Cessna 172R, Operating Handbook

Page: 146 / 500

SECTION 4
NORMAL PROCEDURES
CESSNA
MODEL 172R
COLD
WEATHER
OPERATION
Special
consideration
should
be
given to the operation of the
airplane fuel system
during the winter season or prior
to any flight
in
cold temperatures.
Proper preflight draining of the fuel
system
is
especially important and will eliminate any free water accumulation.
The
use
of
additives such as isopropyl alcohol or diethylene glycol
monomethyl ether
may also be desirable. Refer
to
Section
8
for
information on the proper
use
of additives.
Cold weather often
causes
conditions which
require special care
during airplane operations. Even
small accumulations of frost, ice,
or snow must be removed, particularly from wing, tail and all control
surfaces to
assure satisfactory flight performance and handling.
Also, control surfaces
must
be free of any internal accumulations of
ice or snow.
If snow or
slush
covers the takeoff surface, allowance must
be
made for
takeoff distances which
will be increasingly extended as
the
snow or slush depth increases. The depth and consistency of
jthis
cover can,
in fact, prevent takeoff in many
instances.
A
WARNING
WHEN PULLING THE PROPELLER THROUGH BY
HAND,
TREAT IT AS IF THE IGNITION SWITCH IS
TURNED ON. A LOOSE OR BROKEN GROUND
WIRE ON EITHER MAGNETO COULD CAUSE
THE ENGINE TO
FIRE.
Prior
to
starting
on cold mornings, it is advisable to
pull the
propeller through several times by
hand
to
"break loose"
or
"limber" the oil, thus conserving battery energy.
When air
temperatures
are below 20°F (-6°C), the use of
an
external preheater
and an external
power source are recommended
whenever
possible to
obtain positive starting
and
to
reduce wear
and abuse to the engine
and electrical system.
Preheat will thaw
the
oil trapped in the oil cooler, which probably will be congealed prior
to starting
in extremely cold temperatures.
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