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CHEROKEE 140
"D"
SECTION Ill
7.
The
vacuum
gauge is
provided
to
monitor
the
pressure
available
to assure the
correct
operating
speed of the
vacuum
driven
gyroscopic flight
instruments,
it
also monitors
the condition
of the
common
air
filter by
measuring
the
flow
of air thru the
filter.
If the
vacuum
gauge
registers
lower
than
5"
Hg
+.10"
Hg
at
2000
RPM, the
following items
should
be
checked
before flight:
a.
Common
air
filter,
could
be dirty
or restricted.
b.
Vacuum
lines
could
be
collapsed
or
broken.
c.
Vacuum
pump,
worn.
d.
Vacuum
regulator,
not adjusted
correctly.
The
pressure,
even though
set correctly,
can read
lower
under
two conditions:
(1)
Very
high
altitude,
above 12000
feet,
(2) Low
engine
RPM usually on
approach
or
during
training
maneuvers.
This
is
normal
and should
not
be
considered
a
malfunction.
711102
2 3
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