Mooney M20C - Fuel Filler Cap Inspection and Adjustment; ORing and Shaft Maintenance; Sealing Capability Check; Safety Precautions for Testing

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SUB;IECT:
Fuel
Filler
Caps
(Shaw Aero),
Inspection
and
Adjustment
MODUS/
MZ0C
S/N
2623
and
ON,
M20D S/N 201 gr
ON,
ALL
M20E, M20F, M20G,
M20J,
M20K
S/N
AFFECTED:
and
M22 Aircraft
TIME
OF
COMPLIANCE:
Within next
25
night
hours,
and
every
100 hour/annual
inspection
thereafter.
INTRODUCTION:
Exposure
to
weather.
fuel
fumes,
fuel and
possibly
other elements
have
a
deteriorating
effect
on
O’ring packings
and
seals. The
two
O’rings
on
the
Shaw
Aero
fuel filler
cap
assembly
have been
reported
to
lose
their resilience and
sealing
characteristics
after
a
period
oftime
when
exposed
to
these elements.
This S.B. is
intended
to
describe
inspection
procedures
for this
deterioration.
INSTRUCTIONS:
Fuel filler
port cap
assemblies
should
be
checked
periodically
for
proper
sealing
and
should
be
serviced
occasionally
to
prevent
hard
to
open
or
close
conditions.
I
Refer
to
Figure
S.B.
M20-229-1
andthe
following procedures
for
these
inspections
and
adjustments:
i.
TheO’ring
real
(1)
amur.d the
cap
assembb
should be
kept
clean and
free
of dirt
orgrit
that
might
cause
abrasive action
on
seal
or
mating nange.
Occasional lubrication with
petroleum
jelly
or
Tri-Flow will
keep
the
O’ring
soft
and
pliable.
2.
The
shaft
(2)
running
through
the
center
of
the
cap
housing,
that actuated the
rotating
lock
plate
(3)
should
be
lubricated
occasionally
with
Tri-Flow,
or
equivalent,
to
prevent
I
binding
while
opening
or
closing
the
cap
assembly.
This should also lubricate the
O’ring
;(4)
that
seals
this shaft.
WARNING
Water
can
enter
the fuel
tank
through
a
loose
fitting
or
damaged
cap.
This
should
be
corrected
as
soon
as
possible.
3.
The
sealing capability
of each
cap
assembly
should be checked
periodically.
This
can
be
accomplished
per
the
following procedures:
A. Remove
cap
assembly
form
wing
filler
port
and
inspect O’ring
(1)
for
any
damage
or
brittleness.
Remove
and
replace
if
needed.
B.
Adjust
tension
of
shaft
(2)
and
rotating
lock
plate
(3)
by
removing
cotter
pin
(5)
from
nut
(6)
on
threaded
portion
of shaft
t2).
Tighten
nut
(6)
so
cap
assembly
handle
(7)
can
be
opened,
turned and
shut
with
hand
pressure
and still
provide
the
necessary
seal
of
cap
assembly
to
keep
water
from
entering
fuel
tank.
C. Fuel
selector
should
be in the
OFF
position prior
to
pressurizing
the
fuel
tanks.
D.
Connect
rubber hose
to
each
tank’s vent
line.
Apply
only
one-half
pound
(1/2
psi)
air
pressure.
Check
for
fuel
cap
leaks
by
soaping
circumference
of ftlIer
cap
assembly
and
observing
bubbles.
Replace
O’rings
if
bubbles
are
observed
and
adjustment
of
the
nut
does
not
stop
the leak.
’’CAUTION"
Use
only
one-half
pou
nd
(0.5
psi)
of
air
pressure
in
tank.
Higher
pressure
ma~
damage
the fuel
tank.
"NOTE"
MZOI<
aircraft
must
have
the
anti-siphon
valve inside
filler
port
propped open
during
this
pressure
testing.
REFERENCE
DATA:
N/A
PARTS
LIST:
(Parts
NOT
included
in kit order
if
needed).
Part
Number
Description
Qty. Required
MS29513-010
O’Ring
tcenter)
1
MS29513-338
O’Ring
touter)
(for
431-9R
and
1
531-001
cap)