
discharge rate shown on the ammeter.
• Caution •
Alternators in this airplane are self-exciting. These alternators
require battery power for alternator starting; however, once
started, the alternators will provide self-generated field power
to continue operation in case of a battery failure. To assure
alternator restart power is available if the alternators fail, the
batteries should not be turned off during flight.
Serials 1005 thru 1581
: A flashing ALT 1 light indicates an excessive
charging rate. This could occur with a very low BAT 1 and heavy
equipment loads. Since the loads on ALT 2 are much lower, it is
unlikely that a flashing ALT 2 light could occur, even with a very low
BAT 2.
Figure 3-2 shows the electrical system power distribution. Individual
loads on each circuit breaker panel bus are shown in the same order
as they are on the panel. Note that items on the circuit breaker panel
Essential buses are powered from ALT 1, ALT 2, BAT 1, and BAT 2.
The circuit breaker panel Main buses and Non-Essential buses are
powered from ALT 1 and BAT 1 only.
• Note •
If it is necessary to reduce electrical loads due to an alternator
malfunction, switch off electrical components and/or systems that are
not essential for the current flight conditions rather than pulling circuit
breakers. Load shedding in this manner will prevent accidental circuit
breaker disconnection and loss of power to flight-critical systems. See
Figure 3-2, Electrical Power Distribution, for details on electrical
busses and what components/systems they power.
(Continued on following page)
Revision A5
Summary of Contents for SR20
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