Cessna 172P - Page 47

engine
power
immediately
and select
a
suitable forced landing
field.
Use
only the minimum
power
required
to reach
the desired
touchdown spot.
ELECTRICAL
POWER
SUPPLY
SYSTEM
MALFUNCTIONS
Malfunctions
in
the eleotrical
power
supply system
ca,n be detected by
periodic
monitoring
of the
a,mmeter
end low-voltage
warning light;
however,
the cause
of these
malfunctions
is
usually
difficult
to
determine.
A
broken
alternator
drive
belt
or wiring is
most tikely the
cause of
alternator
failures,
atthough
other factors
could
ca,use
the
problem.
A
defective
alternator
control
unit can also
cause malfunctions.
Probtems
of
this
nature
oonstitute
an electrical
emergency
and
should be dealt
with
:
EXCESSIVE
RATE
OF
CHARGE
After
engine
sta,rting
and heavy
electrical
usage
at low erigine
speeds
(such
as extended
taxiing)
the
battery
condition will
be
low
enough to
accept
above
normal
chargin
after
thirty
minutes
of
cruisi
less
than two
ncedle
widths
o
to remain
above
this value
on
evapora,te
the
electrolyte
at an
excessive rate.
INSUFFICIENT
RATE
OF CHARGE
CESSNA
MODEL
172P
SECTION 8
EMER,GENCY
PROCEDUR,ES
NOTE
Ilt
and
ammeter
dis-
ch
w RpM
conditions
wi
ch as during
a
low
30
May
1980
8-L7