Cessna 172N - Page 51

CESSNA
MODEL
172N
SECTION
4
NORMAL
PROCEDURES
AMPTIFIED PROCEDURES
STAR,TING
ENGINE
During ergine
starting,
open the throttle
approximately f/g
inch.
In
warm
temperatures,
one or hvo
strokes
of
the
primer
should
be
zufficient.
In
cold
weather, up to
six
strokes of the
primer
may
be necessary. If the
engine
is
warm,
no
primirg
will
be required.
In
extremely
cold
temper-
atures, it may
be necessary to
continue
priming
while
cranking the
engine.
Weak
intermittent
firing
followed
by
puffs
of
black
smoke
from
the
exhaust
stack
indicate
overpriming
or
flooding. Excess
fuel
can
be
cleared
from the combiustion chambers by the following
procedure:
Set
the
mixfure
control
full lean and
the
throttle
full open;
then
crank
the en-
gine
through
several
revolutions
with
the
starter.
Repeat the
starting
procedure
without
any
additional
priming.
If
the engine is underprimed
(most
likely
in
cold
weather
with a cold
engine) i+'will not fire at all, and additional
priming
will be
necessary.
As
soon as
the
cylinders begin
to
fire,
open
the throttle
slightly to keep
it
running.
After
starting, if
the
oil
gage
does not begin
to
show
pressure
within
30
seconds
in
the
zummertime
and about twice
that
long in
very
cold
weather,
stop
engine and investigate, I-ack
of oil
pressure
can cause
seriors
ergine
damage.
After
starting, avoid
the
use of
carbretor
heat
unless icing
conditions
prevail.
NOTE
Additional
details
concerning
cold weather starting
and
operation
may
be found under
COLD WEATHER OPERA-
TION
paragraphs
in this
section.
TAXIIN
G
When
taxiing,
it is important
that
speed
and use
of brakes be
held
to
a
minimum and that all
controls
be
utilized
(see
Taxiing
Diagram, figure
4-2\ to maintain
directional
control
and
balance.
The carburetor heat control
lcrob
should
be
pushed
full
in during
all
ground
operations
unless
heat is
absolutely
necessary. When the lmob is
4-17