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TAXIING.
The carburetor
heat knob should
be pushed
full in during
all ground
operations
unless
heat is absolutely
necessary
for smooth
engine
operation.
When
the
knob is pulled
out
to the
heat position,
air
entering
the
engine
is
not filtered.
Taxiing
over loose
gravel
or cinders
should
be
done
at
low
engine
speed
to
avoid abrasion
and stone
damage
to the
propeller
tips.
Refer
to
figure
2-4 for
additional
taxiing
instructions.
BEFORE TAKE-OFF.
WARM-UP.
Since
the
engine
is closely
cowled
for efficient
in-fIight
cooling,
pre-
cautions
should
be
taken to
avoid overheating
on
the
ground.
Full
throttle
checks
on
the
ground
are
not recommended
unless
the
pilot
has good reason
to
suspect
that the
engine
is not
turning
up properly.
MAGNETO
CHECK.
The magneto
check
should
be made
at
1700 RPM
as
follows.
Move
ignition
switch
first
to
R position
,
and
note RPM.
Next move
switch
back
to
BOTH
to
clear
the
other
set of plugs.
Then
move
switch
to
L
position,
note RPM and return
the
switch
to the
BOTH position.
RPM
drop
should
not exceed
150 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
speed will
usually
confirm
whether
a deficiency
exists.
An absence
of RPM drop
may be
an
indication
of faulty
grounding
of
one side
of
the
ignition
system
or should
be cause
for suspicion
that the
magneto
timing
is set in
advance
of
the
setting
specified.
ALTERNATOR CHECK.
Prior
to
flights
where
verification
of proper
alternator
and
voltage
regulator
operation
is essential
(such
as
night
or
instrument
flights),
a
positive
verification
can be made
by loading
the
electrical
system
momen-
tarily
(3
to
5 seconds)
with
the
landing
light
during
the
engine
runup
(1700
RPM).
The
ammeter
will remain
within
a needle
width
of
zero
if
the
al-
ternator
and
voltage
regulator
are
operating
properly.
2-12
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