Cessna 150 Series - INSTRUMENT PANEL; DESCRIPTION; REMOVAL AND INSTALLATION; SHOCK-MOUNTS

15-3.
INSTRUMENT
PANEL.
or back plate
could
change calibration
of gages.
15-4. DESCRIPTION.
The instrument
panel assem-
15-10.
PITOT AND
STATIC SYSTEMS.
bly consists
of a stationary
and shock-mounted
panel.
The
stationary
panel contains
fuel and
engine instru-
15-11. DESCRIPTION.
(Refer
to figure 15-2.)
ments,
which
are NOT
sensitive
to vibration.
The
The pitot
system
conveys
ram air
pressure
to the
shock-mounted
panel contains
major
flight instru-
airspeed
indicator.
The
static system
vents vertical
ments such
as horizontal
and directional
gyros
which
speed indicator,
altimeter
and airspeed
indicator
to
ARE affected
by vibration.
Most
of the instruments
atmospheric
pressure
through plastic
tubing
connect-
are
screw-mounted
on
the panel
backs.
ed to a static
port.
A static
line sump
is installed
at
source button
to collect condensation
in static system.
15-5. REMOVAL
AND
INSTALLATION.
(Refer
to
A pitot tube
heater
may be installed.
The
heating
figure
15-1.
The stationary
panel
is secured
to
en-
element
is controlled
by a
switch at
instrument
panel
gine stringers
and a forward
fuselage bulkhead
and
and powered
by the electrical
system.
ordinarily
is not considered
removable. The shock-
mounted
panel
is secured
to stationary
panel
with
15-12. MAINTENANCE.
Proper maintenance
of
rubber
shock-mounted
assemblies.
To
remove shock-
pitot and
static system
is
essential
for proper
op-
mounted
panel
proceed as
follows:
eration of
altimeter,
vertical speed
and airspeed
a. Unscrew
threaded
buttons securing
decorative
indicators.
Leaks,
moisture
and obstructions
in
cover to
panel and
remove
cover.
pitot
system
will result
in false
airspeed
indications,
b. Remove
nuts
from shock-mounts,
tag
and dis-
while
static
system malfunctions
will affect
readings
connect
instrument
wiring
and plumbing
and pull
panel
of all
three instruments.
Under
instrument
flight
straight
back.
conditions,
these
instrument
errors
could
be hazar-
c. Reverse
preceding
steps
for installation.
En-
dous.
Cleanliness
and security
are the
principal
sure ground
strap
is properly
installed.
rules
for system
maintenance.
The pitot
tube and
static ports
MUST
be kept clean
and unobstructed.
15-6.
SHOCK
MOUNTS.
Service
life of instruments
is directly
related
to adequate
shock-mounting
of
15-13.
STATIC
PRESSURE
SYSTEM
INSPECTION
panel.
If removal
of panel is
necessary,
check mounts
AND
LEAKAGE
TEST. The
following
procedure
for deterioration.
outlines
inspection
and testing
of static
pressure
system,
assuming
altimeter
has been
tested
and in-
15-7. INSTRUMENTS.
spected in accordance
with current
Federal Aviation
Regulations.
15-8. REMOVAL.
(Refer to figure
15-1.)
Most in-
a. Ensure
static
system is
free from
entrapped
struments
are secured
to panel with
screws inserted
moisture and
restrictions.
through
panel face.
To remove
an instrument,
re-
b. Ensure
no alterations
or
deformations
of air-
move
decorative
cover,
disconnect
wiring
or plumb-
frame surface
have
been made
which
would affect
ing to instrument,
remove
mounting
screws
and take
the relationship
between
air pressure
in static
pres-
instruments
out from
behind,
or in some
cases, from
sure
system and
true ambient
static air
pressure for
front
of panel.
Instrument
clusters
are
installed
as
any
flight configuration.
units and are
secured by a
screw at each
end. A
c. Attach
a source of suction
to static pressure
cluster
must
be removed
from
panel to
replace an
source
opening.
Figure 15-3
shows
one method
of
individual gage.
In all cases
when an instrument
is
obtaining suction.
removed,
disconnected
lines
or wires should
be pro-
d.
Slowly apply
suction until
altimeter
indicates
a
tected.
Cap open
lines and cover
pressure
connec-
1000-foot
increase
in altitude.
tions on instrument to prevent thread damage and
entrance
of foreign
matter. Wire
terminals
should
CAUTION
be
insulated
or tied up
so accidental
grounding
or
short-circuiting
will not occur.
When applying
or releasing
suction,
do not
exceed range
of vertical speed
indicator or
15-9,
INSTALLATION.
Generally,
installation
pro-
airspeed
indicator.
cedure
is the reverse
of removal
procedure.
Ensure
mounting
screw
nuts are
tightened
firmly,
but do not
e.
Cut off
suction
source to
maintain
a "closed"
over-tighten,
particularly
on
instruments
having
system
for one
minute. Leakage
shall
not exceed
plastic
cases.
The same rule
applies
to connecting
100
feet of altitude
loss
as indicated
on altimeter.
plumbing
and wiring.
f.
If leakage
rate is
within tolerance,
slowly
re-
lease suction
source.
NOTE
All
instruments (gages
and indicators), requiring
a thread
seal or lubricant, shall be installed using
If leakage rate exceeds maximum
allowable,
teflon tape on male
fittings only. This
tape is
first tighten all connections,
then repeat
I available through
Cessna Parts Distribution
leakage test. If leakage
rate still exceeds
(CPD
2).
maximum
allowable, use following
procedure.
When
replacing an
electrical
gage in an instrument
g.
Disconnect
static pressure
lines from
airspeed
cluster assembly,
avoid
bending
pointer or
dial
indicator
and vertical
speed indicator.
Use
suitable
15-2
Change
1