Mooney M20M - Airspeed Indicator; General; Heated Pitot-Trouble Shooting

MOONEY AIRCRAFT CORPORATION M20M
SERVICE
AND
MAINTENANCE
MANUAL
34-00-00
-GENERAL
CAUTION
All
flight
instruments
are
grouped
on
the
shock
Release the air
pressure
slowly by unrolling
the
mounted
panel
directly
in
front of
the
pilot.
Flight
rubber
tubing,
a
sudden release
of the air
instruments
are
operated by:
(1)
filtered
air
drawn
into
pressure may
damage
the
airspeed
indicator.
an
evacuated instrument
case,
(2)
barometric
pressure
2.
Pitot
system
hose
inspections-After
the
pitot
or
barometric
impact
air
pressure
differences,
(3)
system
is
checked
for
leaks.
inspect
the
hose
sections
variations in
electric
current
due
to
mechanically
varied
for
signs
of
deterioration.
Check
all
tubing
for
resistance,
(4)
reference
to
the earths
magnetic
field
or
brittleness,
checks
or
cracks
particularly
at
the
bends
(5)
aircraft electrical
power.
or
connecting
points.
When
new
hose is
installed,
The
glareshield
must
be removed
and
plumbing
recheck
thesystem
for leaks
using
the
PITOT
disconnected
on
many
of
the
Right
instruments
before
SYSTEM LEAK
TEST
procedure.
they
can
be
removed.
Remove
glareshield
attaching
3.
Static
system
cleaning.-8low
low
air
pressure
screws,
center
post
cover screws
and
carefully
lift
(10-25
PSI). through
the lines
from the disconnected
center
post
cover
and
glareshield
from
the
panel,
line
at
the
airspeed
indicator
to
the static
ports.
Cover
Disconnect
the
glareshield
and
compass
lights.
each static
port
separately
when
blowing
to
insure
that
Reinstall
the
glareshield
in
reverse
sequence.
each line
is
clear. Instrument
error or
possible
damage
may
result
if
even
one
port
is
clogged
with
dirt
or
34-10-00
PITOT 8( STATIC AIR
PRESSURE
foreign
matter.
SYSTEM
CAUTION
Static
pressure
instruments
are
extremely
sensitive
to
pressure
changes;
therefore,
the
pitot
and static
NEVER BLOW AIR
through
the
line
TOWARD
system
must
be
kept
free from
moisture
and
the
INSTRUMENT
panel;
to
do
so
will
seriously
obstructions.
Drain the
pitot
and
static
systems
after
damage
the instruments. When
blowing
back
humid
or
wet
weather.
If
instrument
operation
is erratic
through
the
line
from the
instrument
panel,
make
sure
that
no
air is
blown into
the
or
inoperative
after
draining,
perform
the
following:
instruments.
1.
Pitot
system
leak
test.-(Make
sure
Master
switch
is
OFF and Gear
Control
is
in
DOWN
position.)
4. Static
system
leak test.-The
static
system
should
be checked for
leaks in
accordance
with the
A.
Slip
end
of
a
short
rubber hose
over
pitot
tube.
instructions
in
Federal
Aviation
Regulation
91.171.
B.
Close
open
end
of
hose;
slowly
roll
up
hose
until
CAUTION
airspeed
indicator
reads
150
MPH.
To avoid
damaging
either
the
airspeed
indicator
C.
Clamp
hose
and
hold
for
one
minute,
or
the
landing
gear
airspeed safety
switch
an
D.
If
airspeed
indicator
falls
more
than
9
KIAS,
equal
pressure
should be
applied
to
the
pitot
within
one
minute,
check
system
for
leaks
and
tighten
side
of the
indicator while leak
testing
the
static
line
fittings.
system.
E.
Repeat
steps
B, C,
and
D until
obtaining
less
5.
Altemate static
source.-An
altemate static
source
than
a
9
KIAS indicator
reading
drop.
valve
is
provided
to
change
the static
air
source
from
outside the
aircraft
to
inside the cabin. The
valve
is
located
on
the
lower
panel
under the
pilots
control
column.
Airspeed
indicator and
altimeterreadings
will
be
slightly
affected
when
using
the
altemate static
source.
34-10-01
HEATED
PITOT
TROUBLE
SHOOTING
Tube
does
not
heat
or
clear
Switch
circuit
breaker
tripped.
Reset
circuit
breaker.
itself
of
ice
with switch
on.
Open
circuit.
Repair.
Excessive
voltage
drop
between
Check
for
bad
connections
in
battery
and
pitot
head.
connectors
and
cables
leading
to
the
pitot
head.
Heating
element
burned
out.
Replace
pitot
head.
4-99
34-00-00
OLDWILLWAYNE