Mooney M20M - Page 280

SERVICE
AND
MAINTENANCE
MANUAL
M20M
MOONEY AIRCRAFT CORPORATION
PROPELLER
GOVERNOR TROUBLE SHOOTING
(CON’T.)
TROUBLE
PROBABLE CAUSE
REM EDY
NOTE:
Low
engine
power.
Consult
engine
manual.
Takeoff
RPM
should
not
be
attained
during
static
ground
run.
RPM
should be
approximately
2525
RPM.
Erroneous
reading
tachometer
or
Calibrate
or
replace
instruments.
manifold
pressure
gauge.
Sticky pilot
valve.
Remove head and clean
pilot
valve with
crocus
cloth. Maintain
sharp pilot
valve
land
comers.
Check for
straightness
of
pilot
valve;
if
bent,
replace
valve.
RPM will
not
stabilize:
Sludgein
governor
pilot
valve Disassemble and clean.
or
relief
valve.
Burrs
on
pilot
valve lands. Disassemble and clean with
crocus
cloth.
Backlash
in
governor
control
Re-rig
or
adjust
control
system.
system.
Short
control
lever
making
fine
Re-rig
control
system.
speed
adjustment
impossible.
Sticky
relief
valve.
Inspect
for
burrs,
and
clean.
Erroneous
reading
tachometer. Calibrate
or
replace
instrument.
Excessive oil
leakage
in
engine
Refer
to
engine
manual.
transfer
bearing.
High propeller
friction.
Refer
to
propeller
overhaul
manual.
Governor function
upset
by
Repair
engine
for
smooth
operation.
malfunctioning
engine.
Air
trapped
in
propeller.
Cycle propeller
from
MIN
to
MAX
pitch
several
times
to
purge
air.
Sticky
pilot
valve.
Remove
head
and
pilot
valve.Clean
away
sludge
and vamish. Check
speeder spring
ends for
proper
settings.
Bent
pilot
valve.
Remove head and
replace pilot
valve.
Excessive
intemal
leakage
in Check
rigging
and make
necessary
part
governor.
replacements.
Excessive
over-speeding:
Wrong
governor
setting.
Reset
governor.
Use
test
rig
if
available.
Too
rapid
throttle
opening.
Advance throttle
evenly
and
slowly.
Damaged
or
wrong
gasket
Install
correct
new
gasket.
between
governor
base and
engine mounting pad.
Sticky
governor
pilot
or
relief
Disassemble,
clean,
and check for
valve.
burrs.
Replace
bent
pilot
valves.
Erroneous
reading
tachometer
or
Calibrate
or
replace
instrument.
manifold
pressure
gauge.
Inabilityto
attain
positive
high
Nigh-RPM
screw
adjusted
too
far
Remove control
arm
and
rotate
one
pitch:
IN,
causing
restricted
arm
travel, serration clockwise.
Back
out
high-RPM
screw
to
required
maximum
RPM.(One
tum
equals
27
RPM.)
Surging:
Excessive
propeller/bladeseat
Examine
propeller
hub
for
cause
of
friction.
friction.
61-20-30
4-99
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