Table of Contents
Advertisement
-~
CESSNA
MODELT210M
SECTION 7
AIRPLANE
&
SYSTEMS DESCRIPTIONS
MANIFOLD
PRESSURE
VARIATION
WITH
INCREASING
OR
DECREASING FUEL FLOW
When the waste gate is open, movement of the mixture control has little
or no effect on the manifold pressure of the turbocharged engine.
When the waste gate is closed, any change in fuel flow to the engine will
have a corresponding change in manifold pressure. That is, increasing the
fuel flow will increase the manifold pressure and decreasing the fuel flow
will decrease the manifold pressure. This is because an increased fuel flow
to the engine increases the mass flow of the
exhaust.
This turns the
turbocharger faster, increasing the induction air flow and raising the
manifold pressure.
MOMENTARY OVERSHOOT OF MANIFOLD PRESSURE
Under some circumstances (such as rapid throttle movement, espe-
cially with cold oil), it is possible that the engine can be overboosted
slightly above the maximum five minute takeoff manifold pressure of 36.5
inches. This would most likely be experienced during the takeoff roll or
during a change to full throttle operation. in flight. The induction air
pressure relief valve will normally limit the overboost to 2 to 3
inches.
A slight .overboost of 2 to 3 inches of manifold
pre,
s sure is not
considered detrimental to the engine as long as it is momentary. No
corrective action is required when momentary overboost corrects itself
and is followed by normal engine operation.
However,
if overboosting of
this nature persists when oil temperature is normal or if the amount of
overboost tends to exceed 3 inches or more, the throttle should be retarded
to eliminate the overboost and the controller system, including the waste
gate and relief valve, should be checked for necessary adjustment or
replacement of components.
ALTITUDE OPERATION
Because a turbocharged
airplane
will climb faster
and
higher than a
normally aspirated
airplane,
fuel vaporization may be encountered. When
fuel flow variations of ±.5 lbs/hr or more are observed
(as
a "nervous" fuel
flow
needle),
or if a full rich mixture setting does not provide the desired
fuel flow, placing the auxiliary fuel pump switch in the ON position will
control vapor. However, it ·will also increase fuel flow, making it
necessary to adjust the mixture control for the desired fuel flow. The
auxiliary
fuel pump should be left on for the remainder of the climb. It can
be turned off whenever fuel flow will remain steady with it
off,
and the
mixture must be adjusted accordingly. The auxiliary fuel pump should be
turned off and the mixture reset prior to descent.
7-27
Hide quick links:
Advertisement
Table of Contents
