Cessna T188C - Page 227

MODEL
188
& T188
SERIES
SERVICE
MANUAL
11B-39.
IDLE SPEED
AND IDLE MIXTURE
ADJUST-
e. If
mixture is set
too LEAN, engine
speed will
MENT.
(See figure
11B-2.)
The idle
speed adjust-
drop immediately,
thus requiring
a richer
mixture.
ment is a conventional
spring-loaded screw located in
Tighten adjusting nut (clockwise)
for a richer mixture.
the air throttle
lever. The idle mixture adjustment
f. If mixture is set
too RICH. engine speed will
in-
is the locknut at the metering
valve end of the linkage.
crease above 50 rpm, thus
requiring a leaner mix-
Tightening the nut to shorten
the linkage provides a
ture. Back off adjusting nut (counterclockwise)
for
richer
mixture.
A leaner
mixture
is
obtained
by
a leaner
mixture.
backing
off
the nut
to lengthen
the
linkage.
Idle-speed
and mixture
adjustment should be accomplished
after
NOTE
the engine
has
been
warmed
up. Since
idle
rpm may
be affected
by idle mixture
adjustment,
it may be
After
each adjustment
to the idle
mixture,
necessary
to readjust idle rpm after
setting the idle
run engine up to approximately
2000 rpm
mixture correctly.
to clear
engine of excess fuel to
obtain a
a.
Set the throttle
stop
screw to obtain
600 *
25 rpm,
correct
idle speed.
with
throttle
control
pulled
full out
against
idle
stop.
NOTE 11B-40. INDUCTION AIR SYSTEM.
Engine idle speed may
vary among different
11B-41. DESCRIPTION.
The engine air induction
engines.
An engine should
idle smoothly,
system receives
air from a
scoop on the left
side of
without excessive
vibration and the idle
speed the cowling.
It passes through an automotive
type
should
be high enough to maintain
idling oil air filter
into a duct assembly containing
the rotary
pressure and to
preclude any possibility of
alternate air valve,
and into the compressor section
engine
stoppage in flight
when the
throttle is
of the turbocharger.
The centrifugal
compressor
closed.
increases air pressure forcing
it to flow through the
fuel
air
control
into the
intake
manifold,
and
then
b.
Advance throttle to increase engine
speed to the cylinders.
A maximum power
loss of five (5)
1000 rpm
inches may
be a direct result of the completely
c Pull mixture
control knob slowly and steadily
blocked air filter,
and alternate rotary air valve
toward
the idle cut-off
position, observing
tacho- open
situation.
meter.
then return control
full IN
(RICH) position
before
engine
stops.
11B-42.
AIRBOX
REMOVAL
AND INSTALLATION.
d.
Adjust mixture
adjusting nut
to obtain a slight
a.
Remove the lower
left hand engine
cowl section.
and momentary
gain of 25 to
50 rpm at 1000 rpm
b. Disconnect:
engine
speed as mixture
control
is moved from
full
1. Throttle and
mixture controls
at bellcranks.
IN (RICH) toward idle cut-off
position. Return con-
2. Electrical wiring from
inlet air temperature
trol to full IN (RICH) to prevent engine stoppage. probe at connections, and tape ends.
IDLE SPEED ADJUSTMENT
[DLE
MIXTURE
ADJUSTMENT
Figure
11B-2.
Idle Speed
and
Idle Mixture
Adjustment
11B-13