Textron Cessna 172R User Manual

SECTION
3
EMERGENCY
PROCEDURES
CESSNA
MODEL
172R
ELECTRICAL
POWER
SUPPLY
SYSTEM
MALFUNCTIONS
Malfunctions
in
the
electrical
power
supply
system
can
be
detected
by
periodic
monitoring
of
the
ammeter
and low
voltage
lannunciator
(VOLTS);
however,
the
cause
of
these
malfunctions
is
usually
difficult
to
determine.
A
broken
alternator
drive belt
or
wiring
is
most
likely
the
cause
of
alternator
failures,
although
other
factors
could
cause
the
problem.
A
defective
alternator
control unit
can
also
cause
malfunctions.
Problems
of
this
nature
constitute
an
electrical
emergency
and should
be
dealt
with
immediately.
Electrical
power
malfunctions
usually
fall
into
two
categories;
excessive
rate
of
charge
and
insufficient
rate
of
charge.
The
following
paragraphs
describe
the
recommended
remedy
for
each situation.
EXCESSIVE
RATE
OF
CHARGE
After
engine starting
and
heavy
electrical
usage
at
low
engine
speeds
(such
as
extended
taxiing)
the
battery
condition
will
be low
enough
to
accept
above normal
charging during
the initial
part
of
a
flight.
However,
after
thirty
minutes
of
cruising
flight,
the
ammeter
should be
indicating
less than
two
needle
widths
of
charging
current.
If
the
charging
rate
were
to
remain
above
this
value
on a
long
flight,
the
battery
would overheat
and
evaporate
the
electrolyte
at
an
excessive
rate.
Electronic
components
in
the electrical
system
can
be
adversely
affected
by
higher
than
normal
voltage.
The
alternator
control unit
includes
an
overvoltage
sensor
which
normally
will
automatically
shut down
the
alternator
if
the
charge
voltage
reaches
approximately
31
.5
volts.
If
the
overvoltage
sensor
malfunctions,
as
evidenced
by
an
excessive
rate
of
charge
shown
on
the
ammeter,
the
alternator
should
be
turned
off,
nonessential
electrical
equipment
turned
off
and
the
flight
terminated
as soon as
practical.
3-22
Revision
7
All manuals and user guides at all-guides.com

Textron Cessna 172R Specifications

General

Brand	Textron
Model	Cessna 172R
Category	Aircrafts
Language	English