Mooney M20K - Pitot & Static Air Pressure System; Heated Pitot - Trouble Shooting

MOONEY
AIRCRAFT
CORPORATION
M20K
SERVICE
AND
MAINTENANCE
MANUAL
34-00-00
-GENERAL
CAUTION
Release
air
pressure
slowly
by
unrolling
rubber
All
Right
instruments are
grouped
on
shock
mounted
tubing,
a
sudden
release
of air
pressure
may
panel
directly
in
front
of
pilot.
Flight
instruments
are
damage
airspeed
indicator.
operated
by:
(1)
filtered
air
drawn
into
an
evacuated
instrument
2.
Pitot
system
hose
inspections.
After
pitot
system
case,
is
checked
for
leaks,
inspect
hose
sections for
signs
of
(2)
barometric
pressure
or
barometn’e
impact
air
deterioration.
Check
all
tubing
for
brittleness,
checks
or
pressure
differences,
cracks
particularly
at
bends
or
connecting
points.
When
new
hose
is
installed,
recheck
system
for
leaks
~3)
van’ations
in electn’c
current
due
to
mechanically
using
PITOT
SYSTEM
LEAK TEST
procedure.
vaned
resistance,
3.
Static
system
cleaning.
Blow low
air
pressure
(4)
reference
to
the
earths
magnetic
field
(10-25
PSI).
through
the
lines
from
the
disconnected
(5)
aircraft
electn’cal
power,
line
at
the
airspeed
indicator
to
the
static
ports.
Cover
each
static
port
separately
when
blowing
to
insure
that
The
glareshield
must
be removed
and
plumbing
each
line
is
clear.
Instrument error
or
possible
damage
disconnected
on
many
flight
instruments
before
they
may
result
if
even one
port
is
clogged
with
dirt
or
can
be
removed.
Remove
glareshield
attaching
foreign
matter.
screws,
center
post
cover
screws
and
carefully
lift
center
post
cover
and
glareshield
from
the
panel.
CAUTION
Disconnect
glareshie(d
lights.
NEVER
BLOW
AIR
through
lines
TOWARD
the
Reinstall
glareshield
in
reverse
sequence.
INSTRUMENT
panel;
to
do
so
will
seriously
3610-40
PITOT
STATIC
AIR
PRESSURE
damage
instruments.
When
blowing
back
SYSTEM
throughlines
from
the
instrument
panel,
make
sure
that
no
air is
blown
into
instruments.
Static
pressure
instruments are
e>ctremely
sensitive
to
pressure
changes;
therefore,
the
pitot
and
static
4.
Static
system
leak
test.
The static
system
shoukl
system
must
be
kept
free
from
moisture
and
be
checked
for
leaks
In
accordance
w~h the
obstructions.
Drain the
pitot
and
static
systems
after
instructions
in
Federal
Aviation
Regulation
91.171.
humid
or
wet
weather.
If instrument
operation
is
erratic
or
inoperative
after
draining,
perform
the
following:
CAUTION
1.
Pitot
system
leak
test.
(Make
sure
Master
switch
To
avoid
damaging
either
the
airspeed
is
OFF
and
Gear
Control is
in
DOWN
position.)
indicator or
the
landing
gear
airspeed
safety
A.
Slip
end
of
a
short
rubber
hose
over
pitot
tube.
switch
an
equal
pressure
should
be
applied
to
pitot
side
of the
indicator
while
leak
testing
the
B.
Close
open
end of
hose;
slowly
roll
up
hose
until
static
system.
airspeed
indicator
reads
150
MPH
(132
KIAS).
C.
Clamp
hose
and
hold
for
one
minute.
5.
Alternate
static
source.
An anemate
static
source
valve
is
provided
to
change
the
static air
source
from
D.
If
airspeed
indicator
falls
more
than
10
MPH
outside
aircraft
to
inside
cabin. The
valve
is
located
on
(9
KIAS),
within
one
minute,
check
system
for
leaks
the lower
panel
immediately
to
the
left of
the
pilots
and
tighten
line
fbtings.
control
column.
Airspeed
indicator
and
altimeter
E.
Repeat
steps
B,
C,
and D until
obtaining
less
readings
will
be
slightly
affected
when
using
the
than
a
?O
MPH
(9
KIAS)indicator
reading drop.
altemate
static
source.
361091
HEATED
PITOT
TROUBLE
SHOOTING
TROUBLE
PROBABLE
CAUSE
REMEDY
Tube
does
not
heat
or
clear
Switch
circuit
breakertripped.
Reset
circuit
breaker.
itself of
ice
with
switch
on.
Open
circuit.
Repair.
Excessive
voltage
drop
between
Check
voltage
at
pitot
head.
battery
and
pitot
head.
Heating
element
bumed
out.
Replace
pitot
head.
3600-00
OLDWILLWAYNE