Piper Lance II - Page 397

LANCE
II
SERVICE
MANUAL
CAUTION
Do
not
use pipe
tape,
thread
dope,
hydrocarbon
oil or
grease,
as
these
can contaminate
pump
and
cause
malfunction.
c.
Use
the
following
steps
for
fitting
installation:
I.
Secure
pump
as noted
above.
2.
Insert
fittings
in
pump
ports
and
hand
tighten
firmly.
3.
Using
a wrench,
tighten
each
fitting
from
one-half
to
two
additional
turns.
10-19.
INSTRUMENT
AIR
SYSTEM.
(Refer
to
Figure
10-2.)
The instrument
air
system
consists
of
a pitot
air
system
and
a static
air system.
Refer
to
Figure
10-2 for
system
layout.
Pitot
air system
consists
of a
pitot
mast
located
on the
bottom
side
of
the left
wing.
with
its' related
plumbing.
Impact
air pressure
entering
the
pitot
is transmitted
from
the
pitot
inlet through
hose
and
tubing
routed
in through
the
wing to
the airspeed
indicator
on
the
instrument
panel.
Static
air
system
consists
of
a static
port
located
on
the bottom
of the
pitot
mast.
The
static
port
is directly
connected
to
the airspeed
indicator,
altimeter
and
rate
of climb
indicator,
on
the instrument
panel,
by
means
of hose
and
tubing
routed
through
the wing
along with
the
pitot line.
An alternate
static air
source
is located
below
the instrument
panel
in front
of
the pilot.
The
alternate
static
source
is part
of the
standard
system
and has
a
shutoff
valve
which
closes
the
port
when it
is not
needed.
A
placard
giving
instructions
for
use
is located
on
the
instrument
panel.
10-20.
DIRECTIONAL
GYRO.
10-21.
GENERAL.
The
directional
gyro
is a flight
instrument
incorporating
an
air driven
gyro
stabilized
in the
vertical
plane.
The
gyro is
rotated
at high
speed
by lowering
the
pressure
in the
air tight
case
and
simultaneously
allowing
atmospheric
air
pressure
to
enter
the
instrument
against
the
gyro
buckets.
Due
to gyroscopic
inertia,
the
spin axis
continues
to point
in
the
same
direction
even
though
the aircraft
yaws
to the
right
or
left. This
relative
motion
between
the gyro
and
the instrument
case
is shown
on the
instrument
dial
which
is
simular
to a
compass
card.
The
dial, when
set
to agree
with
the
airplane
magnetic
compass
provides
a
positive
indication
free from
swing
and
turning
error.
However,
the
directional
gyro
has
no
sense
of direction
and
must
be set
to the
magnetic
compass,
since
the magnetic
compass
is
subject
to errors
due
to magnetic
fields,
electric
instruments
etc.,
the
directional
gyro
is only
accurate
for
the heading
it has
been
set
for.
If the
gyro
is set
on
270
°
, for
instance,
and
the
aircraft
is turned
to some
other
heading,
there
can be a
large error
between
the
gyro
and the
magnetic
compass
due
to the
error
in compass
compensation,
this
will
appear
as
gyro precession.
The gyro
should
only
be checked
on
the heading
on
which it
was
first
set.
also
due to
internal
friction,
spin axis
error,
air
turbulence
and
airflow,
the
gyro
should
be set
at least
every
15 minutes
for accurate
operation,
whether
it has
drifted
or not.
Issued:
1/3/78
INSTRUMENTS
2E13