Mooney M20R - Heated Pitot Troubleshooting; Pitot and Static Air Pressure System

MOONEY AIRCRAFT
CORPORATION
M20R
SERVICE
AND
MAINTENANCE
MANUAL
34-00-00
-GENERAL
CAUTION
Release
air
pressure
slowly by
unrolling
rubber
All
flight
instruments
are
grouped
on
the
shock
tubing.
A
sudden
release
of the air
pressure may
mounted
panel
directly
in
front of the
pilot.
Flight
in-
damage airspeed
indicator.
struments
are
operated
by:
(1)
filtered air
drawn
into
an
evacuated
instrument
case,
(2)
barometric
pressure
or
2
Pitot
system
hose
inspections.-8fter pitot
system
barometric
impact
air
pressure
differences,
(3)
varia-
is checked for
leaks,
inspect
hose sections
for
signs
of
tions
in
electric
current
due
to
mechanically
varied
deterioration.
Check
ail
tubing
for
brittleness,
checks
or
resistance,
(4)
reference
to
the
earths
magnetic
field
or
cracks
particularly
at
bends
or
connecting
points.
(5)
aircraft electrical
power.
When
new
hose
is
installed,
recheck
system
for leaks
The
glareshield
must
be
removed and
plumbing
dis-
using
PITOT SYSTEM
LEAK
TEST
procedure.
connected
on
many
flight
instruments before
they
can
3.
Static
system
cleaning.-Blow
low
air
pressure
(10-
be
removed.
Remove
glareshield
attaching
screws,
25
PSI) through
lines
from
disconnected
line
at
center
post
cover screws.
Carefully
lift
center
post
airspeed
indicator
to
static
ports.
Cover each
static
cover
anal
glareshield
from
panel.
Disconnect
port
separately
when
blowing
to
insure that
each line
is
glareshield
and
compass
lights,
clear.
Instrument
error or
possible
damage
may
result
Reinstall
glareshield
in
reverse
sequence.
if
even one
port
is
clogged
with dirt
or
foreign
matter.
34-10-00
PITOT
STATIC
AIR
PRESSURE
CAUTION
SYSTEM
NEVER
BLOW
AIR
through
the line
TOWARD
the
INSTRUMENT
panel;
to
do
so
will
seriously
Static
pressure
instruments
are
extremely
sensitive
to
damage
instruments. When
blowing
back
through
pressure
changes,
therefore,
the
pitot
and static
sys-
line from instrument
panel,
make
sure
that
no
air
tem must
be
kept
free from
moisture and obstructions.
is blown into instruments.
Drain
pitot
and static
systems
after humid
or
wet
weather.
If
instrument
operation
is erratic
or
inoperative
4. Static
system
leak tes´•t.-The static
system
should
after
draining, perform
the
following:
be checked for leaks
in
accordance
with
instructions
in
1.
Pitot
system
leak
test.-(Make
sure
Master
Switch
Federal Aviation
Regulation
91.171.
is
OFF and
Gear Control
is
in
DOWN
position.)
CAUTION
A.
Slip
end of
a
short
rubber
hose
over
pitot
tube.
To
avoid
damaging
either the
airspeed
indicator
or
B.
Close
open
end of
hose;
slowly
roll
up
hose
the
landing
gear
airspeed safety
switch
an
equal
until
airspeed
indicator
reads
150
MPH.
pressure
should be
applied
to
the
pitot
side
of
the
C.
Clamp
hose
and
hold for
one
minute.
indicator while leak
testing
the static
system.
D.
If
airspeed
indicator
falls
more
than
9
KIAS,
within
one
minute,
check
system
for
leaks and
tighten
5.
Alternate static source.-An
alternate
static
source
line
fittings.
valve is
provided
to
change
the static air
source
from
E.
Repeat steps
B,
C,
and
D
until
obtaining
less outside the aircraft
to
inside the cabin. The valve is lo-
than
a
9
KIAS indicator
reading
drop.
cated
on
the lower
panel
under the
pilots
control
column.
Airspeed
indicator
and altimeter
readings
will
be
slightly
affected when
using
the
alternate static
source.
3410-01
HEATED
PITOT
TROUBLE SHOOTING
TROUBLE
PROBABLE
CAUSE
REMEDY
ube
does
not
heat
or
clear itself
of
Switch
circuit breaker
tripped.
Reset circuit
breaker.
ice
with
switch
on.
Open
circuit.
Repair.
Excessive
voltage drop
be-
Check
for
bad
connections
in
connec-
tween
battery
and
pitot
head.
tors
and cables
leading
to
the
pitot
Read.
Heating
element burned
out.
Replace pitot
head.
a4-OQ-OQ
Island Enterprises