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••••••
ENGINE START
Use of a
GPU
for
an
engine start is recommended
at
ambient temperatures
of
32°F
(O°C)
or
below. Ensure GPU
is
regulated
to
2S
VDC, has adequate
capacity (at least
500
amps),
and
is
limited
to
1100
amps.
Use of
SPR
is recommended for engine
starts
at
ambient temperatures
of
OaF
(-17 .S°C)
or
below. During
an
engine start using SPR, discontinue
SPR
at
30Q-400°C Turbine Temperature
(rrn.
:s:~
Use
of
SPR
is
not
required above
OaF
(-17.S°C). Do
not
energize
SPR
at
any
time other
than
engine start.
If
the
engines are exposed
to
extremely cold temperatures (below -40°F
(-40°CD
for
an
extended period,
the
engines should
be
preheated prior
to
attempting a start. For ambient temperatures between -40°F
and
-65°F
. (-40°C
and
-53. 9°C), direct warm
air
flow
into
each
engine for a minimum
of
30
minutes prior
to
engine start.
During engine starts in cold
weather,
engine acceleration, particularly
Fan
Speed (NI), is much slower
than
normal and Turbine Temperature
(fIT)
has
a tendency
to
increase more rapidly due
to
the increased spool-up times.
Additionally, higher than normal oil pressure can
be
expected
which
may
exceed
the
maximum allowable transients.
During engine starts in cold conditions:
• If Fan SPeed (Nt) does
not
rise with Turbine
Speed
(N2)
or
stops during the start attempt, abort start.
• If Turbine Temperature (fIT)
is
rising rapidly
and
ap-
pears
likely
to
exceed the start limit, abort start.
• Exceeding idle power with oil temperature below
30°C
is
not
recommended. However,
if
ambient tem-
perature preuents attainment of
300c,
idle power
may
be
exceeded as required
to
further warm the oil
to
normal operating limits prior
to
takeoff.
•
If
abnormal engine vibration occw:s
during
or
after
engine start, immediately
abort
start
or
shutdown
en-
gine
and
investigate for possible ice formation
on
back of fan blades.
When
the
aircraft has been cold soaked at ambient temperatures below
-13°F (-25°C), the engines should be operated a minimum of 3 minutes
to
.bring
the
hydraulic system
up
to
normal operating temperature.
FAA
APPROVED
4-30-76
REISSUED
2-25-81,
CHANGE
10
2-41
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