Piper SENECA III - Preheating

SECTION
4
PIPER
AIRCRAFT CORPORATION
NORMAL
PROCEDURES
PA-34-220T,
SENECA
III
4.25
PREHEATING
The
use
of
preheat
and
auxiliary
power
(battery
cart)
will
facilitate
starting
during
cold
weather
and
is
recommended when
the
engine
has
been
cold
soaked
at
temperatures
of
10°F
and
below
in
excess
of
two
hours.
Successful
starts
without
these
aids
can
be
expected
at
temperatures
below
normal,
provided
the
aircraft
battery
is in
good
condition and
the
ignition
and
fuel
systems
are
properly
maintained.
The
following
procedures
are
recommended
for
preheating,
starting,
warm-up,
run-up
and
takeoff
(a)
Select
a
high
volume
hot
air
heater.
Small electric
heaters
which
are
inserted
into
the
cowling
"bug
eye"
do
not
appreciably
warm
the
oil
and
may
result
in
superficial
preheating.
WARNING
Superficial
application
of
preheat
to
a
cold-
soaked
engine
can
have
disastrous
results.
A
minimum
of
preheat
application
may warm
theengineenough
to
permit
starting
but
will
not
de-congeal
oilin
the
sump.lines,
cooler,
filter,
etc.
Typically,
heat
is
applied
to
the
upper
portion
of
the
engine
for
a
few
minutes
after which the
engine
is
started
and
normal
operation
is
commenced.
The
operator
may
be
given
a
false
sense
of security
by
indications
of oil
and
cylinder
temperatures
as
a
result
of
preheat.
Extremely hot
air
flowing
over
thecylindersand
oil
temperature
thermocouples
may
lead
one
to
believe
the
engine is
quite
warm:
however,
oil
in
the
sump
and
filter
are
relatively
remote
and
will
not
warm as
rapidly
as a
cylinder.
For
example,
even
when
heat
is
applied
directly,
oil lines
are
usually
"lagged"
with material
which
does
an
excellent
job
of
insulating.
Congealed
oil
in
such
lines
may
require
considerable
preheat.
The
engine
may
start
and apparently
run
satisfactorily,
but
can
be
damaged
from lack
of lubrication
due
to
congealed
oil
in
various
parts
of
the
system.
The
amount
of
damage
will
vary
and
may
not
become
evident
for
many
hours.
On
the
other
hand,
the engine
may
be
severely
damaged
and
could
fail
shortly
following
application of
high
power.
Improper
or
insufficient
application
of
preheat and the
REPORT:
VB-III0
ISSUED: JANUARY
8, 1981
4-22