CESSNA SECTION 7
MODEL T182T NAV III AIRPLANE AND SYSTEM DESCRIPTION
GFC 700 AFCS
U.S.
ENGINE (Continued)
TURBOCHARGING SYSTEM (Continued)
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 OVERBOOST OF MANIFOLD PRESSURE
Under some circumstances (such as rapid throttle movement,
especially with cold oil), it is possible that the engine can be over
boosted slightly above the maximum takeoff manifold pressure of 32
in.hg. 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 pressure 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
reduced 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.
(Continued Next Page)
T182TPHBUS-00
7-45
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