Textron Lycoming IO-540 Series User Manual

TEXTRON
LYCOMING
OPERATOR'S
MANUAL
0-540
& 10-540
SERIES
SECTION
3
To
avoid this condition,
all installations
are equipped
with a system
for
preheating
the incoming air
supply to the carburetor.
In this
way, sufficient
heat is added
to replace the heat
loss due to
vaporization of
fuel; and the
mixing
chamber's
temperature
cannot drop
to the freezing
point
of water.
This air preheater
is essentially
a tube or jacket
through
which the ex-
haust
pipe from one
or more cylinders
is passed,
and the air flowing
over-
these surfaces
is raised to
the required temperature
before
entering the
carburetor.
Consistently
high temperatures
are to
be avoided because
of
a loss in
power and a
decided variation
of the mixture.
High charge
temperatures
also
favor detonation
and preignition,
both of which
are to
be avoided
if normal service
life is to be
expected from
the engine. The
following
outline
is the proper
method
of utilizing
the carburetor
heat
control.
(1)
Take-off - Take-offs
should
be made with
carburetor heat
in full
cold position.
The possibility
of icing at
wide throttle
opening is very
remote.
(2) Flight
Operation
- The carburetor
air heat
control should
be left
in the cold position
during normal
flight operations.
On damp,
cloudy,
foggy
or hazy days, regardless of
outside temperature, keep
a sharp
lookout
for loss
in manifold pressure
or RPM
or both, depending
on
whether
a constant
speed or fixed
pitch propeller
is installed
on the
aircraft. When
this situation
arises, apply
full carburetor
air heat and
open the throttle to limiting
manifold pressure. This will
result in an
additional drop
in manifold
pressure which
is normal and
this drop
will be regained
as the
ice is melted out
of the induction
system. When
the
ice has been
melted from
the induction
system the carburetor
heat
control should
be returned to
the cold position.
Only in
aircraft
equipped with
a carburetor
air temperature
gage may
partial heat
be
used to keep the mixture temperature
above the freezing
point
(32
0
F.).
WARNING
Exercise
caution
when operating
with partial carburetor
heat, if
there is no
carburetor
air-temperature gage. Ice
crystals that would normally pass
through
the induction system can melt
from the partial heat. If this moisture
should
then drop sharply in temperature,
when passing through the
venturi it could
refreeze
and accumulate to form carburetor
icing. It is advisable,
therefore,
to use
either full heat or no heat in
aircraft not equipped with a carburetor
air-temperature
gage.
3-9

Textron Lycoming IO-540 Series Specifications

General

Brand	Textron
Model	Lycoming IO-540 Series
Category	Engine
Language	English