Cessna 172K - Pre-Take-Off and Take-Off Procedures; Engine Warm-Up and Magneto Check; Take-Off Power Check

BEFORE
TAKE-OFF.
WARM-UP.
"
o
4
woo -
If
the engine
accelerates
smoothly,
the airplane is
ready
for
take-off. ---
Since
the
engine
is
closely cowled for efficient
in-flight
engine
cooling,
precautions should be
taken to
avoid
overheating during
prolonged engine
operation on the ground.
Also,
long
periods of
idling may
cause
fouled
spark
plugs.
MAGNETO
CHECK.
o
The magneto check should be made at 1700 RPM
as
follows:
Move
ignition switch first to
"R"
position,
and
note
RPM.
Next
move switch o
o
back to "BOTH"
to clear the other
set
of
plugs.
Then
move switch to
the
"L"
position
and note
RPM.
RPM
drop
should
not exceed 125 RPM
on
either magneto or
show greater
than 50
RPM
differential
between
magnetos.
If
there is a
doubt
concerning
operation of
the ignition system,
RPM checks
at higher engine speeds will
usually
confirm
whether a
deficiency
exists.
An absence
of
RPM drop
may be an indication
of
faulty
grounding
of
I
g
... ....
one side of
the ignition system
or
should be cause for
suspicion
that
the
Zo
z
magneto
timing
is set in advance
of
the setting
specified.
Oo
TAKE-OFF.
POWER CHECK-
It
is important to check
full-throttle
engine operation
early
in the
take-off
run.
Any
signs of rough
engine operation or sluggish
engine
acceleration is good
cause
for discontinuing
the
take-off.
If
this
occurs,
you are justified
in
making
a thorough
full-throttle,
static runup
before
another
take-off
is attempted.
The
engine should run
smoothly
and
turn
approximately 2260
to
2360
RPM
with carburetor heat off.
°
NOTE
Carburetor heat
should not be
used
during
take-off
gg
-'
= x
unless it
is
absolutely
necessary
for
obtaining
smooth
engine
acceleration.
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