Cessna 172N - Page 54

SECTION
4
NORMAL
PROCEDURES
CESSNA
MODEL
172N
takeoff
nrn.
Any
sign
of
rough
engine
operation
or sluggish
engine
accel-
eration
is
good
cause
for
discontinuing
the takeoff. If
this
occurs,
you
are
justified
in
malcing
a thorough
full-throttle,
static
runup before
another
takeoff
is
attempted.
The
engine
should
run smoothly
and turn approxi-
mately
2280
to
2400
RPM
with
carburetor
heat
off and
mixture
tull
rich.
NOTE
Carhrretor heat
should
not
be used
dunng
takeoff unless
it is
absolutely necessary for
obtaining
smooth
engine
acceleration.
Full-throttle
runups
over
loose
gravel
are especially
harmful
to
pro-
peller
tips.
When
takeoffs
must be made
over a
gravel
surface,
it
is
very
important
that the
throttle be advanced
slowly.
This
allows
the airplane
to
start
rolling
before high
RPM is developed,
and
the
gravel
will
be blown
back
of the
propeller
rather than
pulled
into
it. When
unavoidable small
dents
appear
in
the
propeller
blades,
they
should
be immediately
correct-
ed
as
described
in Section 8 under Propeller Care.
Prior to takeoff
from fields above 3000
feet
elevation,
the mixture
shotrld
be
leaned to
give
mardmum
RPM
in
a full-throttle,
static
runup.
After
full
throttle
is
applied, adjust the
throttle friction lock
clock-
wise to
prevent
the
throttle
from
creeping
back from a
maximum
power
position.
Similar
friction
lock
adjustments
should
be
made
as
required
in
other
flight conditions
to maintain
a fixed
throttle
setting.
WING
FtAP
SEITINGS
Normal
and
short field
takeoffs are
performed
with
flaps up. Flap
settings
greater
than 10"
are
not approved
for
takeoff.
Use of
10o
flaps is
reserved
for minimum
ground
runs or for takeoff
from
soft
or rough
fields.
Use of
10o
flaps
allows safe use
of slightty
lower
takeoff
speeds
than
with
flaps
up.
The
lower speeds result in
shortening
the
ground
run and
total
distance
over a 50 foot
obstacle by
approximately
10Vo.
However,
this advantage
will be lost if flaps
up
speeds
are used,
or in
high
altitude takeoffs
in
hot
weather at maxi-
mum
weight
where
climb
would
be marginal with
10o
flaps. Therefore,
use of 10"
flaps
is not
recommended
for takeoff
over
an obstacle at high
altitude
in hot
weather.
SHORI FIELD
TAKEOFF
If an
obstruction dictates
the
use
of
a steep
climb angle, after
liftoff
4-t4