Mooney M20R - Electric Propeller De-Ice Troubleshooting; Helpful Tips; Trouble Shooting

MOONEY
AIRC
RAFT
CORPORATION
M20R
SERVICE AND
MAINTENANCE
MANUAL
30-61-01
HELPFUL
TIPS
4.
A
considerable
number
of timers
have
been
re-
turned for
repair
which
proved,
on
test,
to be
fully
oper-
1. The
Voltmeter
reading
will
be
slightly
lower
whe~
sys-
able.
Before
concluding
that
the timer
is
faulty,
test
it
per
tem
is
operated
on
battery
voltage
than
when
enI~ine
is
"De-lcer Timer
Check"
(30-63-00).
running.
5.
For
insulation
resistance
tests,
use
a
"megger"
2.
Use
"heat
test"
(30-64-00)
and
"load
meterl
test"
I’Meg"
type
insulation
tester,
James
G. Biddle
Company,
(30-62-00)
to
determine
which
De-leers
are
not
opeliating.
Plymouth
Meeting,
PA.)
or
other
tester
having
a
500
VDC,
Use
wiring
schematic
to
trace
circuits.
1000
megohm
capacity.
3.
Excess
current
reading
on
the
ammeter maj
indi-indi-
6.
Defective
wiring
in
propeller
mounted
components
cate
a
power
lead
shorted
to
ground.
Thus,
when
tr~uble
may
be
indicated
by
normal
current
readings
in
ground
of this
nature
is
found,
it
is vital that
the
grounded
cpower
checkouts
(propellers
not
rotating)
but
low
current with
lead be
located
and
corrected.
propellers
rotating
at
cruise
RPM.
30-61-02
TROUBLE
SHOOTING
CHART
-JELECTRIC PROPELLER
DE-ICE
TROUBLE
PROBPIBLE
CAUSE
REMEDY
Buss
load
meter/ammeter
shows 0
No
poweri
from aircraft.
If
no
voltage
into
circuit
breaker,
locate
current
all
phases
of
the
timer
cycle.
and
correct
open.
Tripped
cjrcuit
breaker.
Locate and
correct
short
before
resetting
circuit
breaker.
Circuit
br~aker
or
switch
faulty.
If
no
voltage
at
circuit breaker
output
with
voltage
at
input
and circuit
breaker
does
not
reset,
replace
circuit
breaker. If
voltage
is OK
at
output,
check
switch in
same manner.
Open
Bu~s
load
meter/ammeter
Disconnect
harness
at
timer
and
check
to
timer,
for
voltage
at
harness
Terminal
B
to
ground.
If
none,
locate
and
correct
open.
Open
tim$r
to
brush
assembly.
Disconnect
wire
harness
at
brush
assem-
bly
and
check
voltage
to
ground
from
leads.
(See
de-icing
system
wiring
sche-
matic for
power
and
ground
lead
and
pin
identification.)
If
low
or no
voltage,
lo-
cate and
correct
open
or
high
resistance
in wire
harness.
Check
continuity
from
Terminal
G,
or
lead
to
ground;
if
high
resistance
is
indi-
cated,
check
ground
wire for
breakage
and
ground
connections
for
correctness
and
tightness.
Correct
as
required.
Open
in
qe-lcer,
De-leer
wire
Disconnect
De-leer
leads
and
check
re-
harness
or
slip
nng
assembly
sistance
per
manufacturer’s
service
data.
leads.
If
not
OK,
replace
faulty
De-leer
boot.
If
OK,
check
for
land
repair)
open
in
de-
ice boot
wiring
harness
leads.
Ohmme-
ter
needle
must not
flicker
when
leads
are
stretched
or
flexed.
Replace
as
re-
quired
Open
on
poth
ground
brushes.
Remove
brush
block
assembly
and
check
both
ground
brushes
for
continu-
ity
between
the brush
and
pigtail
lead. If
an
open
is
found,
repair
brush
block
as-
sembly.
If
OK,
reinstall
and check
for
proper
face
alignment
and
brush
projec-
tion
per
manufacturer’s
Service
Data.
Buss
load
meter/ammeter shows
nor-
Open
in
~iring
between
timer
See
"Open
Timer
to
Brush
Assembly"
mal
current
part
of
cycle,
zero
and
brush/
block
assembly.
above.
current rest
of
cycle.
Open
in
Die-leer
or
de-ice
boot See
"Open
in
De-leer"
above.
wire
harngss.
30-61-01
REV.
7-96
Island Enterprises