Operator`s manual
OVERHAUL
MANUAL-
LYCOMING
DIRECT
DRIVE
AIRCRAFT
ENGINES
Section 5
Accessory
Housing
SECTION
5.
ACCESSORY
HOUSING
5-1.
It is
assumed,
at this
time,
that
the magnetos
and
all
accessories
have
been
removed
from
the
accessory
housing.
5-2.
Unless
specifically
called
out
tothe
contrary,
all
references
to
component
parts
will
apply
to all
engines
except
those
with
a
housing
incorporating
dual
mag-
netos
in
a single
housing.
These
housings
willbe
iden-
tified
as
Dual
Magneto
Housings.
DISASSEMBLY
5-3.
Fuel
Pump
(Diaphragm
type)
- See
figure
5-3.
The
fuel
pump,
(7)
located
at the
lower
left of
the
ac-
cessory
housing,
is
removed
by
unscrewing
the
two
capscrews
securing
it to
the housing.
5-4.
OilPressure
ScreenHousing.
(Where
applicable)
See
figure
5-1.
This
housing
(3)located
just
abovethe
center
of
the
accessory
housing,
is removed
by
un-
screwing
the
four
capscrews
or
three
capscrews
and
one
nut
(whichever
is
applicable)
that
secure
it
to the
accessory
housing.
On
the
O-290-D
series,
the
oil
cooler
adapter
is removed
along
with
the oil
pressure
screen
housing.
5-5.
Thermostatic
Valve
and
Oil
Pressure
Screen
Housing.
See
figure
5-1.
This
unit,
(5)
used
on
some
installations,
is
located
at
the
same
place
as
the
oil
pressure
screen
housing
described
in
paragraph
5-4
and
is removed
in
the same
manner.
5-6.
Oil
Filter
and Adapter.
See figure
5-1.
This
unit,
usually
installed
as
an
option,
replaces
either
the
oil
pressure
screen
housing
or
the thermostatic
valve
and
oil
pressure
screen
housing.
It
can
be
removed
as
a
unit
from
the
accessory
housing.
Consult
Service
Letter
157 for
more
detail
information
on
all models.
5-7.
Oil
Cooler
Bypass
Valve
Assembly
- See
figure
5-1.
This
assembly
is
used
only
in
conjunction
with
the
oilpressure
screen
housing
andopening
is plugged
when
using
either
thermostatic
valve
or
oil
filter
and
adapter.
Remove
plug
(8),
gasket
(2),
spring
(7),
and
plunger
(12).
5-8.
Oil
Filter
(Dual
Magneto
Housing)
See
figure
5-2.
Remove
filter
assembly
(11)
by
unscrewingthe
center
bolt
from
the
housing.
Remove
the
thermostatic
oil
cooler
bypass
valve
(21)
and
gasket
(20).
Remove
re-
taining
ring
(10),
sleeve
(9),
seat
(8) and
spring
(7)
of
the
oil filter
by pass
valve.
5-9.
FuelPump
Driven
Gear,
AN
Type
(Where
appli-
cable)
See
figure
5-4.
Removethe
adapter
(3)
and
gear
(5)
from
the
mounting
pad
on
the
lower
left
side
of
the
accessory
housing.
5-10.
Vacuum
Pump
Driven
Gear
(Where
applicable)
See
figure
5-3.
Remove
the
adapter
(4)
and
gear
(6)
from
the
mounting
pad
on
the
upper
right
side
of the
accessory
housing.
5-11.
Hydraulic
Pump
Driven
Gear
(Whereapplicable)
Remove
the
adapter
and
gear
from
the
mounting
pad
on
lower
right
side
of the
accessory
housing.
5-12.
Propeller
GovernorDriven
Gear
(WhereAppli-
cable)
See figure
5-3.
Remove
the
propeller
governor
oil
line
(12).
Remove
the
adapter
(10)from
the
mount-
ing pad
on
lower
right
side
of the
accessory
housing.
Remove
retaining
ring
(9), washer
(5)
from
shaft
gear
and
remove
shaft
gear
(11)
from
adapter
(10).
5-13.
Dual
Drives
- Vacuum
Pump
and
Hydraulic
Pump-
See
figure
5-5.
Remove
brace
(2),
vacuum
and
hydraulic
pump
adapter
(13),
and dual
drive
adapt-
er
(8). Remove
accessory
drive
gear
(9),
dual acces-
sory
drive
gear
(10),
vacuum
pump
driven
gear
(12)
and
idler
gear
(11).
5-14.
DualDrives
-
Vacuum
Pump
and
Propeller
Gov-
ernor
-
See figure
5-5.
Remove
brace
(2), vacuum
pump
and
propeller
governor
drive
adapter
(5),
and
dual
drive
adapter
(8).
Remove
accessory
drive
gear
(9),
dual
accessory
drive
gear
(10),
vacuum
pump
driven
gear
(12)
and
idler
gear
(11).
5-15.
Removal
from
Engine.
The
accessory
housing
is
removedfrom
the
engine
by
removingthe
attaching
parts
to
the crankcase
and
oil
sump.
Since
various
gears
are held
in
place
through
contact
with the
crank-
case,
put
the
housing
on
the bench
with
the
inside
up
to
avoid
dropping
loose
gears.
5-16.
See
figure
5-4.
If
engine
is
equipped
with
"AN"
type
fuelpump
drive,
remove
the fuel
pump
idler
gear
(7)
from
the
idler
gear
shaft
(8).
Remove
the
idler
gear
shaft
from
the
housing.
5-17.
Oil
Pump.
See
figure
5-6.
Remove
the
oilpump
body
assembly
from
the accessory
housing
and detach
the
oil
pump
impellers.
Pull
oil pump
drive
shaft
from
the body.
Do not
remove
the
oil
pump
idler
shaft
un-
less obvious
damage
is
apparent.
A later
oil
pump
as-
sembly
(see
figure
5-7)
employs
sintered
iron
impel-
lers
and
the
idler
shaft
and
driven
impeller
are
one
unit.
In additionthe
oil pump
drive
shaft
gear
is
keyed.
These
assemblies
are
not interchangeable.
5-18.
OilSuction
Tube
(Where
applicable)
Removethe
cotter
pins,
nuts
and
washers
from
inside
of
housing
and
bolts
from
the
outside
of the
housing
and
remove
the
oil
suction
tube.
Revised
October
1974
5-1